Hydrolysis Of Particulate Organic Matter And The Effect On Carbon Supplement Of Hydrolysis Products In Nitrogen And Phosphorus Removal Process

For low C/N urban sewage, how to efficiently utilize the carbon source is the key to improving the removal effect of nitrogen and phosphorus. As an important composition of carbon source in waste water, if particulate organic matter can be well utilized, the lack of carbon source in biological treatment can be solved at the lowest cost. In the basis of SBR process running in the way of nitrogen and phosphorus removal, by setting the comparative tests, this paper deeply studied the hydrolysis of particulate organic matter and the effect on the carbon supplement of hydrolysis products in nitrogen and phosphorus removal process, and further analyzed the impact to carbon supplement of particulate organic matter by the influent primary settling time, the influent type and concentration of organic matter, to provide a theoretical basis for the practical application of particulate organic matter acted as a carbon source.Research results show that:(1)Using SBR process to treat low C/N urban sewage(C/N=2.5, particulate organic matter concentration was 150-200mg/L), the total amount and distribution of dissolved organic matter along the process changed significantly, and the removal rate in the anoxic phase was up to 70%, some particulate organic matter could be gradually hydrolyzed to low molecular weight organic compounds for microbes.The comparison experiments showed that the DOM concentration of influent was about 34mg/L, its molecular weight was mainly distributed in 300-1kD which accounted for 50.89%.After stirring,the concentrations of DOM decreased to 13mg/L,7mg/L respectively for reactors which had particulate organic matter in influent or not, and each interval distribution was quite different.After aeration, DOM concentrations were 10mg/L and 7mg/L, the effluent DOM remained lower than 7mg/L.Organic matter variation of molecular weight interval<300D and 0.1-0.45μm were 1.52mg/L,1.39mg/L higher than the control group in the anoxic mixing stage by the role of particulate organic matter,<lk and 3k-lw interval were higher than the control group in the aerobic aeration stage,while 0.1-0.45μm interval was 1.31mg/L lower than the control group.(2)For low C/N urban sewage (C/N=2.5,particulate organic matter concentration was 150～200mg/L),the amounts of carbon supplement for Nitrogen and Phosphorus removal by particulate organic matter in the SBR reactor were estimated.When the COD of particulate organic matter in influent was 220.8mg/L,the corresponding removal quantity of NO3--N increased 5.85mg/L compared with the control group,20.475mg/L particulate organic matter involved in denitrification,accounting for 9.27% of the total particulate organic matter in influent, the amount of particle organic carbon supplement for Nitrogen was about 0.0265mgNO3--N/mgPOM.TP removal increased by 0.67mg/L, calculate the effect of particulate organic matter for phosphorus was 14.94mg/L, accounting for 6.77% of the total particulate organic matter, the amount of particle organic carbon supplement for phosphorus was 0.003mgTP/mgPOM.(3)The change of influent primary settling time had no significant effect on the removal of soluble COD,but had a great effect on the removal of TN,TP in SBR reactor,especially in 10min, 30min,and with the extension of influent settling time,the improvement of TN, TP removal rate became unobtrusive.The comparison experiments showed that the removal rates of soluble COD were floating between 40%～90%, and the trend were consistent.The TN removal rate of the situation of influent precipitation Omin, 10min,30min, 1h,2h were increased by 20%,23%, 25%,10%,10% than the control group,TP removal rate increased by 18%,22%,20%,8%, about 3%,respectively.Among them, DOM nitrogen contribution rates were 0.06～0.07mgTN/mgDOM, POM nitrogen contribution rates were 0.04～0.06mgTN/mgPOM,the nitrogen contribution rates of its own organic particles reached above 0.055mgTN/mgDOM in the situation of influent precipitation 10～30min;DOM phosphorus contribution rates were 0.0067～0.0085mgTP/mgDOM, POM phosphorus contribution rates were 0.0006～0.0049mgTP/mgPOM.(4)There were big differences for the contribution of nitrogen and phosphorus in different types and concentrations of organic in wastewater.When there were DOM+POM,only DOM,only POM in influent, the removal rates of TN decreased gradually,they were approximately 38.36%, 36.59%,12.46%, and with the increment of the concentration of POM,TN removal rate increased.When the influent is DOM+3POM, TN removal rate was up to72.7%.The removal rates of TP were approximately 65.38%,54.56%,53.23%,when the influent is POM+DOM, its TP removal rates were 10% higher than the situation of only DOM or POM in influent.(5)The presence of dissolved organic matter had an inhibitory effect on the conduct of particulate organic carbon for denitrification in some extent. Adding an equal COD of particulate organic matter in the influent which contained dissolved organic matter,the TN removal rate increased only 1.77%, the nitrogen contribution rate of particulate organic matter was 0.012mgTN/mgPOM, while the influent had only equal COD of particulate organic matter, the TN removal rate was 12.46%, the nitrogen contribution rate of particulate organic matter was 0.066mgTN/mgPOM.(6)The presence of dissolved organic matter had an inhibitory effect on the conduct of particulate organic carbon for phosphorus in some extent,and without the presence of dissolved organic matter, phosphorus contribution of particulate organic matter may equal or even exceed the dissolved organic matter. Changing the types and concentrations of organic matter in influent,the phosphorus contribution rates of particulate organic matter were between 0.003～0.025mgTP/mgPOM,while the dissolved organic matter was about 0.015mgTP/mgDOM,estimating that the contribution rates ratio of particulate organic matter in the present/absence of equal COD of dissolved organic matter was about 4.9.