Startup And Testrun Of Anaerobic Reactor In A₁/A₂/O₁/O₂ System For Coke Plant Wastewater Treatment

The feasibility of the novel fixed bioreactor anaerobic-anoxic-aerobic-aerobic system for treatment of coke plant wastewater has been tested at pilot-scale in TongShiDa Company. In this system, the anaerobic process acted as a pretreatment for partial degradation of some refractory and inhibitory organic compounds. Through anaerobic reactor, organic compounds with complicated structures and large molecules in coke plant wastewatercould be partially converted into more biodegradable organics. More suitable wastewater could be supplied to later reactors.The results of biofilm culturing showed that: the hydrolysis acidification bacterium's generation time is short, adsoroption ability is feeble,so it needed longer time to cultivate and multiplicate the bio-film,once the pH and COD concentration of the wastewater changed, the hydrolysis acidification bacterium would be impacted strongly, and the running effect of anaerobic reactor was also influenced severiously. When the system influent temperature was about 30℃ and 3-6mm light granular ceramics as carrier of anaerobic-reactor, it took 40d to form the principial biofilm by the combination of naturally culturing and artificially culturing with seeding .The results of test-run revealed that: The anaerobic reactor achieved 15% COD average removal and 9.7% BOD average removal at a hydraulic retention time (HRT)of 7.5h. The ratio of BOD to COD was enhanced about 0.15 while the influent BOD/COD range was 0.16—0.26 and the effluent BOD/COD range was 0.30~0.42.The max effluent BOD/COD could attain 0.42 by 0.19. The effluent quality of anaerobic reactor was high as long as the influent temperature was above 20 °C , when ifluent temperature changed within 20 °C ~ 35 °C ,it had little influence on the COD removal efficiency. The optimum influent temperature range was 25 °C ~ 30 °C, and the optimum pH range was 7.2~7.8oIn test-run phase, Bioreactor system effluent COD and NH3-N concentrations had attained primary and secondary national standard about wastewater discharge GB8978-1996? respectively.