Pilot Trial Research Of Denitrification Deep Bed Filter And Bioleaching Process Of Sludge Conducted In Nanning Jiangnan Sewage Treatment Plant

According to the requirements of relevant national policies,it is an inevitable trend for upgrading and reconstruction of sewage plants(reaching grade A standard)and effectively dispose of sludge and realize utilization of the sludge.At present,the effluent index of Jiangnan Sewage Treatment Plant in Nanning is conducted according to first-grade B standard.According to the first-grade A standard,COD and BOD5 in the effluent index could reach the first-grade A standard stably,while TN,TP and SS could not.Therefore,the key to achieving the standard of grade A is to further reduce SS and control TN and TP of effluent.In addition,the sludge produced by Jiangnan Sewage Treatment Plant is dehydrated by belt filter press,with a water content of about 80%after dehydration.Reducing water content is the key to realize harmless and resource utilization of sludge.After the preliminary investigation,the denitrification deep bed filter process is to be used to treat the effluent of Jiangnan Sewage Treatment Plant in depth,and the sludge Bioleaching and deep dehydration process is used to reduce the sludge moisture content.In addition,in order to further verify the applicability of the two processes in Jiangnan Sewage Treatment Plant,a pilot test was conducted to verify the deep treatment effect of denitrification deep bed filter and deep dehydration effect of sludge bioleaching.The result shows that:(1)The removal effect of denitrification deep bed filter on TN,TP and SS is obvious:After the addition of carbon source and PAC phosphorus removal agent,the removal effect of SS was obvious.SS in water was less than 10mg/L,and SS in most cases was less than 5mg/L.When adding carbon source according to the ratio of sodium acetate to TN removal of 5.5:1,the removal effect of TN was the best,and the COD value of water was not affected by the addition of carbon source.In the absence of phosphorus removal agents,the biological effect of the filter tank has a certain removal effect on TP.After the addition of PAC phosphorus removal agent,the TP removal amount was increased,and the TP value of the effluent was stable below 0.5mg/L.In addition,while TN,TP and SS were removed,COD and BODs could also be filtered out in the deep bed filter,thus reducing COD,BOD5 and other organic matter indexes of the effluent.The effluent can be ensured to stably meet the requirements of class A standard of Urban Sewage Plant Pollutant Discharge Standard(GB18918-2002).(2)Bioleaching sludge treatment technology has obvious effect on sludge dehydration:When the bioleaching reaction time of sludge in Jiangnan Sewage Treatment Plant is between 40 and 44 hours and the ratio of nutrients is between 11%and 13.5,the target dehydration effect can be achieved.The consumption of nutrients is less,and the production capacity is higher than similar projects;Without the addition of any flocculant(PAM),bioleaching and plate-frame pressure filtration can dehydrate the sludge in depth,effectively reduce the moisture content of the original sludge in Jiangnan plant to below 60%,and basically keep the organic matter content unchanged,which is convenient for the subsequent disposal of the sludge and maximize the utilization of the sludge.