Stduy On Reuse Of Sludge Carbon Source And Simultaneous Nitrogen And Phosphorus Removal Technology Based On Ferrate Oxidation

The problems causing by the shortage of carbon source in urban sewage treatment have become prominent.At the same time,the reduction and reuse of waste activated sludge（WAS）are concerned as well.More attention has been payed to reuse WAS as carbon source by physical,chemical and other cracking methods.During WAS disintegration,a lot of nitrogen and phosphorus were dissolved along with organic matters releasing,it would increase nitrogen and phosphorus load when using WAS as carbon source.So the reuse of WAS may lead to nitrogen and phosphorus exceeding standard discharge.Therefore,Composite Ferrate Solution（CFS）was used to disintegrate WAS.Ferrate has strong oxidation and the Fe（III）reduced form Fe（VI）could reduce phosphorus in solution,which could achieve simultaneous phosphorus removal during WAS oxidation.Then,the WAS cracking solution was reused as carbon source to increasing removal efficiency of nitrogen and phosphorus.The main factors affecting the removal of phosphorus by potassium ferrate were studied by single factor experiments and the p H adjustment effect on phosphorus removal rate.The experiment results showed that the optimum condition was:p H=2,Fe/P=5,react for 5 min,C/C0≦0.1.The NH₄⁺and ionic strength in water could promote the removal of phosphorus by potassium ferrate.The effect of humic acid on phosphorus removal was affected by p H.The adjustment of p H after reaction could enhanced the removal rate of phosphorus.During WAS disintegration by CFS,the intracellular materials were dissolved,and the released phosphorus was removed simultaneously.Under the optimal reaction conditions,ΔVSS/VSS>60%,DDSCOD≈26%,and phosphorus removal rate≈60%.The p H adjustment after reaction enhanced the removal of phosphorus.It may be due to that p H could affect floc’s surface charge,iron-phosphorus fate,and the form of phosphorus in the sediment.Adjustment of p H after reaction was beneficial to improve the phosphorus removal efficiency of Fe（III）and its compounds,increase the proportion of phosphorus in solid phase,and increase the mass concentration of NAIP in sediment.Cations that make up NAIP dissolved when p H=2,for which the phosphorus removal efficiency was reducedNUR experiments and anaerobic phosphorus release experiments were carried out to investigate CFS sludge disintegration solution’s efficiency of removing nitrogen and phosphorus.Experiment results showed that CFS sludge disintegration solution could be used as carbon source for nitrogen and phosphorus removal.For the sludge disintegration solution,C/N=26.36,C/P=63.80,the proportion of Ss was 31.82%,v _DN=4.07mg?（g VSS?h）-1 and P_DN=0.13g N?（g COD）.Analysis and comparison results confirmed that the denitrification efficiency of sludge disintegration solution was better than that of glucose and food industry wastewater,and slightly lower than that of sodium acetate and sludge fermentation.Anaerobic phosphorus release experiments confirmed that the phosphorus removal efficiency of sludge disintegration solution was similar to that of sodium acetate.CFS-AAO process was proposed by combining AAO process and CFS cracking sludge process,CFS-AAO process could enhanced nitrogen and phosphorus removal by using excess sludge as carbon.Compared with AAO process,CFS-AAO process could reduce the excess sludge discharge by 34.09%,TN and TP in effluent decreased from7.89mg·L^-1and 0.38mg·L^-1to 4.93mg·L^-1and 0.22mg·L^-1,respectively.The material balance calculation results showed that the sludge organic matter added in influent was utilized as supplementary carbon source by denitrifying bacteria and phosphorus accumulating bacteria.