In a wastewater treatment system, it would be valuable if one could learn in advance how operational changes such as the addition of certain chemicals, nutrient, or bioaugmentation products might affect the biological wastewater treatment plant. It would also be beneficial if a plant could determine the biodegradable fractions of a stream or the optimal food to mass (F/M) ratio and sludge retention time. This knowledge would allow one to make better business and operational decisions, minimize upsets, and prevent potential compliance issues.

EBS utilizes a laboratory method known as respirometry to answer these questions. Respirometry is a versatile tool that allows us to conduct studies aimed at evaluating and optimizing treatment plant performance. Respirometry testing is an ideal technique for evaluating the effects of chemical and biological additives in biological wastewater treatment systems. Other process control factors that can be measured include the kinetics of wastewater treatment, oxygen utilization rates, and the impact of toxic shock events.

What is respirometry?

Respirometry is a technology used to measure and interpret oxygen consumption in the biomass as total consumption or rate of consumption in a biological wastewater treatment plant. This oxygen consumption, or respiration, is proportional to the biodegradable fraction of the COD where the more substrate available to the bacteria, the more oxygen is consumed. In other words, oxygen uptake is proportional to bacterial activity in the sludge. Changes in oxygen uptake can occur in the presence of a toxicant or any inhibitory condition that specifically affects the biomass. Respirometry can take the form of more advanced tests utilizing computer-controlled tests spanning hours to days that are run on our Surcis or Challenge systems to simple tests run on dissolved oxygen meters.


Computer-controlled respirometers can be used for more advanced BOD testing, biodegradation assessments, bioremediation testing, and toxicity screening studies. These instruments precisely supply and measure oxygen concentrations needed to sustain biological reactions in liquids or semi-solids within reactors over extended periods of time. The two types of respirometers that EBS utilizes are the Challenge Respirometer and the Surcis Respirometer.

Surcis BM Respirometers

EBS is now the exclusive United States distributor and an end user of the Surcis BM Series of advanced multi-purpose respirometers. Surcis BM Respirometers are batch-type, open system respirometers. This revolutionary system allows addition or removal of substrate, nutrients, biomass, and more from the reactor while running a test. This is far different than other respirometer technology, which only allows for changes to be made during the set-up phase of the test.

The BM Respirometry System by Surcis S.L employs a reaction vessel that can replicate a treatment system and assess the process through fundamental measurements such as the respiration rate, short term biological oxygen demand, biodegradable fractions of COD, non-biodegradable fractions of COD, specific toxicity for a determined activated sludge process, nitrification activity, etc. Surcis BM respirometers give results in a quick and practical manner by utilizing the actual biomass from the aeration basin. 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 provides valuble data for troubleshooting and optimization of treatment systems. The Surcis respirometer is now being distributed in the United States by Environmental Business Specialists. For more information about this revolutionary research tool please contact EBS.

Automatic measurements: OUR, SOUR, bCOD, rbCOD, sbCOD, U, q
Automatic temperature control in the analyzer
pH control system
Low maintenance and user friendly operation
No oxygenation restriction during test performance
Capacity for different respirograms and simultaneous overlying graphs
Open system with the capacity to modify conditions,


Challenge Respirometer

The Challenge Respirometer System facilitates precision measurement and continuous recording of respiration rates on up to 32 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.

Challenge AER200

Dissolved Oxygen Testing via DOUR/SOUR

The Dissolved Oxygen Uptake Rate (DOUR; mg O2/L/h) test measures the respiration rate of microorganisms by calculating how quickly the biomass consume the oxygen. This test can be completed in a matter of minutes and gives us an idea about how much BOD is available for respiration.  The Specific Oxygen Uptake Rate (SOUR) is the DOUR standardized to the biomass of the solution; it is defined as the milligram of oxygen consumed per gram of volatile suspended solids (VSS) per hour (mg O2/g VSS/h). DOUR/SOUR can be used as a real time monitoring approach to improve process operation and troubleshoot a variety of treatment issues.

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



More Information

Download EBS Surcis Respirometry Brochure

Distributed in the US exclusively by:

Environmental Business Specialists, LLC
Phone: (985) 674-0660
Fax: (985) 674-3483