How to better select two-stage biochemical treatment facilities to achieve a COD effluent level of 50 mg/L
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How to better select the combination of two-stage biochemical treatment facilities to achieve effluent parameters of 50 mg/L for COD and 25 mg/L for ammonia nitrogen. The influent to the biochemical treatment facility has a COD level of 800–1000 mg/L and an ammonia nitrogen level of 60 mg/L. If it is refinery wastewater and an Oberle oxidation ditch is already in use, it is necessary to decide whether to install a first-stage biological treatment unit before the oxidation ditch or a second-stage biological treatment unit after it. Please discuss which approach would be better.
Please provide a detailed description of the components in wastewater; for some organic components, biochemical treatment can only reduce the COD level to 200–300, and further reduction is very difficult to achieve.
For refinery wastewater, the COD level can currently be around 100; in the best cases it can reach 80, while the BOD is around 30
Two-stage biochemistry? Hydrolytic acidification, A2O