| Coke-plant wastewater is typical toxic pollutant, which is degraded with difficulty. The effluent of coke plant greatly pollutes environment in our country, because concentration of ammonia nitrogen is much higher than standard level. Stable and good results are obtained to treat coke-plant wastewater by being pretreated with iron scrap-anaerobic-oxic-oxic-anoxic SBR process via nitrite pathway. The removal efficiency of NH3-N and COD is high. When the concentration of NH3-N and COD in influent is 601.8mg/L, 2307.6mg/L respectively, the concentration of NH3-N, COD in effluent is 12.3mg/L, 85.6mg/L respectively, and the removal efficiency of COD and NH3-N is 97.9%, 96.3% respectively. Compared with anaerobic-anoxic-oxic continuous process, the process in this paper will be reduced by 20% in volume and 30.8% in power consumption. When iron scrap method is used to treat coke-plant wastewater, the removal efficiency of COD comes up to 35.8% on condition that the addition of coke, NaCl and iron scrap is 50g/L, 300mg/L and 200g/L respectively in wastewater. After wastewater is pretreated by iron scrap method, the ratio of COD/N lowers, nitritation process will be carried out much earlier, which is beneficial to shortening the total aeration time. Nitrosomonas is successfully cultured in two aerobic reactors in this paper. Experimental results show that two-stage SBR is superior to one-stage SBR at the same hydraulic residence time. Stable nitritation is realized because the nitrobacter is sensitive to the changing environment. When the dissolved oxygen and pH values in SBRâ… and SBRâ…¡are 2.4-3.0mg/L,7.0-8.5, 1.5-2.0mg/L and 7.0-8.5 respectively, a lot of nitrate isn't found during operation in two months ,and nitrosation rate is over 80% in two aerobic reactors.The mixture of aerobic and anaerobic sludge is used to culture denitrifying bacteria using ammonium as donors in anoxic reactor. The aim of NH3-N degradation in anoxic reactor is achieved. In order to intensify the nitrogen removal via simultaneous nitrification and denitrification pathway, anaerobic sludge containing denitrifying bacteria is enclosed in many pieces of cloth and made into many little balls. These balls are hung in an aerobic reactor. It isn't easy for dissolved oxygen to penetrate them, which will offer good anaerobic and anoxic conditions in ball and simultaneous nitrification and denitrificationwill take place more easily than in other methods. Nitrogen removal rate increases with COD/N, but the oxidization of ammonium will be inhibited and nitrogen removal rate will decrease when COD/N is too high. Nitrogen removal rate increases with dissolved oxygen, but the anaerobic area will decrease and nitrogen removal rate will decrease because of the balance being broken between nitrification and denitrification when dissolved oxygen is too high. The experimental results show that the nitrogen removal rate is the highest on condition that the rate between aerobic and anaerobic sludge and COD/N and the value of dissolved oxygen are 2:1,2.3,1.8-2.4mg/L respectively. The quality of water is unstable in oxic and anoxic reactors. If the quality of wastewater can be predicted, operation will become much more easier and that the process is controlled by computer will be easily realized. A three-layer simple recurrent neural network model is proposed to accurately predict the quality of wastewater in the first and second oxic reactors and the anoxic reactors, and the individual average fractional error is 2.86% and 4.99% and 4.2% respectively.
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