Research On Energy Consumption And Sludge Anaerobic Digestion Of Xi'an Fifth Wastewater Treatment Plant

According to the statistical analysis of actual energy consumption data in Xi'an Fifth Wastewater Treatment Plant(WWTP),the average power consumption of the plant was 0.288 kW�h/m3,of which the energy consumption of pretreatment unit,secondary treatment unit,sludge treatment unit account for 24.87%,58.88% and16.26%,respectively.The total energy consumption of water pumping station and aeration system of biochemical reaction pond accounts for more than 55%.Therefore,optimizing the working conditions of water lift pumps and blowers will save much energy and the corresponding optimization measures are put forwarded.On the basis of the actual operation parameters of the sludge anaerobic digestion system,biogas production in actual operation of sludge digestion tank and actual utilization of methane are investigated.The results show that the test biogas production rate of digestion tank is 8.5 m3/m3 sludge and biogas production of decomposing unit VSS is 1.186 L/g,which is showing a satisfactory biogas production capacity of sewage sludge;The biogas consumption of biogas boiler,methane air blower and biogas buring tower accounts for 41%,33% and 26% of the total production respectively,which is showing a low biogas utilization ratio.Thus,it is recommended to intensify maintenance of methane air blower and improve gas production rate and utilization ratio of biogas to reduce energy consumption of wastewater treatment plant in operation.WWTP carbon emissions and carbon emission reduction of sludge anaerobic digestion were calculated.The total amount of carbon emissions during the accounting period of the WWTP is 151432 tCO2 and the amount of carbon emissions from the unittreated water is 2.32 kgCO2/t.The annual carbon emission reduction of sludge anaerobic digestion system is 885.4tCO2,which is equal to 0.194 tCO2/tDS.The carbon emission reduction level of unit sludge is low and has great optimization potential.Sludge anaerobic digestion system and biogas utilization equipment in a good working condition can greatly reduce the energy consumption of WWTP and improve the utilization of sludge resources,and also can greatly reduce the CH4 emissions of WWTP and follow-up sludge disposal,which has a significant effect on energy saving and carbon emission reduction.From the perspective of low-carbon development and the response of climate change,large and medium-sized sewage treatment plant should promote sludge anaerobic digestion process.