Restaurant Waste-water Depth Treatment By Moving Bed Biofilm-Membrane Process

This paper focused on developing a treatment technology of restaurant waste-water, which serves as an primary pollution source of urban sewage. The objective was to achieve the reuse of restaurant waste-water in this paper. Restaurant waste-water was difficult to treat, since they were usually discharged from sporadic sources, containing high content of organic components, and changed frequently in the amount of discharge. In order to realize reclaimed water reuse in restaurant wastewater, we setup a set of new complex sewage treatment device by integrating a moving bed biofilm treatment device with a microfiltration membrane. A series of restaurant wastewater treatment experiments were carried out, mainly discussed the effects of raw water load, aeration rate, hydraulic retention time, temperature and pH on restaurant wastewater treatment. Comparisons with traditional sequencing batch type biological reaction processes(SBR) demonstrated that the feasibility of new process used for reclaiming water reuse of restaurant wastewater. Moreover, a comprehensive evaluation about this new process was performed in this paper. The technology will lay the necessary theoretical and experimental foundations for promoting technology development for reclaimed water reuse in our country and establish efficient process for restaurant wastewater treatment technology.The research results showed that:(1) The cultivation and domestication cycle of moving bed biofilm-membrane reactor is rather long, which would last about2months. Once the biofilm hanged successfully, the system can achieve efficient processing of restaurant wastewater, removal rate for COD remains above80%;(2) By implanting microfiltration membrane into moving bed biofilm-membrane reactor, it not only can effectively improve the resistance to impact of system, but also can improve on the depth of sewage treatment system. As a result, the quality of discharge water can be improved;(3) Among the factors that affect the performances of the treatments, aeration rate and hydraulic retention time play the most important role on the removal of COD, ammonia nitrogen and total phosphorus. The optimal aeration rate and hydraulic retention time of moving bed biofilm process and moving bed biofilm-membrane reactor are0.4m3/h and12h, respectively. Under optimal condition, the former’s removal rate of COD, ammonia nitrogen, total phosphorus and turbidity can reach91%,89%,89%and85%, respectively; The latter process can reach95%,94%,94%,92%, respectively. When we use SBR process to treat the restaurant wastewater, we can get the best result with the aeration rate and hydraulic retention time of0.45m3/h and14h, respectively. At the same time, the removal rate of COD, ammonia nitrogen, total phosphorus and turbidity reached92%,85%,89%and87%, respectively. Both oxygen and hydraulic retention time can affect the treatment effect of the reactor;(4) The temperature of raw water and the value of pH also have a great influence on the efficiency of each operation of the system. When the temperature of water is about30℃, the weakly alkaline environment created by the water is more conductive to the growth of microorganism and the removal of ammonia and phosphorus. The effect of the temperature on the system capacity is mainly reflected on biological activity. When the temperature is too low or too high, it will inhibit microbial growth or even lead to their death. The value of pH has a great influence on removal of nitrogen and phosphorus in the system. However, acidic environment will inhibit its nitrogen and phosphorus removal reactions;(5) After the moving bed biofilm-membrane process, each quality indicators of water can achieves the Level1urban sewage discharge standard, and it also can meet the requirements for reclaimed water reuse in restaurant wastewater.