A METHOD FOR TESTING NITRIFICATION INHIBITION CHARACTERISTICS (NIC) IN WASTEWATER

As water quality standards become stricter, more wastewater treatment facilities will be required to implement Limit of Technology (LOT) nutrient removal programs. LOT nutrient removal will require facilities to completely nitrify their wastestream, with little room for error or variability. In these situations, inhibition of nitrification will become a serious design, operational control, and industrial pretreatment program issue. The industry will require reliable methods to identify and quantify inhibition on an ongoing basis.A method has been developed that allows wastewater treatment plant operators, industrial pretreatment personnel, industries, and consulting engineers to test for the presence of nitrification inhibition in real wastewaters in a simple method that provides results that are as realistic as possible. The test method, which is based on direct measurement of NO3-N production, was developed to meet the following criteria:The method should be suitable for use in wastewater samples. Therefore, the method should account for the interferences due to biodegradable COD. For this reason, the control samples should also closely mimic actual wastewater.The method should be able to simulate the plant's actual operating conditions, including sludge, MLSS, HRT, etc.The method should be simple enough for use as a routine testing method at treatment plants. It should be reliable, straightforward and have minimal equipment and instrument requirements.The method was successfully used in monitoring the NIC of the influent and effluent from different processes at a wastewater treatment plant in Maryland for approximately six months. The method provided consistently reliable information to assess the nitrification inhibition characteristics of the tested wastewater and provided valuable input to the process design team.