| Power consumption caused by biological wastewater treatment systemsis the major expenditure during the decentralized wastewater treatment plantrunning. More flexible layout of decentralized wastewater treatment systemshave been widely used in some remote areas in China, especially in ruralareas. But the wastewater treatment facilities constructed by the governmentdid not operated properly due to lack of funds. In recent years, with thedevelopment of new energy, solar energy is considered to be one of the mostpromising new energy. Combined with the step feed process could beflexible adjustment to the laws of the discharge of sewage influent, thebiofilm process had a strong impact resistance for the decentralizedwastewater. The purpose of this paper is aimed to establish a step feedintegration of biofilm wastewater treatment reactor using solar energy andreducing the running costs of the sewage treatment system, to providetechnical support for decentralized rural sewage treatment.In this thesis, solar energy resources of Beijing was investigated byliterature research and field monitoring. The capacity of photovoltaic powergeneration system had been calculated according to the energy consumptionof the reactor. To made full use of solar energy resources, four differentenergy consumption levels of sewage treatment mode had been established.With the battery voltage as input variables, PLC(Programmable LogicController) automatic control system would select the mode of operation ofthe corresponding energy consumption rating. What’s more, differentinfluent loading, the C/N rate, temperature and different fillers which wouldeffect sewage treatment efficiency were studied to optimize the operatingconditions of the reactor. The main results are as follows: （1）The periodic variation of the solar radiation intensity wasinvestigated in literature research and field monitoring in this study. Theresults showed that: the solar radiation intensity distribution in the Beijingarea is about4686MJ/m2～5690MJ/m2a year. The annual average sunshinehours are amoung2000to2800h. Capacity of PV modules: the number ofsolar panels in series were two, parallel numbers were4. Considering thecharge margin,10solar panels were selected with the way of two bunchesconnection. The size of the total power was1350W. The storage battery inthis study only played a role as a buffer capacitor capacity whose size was100Ah.（2）In the method of gaining the automation and control parameters,by monitoring the voltage of the buffer capacitance changes, access toreal-time voltage introduces PLC automatic control system to achieveautomatic control and distribution of photovoltaic electricity. While thevoltage was23V≤U＜24V, the reactor chose the low energy comsuptionmode. While the voltage was24V≤U＜25V, the reactor chose the middleenergy comsuption mode. While the voltage was U≥25V, the reactor chosethe high energy comsuption mode. While the voltage was22.5V≤U＜23V,the reactor chose the night energy comsuption mode.（3）When the flow of step feeding integration reactors are5.25L/h,3.25L/h and1.25L/h, the load distribution was called uniform and removalefficiency improved significantly. The removal rate of CODCr, NH3-N andTN were92.5%,68.68%and59.8%respectively. The ratio of C/N and watertemperature were the main parameters which affected the removal efficiency.（4）Sewage treatment in the operating mode of the high energyconsumption was better than middle energy consumption and low powerconsumption. The swage treatment efficiency of middle energy consumptionwas similar to the low power consumption operation mode. The night modeonly when the solar radiation intensity was very low, and its removalefficiency was not considered. Solar power automation control and powerdistribution automation control program to switch between the variousmodes. At the beginning of30days, removal rate of CODCrreached to90%with the effluent concentration amoug25to40mg/L, NH3-N and TN removal rate were16%and22%. After30days, pollutants removal effectgradually increased and removal rate of NH3-N and TN is from the early16%and22%up to81%and78%, the CODCrremoval rate was still above90%.（5）Within two weeks after vaccination biofilm, CODCrremoval rateof three types of filler were high with the effluent concentration of20mg/L.Nitrogen has not detected in the effluent of soft stuffing and hollow spherepacking. The total nitrogen removal of the pre-vaccination due to the softfiller easily attached to the adsorption, pre-training is better than the othertwo, while in the late days, due to the hollow ball packing had a largersurface area which provides greater habitat and attached to the space for themicroorganisms, the microorganisms attached to rapid growth and removalefficiency gradually increased.Based on the above results, solar-powered integrated step feedingbiofilm reactor could be effectively combined with changes in solarradiation intensity under automation ontrol systems, and it could select thecorresponding energy consumption level of sewage treatment modeautomatically. The removal rate of CODCrwas above90%, NH3-N and TNremoval rate were81%and78%. Stand-alone PV systems can be completelyout of the municipal power grid. Sewage treatment problem of high cost ofpower consumption had been solved and it provided a technical support fordecentralized rural sewage treatment. |
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