Enhancing the Efficiency of Your Wastewater Treatment Plant

Water is becoming increasingly precious as climates change and populations continue to grow. Many areas are projecting drastic changes to their water consumption and wastewater production in the coming years. With changes in volume will come changes in quality as well. Your wastewater will have new contaminants and varying concentrations of current contaminants as your population changes. To meet these demands, wastewater treatment plants (WWTPs) will need to be as efficient as possible to remain profitable and serve their communities’ needs. Following a few steps can increase your water treatment plant’s efficiency and better prepare your facility for the future ahead.

The Importance of Water Treatment Efficiency 

Too often plants treat efficiency as a nebulous metric that should always be measured for improvement. As a result of this goal always being present but never fully understood, water treaters push it to the back of their mind. They know that they want to increase the efficiency of their water treatment systems, but they do not understand the value of meeting that goal. Enacting a focused plan to improve efficiency of your water treatment will lead to benefits for your business and the surrounding community. Increased water treatment efficiency helps protect the environment, keeps your WWTP within regulations, and keeps your facility modern.

Protects the Environment

Wastewater treatment plants directly affect the environment around them. The effluent they discharge can alter the chemistry of the surrounding aquatic environments, impacting the health of flora and fauna. For example, an excess of ammonia, nitrogen, or phosphate could result in algae blooms or eutrophication of surrounding waters. Maintaining an efficient wastewater treatment program ensures you are releasing high quality effluent consistently, minimizing the impact to natural waters. Improving efficiency also protects the environment in a less direct way. A more efficient WWTP will consume less energy and water treatment chemicals, which decreases the carbon footprint of your facility.

Meets Regulations

Most wastewater treatment plants are under strict regulations from the federal and local levels of government. Exceeding the limits set by your permit or other standards could lead to expensive fines. When auditing your treatment systems for efficiency, you will be working within the set limits of your permit. The technologies and processes you establish will naturally help you stay within your regulations. An efficient wastewater treatment facility requires less maintenance and gathers consistent reliable data, both of which will keep you within regulations.

Keeps the Facility Modern

Technology is evolving, and the wastewater industry is no exception. New products such as chemical feed pumps, online analyzers, reverse osmosis systems, and flow switches are helping operators do more with less resources. By including potential upgrades and new technologies in your efficiency audit, you will keep your facility up to date and in-line with the latest practices.

The efficiency of your wastewater treatment program is not just another goal to mention on a checklist. The efficiency of your water treatment is the foundation to creating high quality effluent at the lowest cost to your plant.

The Benefits of Improving the Efficiency of Wastewater Treatment 

Efficiency is clearly important to a wastewater treatment plant and the surrounding community, but what are the benefits of being more efficient? The immediate benefit of increased efficiency is cost savings. However increased efficiency will also conserve water, reduce energy consumption, and increase the overall capacity of your facility.

Saves Money

Optimizing wastewater treatment will have an upfront cost, but in the long run it will save money. Don’t view the time, labor, or equipment being used to increase efficiency as a cost. View it as an

investment instead. By upgrading your equipment or process, you are spending money to lower costs moving forward. Replacing an aging pump that requires frequent maintenance may be expensive but overtime you can make that money back in labor time saved. The time previously spent on maintenance for the old pump can be put to good use elsewhere in the WWTP. The same thing will occur when replacing an inefficient process with a more streamlined version. It may take some time to implement the new process, but in the end your team will be more efficient and lower the labor cost. Over time the more efficient equipment or method will pay for itself with the savings gained.

Conserves Water

An efficient WWTP helps conserve water for the entire community. Without wastewater treatment, untreated sewage would enter natural water sources until they became polluted to the degree that they could not support life. A municipal wastewater treatment plant with high efficiency will be able to handle spikes in influent and prevent untreated water from entering the environment. The treated wastewater will replenish water sources through being returned to the water board. The effluent will help recharge ground water, streams, and rivers conserving water for your community.

Reduces Energy Consumption

Removing organic matter, microbes, suspended solids, and chemicals from water takes energy. The efficiency of your water treatment correlates to how much energy is utilized. As you work to improve the efficiency of your onsite wastewater treatment, you will actively reduce your energy consumption. Most technologies and strategies you will implement will be more energy efficient than your current implementation. Using less energy will lower your wastewater treatment cost and make your process more environmentally friendly.

Increases Capacity

Most operators imagine building more tanks or increasing the footprint of their plant when they imagine increasing capacity. However, by optimizing your processes you can increase capacity without building extensive infrastructure. When improving efficiency, you will likely ease bottlenecks you had previously. Opening the bottlenecks will allow higher flow rates through your system, improving the overall capacity of your treatment process.

7 Steps to Enhance the Efficiency of Your Wastewater Treatment Plant

1. Assess Current Performance

The first step to improving efficiency is understanding how efficient your plant is now. Sit down and consider what metrics you use to evaluate your efficiency. Frequently used key performance indicators (KPIs) include amount of chemical used, maintenance to operation time ratio, and energy consumed, but each plant will have their own KPIs. You don’t want to have too many KPIs, but you should touch on the important aspects of your facility. Once you have decided on your KPIs you need to gather baseline data for each one. Try to gather 2-3 months of data and account for seasonal changes. With reliable baseline information you will be able to set reasonable goals for your plant and determine the true impact of the changes you implement.

2. Inspect Flow Rates

Flow rates are particularly important to a wastewater facility and deserve a special mention. A common area to find bottlenecks are with water pumps in the treatment process. Pumps that are not working at peak efficiency can lead to increased cost and potential problems further in the system. If you were not already tracking your pump’s discharge rate, be sure to start now. You want to ensure that you are using an appropriate capacity pump. Too small and you may not meet peak demand, too large and you may be wasting energy. If you notice that the flow rate is lower than expected, it could be due to leaks, clogs, or worn-out parts in the pump. Depending on the problem the pump may require maintenance or an entire replacement.

3. Evaluate Infrastructure and Technology

Once KPIs are identified it is time to evaluate the technology and infrastructure the plant is utilizing. Audit the performance of your plant from influent to effluent and evaluate the equipment at each step. Check the age and effectiveness of your equipment both large and small. Review pumps, filters, feed and control equipment, and flow switches but also large pieces like reverse osmosis systems, settling tanks, and aeration systems. Don’t forget technology infrastructure like modems either. These keep your devices connected to the internet and offer secure connections. If any piece of the process is underperforming, assess why and determine if you are able to correct the issue with maintenance or if it is time for an upgrade.

4. Consider Upgrading Your Equipment

Some of your equipment may be out of date and require an upgrade. Consider how much maintenance a piece of equipment requires. Also ask yourself if it is creating a bottleneck for the rest of your water treatment process. If either of these answers is yes, it might be time to consider upgrading. Much of your WWTP’s technology was put into place when your community’s population level and wastewater make-up was different. Even if it is still functional, you may be more efficient performing an upgrade now. Research what your options are. If equipment is 10+ years out of date, there may be an energy efficient version or even alternative.

5. Implement New Systems and Technology

Identifying and implementing new technology to areas needing improvement can be difficult. This can be a struggle is that you need to be aware of the possibilities of these items prior to your review. You may not realize that new developments have been made in water treatment that could streamline your process. For example, your activated sludge process may be functional but new technologies like Membrane Aerated Biofilm Reactors (MABR) may be more efficient for your treatment system. Keep an open mind to new technologies and do your best to stay informed on new industry developments.


Integrating a new system or technology can be difficult and the upfront cost may be high, but through better energy efficiency, saved labor time, and reduced maintenance time an upgrade will pay for itself.

6. Automate Your Operations

The ability to automate processes in wastewater facilities has grown in recent years. Complex software now has simplified user interfaces and mobile apps for added convenience. The technology is poised to leap forward again with the introduction of AI predictive models. When reviewing your systems, determine if your process could be automated to save labor cost and time. Feed and control software can help you automate dosing of chemicals while data management platforms allow you to automate report generation. Automation will make your plant more efficient by reducing the time your operators have to spend on simple tasks and allow them to tackle the more complex issues where their expertise is required.

7. Review the Data

Once you have made a change to optimize your wastewater treatment you must collect and record the necessary data to verify that the improvement is working as intended. Too often operators implement a change and do not review the data to determine how successful the change is. Refer back to the baseline data you gathered during your audit. Consider the direct change as well as secondary effects like saved labor or energy. If your modification has alleviated a bottleneck, you may find that your data will reveal new areas for improvement. This information can also help you secure further funding for other improvements.

How Feed and Control Equipment Boosts Efficiency

The right feed and control equipment can provide a big boost to your WWTP’s efficiency. Feed and control metering pumps act as the primary delivery system for liquid chemicals. High-quality chemical feed pumps can accurately and safely deliver the required quantity of product to the treated system. These pumps are programmed with a computer called a controller. The pumps can be programmed to dose chemicals at a set time or as a reaction to conditions in the water. These features will increase chemical dosing accuracy and conserve resources for your wastewater treatment facility.

Increases Dosing Accuracy

Walchem-Panel-Intuition-9-Controller-719x1024A quality feed pump and controller can increase your dosing accuracy. With today’s technology pumps can be programmed to very specific conditions. When paired with an accurate measurement of water quality, an operator can program their pump to dose the exact quantity of chemical needed to keep the water quality consistent. This removes the chance of operator error in measuring and does not require someone to spend time manually dosing the system. With remote monitoring and wireless technology, operators can adjust pumps from anywhere or pre-program them to keep dosing accurate and efficient. Controllers should be sized correctly to the number of inputs and outputs required and can integrate easily into your data management software.

Conserves Resources

Having the appropriate control and feed equipment will conserve resources across the wastewater treatment process. Accurate dosing will prevent wasted chemicals while wireless access and programmable pumps will conserve labor hours. When paired with the appropriate data management software, you can save time and labor generating reports as well.

Achieve Greater Wastewater Treatment Efficiency with AquaPhoenix Scientific

AquaPhoenix Scientific is here to assist you with your efficiency goals. We manufacture and distribute wastewater supplies from reagents to equipment. Whether you need reagent for your testing lab or customized chemical feed and control systems, AquaPhoenix is here to be your one source for testing needs.

Connect with our team today to save time in the field and improve your service visits. Download our industrial catalog to browse thousands of products or request a quote to get started on your next job.

The Measurement of Dissolved Ozone in Water

Why Measure Ozone in Water?

Ozone (O3) treatment has become an important tool for water quality engineers. As new more stringent requirements from regulators and customers must be met, ozone is often the oxidizer and disinfectant of choice for a wide range of process applications. Ozonation is used for viral, bacterial, and parasitic disinfection, the removal of taste- and odor-causing compounds, the destruction of refractory/toxic organic matter and the coagulation or oxidation of inorganic impurities such as iron, manganese and sulfides1.

With the rising popularity of ozone in water treatment comes the need for a versatile analytical method for the routine measurement of dissolved ozone in a variety of solution matrices. The indigo trisulfonate method has become a favorite as it is accurate and precise over a wide concentration range, insensitive to interferences, and easy to use and dispose of. This method uses a non-toxic blue dye that is instantly decolorized by ozone. Interference from the most common oxidizer, chorine, can be masked with malonic acid (C3H4O4). The method is described in Standard Methods for the Examination of Water and Wastewater (Method 4500-O3 B)2 and is offered as a product in various forms by a number of companies.

More protective public health standards for drinking water have led to the expansion of ozonation for water treatment. For example, more stringent regulations have been implemented to reduce the concentration of harmful disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), that are formed as a result of disinfection with chlorine and other halogens. Treatment with ozone does not produce DBPs and is therefore preferable. Ozonation is also an effective treatment option in circumstances where disinfection for more resistant pathogens, such as Cryptosporidium oocysts and some viruses, is required. In order for chlorine to be effective at disinfecting the more resistant pathogens, the concentration and/or contact time must be increased beyond what would otherwise be necessary. This tends to increase THM and HAA concentrations to levels that could be dangerous. Some utilities have installed ozone contactors to boost disinfection potential without increasing DBP production. However, conditions can limit the suitability of ozone for water treatment. When bromide ion (Br) is present in the source water, its oxidation by ozone can result in the production of bromate (BrO3), a DBP with an EPA drinking water limit of 10 ppb3.

Utilities that choose ozonation tend to have greater customer satisfaction due to improvements in other water quality parameters such as color, taste, odor, and clarity. Ozone also removes dissolved inorganic impurities such as iron, manganese and sulfide through coagulation and oxidation. Ozone can remove these impurities more efficiently than a conventional aerator, allowing reduced coagulant dosage and contact time. Advanced Oxidation, or ozone supplemented with hydrogen peroxide or UV radiation, may be required when oxidation of refractory or toxic organic matter, such as humic acids and pesticides, is required. These compounds are not degradable by chlorine, biological oxidation, or ozone alone. Combining ozone with hydrogen peroxide or UV radiation causes the ozone to degrade rapidly, resulting in a pulse of extremely reactive free radicals.

A sample of water being tested for ozone with a CHEMetrics K-7433 ampoule.

Industrial and Commercial Applications of Ozone

Food Industry

New avenues for the application of ozone in the food industry were opened in 1997 when the U.S. Food and Drug Administration granted “generally recognized as safe” (GRAS) status to ozone. Cleaning fruits and vegetables by washing with ozonated water decreases the concentration and volume of waste, the total water consumption, and contamination by mold and bacteria4. For meat, poultry and seafood, ozone can extend shelf-life and reduce processing costs. Generally, products are sprayed with ozonated water then kept in an ozonated atmosphere to further decrease spoilage.

Bottled Water

Ozone treatment is common in bottled water manufacturing. Although production methods vary depending on the size of the operation and quality of the source water, all methods for the U.S. market must produce a product that can pass the U.S. FDA regulations, which are required to be at least as protective of public health as those required by the EPA for public drinking water. Due to the use of filtration, reverse osmosis, activated carbon adsorption, and ozone treatment, there have been no major outbreaks of illness associated with bottled water in the past decade in the United States5.

In a bottled water plant, ozone is added to the water in the final operation just before bottles are filled. Generally, ozone gas is injected into a large tank of water until it reaches a desired concentration after which the water is transferred to the bottle. The ozone concentration must be high enough to kill any organisms, yet low enough that it does not attack the bottle or linger greet the consumer. This is about 0.4 ppm (mg/L) ozone.6 As with public drinking water, ozone may introduce the disinfectant byproduct bromate if the source water contains a significant amount of bromide.

Other Industries

Ozone is also applied as a disinfectant and oxidizer in these applications: aquaculture (nitrite oxidation), pools and spas, soil/groundwater remediation (underground storage tank contaminants), farming, winery sanitation (barrel/tank cleaning), electronics (surface cleaning), cooling water towers, laundry (deodorizing), indoor air pollution (particle removal), and industrial wastewater in general.

Ozone Analysis Using Sensors and UV Equipment

The techniques for measuring dissolved ozone can be divided into two methods: instrumental and colorimetric. The three main instrumental methods are: Oxidation/Reduction Potential (ORP), membrane probe, and UV absorbance. These methods all offer the advantage of giving continuous readings, and they avoid ozone degassing during sampling when used in-line. The instruments are generally calibrated using colorimetric methods, except for the UV absorbance method.

Oxidation/Reduction Potential

The ORP method measures the voltage generated by ozone in the solution at a platinum electrode relative to a standard reference electrode. It requires very clean water with at most moderate turbidity.

Classical Wet Chemistry Methods for Measuring Ozone

The three main wet chemistry methods for measuring ozone in water are: iodometric titration,  N, N-diethyl-p-phenylenediamine (DPD) and indigo trisulfonate.

Iodometric Titration Method

In the iodometric method, ozone reacts with potassium iodide (KI) to form iodine (I2), which is then titrated with thiosulfate to a starch indicator endpoint with the sample buffered to pH 2. However, this method requires training and skill as the stoichiometry of the reaction is sensitive to pH, buffer composition and concentration, iodide ion concentration, sampling techniques, and reaction time7.

DPD Colorimetric Chemistry

In the DPD method, ozone reacts with potassium iodide (KI) to form iodine which then reacts with DPD to produce a pink compound. The intensity of the pink color is proportional to the ozone concentration and is measured at about 515 nm on a colorimeter or spectrophotometer. Iodometric and DPD methods have the disadvantage that they cannot discriminate between ozone and other common oxidizers. Several vendors manufacture colorimetric test kits that utilize DPD/KI in either powder or tablet form. However, the sample manipulation required to dissolve the tablet or powder can cause a loss in measured ozone concentration. This drawback is minimized by an ozone test kit with a liquid KI reagent that is added to the sample with a dropper bottle. This method, manufactured only by CHEMetrics, also uses a liquid DPD reagent packaged in a unit-dose glass ampoule sealed under vacuum. The reaction takes place inside the ampoule which increases the overall accuracy and precision of the method. The method is applicable to samples that do not contain chlorine.

K-7423 utilizes the DPD chemistry. Vacu-vials ampoules work with Single Analyte Meters (sold by CHEMetrics) or any spectrophotometer that accepts a 13mm round cell.


Indigo Trisulfonate Colorimetric Chemistry

The indigo trisulfonate method has several advantages over the other two techniques. According to Standard Methods, “The indigo colorimetric method is quantitative, selective and simple. The method is applicable to lake water, river infiltrate, manganese-containing groundwaters, extremely hard groundwaters, and even biologically treated domestic wastewaters.” Indigo trisulfonate is usually sold as the potassium salt. The purity of indigo trisulfonate may vary between vendors and even between different lots from the same vendor. Both purity and age of the indigo trisulfonate have been shown to affect the stoichiometry of the reaction with ozone.8 High purity indigo trisulfonate (>80%) has a molar absorptivity of about 20000 M-1cm-1 at 600 nm.

The method is based on the decolorization of the indigo dye by ozone. The loss of color is directly proportional to the ozone concentration. The sample is generally adjusted to near pH 2 to minimize destruction of the ozone by reaction with hydroxide ions. The most common analytical procedure subtracts the absorbance of indigo trisulfonate after reaction with a sample from that of an ozone free blank. Chlorine decolorizes indigo trisulfonate at a moderate rate, but this can be significantly slowed by the addition of malonic acid.

Oxidation products from the reaction of the manganous ion (Mn+2) with ozone can destroy indigo trisulfonate. To measure ozone in the presence of manganous ion, glycine is added to a sample to selectively destroy the ozone, then indigo trisulfonate is added to measure the apparent ozone concentration due to the reaction with manganous ion oxidation products. This value is subtracted from the value obtained from a sample without glycine added.

Indigo Trisulfonate Test Kits

CHEMetrics is a major manufacturer of indigo trisulfonate test kits. The kits feature self-filling reagent ampoules that contain the active ingredients potassium indigo trisulfonate and malonic acid. The malonic acid in the reagent prevents interference from up to 10 ppm chlorine. The ampoules contain a liquid reagent, advantageously allowing the dissolved indigo trisulfonate to instantly react with the ozone in the sample as it is drawn into the ampoule.

CHEMetrics’ indigo ozone product measures an ozone concentration range of 0-0.75 ppm. The ampoules have a 13 mm diameter and are compatible with most spectrophotometers.

Contents and packaging of K-7433 Ozone Vacu-vials Test Kit. Click to shop for this test kit.

K-7433 utilizes the indigo trisulfonate chemistry. Each ampoule can self-zero for simplified testing.


Since the ozone concentration is measured by the loss of indigo trisulfonate, both initial and final absorbance measurements are required. To accomplish this, the CHEMetrics product uses a “self-zeroing” method that measures the absorbance of the same ampoule before and after sampling, eliminating the need to generate an initial indigo trisulfonate absorbance ampoule each time a test is run. The initial absorbance measurement, before taking in the sample, is divided by a factor that takes into account the dilution once the ampoule has filled. The difference between the initial absorbance divided by the factor, and the absorbance after sampling, is converted to ozone concentration. A direct read photometer, called a Single Analyte Meter, is available that automatically makes all appropriate calculations.



  1. Rakness, K., (2005) Ozone in Drinking Water Treatment: Process Design, Operation, and Optimization.
  2. Standard Methods for the Examination of Water and Wastewater, 22nd ed. (2012) 4500-03 B, 4-145 .
  3. Haag, W. R., and J. Hoigne (1983) Ozonation of bromide-containing waters: kinetics of formation of hyprobromous acid and bromate. Environ. Sci. Technol. V17, p 261.
  4. Spartan Environmental Technologies, LLC, Tech. Bulletin TA-112064.
  5. Edberg, S., Microbial Health Risks of Regulated Drinking Waters in the United States: A Comparative Microbial Safety Assessment of Public Water Supplies and Bottled Drinking Water (2013) Drinking Water Research Foundation, 31 p.
  6. Bollyky, L. J., Benefits of Ozone Treatment for Bottled Water (2001)
  7. Langlais, B., D.A. Reckhow, and D.R. Brink eds. (1991) Ozone in Water Treatment: Application and Engineering. Chelsea, Mich.: Lewis Publishers, Inc.
  8. Gordon, G., R. Gauw, Y. Miyahra, B. Walters, and B. Bubnis (2000) Using Indigo Absorbance to Calculate the Indigo Sensitivity Coefficient. Jour. AWWA, V92, pp. 96-100
How to Run a CHEMetrics COD Test

What Is a COD Test?

A Chemical Oxygen Demand, or COD test, measures how much dissolved oxygen (DO) is consumed by the oxidation of organic matter and inorganic compounds such as ammonia or nitrite under controlled conditions. COD is widely recognized as an indicator of wastewater influent and effluent quality. COD analysis is typically performed using the UESPA accepted dichromate reactor digestion method. This method has a water sample react with a mixture of sulfuric acid and potassium dichromate in a sealed container and then digested for 2 hours at 150oC. The sample is then read in a spectrophotometer to determine the results. You can often find Chemical Oxygen Demand tests supplied in screw top vials that contain a premeasured sulfuric acid and potassium dichromate mixture. You can find all of our COD product offerings on our COD test kits page.

CHEMetrics COD vials 25 pack

Figure 1: CHEMetrics COD vials come in packs of 25 or 150 (98 for HR+).

How to Perform a COD Test

COD analysis can take over two hours to perform due to the digestion required, so ensuring that you’ve followed the test method correctly can save you a lot of wasted time. The video below shows you step by step instructions on how to follow COD lab test procedures with any of the CHEMetrics COD test kits. If you prefer step-by-step instructions continue reading below.



COD Test Lab Test Procedure

An easy-to-use printout of our instructions comes with every pack of vials and is available on our website.

  1. Homogenize 500 ml of sample for two minutes in a blender to ensure an even distribution of solids throughout the sample. This will ensure regular results and prevent wild variations between vials.
  2. Preheat the digestor block to 150oC (302oF).
  3. Remove the cap from each COD vial. Store the vials in a vial rack to prevent any spillage.
  4. Pipet two milliliters of sample into each vial. Be aware that adding the sample will cause an exothermic reaction and the vial will become hot. Just another reason to ensure you are wearing the proper safety equipment!
    1. If you are using a high range kit (CHEMetrics: K-7370S, K-7375, K-7371S, and K-7376) pipet 0.2 mL instead.
  5. Secure the cap onto each COD vial. Be sure not to overtighten the cap as it could damage the closure.
  6. Immediately invert each vial ten times while holding the vial by the cap only as the vial will be hot from the reaction caused when adding the sample.
  7. Prepare the reagent blank by removing the COD vial cap and pipetting deionized water rather than sample into the vial. Make sure that the reagent blank vial is the same lot number as the test vials.
    1. Note: At least one reagent blank must be run with each set of samples with each new lot number of COD test vials.
  8. Wipe the vials with a damp towel to remove smudges and fingerprints from the vial and place them in the preheated digestor block.
  9. Allow the vials to heat in the digestor block at 150oC (302oF) for two hours.
  10. Once the two hours are finished, turn the digestor block off and allow the vials to remain in the unit for 15 to 20 minutes to cool. Remove the vials and return them to the vial rack. CAUTION: the vials will still be hot.
  11. Ensure all caps are secured tightly, then invert each vial several times. Be aware that hot vials may shatter if dropped or cooled rapidly.
  12. Store the vials in the dark for 30 minutes as they cool to room temperature.

Obtaining the Results of Your COD Test

When obtaining results, the analyst may use Hach instrumentation, a CHEMetrics photometer, or any other manufacturers’ spectrophotometer. Before moving on, wipe down the reagent blank and test vials until they are clean and dry.

Hach Spectrophotometer Instructions:

  1. Apply program number 430 for low-range COD vials (CHEMetrics: K-73050S, K-7355, K-7351S, and K-7356) or program 435 for high-range vials (CHEMetrics: K-7360S, K-7365, K-7361S, and K-7366).
  2. Zero the instrument with the reagent blank vial.
  3. Remove the reagent blank and place your first vial in the sample compartment.

CHEMetrics V-2000 Photometer Instructions:

  1. Install the 16 mm sample cell adapter into the photometer and power it on.
  2. Insert the ZERO vial into the V-2000, cover it with the light shield, and press the zero key.
  3. Enter program 48 to read low-range COD test vials or program 49 for high-range or high-range plus COD vials, then press the yes key.
  4. Press setup and use the arrow keys until “BLANK” is displayed, then press yes
  5. When “SET BLNK?” appears, press yes.
  6. When “SAMPLE?” appears, insert the reagent blank COD vial, cover with the light shield, and press yes. The display will briefly show an absorbance value, then move to the next function.
  7. Press the measure key to exit the setup menu
  8. Remove the reagent blank via, insert the test vial, cover with the light shield, and again press the measure key. The instrument will read the vial and display the test result which may be logged manually.
  9. For high range plus COD Vials, multiply the result by 10.
  10. For instructions on logging COD analysis results manually or automatically to the memory, see the V2000 operator manual.

Figure 2: A V-2000 can read multiple CHEMetrics tests including COD

 CHEMetrics A-7320 or A-7325 Single Analyte Meter:

  1. Press the power key. The display will show “cod”.
  2. Insert the COD reagent blank into the sample compartment and press the Zero/Test key. The “cod” symbol will flash for approximately eight seconds.
  3. Insert the COD test vial into the sample compartment making sure it’s properly seated and again press the Zero/Test key.
  4. The “cod” symbol will flash for three seconds, then the sample test result will appear in the display as part per million COD. Record the test result.

Figure 3: A Single Analyte Meter Reading a COD Test

Other Spectrophotometers:

For other brand spectrophotometers, refer to the specific instrument’s operator manual for appropriate set-up instructions. Use a 420 nanometer wavelength for low-range COD vials or a 620 nanometer wavelength for the high-range and-high range plus vials. Refer to CHEMetrics COD analysis instructions for range-specific calibration equations to convert absorbance values to test results as part per million COD.


Chemical Oxygen Demand testing can be time-consuming so understanding the ins and outs of the lab test procedures before you run one can prevent headaches further down the line. When performing these tests, it is recommended that analysts use COD standards of known concentration to verify instrument performance and accuracy of test results. CHEMetrics offers the A-7301 1000 ppm COD calibration standard as well as the A-7310 10,000 ppm COD calibration standard. For questions about how to run this or any other CHEMetrics test, please contact us or call us at 800.356.3072 and ask for technical support.

How To Read a CHEMetrics Comparator

What Is a Comparator?

A comparator is a set of sealed ampoules containing color standards made of dye mixtures that closely match the color (hue) and intensity of CHEMetrics test ampoules when the tips are snapped in solutions of corresponding analyte concentrations.

By sealing the dyes in ampoules, we can more closely recreate the color generated in the test ampoules. CHEMetrics offers two types of comparators:

  • A round comparator is cylindrical and is viewed through the length of the ampoule for low range measurements.
  • A flat comparator is viewed through the width of the ampoule on a white background for high range measurements.

Follow these recommendations to obtain the most accurate readings using a comparator.

First Consider Your Light Source

The color of an object is affected by the light source. Fluorescent lighting is often appropriate for optimal color matching however, LED and natural outdoor light sources are adequate. If taking multiple readings, it is best to keep the light source as consistent as you can. Reading the comparator requires a moderate light source, like normal indoor lighting. Some sources, like full sunlight, can be too intense and may require some shade.

Figure 1: An operator reads a flat comparator under LED lights in a lab.

Figure 2: The operator reads the same comparator in Figure 1 outside.

Reading a Round Comparator

When reading a low range comparator, insert the ampoule, flat end first, into the comparator, point the comparator toward the light source and view from the bottom. Align the test ampoule directly above the color standard with the lowest concentration. Then slowly turn the comparator counter-clockwise until the intensity of the test ampoule’s color appears to be the same as a color standard or in between those of two color standards. To help see subtle differences in intensity change the angle of the comparator slightly back and forth while rotating the comparator slowly. If the reading is between two color standards, consider where the intensity of the test ampoule falls between the two. The easiest way is to estimate by using fractions like halfway (1/2) between the color standards or 1/4th. Once you’ve determined a fraction, you can convert it to a concentration by multiplying it times the concentration difference between the adjacent color standards, and either adding this value to the concentration of the lower color standard or subtracting it from the concentration of the upper color standard, whichever it is closest to.

For example, here’s a scenario where a reading is a little more intense than the nearest color standard. The reading falls between 0.6 and 0.8 ppm. The analyst interprets the reading as being ¼ (or converting that to a decimal, 0.25), darker than 0.6 ppm. So, [0.25 * (0.8 – 0.6)] + 0.6 = 0.65 ppm.

If your reading is more intense than the highest color standard of the comparator, this means that the sample concentration is higher than the range of the round comparator. When available, compare the test ampoule to the flat comparator included in your test kit.

Reading a Flat Comparator

When reading a high range comparator it is very important to hold it in a manner that eliminates glare and reflection from your light source. This can be accomplished by angling the comparator relative to the light source until the light reflection disappears. Some analysts prefer to hold the comparator so the bubble is at the top of the ampoule while others like to angle the top of the comparator down to make the bubble disappear into the body of the comparator. Either method will work, but the latter method presents the color standard with a longer continuous color with which to match the test ampoule.

Next, the test ampoule should be placed between the first and second color standards at the left (lower concentration) end of the comparator and progressively moved to the right until the intensity of the test ampoule appears to be the same as or in between two color standards. Move the test ampoule one color standard further to the right to be sure its intensity is less than the color standard now to its left. If it is not clearly less intense than the color standard to its left then it is probably very close to, or equal to, that intensity. Make sure to vary the angle of the comparator to ensure that the intensity is really the same and its not a glare or shadow affecting the intensity. Once you are sure of the intensity you can get your reading in the same manner as with the low range comparator.

If your reading is more intense than the highest color standard of the comparator, the sample concentration is greater than the range of the flat comparator.  Manually dilute your sample if appropriate or use a higher range test kit.

Color Matching Tips

Figure 4: A round comparator with a poor color match.

Figure 3: A round comparator with a strong color match.

Sometimes the color match between the test ampoule and the color standard is not ideal due to color impurities or turbidity in the sample.  When this happens, it is important to distinguish the intensity of the color caused by the analyte from the color caused by the impurity.

CHEMetrics A-0004 Comparator Light Source

CHEMetrics offers a self-contained light source, or CLS, which incorporates an LED light with an adapter that is designed to be used with a  round comparator. This device makes it easier to obtain test results in low-light environments such as power plants or any industrial setting where lighting conditions are poor.

Simply attach the CLS accessory to your comparator to illuminate the color standards. The CLS has been validated for use with CHEMetrics C-7518, C-7540 and C-7599 ppb Dissolved Oxygen and C-1001 Filming Amine comparators.


Our eyes are very good analytical “instruments”. CHEMetrics visual test kits permit water analysis measurements at very low analyte concentrations that rival laboratory optical equipment. Although reading a comparator is a simple task whether you are working in the field or the lab, new users may need some practice manipulating the test ampoules in the comparators to determine for themselves the techniques that work best for them. Check out the video tutorial below and if you have any other questions please contact us.


Food and Beverage Industry: Measurement of Hydrogen Peroxide at Critical Control Points

Food and beverage packaging takes many shapes and forms in today’s marketplace. In an effort to maintain grocery shelf-life and flavor quality, these products are processed and assembled by sophisticated packaging equipment that has evolved away from traditional bottling and canning methods.

Systems of quality control in the food and beverage industry have become more sophisticated as well as companies have come under the FDA’s Hazard Analysis and Critical Control Points (HACCP) guidelines. They call for food companies to develop quality monitoring procedures at critical control production points. Furthermore, corrective actions must be identified and taken if established limits are not met. Lastly, effective recordkeeping of food safety monitoring must be maintained to document the various HACCP-mandated processes.

Aseptic Packaging

Aseptic packaging technology utilize both hydrogen peroxide and heat to achieve sterility enabling food products to be distributed through ambient temperature channels. FDA approved these processes in January 1981 in response to a petition by Tetra Pak. Within months, some of the largest U.S. beverage producers (juice, dairy, etc.) began employing aseptic packaging sterilization procedures. Although new to the U.S. at that time, the technology’s origin can be traced to Sweden’s Tetra Brik packaging introduced in 1963.

Figure 1: A close up of a bottling line

Extended Shelf Life

The chilled food and beverage segment of the market has boomed since the 1980s as packaging engineers have employed variations on the “aseptic theme” to produce systems that prolong shelf life beyond that of traditional pasteurized products (hence extended shelf-life or ESL). Although ESL processes apply a heat/time regimen to the product that is regarded as a sterilization process, ESL packaging operations do not necessarily sterilize the packages or package enclosures, therefore all ESL products are distributed through refrigerated channels. Examples of ESL products offered in the refrigerated section of the grocery store are orange juice (not from concentrate), flavored milk, coffee creamers, and puddings.

General Protocols Used in Packaging Systems

Regardless of the food packaging system being considered, packaging vendors apply the same basic microbiological and engineering principles to design their food safety monitoring equipment. Precise details of the processes are dictated by the product type – high acid or low acid (aka pH). The general procedures used to sterilize either the product or packaging systems before any product or package enters the system involve:

  • steam
  • steam plus hydrogen peroxide
  • hydrogen peroxide
  • peracetic acid
  • other chemical treatments, or
  • hot water.

When chemical sterilization is applied to package interiors or closures, residual chemical must be removed prior to filling not only to comply with FDA residual regulations but also to maintain sensory quality and prevent flavor degradation.

Hydrogen Peroxide Measurement, Monitoring and Control

In 21 CFR 178.1005 (a) of the Code of Federal Regulations, hydrogen peroxide is defined to be a 35% aqueous solution. In subsection (d) of this same standard, it specifies limits on the hydrogen peroxide residual. “No use of hydrogen peroxide solution in the sterilization of food packaging material shall be considered to be in compliance if more than 0.5 part per million of hydrogen peroxide can be determined in distilled water packaged under production conditions (assay to be performed immediately after packaging).”

Figure 2: Within facilities of this size there may be more than one testing location.

Analytical Tools for the Detection of Hydrogen Peroxide

The traditional laboratory bench method used to determine hydrogen peroxide levels is a titration with potassium permanganate (KMnO4). This requires volumetric glassware, use of buret, and standardization of the KMnO4 prior to testing. Typically, titrations are repeated up to three times to determine an averaged test result. In the manufacturing arena, where it is not uncommon for lines to produce hundreds of bottles per minute, waiting for a lab result to confirm residuals is costly.

Paper hydrogen peroxide test strips offer advantages over titrimetric methods. Typically, a strip is dipped in a sample for a specified time, removed and allowed to stand while a color reaction develops on the reagent pad. The developed color is then matched to a printed color standard. One disadvantage of paper test strips is that they are deactivated by moisture. Care must therefore be taken to prevent exposure of the strips to air.

Even under ideal conditions, hydrogen peroxide test strips have a limited shelf-life. Furthermore, test strips may not offer the sub-ppm sensitivity required for residual testing. Lastly, test results may be influenced by user technique – for example, how vigorously the strip is stirred in the sample, and the degree to which the sample is allowed to drain from the strip once the strip is removed from it.

About CHEMetrics

CHEMetrics manufactures an innovative, colorimetric hydrogen peroxide test kit that is economically priced and offers:

  • immediate test results (in less than 2 minutes) at the point of testing, not in the lab
  • long term reagent stability
  • sub ppm sensitivity, and
  • accuracy independent of user technique.

In this analytical system, the hydrogen peroxide liquid reagent is pre-dosed and packaged in a vacuum-sealed ampoule. In the visual test kit, the CHEMets® ampoule tip is immersed in the sample, the tip is snapped off, and the sample is automatically drawn into the ampoule. After the ampoule is inverted several times to facilitate mixing, it is compared to color standard ampoules to obtain a test result. An instrumental version of this hydrogen peroxide test kit is also available. The same test procedure is followed except that the ampoule (Vacu-vials®) is read in a photometer rather than compared visually to color standards.

Figure 3: CHEMetrics offers both visual and instrumental test kits for the measurement of Hydrogen Peroxide in Water.

CHEMetrics offers a variety of methods and test kit configurations that permit the measurement of hydrogen peroxide concentrations ranging from sub ppm to percent levels. The analytical method that is most widely used by food and beverage customers for hydrogen peroxide food safety is the ferric thiocyanate chemistry. In this chemistry, the ampoules contain a ferrous ammonium thiocyanate reagent. Hydrogen peroxide in the sample converts ferrous ammonium thiocyanate to ferric thiocyanate. The intensity of the orange-brown colored ferric thiocyanate is proportional to the hydrogen peroxide level in the sample. Test results are obtained in two minutes or less. The measurement range for the ferric thiocyanate CHEMets® test kit (visual) is 0 – 0.8 ppm and 1 – 10 ppm, with a detection limit of 0.05 ppm. The measurement range for the ferric thiocyanate Vacu-vials® test kit (instrumental) is 0.15 – 6.00 ppm, with a detection limit of 0.15 ppm. VACUettes® kits are also available in which the ampoules have been fitted with an auto-dilutor tip, thus allowing for measurement up to 1.2% (12,000 ppm) hydrogen peroxide.

Other CHEMetrics kit options available for measuring high levels of hydrogen peroxide (up to 20%) employ a titrimetric ceric sulfate reagent and a ferroin indicator. Titrets® ampoules employ a reverse titration method that employs pre-dosed, vacuum-sealed reagent. The sample is drawn into the ampoule in small doses until a sharp endpoint color change signals the equivalence point has been reached. Quantitative test results are read directly from a scale printed on the side of the Titrets® ampoule.

Lastly, a ceric sulfate Go-No-Go test kit format is available upon request for situations where a Pass/Fail result at a specified control point is sufficient. A single, small dose of sample is added to a screw cap vial containing the hydrogen peroxide liquid reagent and endpoint indicator. An immediate color change occurs to signal that the hydrogen peroxide level in the sample is either above or below the specified control point.

Food processors must weigh analysis cost, turn-around time, accuracy, sensitivity and ease of use when determining which analytical sterilization test method suits their requirements. CHEMetrics hydrogen peroxide test kits, with their “snap and read” approach to sample analysis, fulfill each of these requirements with distinction.

The chemical feed and control system is key to the success of a water treatment solution. Along with delivering the water treatment chemistry to the system, the feed and control equipment package also assumes the task of controlling and monitoring system parameters such as conductivity, pH, ORP, and more. A feed and control solution is comprised of controllers, sensors, pumps, valves, tanks, feeders, analyzers, and sometimes customer-provided system data.

All these work in concert to ensure that the water treatment solution is properly delivered, monitored, and controlled. As communication technology has evolved, electronic data management has become essential as well. Remote monitoring, data acquisition, and alarming have become commonplace in many chemical feed and control equipment packages.

 How Do Chemical Feed and Control Systems Work? 

The parts of a feed and control system can vary by the type of system being treated, but they all share very similar components. These include a controller, pumps and/or other chemical delivery apparatus, sensors, valves, and in some cases, bulk storage tanks.

In a typical chemical feed and control system, a controller or PLC monitors various system parameters and acts on these parameters based on settings (setpoints) that have been predetermined by the water treatment professional. These can include parameters such as conductivity, pH, ORP, tank level, chemical treatment levels, etc.

An example of parameter-based control is conductivity control. This control loop or algorithm is comprised of a conductivity sensor and a control valve. The setpoint is typically a “force lower” setpoint, meaning that as the conductivity rises past its setpoint, the system forces it lower by opening a valve to let the high conductivity water out, thus allowing lower conductivity makeup water to be added to the system. It’s important to note that the act of bleeding water from the system does not lower the conductivity; it’s the addition of the lower conductivity makeup water that accomplishes this.

Chemical addition can be accomplished using pumps, valves, eductors, erosion feeders, pot feeders, etc. The most common method for chemical addition is via metering pumps. The pump draws the water treatment chemical from either a drum, pail, or bulk container and “injects” it into the system. Metering pumps are precision instruments and can be activated using several methods:

  • Sensor-based control
  • Timer-based control
  • Scenario-based control

An example of sensor-based control is the use of a fluorometer to control the addition of chemical to a system. This is a “force higher” feed method where a sensor, typically PTSA, monitors the level of product in a system by looking for PTSA that is present in the system as a tag or tracer that corresponds to the level of scale and corrosion inhibitor present in the system. When the level of PTSA falls below a setpoint, a metering pump is activated and delivers product that is tagged with PTSA to the system. Once the system recognizes that the PTSA level has come up into the desired control range, the pump turns off, and the system continues to monitor the PTSA level.

These are just a few of the many ways a chemical feed and control system works. Modern systems have a virtually limitless number of methods to ensure that the feed and control equipment meets the demands of the treated system.

The Benefits of Chemical Feed and Control Systems 

In addition to the basic chemical feed and control role that equipment plays in the water treatment program, chemical feed and control systems offer several other benefits. These include the ability to control parameters based on system chemistry, operating conditions, and other system parameters that may be ignored without modern feed and control equipment.

Improve Dosing Accuracy

Dosing accuracy is improved by setpoint-based control vs. the past choice of timer-based control. With the addition of water meters and remote monitoring and/or local alarming, modern feed and control systems will alert personnel if a system uses an excessive amount of water. This simple solution can save a large amount of water and, therefore, money by detecting common issues such as a malfunctioning makeup valve. If undetected, even a small valve leak can lead to a substantial loss of water and chemicals from the treated system.

 Maintain System Efficiency

Along with water loss, excessive water retention is also detrimental to system performance and can lead to fouling of the heat exchange surfaces. Systems are designed to function properly with the correct ratio of cycles of concentration and chemical levels. An increase in cycles of concentration due to a loss of ability to release water from the system can lead to scaling or fouling. Similarly, failing to add the proper amount of deposit control chemistry or biocides can lead to the same. The energy increases due to fouled heat exchange surfaces can be many times more costly than excessive water use.

 Reduce Operating Costs

The financial and environmental payback of a quality feed and control system is difficult to overstate, as even a minor excursion can result in costly repairs, excessive energy use, overuse of water, and in some cases, safety issues. Properly configured feed and control equipment will ensure systems run at peak performance while bringing measurable ROI to your customer.

Types of Feed and Control Systems 

There are many types of feed and control systems on the market. The following are the most commonly available.

 Pre-packaged Water Treatment Controllers

Pre-packaged feed and control systems come pre-configured with industry-standard feed methods and are typically designed specifically for industrial water treatment. These systems are comprised of a base controller and sensors. The water treatment controllers in this setup will have a limited number of inputs and outputs, the number of which is generally sufficient for most water treatment programs. The controller manufacturer provides a line of sensors that have been designed to work with the base controller. This simplifies the operation since the calibration, configuration, and diagnostics are incorporated into the controller for these sensors. Along with these, most OEM water treatment control systems will allow for the addition of generic sensors. These include level sensors, fluorometers, analyzers, water meters, and a multitude of analog and/or digital sensors. The addition of these may necessitate additional boards (cards) in the base control system. A major benefit to these systems is the built-in programming and simplicity of configuration. This system can be configured and maintained by a water treatment professional or system operator and does not require any true programming.

 PLC (Programmable Logic Controller) Systems

Occasionally the basic water treatment control systems may not be sufficient for an application. A specific customer requirement or control algorithm may not be available in a pre-packaged control system and must be custom programmed in a PLC system. PLC systems are comprised of a processor, input/output modules, and an HMI, or Human Machine Interface, used to interact with the PLC. These are commonly referred to as a touch screen or operator interface. PLCs can be costly due to the equipment cost and programming time associated with this type of system, however, the benefits of meeting a specific system need often offset these costs. These systems require true programming. Modifications to feed methods will most likely need to be performed by a programmer or systems integrator.

 The Role of Controllers in Feed and Control Equipment 

As the heart of the treatment program, the chemical feed and control system is key to its success. It not only monitors the system and delivers the product, but it also acts as the water treatment professionals’ eyes and ears. The feed and control equipment monitors system parameters 24 hours a day and can be invaluable as it can provide the data used to determine the cause of an unfortunate system failure. These control systems may also possess the ability to adjust chemical use.

Since most modern control systems now offer the ability to data log and, in many cases, push that data to the cloud, electronic data management and analysis has become commonplace amongst water treatment professionals. Online solutions like eSR with Flex Reports provide a centralized location to store controller data and allow you to compare the data with field-acquired data such as daily operator logs, service reports, corrosion data, microbiological data, etc.

When combined with cellular technologies, modern feed and control systems can be monitored and configured remotely. This gives the water treatment professional the ability to monitor critical systems and parameters between regular service visits that would historically require additional site visits. By using remote monitoring software and automated alarms, you can be notified of problems in real-time that would otherwise go undetected until the next regularly scheduled site visit.

Simplify your Equipment Set-up with AquaPhoenix Scientific

As an industry leader in feed and control technology, we can create a standardized chemical feed and control equipment package for you. When you design a system with AquaPhoenix, you get to choose from all the top brands. Our team will work with you to recommend and select the best equipment for your application.

By integrating these components into one of our custom panel and/or skid systems, you can deliver a true water-in, water-out control system that will greatly simplify the installation and maintenance of your feed and control equipment.

Connect with our team today to save time in the field and improve your service visits. Download our industrial catalog to browse thousands of products or request a quote to get started on your next job.

Monochloramine As A Disinfectant In Water

Water disinfection is a key step in water treatment for the wastewater and drinking water industries. Disinfection renders dangerous pathogens inert, preventing disease. While every water utility has its own method for disinfecting water, chlorine and monochloramine are two of the most common chemicals used for water disinfection. Many people are familiar with chlorine, but awareness of monochloramine is less common. While both chemicals are disinfectants, they are used in different capacities. In this post we will provide some basic information on monochloramine, how it is used, how it compares to chlorine, and how it is measured.


What is Monochloramine?

Chloramines are a group of chemical compounds that contain ammonia and chlorine. Monochloramine (NH2Cl) is the simplest chemical compound of the chloramine group and as a result is often referred to as “chloramine.” Monochloramine is a colorless liquid that is soluble in water. It is commonly added to drinking water to function as a secondary disinfectant in a process called chloramination. Monochloramine is formed by the reaction of free ammonia (NH3 and NH4+) with free chlorine. Dichloramine (NHCl2) and trichloramine (NCl3) will also form if free chlorine remains in solution after all free ammonia has been converted to monochloramine. Dichloramine and trichloramine are less effective at disinfection and impart an unpleasant odor to the water. Therefore, chloramination processes are optimized for monochloramine production.


The Difference Between Primary and Secondary Disinfectants

Municipal water facilities employ disinfection processes based on the characteristics of certain water quality parameters at the site. Sometimes facilities use a disinfection strategy that utilizes a primary disinfectant followed by a secondary disinfectant. The primary disinfectant is used to render inactive or kill, bacteria, viruses, and parasites, while the secondary disinfectant is used to support the primary disinfectant and maintain a disinfection residual as it passes through the distribution system.

Primary disinfectants do the majority of the disinfection work. They are powerful but typically do not persist in the system to offer continuous protection. The most common primary disinfectant for drinking water and wastewater treatment is chlorine. Adding chlorine to disinfect water is called chlorination. Due to chlorine’s reactive nature, it disinfects rapidly but does not last long within the system. Adding excessive chlorine can affect water smell and taste. Chlorine can also create harmful disinfection byproducts (DBP) when it combines with trace levels of naturally occurring organic compounds in the water. Chlorine treatment levels can be reduced when a secondary disinfectant process is added to the system. Typically the secondary disinfectant is added to drinking water at the last stage of the water treatment process. Many water utilities are using or starting to use the chloramination process to produce monochloramine as the secondary disinfectant. Since it is less reactive than chlorine, monochloramine persists in a system longer but disinfects more slowly. These properties make it a more cost-effective secondary disinfectant than chlorine. It may also reduce DBP formation and does not affect the taste and smell of water like chlorine does as long as it is maintained below a certain threshold.


Testing for Monochloramine

Traditionally, monochloramine (NH2Cl) is measured using the N,N-diethyl-p-phenylenediamine (DPD) chemistry. To determine the concentration of monochloramine, the difference between two test results is calculated. The first test measures total or combined chlorine and is performed using DPD plus potassium iodide (KI). The second test measures free chlorine and employs DPD alone. By subtracting the free chlorine result from the total chlorine, an estimate of how much chloramine is in the solution is obtained. However, this measurement technique may overestimate the monochloramine concentration and, therefore, the disinfection status of the sample since the total chlorine DPD method measures all forms of chloramines, including organic amines, mono-, di- and trichloramine. To maintain efficient disinfection processes, a method of analysis that is specific to monochloramine is necessary.



Figure 1: K-6802 and K-6803 Monochloramine Test Kits are available for purchase on

CHEMetrics New Monochloramine Test Kits

CHEMetrics new Monochloramine Vacu-vials Test Kit (Cat. No. K-6803) and CHEMets Test Kit (K-6802) use the hydroxybenzyl alcohol (HBA) chemistry to selectively measure monochloramine. Monochloramine reacts with HBA in the presence of sodium nitroferricyanide to form a green indophenolic compound in direct relation to the concentration of monochloramine in the sample. The results are expressed in ppm (mg/L) monochloramine as chlorine, NH2Cl-Cl2. K-6803 can be used to determine monochloramine in the 0 – 8.00 ppm range with any spectrophotometer that accepts a 13mm cell or with the CHEMetrics V-3000 photometer. When using the V-2000 photometer, K-6803 has a range of 0 – 15.0 ppm. K-6802 is a visual test kit and can measure from 0 to 20 ppm NH2Cl-Cl2.

 October 2022

Using Glass and Plastic Impingers To Measure Peracetic Acid In Air

What is a Research Paper Summary?

At CHEMetrics we love learning about how scientists use our test kits in the course of their research endeavors. To that that end, we keep our ears tuned for reports in the chemistry, medical, environmental and engineering oriented literature to find real world examples of how data generated from our test kits support recommendations for adapting or changing existing processes in order to improve desired outcomes. We will periodically highlight an example of these research topics to illustrate the wide range of scientific applications to which CHEMetrics test kits find use. The web link to the original publication will be provided at the end of the post for readers who wish to dig deeper into the subject of peracetic acid air monitoring.


Properties and Uses of Peracetic Acid

Peracetic acid (PAA) is a versatile oxidizing disinfectant that is formed from a reaction between acetic acid and hydrogen peroxide. It is commonly used as a sanitizing agent in the poultry processing and beverage industries to disinfect carcasses, equipment, pasteurizers, tanks, pipelines, evaporators, fillers, and contact surfaces. The pulp and paper industry uses peracetic acid as a delignification and bleaching agent. PAA is also finding use as a biocide in wastewater treatment and is even used in aquaculture tanks. Part of PAA’s rising popularity is that it decomposes into non-toxic by-products. However, since PAA is irritating to mucous membranes of the respiratory tract, skin, and eyes, occupational health professionals must consider the effect of worker exposure to PAA vapors. Consequently, there is a need to quantify and monitor air concentrations of PAA quickly and accurately in the workplace to compare against concentration thresholds that have been established for irritation to the upper respiratory tract and lacrimation.


Measuring Peracetic Acid Vapor Using Impingers

Recently an article published in the Journal of Occupational and Environmental Hygiene reported on a new method for measuring peracetic acid in air. The article, co-written by three authors from the National Institute for Occupational Safety and Health, is titled “A field-portable colorimetric method for the measurement of peracetic acid vapors: a comparison of glass and plastic impingers.” An impinger, a device designed to sample and collect airborne contaminants, consists of an inlet that is connected to a calibrated pump. The inlet is also connected to a receiving tube or nozzle which is submerged in a known volume of water that functions as a trap for the contaminant. The air is bubbled through the water. The pump is run for a designated collection period. The volume of air sampled (often expressed as cubic meters) can be calculated from the air flow per minute and the collection time. When the water in the trap is analyzed for the contaminant concentration, estimates of the mass of contaminant per cubic meter of air can be made (mg/m3).

Figure 1: Depictions of different Impingers. (A), Glass, (B), A plastic impinger with a vertical inlet and a horizontal outlet, (C) plastic with vertical inlets and outlets, (D) a 3D printed impinger.

Using CHEMetrics Vacu-vials® Ampoules In Research

The researchers used CHEMetrics K-7913 PAA Vacu-vials test kit and V-2000 multi-analyte photometer to validate the performance of four impinger designs. To do this, they transferred a precise volume of PAA solution of known concentration to an Acrodisc syringe filter which was connected to the impinger inlet. Then a vacuum pump was turned on for 15 minutes. After the pump was turned off, the water in the trap was diluted and measured with K-7913 and V-2000 Program No. 148.

Figure 2: A V-2000 Photometer like the one pictured here was used as part of the experimental procedure.

Figure 1 provides a graphic of the different types of impingers in this study. One of the impingers was a traditional glass impinger while the other three were made of plastic. Two of the commercially available plastic designs differed in the inlet and outlet impinger orientation (vertical versus horizontal), while the third plastic impinger replicated the horizontal outlet impinger but was differentiated by the nozzle design. In this case, the nozzle was 3D printed and changed from a blunt end to a tapered end. The researchers demonstrated that a tapered nozzle, (Fig. 1 A and D), transfers PAA vapor more efficiently than the blunt or flat ended nozzles, (Fig. 1 B and C).

The researchers also used the CHEMetrics Hydrogen Peroxide Vacu-vials Instrumental Kit (K-5543) to confirm that hydrogen peroxide did not significantly interfere with PAA measurement using CHEMetrics K-7913 PAA test kit. This was a significant finding because other NIOSH colorimetric PAA air sampling methods require the use of a filter cassette to remove hydrogen peroxide.

Validating the performance of a plastic impinger is one of the key results from this study since glass impingers are not always permitted in pharmaceutical and food and beverage facilities. Lastly the researchers were able to establish limit of detection and limit of quantitation values that were below the American Conference of Governmental and Industrial Hygienists’ threshold limit value for short-term exposure (ACGIH TLV STEL).


Results of the Experiment

 The authors concluded the air sampling and measurement method could be used in the field to monitor PAA as part of a measurement strategy to evaluate worker exposure. The test method offers a low-cost alternative that provides a quick analysis turnaround time. They plan to publish their method in the NIOSH Methods Manual soon.

A link to the abstract is available Here

You Can Help The Environment By Testing Water

September 2022

Water Testing for Everyone

As protecting the environment becomes an increasingly popular topic, more of us are wanting to get involved. When searching for ways to get involved many people think of litter clean up, recycling, and conservation efforts, but many may not be aware how they can make a difference by testing local water sources. Key measurements like chlorine concentration, pH, alkalinity, hardness, total dissolved solids, and dissolved oxygen can indicate the health of a body of water. By collecting these measurements and providing them to an open data platform more people can be aware of the water quality around them. Water Rangers freshwater test kits offer testing products that are packed in a convenient carrying bag so you can start local water testing today. Read on to learn how to help the environment and aid your local scientific community, all while taking on a fun and educational activity.

Contents of the Water Rangers Education Kit

Figure 1: The K-0010 The Freshwater Education Test Kit contains everything you need to inspire the next generation of water testers.

Help Establish Baseline Data

To understand the health of rivers, lakes, ponds and streams, a great deal of data must be gathered over time. Some aspects of water will change naturally, so collection of data over an extended period of time is required to determine the difference between normal fluctuations and those that need to be addressed. Dissolved oxygen levels, pH and temperature will change throughout any given day as well as from season to season. Since so much data is required to understand the health of a body of water, the work of active volunteers and citizen scientists are key to developing reference data.

Water Rangers test kits not only come with testing gear; they also provide access to an open data collection platform that allows results to be tracked, mapped and readily available to scientists, governmental agencies, local environmentalists, and other interested volunteer groups. Your data can aid in critical decision making that affects your entire community.


Build Connections With People and Water

Water Rangers test kits can be used by individuals acting on their own, or they can be used in coordination with water testing groups – maybe by one you start. Start your own water monitoring group by asking your friends, family members, or anyone else who is interested in caring for natural waters. Volunteer citizen science groups are an effective way to test multiple streams, lakes, rivers, or other waterways in your area. Some groups will schedule a day to collect data while others will assign each member a specific location to test and report on. However your group chooses to operate, your community will be better off for having citizens engaged in this important work. Thanks to Water Rangers freshwater test kits, it has never been easier to make new friends and help the environment.

Figure 2: Water testing is simple and provides results in minutes.

Inspire The Next Generation of Water Testers

It can be difficult to find educational projects for children, let alone ones that occur outdoors. Water testing is a great way to inspire students to think about the water around them while they engage in hands-on, scientific work. The tests included in the Freshwater Education Test Kit are simple enough that anyone can perform them with results delivered in minutes.

Each kit comes with enough materials for 20 students as well as a teacher’s guide that includes detailed lesson plans. There’s no need to worry if you aren’t a water testing expert; this kit will teach you everything you need to help your students learn the fundamentals of water testing.



Local water testing is an often-overlooked aspect of environmental care that any individual or group can take on. By testing the lakes, rivers, ponds, or any other body of freshwater around you, you can help provide critical data on water quality while you also build a community and educate your neighbors on the importance of caring for natural water. The Water Rangers test kits available on are a great way for anyone to start their water testing journey.

Figure 3: CHEMetrics is proud to partner with Water Rangers!

-Zachary Waszczak

Routine water testing is a necessity for industrial water systems.  These include cooling towers, steam boilers, hot water boilers, drinking water, wastewater, ultra-pure water, and others.  Analyzing water samples is key to understanding the general conditions of the treated system.  The samples are not only indicative of the treatment levels, but also the levels of other constituents that are indicators of the general condition of the treated system and program performance.  The water testing will also ensure that the system is being operated within the prescribed parameters.

To ensure that decisions made around the results of the water testing are based on accurate information, it is important to consider the impact of interferences and other factors that could affect the accuracy of the test results.

What Should Water Be Tested For?

While the specific testing parameters and ranges can vary by the type of system being sampled, the majority are common between systems.  Along with the common testing parameters, there are also testing parameters that are specific to the type of treated system and the treatment program associated with the system.

Common, non-system-specific testing parameters may include:

  • Conductivity
  • Hardness (Calcium, Total, and Magnesium)
  • Alkalinity (Total)
  • pH

In addition to the parameters listed above, the following system-specific parameters are common to the system type.

Cooling Towers

  • Phosphonates
  • Polyphosphate
  • Chlorides
  • Orthophosphate
  • Molybdate
  • PTSA
  • Oxidizing biocide level (total chlorine, bromine, free chlorine, chlorine dioxide, etc.)
  • Non-oxidizing biocide level
  • Copper
  • Silica
  • Azole Level (TTA, BZT, HSA etc.)
  • Biological testing (dip-slides, ATP, etc.)

Steam Boilers

  • Fluorescing tracers
  • Polymers
  • Phosphate
  • Sulfite
  • Amines
  • Dissolved oxygen
  • Alkalinity (P and OH)
  • Iron
  • Low Level Hardness

Heating Boilers (Hot Water Boilers)

  • Nitrite
  • Molybdate
  • Silica
  • Copper
  • Iron
  • Filming Amines
  • Tannins


  • Polymer
  • Various metals
  • Turbidity
  • Jar Testing (product performance)
  • Treatment specific testing
  • Biological testing (dip-slides, ATP, etc.)
  • Chlorine (discharge water)

Drinking Water

  • Oxidizing biocide level (total chlorine, bromine, free chlorine, chlorine dioxide, chloramines, etc.)
  • Biological testing (dip-slides, ATP, etc.)
  • Copper
  • Iron

The examples above are a few examples of industrial water systems.  These systems are found across many industries related to comfort heating or cooling, energy, food sanitation, clean in place, food preparation, manufacturing, laundry, agriculture and many others.

How to Interpret Your Water Test Results 

The water analysis gives the water treatment professionals and system operators a snapshot of

the system conditions.  Interpreting the testing results is key to understanding the overall product and system performance.  Each tested parameter will have a control range or recommended range based on:

  • The water treatment professional’s knowledge of the system
  • Quality of the make-up water
  • Water limitations
  • Discharge limitations
  • Overall performance expectations.

Interpreting the test results should be done using all the testing results.  Many parameters are directly linked to each other and will move up and/or down with another parameter.

An example of this is PTSA and phosphonate in a cooling tower system.  Since PTSA is present in the system as a tracer or indicator of the amount of corrosion/scale inhibitor in the system, the phosphonate level should correlate directly to the amount of PTSA in the system.  For example, if the PTSA level is within the recommended control limits and the phosphonate is over or under the limits, the calibration of the PTSA sensor should be examined.  If the PTSA sensor is properly calibrated, the phosphonate level should be evaluated further as this could be indicative of other system and or product concerns.

Since parameters such as pH, hardness, conductivity, and alkalinity are commonly used to determine important system conditions such as cycles of concentration, close attention should be paid to these and the relationship between them.  Any variation of these parameters from the prescribed control limits should be compared with the overall water analysis.

An example of this is the relationship between conductivity and alkalinity when they are used as indicators for cycles of concentration.  In a water system with a make-up conductivity value of 300 mmhos and 100 ppm of total alkalinity, at four cycles of concentration the system conductivity should be approximately 1200 mmhos and 400 ppm of total alkalinity.  At these levels, the numbers balance with the cycles of concentration.  However, if the pH of the system is being adjusted by the addition of acid or caustic, the alkalinity of the system will not correlate to the conductivity cycles and cannot be used to estimate the cycles of concentration.

Another example is the relationship between hardness and conductivity when used in the same way as our previous example.  If a system has a make-up conductivity of 300 mmhos and a total hardness of 100 ppm, at four cycles of concentration, the conductivity should be approximately 1200 mmhos and the total hardness should be approximately 400 ppm.  If the hardness level is noticeably less, the testing should be evaluated further.  Examples of the conditions that could impact this balance would be a variation in the make-up water chemistry over time or the loss of hardness due to scale formation.

If the testing results do not make sense or do not fit a known scenario, a close examination of the testing procedures may be warranted to ensure that the information is accurate and can be acted upon appropriately.

Interferences That Can Impact Water Testing Results

It is important to understand that there are a variety of conditions and factors that can impact the accuracy of the water sample testing results.  These are generally referred to as interferences and can be related to chemical, mechanical or human issues. The number of interferences is too numerous to list, but there are several examples of these that apply to routine testing.  These may include interferences by products being added to the treated system or even the tested parameter itself. With 80-85% of errors related to water quality results being impacted by user error, it’s important to follow best practices to minimize and eliminate errors

Here are some essential steps to follow:

  • Use clean equipment – properly rinsing and cleaning equipment before and after testing helps to eliminate contamination from previous tests.
  • Collect accurate samples – there are a variety of factors around sample collection. For starters, it’s important to make sure you collect a sample that is representative of the entire system. When performing your test, pouring an accurate sample size is also important. Small errors in sample collection can have a big impact on your results.
  • Use proper testing technique – Holding bottles vertically for consistent drop size, proper lighting and simply following written procedures are very important. While they may seem minor, they can add up in a big way.
  • Interpreting your results – making sure you are using the proper factors and expressing your results properly during your test is also important. Is your test expressing results as sulfite or sodium sulfite or nitrite vs sodium nitrite? When calculating and interpreting your water testing results, these matter.

A common chemical interference is seen in the testing of chlorine using the DPD method.  While DPD is commonly used to determine the amount of chlorine in a sample, higher levels of chlorine can cause bleaching of the reagent and mask the test results.  The phenomenon can occur with as little as 5 ppm of chlorine in the sample.  To mitigate this problem, the sample can be diluted, and a multiplier can be applied to the results to compensate for the dilution.

An example of physical interference is seen when a sulfite test is run on a boiler water sample when waiting for an extended period between sampling and testing.  Exposure to air for an extended period can result in a lower-than-expected result.  To avoid this, the sample container should be capped and the sample tested as soon as possible. It’s also critical that sulfite samples be cooled before testing. Not following these important steps will lead to inaccurate results.

Though the list of possible interferences can be overwhelming, many common interferences are listed within the test kit documentation and can be easily avoided by following the basic procedures outlined in the testing instruction.

Analyze Your Water Supply With Customizable AquaPhoenix Test Kits

AquaPhoenix Scientific offers standard and custom test kit solutions for every water treatment need.  We can formulate custom testing procedures designed around your specific products and application needs. Our EndPoint ID testing procedures are easy to follow with photographic step-by-step instructions to make testing simple and effective for users of all experience levels.  By including testing tips, safety reminders and interferences directly in our test procedures, you can have confidence knowing you are setting your team and customers up for success from the start.

Contact AquaPhoenix Scientific for a quote or reach out to your water treatment professional for questions or concerns about specific testing parameters.

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