Research On Coke-plant Wastewater By Anaerobic-Anoxic-Oxic Process

Coking waste water was the sewage of coal and coke industry, the volume of water changes more than others, the water quality change was also particularly tortuous and typical, there were a large variety of pollutants, including a large number of biologically useless toxic ingredients which were difficult to be degraded, the concentration of COD and ammonia nitrogen was high, water quality was very difficult to pass with the general selection process usually biological disposal, causing serious harm to the whole ecosystem. According to the calculation, the satisfactory effect of efflux coal tar waste water of coking enterprises in China had only 10%, which are up to standard, Therefore, the urgent need was to address governance problems in current coking waste water, go environmental friendly way.Facts that effluent of the coking waste water had significant effect by the process A/A/O method, the anaerobic, anoxic and aerobic three part combination were inclued in A/A/O process, at the same time the practice of testing the waters, the effluent can reach the expected standard after the testing of A/A/O process treatment,besides, the process also was conducive to the upgrading and transformation of the original processing device.After the domestication and cultivation of two stages of 50 d, the COD and the ammonia nitrogen and the degradation of the effluent were good, the water quality remained stable, and the A/A/O reactor was started. So on the selection of A/A/O process for coking waste water, it is completely feasible.Through tests and taking samples, the hydraulic retention time(HRT), pH, dissolved oxygen(DO), mixed liquor reflux ratio(R), the sludge reflux ratio(R) and other factors of pollutant removal effect of contrast were studied, including stable operation of the variation along the pollutants in the process,besides, the suitable condition of stable operation of A/A/O process system was discussed. When the average concentration of influent COD was 5600mg/L and the average concentration influent ammonia nitrogen was 118mg/L, HRT was 80 h, influent pH is 7.5, DO in the aerobic phase was 4 mg/L, the return mixed liquid ratio was 4, the return sludge ratio was 0.5, the treatment effect was best, effluent COD average concentration was 108mg/L,The average concentration of ammonia nitrogen was7.3mg/L, the rest of the pollutants can reach the indirect emissions standards, the device processing effect was better.By GC-MS, a lot of material in coking waste water can be very accurate qualitative separation, chromatographic peaks can be detected. after A/A/O process, the highest content of p henols in the water had almost all removed, the nitrogen heterocyclic organic compounds in water such as quinoline and indole organics were also removed, water surplus materials mainly chain alkanes(ester) and substituted benzene. phenol and its derivatives(raw water accounts for about 95%)were mainly included In the organic components of raw water, followed by quinoline, indole(raw water accounted for 2.8% or so) as the representative of nitrogenous heterocyclic compounds, the types and composition of organic matter complexity with organic matter(removed) were gradually decreased. Phthalate lipids and containing nitrogen compounds in water, these substances are difficult to degrade, which belongs to the degradation of coking waste water by high molecular organic compounds,as the product of microbial metabolism and the form of biochemical effluent COD, ammonia nitrogen mainly exists.