Improving Wastewater Treatment Plant Operations via Respirometry

Respirometry is a laboratory tool frequently used by Environmental Business Specialists (EBS) to generate different types of information that we utilize when consulting for our clients. There are several types of respirometry units on the market, each with the ability to generate certain pieces of information yet not all the pieces needed to obtain the entire picture.

As background, respirometry is a tool that helps wastewater engineers understand and optimize their treatment systems. By acting as a surrogate for full scale changes to the operation of a system, respirometers allow the user to refine operational parameters without fear of permit violations and in a way that can ultimately make the system more efficient.

Due to the number of wastewater treatment system designs in operation as well as the variety of information people desire to learn, different types of respirometers are necessary to accurately model the systems. Surcis BM Respirometers are batch types systems best suited for wastewater systems that operate in batches instead of continuous flow. Eckenfelder reactors are best suited for continuous flow aerobic activated sludge systems. Challenge-type respirometers are general purpose batch systems best suited to aerated stabilization basin systems and tests where large numbers of variables are being studied.

Environmental regulations and business needs drive the demand for treatability results

Increasingly stringent environmental regulations are propelling the treatability market as industries seek to lower their environmental impact. And there is not likely to be a relaxation of these regulations. With TMDL requirements looming and increasing consumer environmental awareness, many industries are finding the need to optimize treatment efficiency to reduce COD/BOD and nutrients in effluent. Additionally, the toxicological effects of new and existing chemicals on the activity of the secondary system bacteria are a prime concern. Studies focusing on the effects of process chemicals in wastewater treatment systems are an important focus point for EBS as we troubleshoot biological system issues.

From the business perspective, companies continue to move process streams from one plant to another, introduce new streams to their plant and wastewater systems, modify current processes or chemicals utilized, or increase/decrease stream strength or amounts. All these changes impact the wastewater treatment system and its biology, which in turn, impacts the company’s ability to maintain permit compliance.

 The particulars of respirometry

Challenge respirometers and similar units are good general purpose closed systems. Their advantage lies in their ability to measure respiration in multiple test vessels simultaneously. The availability of many test vessels allows the user to study many variables. These units allow one to evaluate the impact of different products and dosages on the bacterial population’s ability and rate to reduce BOD levels. The Challenge respirometers work well with clients that have aerated stabilization basin (ASB) wastewater treatment systems.

Eckenfelder-type flow through reactors allow lab personnel to model many types of wastewater systems in a more accurate manner than Challenge and Surcis respirometers. These units allow for continuous feed of influent at the same rate as the system in question. Like the Surcis respirometer, in vitro changes can be done to simulate actual process changes.


EBS currently utilizes Challenge and Eckenfelder-type units in our treatability lab to obtain data on the impact of various wastewater treatment plant scenarios. Although not a basic manufacturer of respirometry systems, EBS’s position as a leader in wastewater treatment consulting, troubleshooting, testing, and optimization allows us to recognize the strengths and weaknesses of each unit and design studies that mimic wastewater treatment systems as accurately as possible.  The goal — to obtain specific data our clients need to run their plants effectively and make business decisions.

EBS currently performs treatability studies as part of our comprehensive wastewater treatment system evaluations or as a standalone laboratory service. As a major U.S. consultant to plants with wastewater treatment systems, EBS has invested in the diverse respirometry tools currently available to support our client’s need for information in order to manage their risk associated with running the WWTP.

Learn about the microorganisms in your wastewater treatment system.