Dear lan, 1.the volume of anoxic and oxic tank both is about 10,000 M3, jet or diffuser type mixed reactor. the Inflow is about 20,000 M3/D, the MLSS of both process is 3,000~4,000 ppm. 2.the COD of influent is about 1,000 ppm, the COD of effluent is less than 80 ppm, the COD reduction rate is all right in the high or low DO of the oxic process. 3.the NH3-N of influent is about 30 ppm, the TKN of influent is about 60 ppm, the NH3-N of effluent is 10 ppm or higher, and the NO2-N produced in the high DO case, while we lower the DO to ~3 ppm, the NH3-N of effluent is less than 3 ppm, the NO2-N is disappear and NO3-N produced in the low DO case. 4.we check the sludge by NGS (Next Generation Sequencing), and find some clue, but we still not know what happen due to the change of DO in the oxic tank.
Published by Lin JYH-YAN, advanced engineer at FORMOSA PETROCHEMICAL CORPORATION
Dear lan,
1.the volume of anoxic and oxic tank both is about 10,000 M3, jet or diffuser type mixed reactor. the Inflow is about 20,000 M3/D, the MLSS of both process is 3,000~4,000 ppm.
2.the COD of influent is about 1,000 ppm, the COD of effluent is less than 80 ppm, the COD reduction rate is all right in the high or low DO of the oxic process.
3.the NH3-N of influent is about 30 ppm, the TKN of influent is about 60 ppm, the NH3-N of effluent is 10 ppm or higher, and the NO2-N produced in the high DO case, while we lower the DO to ~3 ppm, the NH3-N of effluent is less than 3 ppm, the NO2-N is disappear and NO3-N produced in the low DO case.
4.we check the sludge by NGS (Next Generation Sequencing), and find some clue, but we still not know what happen due to the change of DO in the oxic tank.
1 Comment
Hi Lin, my first thought was that you may be getting some anoxic conditions within the MLSS flocs at the lower DO levels, but it seems the literature does not support this theory. The fact that you get some nitrite in the higher DO conditions seems to imply the temperature of the wastewater is quite high (>25 degrees C), which may also affect other biological processes. Lastly, having a single mixed aerator is not normally ideal for nitrification. If possible try to install baffles to divide the reactor and obtain more of a plug flow condition, but test this out on a laboratory scale first. Best wishes
Published by Ian Pearson