Characteristics Of Struvite Phosphorus Recovery From Surplus Sludge In Municipal Sewage Treatment Plant

Phosphorus recovery from surplus sludge of municipal sewage treatment plant is one of the main methods to solve the problem of phosphorus resource shortage.This study were conducted at room temperature anaerobic and ethylenediamine tetraacetic acid(EDTA)anaerobic pretreatment sludge phosphorus release mechanism study and struvite recovery process,determine the optimum reaction conditions of pretreatment and phosphorus recovery.The uncertainty of struvite crystallization phosphorus recovery process are analyzed,and the monte carlo method was applied to simulate the uncertainty,the research results can provide theoretical basis for residual sludge phosphorus recovery.And we found that:(1)The TP concentration increased gradually in the sludge supernatant with anaerobic pretreatment time increased.Combination of sludge microorganism metabolites(SMP)in the trend analysis of proteins,polysaccharides,humic acid,macromolecular organic matter in anaerobic 4d after all have a wide range of increasing trend,as a result of these organisms to late struvite phosphorus recovery experiment effects have an adverse effect,so comprehensive analysis and ultimately determine the best anaerobic time is 4 days.Three dimensional fluorescence spectrum analysis and molecular weight distribution analysis of anaerobic sludge SMP showed that the organic matter in SMP had certain change rule in the anaerobic process.(2)The addition of EDTA can enhance the phosphorus release effect of anaerobic pretreatment,with the optimal EDTA addition amount being 5 mmol/L and the optimal anaerobic time being 5 days.Three-dimensional fluorescence spectrum analysis showed that the humic acid content in sludge was reduced after the addition of EDTA,which was conducive to the subsequent recovery of struvite phosphorus.(3)The best conditions for determining the phosphorus recovery reaction of struvite method by single factor method are:pH=9.5,magnesium phosphorus ratio was 1.5,stirring time was 20 min.Under these conditions,the phosphorus recovery rate of anaerobic pretreatment at room temperature is 94.49%,and the purity is 85.14%,and EDTA anaerobic were 94.57%and 80.42%.The response surface model determined that the optimal phosphorus recovery condition of anaerobic pretreatment was pH=9.4,magnesium phosphorus ratio was 1.5,stirring time was 21 min,The best phosphorus recovery and purity were 93.66%and 86.03%.EDTA anaerobic pretreatment optimal phosphorus recovery condition was pH=9.5,magnesium phosphorus ratio was 1.6,stirring time was 22 min.The best phosphorus recovery and purity were 95.68%and 79.19%.The research results have important reference value for the optimization design of phosphorus recovery process.(4)The uncertainty analysis of phosphorus recovery process by struvite crystallization method found that the conditional solubility product of struvite was not the only definite value,but a range value.The nuclear kinetics of struvite is affected by the uncertainty of pKsp,so its uncertainty should be taken into account in the dynamic study.