Evaluation of kinetic parameters for biological CNP removal from a municipal wastewater through batch tests

Biological carbon, nitrogen, and phosphorus removal from wastewater has become an established process in wastewater treatment practice. Despite the broad knowledge and practical experience that has been accumulated in previous years, there are still certain aspects of nitrification-denitrification-biological enhanced phosphorus removal (NDBPR) which require further research. In this study, biological carbon, nitrogen, and phosphorous removal in a municipal wastewater treatment plant (MWWTP) was investigated using batch tests. These tests include: anaerobic phosphorus release, released phosphorus uptake in aerobic, and anoxic conditions, nitrification, denitrification, and endogenous phosphorus release. Two different substrates: acetate and glucose were used in anaerobic P release tests. Average phosphorus release rate was 0.019 mg P/g VSS min for glucose addition and maximal anaerobic P release rate was 1.63 mg P/g VSS min as an average for acetate addition. Following the anaerobic P release test, P uptake tests were conducted for aerobic and anoxic conditions. The average P uptake rates were 0.0031 and 0.0046 mg P/g VSS min, respectively. In nitrification tests, average NO3-N production rate was determined as 0.034 mg N/g VSS min. In denitrification tests with the addition of acetate, average NO3-N consuming rate was 0.026 mg N/g VSS min and with the addition of glucose NO3-N consuming rate was 0.020 mg N/g VSS min. In endogenous P release tests, average P release rate was determined as 0.0025 mg P/g VSS min. Simple batch methods were proposed to determine Y, kd, μmax, and Ks, which are important for NDBPR process design. In biological kinetic parameter estimation, according to the Monod model, Y and kd coefficients were found 0.70 mg VSS/mg COD and 0.0022 h−1, respectively. The specific nitrification rate (qN) and the specific denitrification rate (qD) were determined 6.87×10−4 mg NO3-N/mgVSS/h and 3.36×10−4 mg NO3-N/mgVSS/h. The kinetic parameters determined in this study can be used to improve the design and operation of wastewater treatment plants.