The Experimental Study Of The Coke Plant Wastewater Treatment By Adding The Immobilized Preponderant Bacilli In A~2/O~2 Process

Coke plant wastewater is a typical, containing high concentration ammoniacal nitrogen, and difficult biodegradational industry wastewater. The traditional method to deal with the coke plant wastewater is a means using by the active dreggy mud, which has less effect on the hard-degraded substance and ammoniacal nitrogen. According to characteristic of the coke plant wastewater, the paper studied the nitrogen removal mechanism and effect in detail by A²/O² process, during which also added the immobilized preponderant bacilli at the process of O₁ and made the systemic study of wiping off the high chroma COD, to treat the coke wastewater of the second coke plant which belongs to one of coal gas company in Taiyuan.The paper experimental results demonstrated: the average level rate of the inpouring coke plant wastewater could reach 5.5L/d by A²/O² process of adding the immobilized preponderant bacilli. The influent COD concentration could reach 817.4¹874.2mg/L and ammoniacal nitrogen could reach144.4⁶87.93mg/L. On the condition that the water could the level of PH 7.0⁸.2 and the average rate of circumfluence was 3.27, the effluent COD and NH3-N removal rate concentration could achieve 93.65% and 97.22% respectively.By comparation between a variety of methods of immobilized, the final decision of this examination used for immobilization of polyvinyl alcohol (PVA) - borate-embedded. The advantage of this method is, PVA have low prices, and the method is easy to operate; the effect of introduction of dium alginate is good, and its protection microorganisms play a role in the and reduce the toxicity of boric acid, and this can improve the relative activity of microorganisms; it is easy to do solid-liquid separation, and be propitious to the next step that help to carry out the tests applied to industrial production of research.The key stage of the process controlling was aerobic reactor (O₁), in which put the immobilized predominance bacterium could control the last effluent COD and let it reduce quickly. The experimental result showed: the temperature of the effluent wastewater was 25.7²7.8℃, the pH value was 5.9⁷.3, the chroma of DO was 2.9⁶.1mg/L, alkalinity was 366.67⁵98.12 mg/L(measured by CaCO3), the COD was 126.7²01.5mg/L(the average was 172.1mg/L), the HRT was 16.76²1.55h(the average was 18.21h),the average removal ratio of COD was 52.79%. Before adding the immobilized predominance bacterium, the average removal ratio of COD was 48.53%. So, adding the immobilized predominance bacterium made the average removal ratio of COD increase 4.26 percent.After the experimentation the whole operating parameters had been got (This parameters was got by the best value when the average reached). Due to the result of this experimentation was adding immobilized predominance bacterium in the aerobic reactor O₁ only, others had no changed, only got the statistical parameters of O₁. Results as follows: When the reactor temperature is above 26.5℃, pH is 6.8, HRT is 18h, DO is 5mg/L at the time of the highest COD removal efficiency.It will make the chroma of effluent COD reach the secondary national standard (COD<150mg/L)about"The standard of sewage comprehensive discharge"(GB8978-1996) to adopt the anaerobic-anoxic-aerobic-aerobic biological reactor(A²/O²), in which put immobilized predominance bacterium to deal with coke plant wastewater when the chroma of effluent of COD increases constantly. This technology is technique feasible and has stable effect.