Current application of clean water aeration test standards for wastewater treatment systems is based on the most commonly and internationally used standards for the clean water test, such as the ASCE(USA), CEN(EU/EFTA), and DWA(Germany). All the standards are mostly unified in respect to the methodology employed to calculate the oxygen mass transfer coefficient K La, in the use of a non-steady state method or a variation of such; in the use of sulfite deoxygenation or a variation of such to give a zero starting point; in the use of probes or a variation of such to measure step change of dissolved oxygen concentration; and, in the use of the non-linear regression method of analysis or a variation of such to estimate the transfer parameters. But there are differences between the various standards, and therefore, there is a need to reconcile all the standards for the benefit of mankind. In particular, this paper addresses a problem common to all the standards, which is the application of clean water test result to in-process oxygen transfer rates, as a first step in the attempt of unifying the standards. In particular, this paper mainly applies to a diffused system but the proposed concept of gas-side oxygen depletion should be applicable to all kinds of aeration systems even for non-submerged aeration equipment.

For any wastewater treatment aeration tank, the paper presents a technique to deal with oxygen uptake rate (OUR) measurements that is primarily related to the biological uptake rate. he proposed dilution vs. the “shake it up” aeration approach to avoid shearing the floc which may increase the OUR artificially, jeopardizing the true measurement in the aeration tank. when the level of dissolved oxygen in the medium falls below a certain point, the specific rate of oxygen uptake is also dependent on the oxygen concentration in the liquid. Since it measures the rate at which oxygen is used, it is a useful tool to evaluate process performance, aeration equipment, and biodegradability of the waste. The OUR is a fundamental physiological characteristics of culture growth and has been used for optimizing the fermentation process, and so it needs to be measured accurately. Oxygen uptake rate (OUR) is the microorganism oxygen consumption per unit time and is one of the few accessible parameters to quantify the metabolism rate of the activated sludge in a wastewater treatment plant. To alleviate the many problems of measurement, the proposed method using dilution with saturated DO may give a more accurate measurement than the current standard method using a sample shaking technique as described in APHA 2017. With a more accurate measurement of the OUR, it may lend credence to justification for the modification of the fundamental equation for oxygen transfer in a respiring system, as applied to an example provided by ASCE/EWRI 18-18

This paper addresses a problem common to all the standards, which is the application of clean water test result to Process Oxygen Transfer Rates. By modifying the conventional model used by the standards for this application, and if proper OUR (oxygen uptake rate) methods can accurately determine the respiration rate, this paper attempts to show that the clean water tests can be used to determine the oxygen transfer efficiency of an aeration device in the field. The new model is based on previously developed mathematical models, and also based on the novel concept of a resistance to gas transfer due to microbial activity in the field. It is postulated that the relative mass transfer coefficient, α (alpha), the ratio of mass transfer coefficient in wastewater KLaf to mass transfer coefficient in water KLa, is independent of microbial activities. The field-determined OTEpw is mathematically associative to the transfer process by addition.