Research On Effect Of Sludge’s Nutirent And Analysis Of Safety Index By Acid-base Coupling Ozone Treatment

At present, the sludge discharge up to30million t (in moisture content80%), of whichabout80%is not properly handled.The content of organic matter in the sludge is rich(about50%~70%), applying directly without disposing or abandoned will cause serious pollutionto the environment.Sludge is consist of bacteria,organic, inorganic particles,while lowchemical stability. Sludge is rich in nitrogen and phosphorus nutrition and some traceelements, which can effectively improve the soil physical and chemical properties, and meetthe need of plant growth, but most of these elements exist with stabilize sulfide,residual stateand the organic combination state form.Sludge treatment technology applies physical andchemical or advanced technology method to decompose macromolecular organic matter ofthe sludge oxidatively, destroy the floc structure and intracellular material would be released,transfer the insoluble or refractory nutrient substances in the sludge into soluble or solublestate. The present study, the disposal method of sludge involved in physics, chemistry,machinery,biological hydrolysis.But incineration and landfill, ultrasonic wave, heat treatmenthave relative limitations to some extent, and the feasibility is poor and operation is difficulteither, the actual application effect is not ideal.This test apply sewage treatment plant activated sludge as the research sample, the mainresearch includes acid and alkali chemical treatment, ozone oxidation treatment and acid-basecoupling ozone treatment on sludge, then evaluates comprehensive indicators such as theeffect of nutrition and hygiene and the safety of heavy metals.In this paper, the main research contents and conclusions are as follows:(1) The nutrient changes with acid-base coupling ozone treatment on sludge. Test resultsshowed that the release of the COD required longer time with acid and alkali separatetreatment compared with ozone treatment on sludge, effect of acid and alkali.Acid-basecoupling ozone treatment on sludge,TN showed a downward trend; The variation in contentof nitrate nitrogen is consistent, both rising, but the coupling treatment obviously ownedhigher nitrate conversion rate. Soluble phosphate coupling after processing results showedthat the strong coupling treatment> weak alkali coupling coupling treatment>> strong alkaliacid and alkali treatment. (2) The evaluation on safety index of sludge with acid-base coupling ozone treatment onsludge. Test result showed that at the beginning of acid and alkali treatment, all conducts of e.coli content exceeded the national security of agricultural standard;strong acid, strong alkalitreatment group met safety standard after7days;content of e. coli with ozone treatment after60min was eligible,but after7days the number of e. coli resurrected up to1300a/100mlwhich exceeded safety standards; acid-base coupling ozone treatment sludge can shorten theeligible time of the content of e. coli, and after7days the resurrection rate is reduced greatly.Acid-base coupling ozone treatment sludge residue state of heavy metals accounted for abigger percentage,alkali coupling treatment groups is higher than acid coupling treatmentgroups in total heavy metals,each branch detection of heavy metals content met the nationalsafety standards in different treating conditions.(3)The optimization model of acid-base coupling ozone treatment on sludge. Adjustingsludge pH value of4,7,10, ozone treatment for10min,35min,60min and sludgeconcentration into1%,3%,5%,doing three factors and three levels orthogonal experiment fora week.The poor analysis of test data concluded that the effects of three factors in primaryand secondary order such as SCOD, NH4+-N and PO43--P is ozone treatment time> pH>sludge concentration.Also concluded that,adjust pH of3%sludge to10, ozone treatment60min,gained the largest release quantity of SCOD;adjust pH of5%sludge to4, ozonetreatment60min,gained the largest release quantity of NH4+-N;adjust pH of3%sludge to4,ozone treatment60min,gained the largest release quantity of PO43--P.In total,acid-basecoupling ozone treatment3%sludge,the optimal treating time is60min,would release thelargest quantity.