| The coking waste water is high in noxious substance content and bad in biodegradability. It is harm to the environment greatly. Most coking waste water which is treated by conventional biological process can't meet the discharge standard. Although the effluent dealed with physics or chemical process could meet the demand of drainage by environmental protection, the operating cost is too high to be accepted by enterprises. In recent years, the effective and improved craft of low devotion becomes focal points to be studied.Taking the coke plant wastewater as the study subject, the Anaerobic-Anoxic-Biological aerated filter system(A1-A2-BAF) was adopted in dealing with coking waste water. The BAF reactor could be utilized as an anaerobic reactor and an anoxic reactor. Part of carbons oxidation, nitrification and denitrification went in the same reactor without sludge refluence.In this process, COD and NH3-N could be removaled preferable. When HRT equaled to 21h, r was between 3 to 4, the COD of effluent was reduced to 139.9mg/L, the NH3-N of effluent was reduced to 7.41mg/L, without carbon source and alkali source. The removal rate of COD and NH3-N could achieve to 85.74% and 96.17% respectively. The quality of effluent from A1-A2-BAF system could meet the secondary national standard about wastewater discharge (GB8978-1996). Namely, COD was not higher than 150mg/L, NH3-N was not higher than 25mg/L. The removal rate of NH3-N was kept above 95%, the effluent could reach the first class standard ensured. All appearance, this system was efficient and stable in COD and NH3-N reductions. This craft was feasible.The experiment result indicated that: the anaerobic hydrolytic in A2 reactor could advance the biodegradability of coking wastewater, and it also could offercarbon source needed in A2 reactor. A majority of organic material degraded in BAF by the effect of biofilm. With the help of nitrobacteria, nitrification was implemented in BAF. The effluent from BAF mixed with the effluent from A1, and then entered A2 eactor to be denitrificated. NO3- -N and NO2- -N were transformed to N2 discharged in A2 reactor.The effect of pH, temperature, HRT, r, organic loading etc. to A1-A2-BAF system were saw in the experiment. Trouble situation in the actual production was also simulated in the research. In the end, the cost of A1-A2-BAF system was estimated and compared to A-O and A1-A2-O system.The experiment result also indicated that: this craft could still keep the treatment result steadily when the quality of influent changed greatly; it coulcl resume production comparatively fast after the trouble. After a few days working, the dealing ability of BAF could be resumed through backwashing.A1-A2-BAF system is easily in production management and lowly in expenditure. It will be used widely in future.
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