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What is respirometry?

Respirometry is a general term encompassing a number of techniques for obtaining estimates on the rates of metabolism of vertebrates, invertebrates, plants, tissues, cells, or microorganisms. In wastewater microbiology, we use it to determine the viability of bacteria via direct or indirect measurement of oxygen consumption.

So how is oxygen consumption measured?

If bacteria are alive, they consume oxygen. One method for measuring oxygen consumption is manually via the DOUR/SOUR test. Computer-controlled respirometers can be used for more advanced measurement.

Manual Oxygen Uptake Testing via DOUR/SOUR

The Dissolved Oxygen Uptake Rate (DOUR) measures the respiration rate of microorganisms. It is the calculation of oxygen uptake (how quickly the microbes are using the oxygen). The Specific Oxygen Uptake Rate (SOUR) is defined as the milligram of oxygen consumed per gram of volatile suspended solids (VSS) per hour. SOUR is the relationship between oxygen uptake and the amount of solids.

DOUR/SOUR is used for:

• Daily performance monitoring

• Identifying toxicity

• Determining viability of lightly loaded systems

• Balancing loading and flows in parallel basins

• Monitoring recovery from upsets

DOUR/SOUR can be used as a real time monitoring approach to improve process operation and troubleshoot a variety of treatment issues.

Bench Respirometers

Computer-controlled respirometers can be used for more advanced BOD testing, biodegradability assessments, bioremediation testing and toxicity screening studies. These instruments continuously and precisely resupply oxygen to sealed reactors needed to sustain bio-reactions in liquids or semi-solids over extended periods of time. Two bench respirometers that EBS utilize are the Challenge Respirometer and the Surcis Respirometer.

The CHALLENGE Respirometer System facilitates an automated, precision measured, and continuous recording of respiration rates on up to 24 reactors simultaneously for both aerobic and anaerobic lab-scale cultures. This system can be operated in the aerobic mode in which oxygen uptake is measured or in anaerobic mode in which the production of biological gases is measured.

The BM Respirometry System by Surcis S.L employs a reaction vessel that can replicate the actions occurring in a treatment plant and assess the process through fundamental measurements such as the speed the process consumes oxygen, short term biological oxygen demand, biodegradable fractions of COD, non-biodegradable fractions of COD, specific toxicity for a determined activated sludge process, nitrification activity, and others. Surcis BM respirometry analyzers demonstrate results in a quick and practical manner by utilizing the actual activated sludge from the aeration tank. In addition, it provides a treatment plant operator with essential information to help protect and control the biological process of the plant.

Although new to the industry, the Surcis BM Respirometry System shows promise with regard to the type of valuable data it provides during the troubleshooting phase. The Surcis respirometer is now being distributed in the United States by Environmental Business Specialist. For more information, please contact EBS.

This 3-day event, held last month at our headquarters in Mandeville, Louisiana was rated a great success by more than 30 professionals who attended. They came from the fields of biology and engineering, plant engineering and operations, environmental management, and they included biotechnology providers, research scientists, environmental engineers, technical managers, corporate-level environmental staff, and consultants.

With this seminar, EBS wanted to promote awareness of the most advanced techniques in wastewater troubleshooting. The seminar was organized to exchange information between users, scientists, and engineers regarding the overall operating process, and to share common problems, interests, and solutions related to the wastewater microbiology utilized by those in the pulp and paper, specialty chemical, petrochemical, petroleum refining, and food processing industries.

Our guest speakers were Dr. Cliff Lange (Professor at Auburn University College), Mike Matheny (President of Envera LLC, a biotechnology company), Paul Klopping (Owner of Callan & Brooks, Inc) and our own from EBS, Mike Foster (Principal Consultant) and J’ohnnie Wilson (Director of Training and Business Development). They all shared first-hand knowledge and contributed to a wide-ranging discussion of technical and operational issues.

The seminar started with a Review of the Eight Growth Pressures and Basics of Wastewater Microbiology and Filamentous Identification to start attendees on the same page, dived into a day of Advanced Analytical Techniques and Advances in Bioaugmentation Product Development and Application, and ended with Hands on Lab Work where participants could bring their own samples.

Participants were enthusiastic and are now looking forward to the next advanced wastewater event hosted by EBS.

Last Summer I volunteered with Habitat for Humanity. I assisted in building a home in St. Tammany Parish, La. I had never worked with Habitat for Humanity before, but I immediately felt welcomed. I chose to work with Habitat for Humanity due to their belief that every person deserves a decent place to live. At the job site I worked along with teenagers who were with a church group from Florida. It was a normal, hot and humid summer day in South Louisiana but the fact that these kids came from another state to help build homes in my community gave me extra motivation to put in the good days work. At the end of the day I went home tired, but more importantly I left satisfied knowing that the work that I did that day got a deserving family closer to their dream of owning a house.

As an employee of Environmental Business Specialists, located in Mandeville, La., management encourages employees to take an active role in the community. We are allowed to spend 5 workdays a year performing charitable activities. I appreciate the opportunity to work for a company that stresses the importance of making our communities and the world a better place. I look forward to volunteering with Habitat for Humanity in the near future.

Kermit Francis
Environmental Business Specialists
www.ebsbiowizard.com

There are 2 major types of systems used for wastewater treatment: aerobic and anaerobic systems. Each has different uses along with pros and cons. This particular article focuses on aerobic treatment. Anaerobic treatment is the focus of a companion article written by EBS.

Aerobic Treatment

Aerobic wastewater treatment is a process where bacteria utilize oxygen to degrade organic matter (generally quantified as biochemical oxygen demand or BOD) and other pollutants involved in various production systems. The two most common types of aerated wastewater systems are activated sludge systems and aerated stabilization basins (ASBs). ASBs are commonly found as treatment systems in the pulp and paper industry and are used in some municipalities, as well as other industries.

There are eight growth pressures  that affect a treatment system but we will review two major ones: oxygen and organic loading (BOD). In a typical wastewater treatment system, the influent coming into the system has the most BOD because it hasn’t yet been treated.  As the influent reaches the ASB, it enters an aerated environment where the degradation will begin. Different types of aeration are used in ASBs but the most widely used are either surface aerators or diffused aeration systems. When using surface aeration, multiple units are needed to be properly spaced to treat the water. Diffused aeration is normally air that is supplied by compressors or blowers and piped under the surface where the air is released evenly throughout the ASB. Occasionally, pure oxygen is utilized in wastewater treatment, but this is relatively uncommon in ASBs.

The degradation of BOD is achieved through aerobic bacteria in a system. The bacteria utilize oxygen as an electron receptor in order to convert the organic material (BOD or oxygen demand) to carbon dioxide. Via this process they multiply, which in turn creates more bugs to break down more BOD. As the water flows through the system, many changes will occur. As the amount of BOD in the system reduces, the total number of bacteria will also decrease. The oxygen demand, as measured by oxygen uptake rate (OUR) will decrease and the environmental will become acceptable for more advanced life forms, such as protozoa or metazoan. A few of the common higher life forms are: flagellates, free swimming ciliates, stalked ciliates, and rotifers. The higher life forms will feed on the dispersed bacteria and flocculated bacteria that have been formed after degradation has occurred. Higher life forms are an indication that most BOD has been removed from the system.

ASBs tend to be very resilient systems and generally produce adequate quality effluent for typical discharge requirements. However, proper aerator placement and routine maintenance are critical to ensuring that system performance does not deteriorate over time.

Whether it is aerobic or anaerobic treatment, each treatment system has its place in the world today. They are very different in the process but both are used to achieve maximum degradation, while meeting the strict regulations set by the environmental agencies that regulate what is released into the air, ground, or water.

There are 2 major types of systems used for wastewater treatment: aerobic and anaerobic systems. Each has different uses along with pros and cons. This particular article focuses on anaerobic treatment. Aerobic treatment is the focus of a companion article written by EBS.

Anaerobic Treatment

Anaerobic treatment is a process where wastewater or material is broken down by microorganisms without the aid of dissolved oxygen. However, anaerobic bacteria can and will use oxygen that is found in the oxides introduced into the system or they can obtain it from organic material within the wastewater. Anaerobic systems are used in many industrial systems including food production and municipal sewage treatment systems.

Anaerobic digestion is commonly used to treat sludges in the first areas of a wastewater treatment plant. This process is popular because it is able to stabilize the water with little biomass production. Anaerobic treatment occurs in many different stages. The key microorganisms are methane formers and acid formers. The acid formers are microorganisms that create various acids from the sludge. Methane formers convert the acids into methane.

The two main anaerobic systems are batch systems and continuous systems. In a batch system, the biomass is added into a reactor that is sealed for the rest of the digestion process. This is the simplest form of anaerobic treatment but can have odor issues associated with it. As the most simple, it is also one of the least expensive ways to achieve treatment.

A continuous system has organic matter constantly added to the treatment system. Since it is continuously being fed, there is a need for the byproduct to continuously be removed. The byproduct can result in a constant source of biogas, which can be used as an alternative source for energy. This system is usually more expensive to operate because of the need for constant monitoring and manpower.

Biogas is produced as the bacteria feed off the biodegradable material in the anaerobic process. The majority of the biogas produced is methane and carbon dioxide. These gases can be stored and used for energy production. The methane in the biogas can be burned to produce heat and electricity. The heat and electricity can be used to aid the process of the anaerobic system by providing power and heat for the digestion to occur.

Biogas can also be used as alternative source for fuel. This has received a lot of attention due to the ever-rising cost of burning fossil fuels. To produce fuel, the biogas must be treated to reduce or eliminate hydrogen sulfide. The treatment may become expensive but is necessary because the EPA has strict limits on the amount of hydrogen sulfide released into the atmosphere.

Whether it is aerobic or anaerobic treatment, each treatment system has its place in the world today. They are very different in the process but both are used to achieve maximum degradation, while meeting the strict regulations set by the environmental agencies that regulate what is released into the air, ground, or water.

Biochemical oxygen demand testing can be separated into three measurable categories: total biochemical oxygen demand (tBOD), soluble biochemical oxygen demand (sBOD), and carbonaceous biochemical oxygen demand (CBOD). Total biochemical oxygen demand measures all biodegradable material in the sample. Soluble biochemical oxygen demand measures the dissolved biodegradable material in the sample. Carbonaceous biochemical oxygen demand measures the amount of oxygen required by bacteria to biologically oxide the carbonaceous fraction of organics and removes interference from nitrification.

To test the biochemical oxygen demand (BOD), the water samples of interest are diluted with nutrient rich water (containing a phosphate buffer solution, a magnesium sulfate solution, a calcium chloride solution, and a ferric chloride solution) and seeded with a known amount of bacteria. Dilutions are determined by estimating the amount of biochemical oxygen demand (BOD) in the sample using the measured chemical oxygen demand (COD) or another suitable surrogate. The dissolved oxygen (DO) of the sample is measured initially after mixing the solution and again after five days for the BOD₅ test or after one day for the BOD₁ test. The seed (bacteria) added to each solution will degrade the biodegradable material in each sample relative to the amount of oxygen removed from the water. The sample dilution and amount of oxygen removed can be used to calculate the amount of biodegradable material in the sample in mg/L. Each sample must produce a residual of 1.0 mg/L of dissolved oxygen and have had a dissolved oxygen uptake of at least 2.0 mg/L.

Quality control for this procedure is sometimes misinterpreted from the Standard Methods procedure and care should be taken to ensure compliance is met. This is almost always a NPDES permitted test that requires reporting to state or federal environmental compliance departments.

For more information and/or a full procedure, please contact Environmental Business Specialists Technical Director J’ohnnie Wilson at wilson@ebsbiowizard.com or at her direct line 985-674-0660 ext. 115.

EBS Production and Maintenance Coordinator Kenny Smith has evaluated, purchased, and serviced numerous pump types over the years and has found the Blue-White Industries Flex-Pro ® A3 and A4 Peristaltic Metering Pump http://www.blue-white.com/Products/Peristaltic/flexflo.htm to be an excellent pump for nutrient feed. Kenny indicates that Blue-White Industries provides him with the following benefits:

• dependability,
• ease of operation and maintenance, and
• excellent technical support.

The following information is provided by Kenny based on his experience and does not mean that proper safety precautions and procedures should not be taken. For a Tube Failure Detection (TFD), do not use until proper service is completed as noted below.

1. Before servicing the pump, be sure to have Proper Protective Equipment (PPE) available.
   • Gloves
   • Safety glasses
   • Protective clothing
2. Press the stop button on the pump.
3. Disconnect the suction and discharge tubing from the pump.
4. Remove the four thumb screws from the pump head cover; then remove the cover.
5. Press the start button. Notice that the roller rotates at a slow, safe speed.
6. Grasp the inlet pump tube fitting & pull the fitting straight out of the pump head.   Allow the pump tube to automatically walk itself out of the pump head.
7. Grasp the outlet pump tube fitting & pull the fitting straight out of the pump head.
8. Press the stop button.
9. The roller assembly and the pump head should be inspected and cleaned before installing a new pump tube. This is especially important if the pump tube ruptured and the TFD system was activated.
10. To remove the roller assembly, disconnect the electrical plug.
11. Pull the small spacer washer from the shaft.
12. Remove the roller assembly from the pump head by pulling the assembly straight off of the motor shaft.
13. Inspect the roller assembly. If chemical has come in contact with the roller assembly, wipe clean with a damp cloth and dry thoroughly.
14. Inspect the pump head. Wipe clean any chemical or debris inside the pump head and the TFD sensor pins.
15. Locate the FRONT side of the roller assembly (it is marked “FRONT”). With the FRONT side facing forward, replace the roller assembly back on the shaft.
16. Replace the small spacer washer on to the motor shaft.
17. Apply power to the pump.
18. Press the START button. Notice that the roller will only rotate at a slow safe speed.
19. Locate the inlet fitting on the curved tubing.
    • If the roller rotation is counterclockwise, this will be the bottom fitting.
    • If the roller rotation is clockwise, this will be the top fitting.
20. Press the inlet fitting into the slot in the pump head. Be sure the U-shaped fitting sits securely in the rear of the slot.
21. Allow the pump tube to walk its way into the pump head.
22. An installation tool is included with Blue-White pumps.
23. Install the tool on the pump tube adapter on the outlet side.
24. Gently pull on the outlet fitting until the fitting aligns with the outlet slot. Press the fitting into the pump head and remove the installation tool.
25. Replace the pump head cover. Be sure that the four thumb screws are fully installed.

The service is now complete. The Blue-White Peristaltic Metering Pump is ready to feed nutrient to your wastewater treatment system and make those bacteria happy campers once again. For more information on equipment reliability, please contact Environmental Business Specialists at 985-674-0660 or contact Kenny at Smith@ebsbiowizard.com.

For more information, please contact Environmental Business Specialists at 985-674-0660.

Novak, J.T., Goldsmith, C.D., Benoit, R. E. and O’Brien, J. H. 1985. Biodegradation of methanol and teriary butyl alcohol in subsurface systems. Water Sci. Technol. 17: 71-85.

Verschueren, K. 1983. Handbook of environmental data on organic chemicals. Van Nostrand Reinhold Company. New York, NY.