Study On Moving Bed Biofilm Reactor For Coal Chemical Industry Wastewater Treatment

China’s coal resources are abundant, the energy consumption is dominated by coal and the proportion of consumption by up to70%, while oil and gas is relatively small. In recent years, the coal chemical industry is developing rapidly in order to alleviate the contradiction between supply and demand effectively. However, the operation of the coal chemical enterprises will bring a large number of refractory organic wastewater if there is no effective treatment, and will bring some problems such as damage to corporate image、environmental pollution and so on, therefore, it is particularly important to develop cost-effective coal chemical wastewater treatment technology at the present stage.At present, we usually use biochemical methods to treat the coal chemical industry wastewater, but due to the water quality fluctuations、oily、high temperature and other characteristics, the secondary effluent is not up to requirement and the efflux will cause river pollution, advanced treatment will impact to the follow-up processing unit. This study will focus on characteristics of the secondary effluent from the Olefin Company, Shenhua Group:low COD concentration, low C/N, poor biodegradability, many kinds of organic pollutants and other miscellaneous.we take multipolar moving bed biofilm reactor (MBBR) to improve the effluent quality indicators cost-effectively, such as COD、NH4+-N and other indicators by use of four different processing units. And these are for stabilizing the water quality to the depth of processing unit, reducing the handling risks and pressures of the two-film workshop, saving the post-operating costs; at the same time, this study take the scanning electron microscopy (SEM)、PCR-DGGE technology to analysis the different characteristics of the biofilm surface of the each MBBR functional area as well as the differences of microbial communities, to establish a research tool to compare different biological treatment system from the microbiological point of view. Through which to explore the feasibility of application for the coal chemical industry wastewater by use of the MBBR process, to provide a new way for wastewater treatment in Olefin Company, Shenhua Group and relevant experience for the similar problems in the other enterprises. The results of this thesis include the following:1)When the HRT of9.82h, the influent COD concentration of350-500mg/L, the effluent COD concentration can be stabilized at about100mg/L, the lowest up to52mg/L, the overall removal efficiency of75%, the highest overall removal of the loadingup to the1.17kgCOD/(m3·d), and these can meet the design requirements, which MBBR1decarburization strongest stable at around50%; however, the system for ammonia removal efficiency is poor, and there is little change before and after the adjustment of process parameters, when the influent concentration change within the range of6.38-107.5mg/L, the effluent concentration of5.13to98.1mg/L; finally, when the influent ammonia concentration of7.39to36.1mg/L, the effluent concentration of5.13to30.04mg/L, the removal rate can be stabilized at around30%, therefore, the device for the removal of ammonia should be improved, because of influencing factors are more complex, you can consider adding chemicals into effluent of MBBR4, coagulation and sedimentation to remove ammonia and improve water quality.2) The device is very good for the removal of phosphorus and turbidity, TP removal rate will eventually stabilize at more than50%, the overall removal efficiency of80.77%, when the inffluent TP concentration of0.032to4.02mg/L, the effluent concentration of0.019to2.08mg/L; when the inffluent turbidity concentration of50to80NTU, HRT for9.82h, the effluent concentration of9to25NTU, the removal rate eventually stabilized at about75%, the effluent concentration can be maintained at about15NTU.3) By scanning electron microscopy analysis show that:the flora characteristics significantly different in each functional area of the MBBR, aerobic segment to the rod-shaped bacteria, and spherical bacteria in the hydrolysis、the anoxic dominant; in aerobic condition, asking for little of the survival of rod-shaped bacteria on the substrate concentration, dissolved oxygen is the key factor to limit its growth, the substrate concentration is the limiting factor for growth of spherical bacteria; in hypoxia or anaerobic condition, the spherical bacteria’s survival does not depend on substrate concentration, dissolved oxygen is the key factor to limit its growth.4) Can be obtained by PCR-DGGE technology and the sequencing analysis of some characteristic bands, it has significant difference in four DGGE profiles separation mode, in addition, different operating conditions, processing technology, and culture environment can affect the turnover of the microbial community and part of the dominant florachanges in the status; abundance and diversity of the biofilm microbial populations are significantly higher than the activated sludge system, the diversity index and richness index in the same trend, and changes in the dominance index is just the opposite; the dominant species in each functional area of the MBBR are significantly differences, in view of the water quality of coal chemical industry wastewater, a number of dominant species can be cultivated and domesticated which can degrade recalcitrant organic matter such as oils, olefins, benzene ring, heterocyclic and so on, the dominant flora in biofilm system is richer than the original CAST pool, and the treatment effect is therefore more stable and efficient.