The Research On The Characteristics Of The Process That The Particulate Organic Carbon Providing Carbon Source During The Sewage Denitrification

To solve the problem that lack of carbon source, many studies tend to dig the carbon source from the inside of Sewage Treatment Plant. Currently digging carbon source from internal sewage plant is a worthy advocate approach.As carbon sources of internal sewage own,particulate organic often are removed through primary sedimentation and other physical processes before biological treatment, resulting in a waste of available carbon source. For the low C/N urban sewage,to optimize the control of carbon source entering the biochemical system and reasonable use of particulate carbon source are significant,.In this paper, the carbon characteristics of particulate organic matter in the process of denitrification are studied, for to provide theoretical basis for the rational utilization and optimal control of the Particulate organic matter.The results show that:(1) Particulate organic matter can provide carbon for denitrification.The hydrolysate of the particulate organic matter can provide electronic for the whole process of denitrification,to make the denitrification process are more thoroughly. The denitrification rate was1.059mgN/gMLSS·h,and the removal rate was50.91%.The nitrite nitrogen content is very few,the largest concentration was2.65mg/L,then fell to about0.059mg/L, accounted for about0.29%of the total nitrate removal, no accumulation basically.The quantity nitrous oxide release accounts for about4.44%of the amount of nitrate nitrogen removal.(2)Particulate organic matter for the carbon source that the denitrification required,the soluble organic matter under hydraulic mixing dissolution without microbial activities is very little, illustrate the key step of the process that particulate organic matter provide carbon source is microbial biochemical effect, namely the extracellular enzyme hydrolysis enzyme solution, put0.5g particulate organic matter in1L deionized water and then start stirring the solution, the TOC of dissolving soluble organic matter just increased10-14mg/L after the solution was stirred for twelve hours. The TOC increment of thesoluble organic matter provided by the largest particulate organic matter (180-830μm) is9.86-10.98mg/L, accounting for about4.74%to5.24%(COD/COD); The TOC increment of the soluble organic matter provided by the smallest particulate organic matter (<61μm) is9.86-10.98mg/L, accounting for about5.88to6.36%(COD/COD).(3)When particulate organic matter provide carbon source for denitrification, particles basiclly maintained the steady state that being used while hydrolysis. Small organic molecules(0-500D) are absorbed quickly,so that the concentration is low and the trend of the concentration is flat after decrease in first30min.The concentration of small organic molecules(0-500D) is fluctuated between3.72to4.65mg/L,accounted for7.64-11.64%of total amount of dissolved organic matter.The concentration of macromolecular organic matter is high.The macromolecular organic matter of which the molecular weight is between1wD-0.45μm accounted for37.55-52.45%.Macromolecular organic matter accumulated from37.55%to47.23%within30min after the reaction began,and then also roughly in a trend of fluctuations, no significant increase or decrease. At the beginning of the reaction, microbes secrete more hydrolytic enzymes to "eat"the particles,make the macromolecules (especially>10wD) has accumulated.Along with the increase of the macromolecular organic matter,the microbes secrete more corresponding hydrolytic enzymes to decompose and use the large molecules.These illustrate the secretion of hydrolytic enzyme always adapt to the carbon source environment to meet their own needs.(4)The trend of the hydrolysate such as protein, polysaccharide, amino acid etc.is generally similar with molecular weight distribution.At the beginning of the protein concentration in the growing faster,Increased by2.86mg/L to9.1mg/L Within60min,and then keep fluctuations in8to10mg/L.The content of the small molecule organic matter such as amino acids,, etc is less, the concentration of amino acids is in the range of0.86-3.02mg/L,content of reducing sugar is within the scope of0.5to2.27mg/L.The fast use of small molecule substance by microorganism and transformation from large molecules make the small molecule substance content to keep dynamic balance.(5)The particle size of the particulate carbon source have great influence on the denitrification efficiency,the consumption of carbon source and the microbial growth.The smaller the particle size of the particulate carbon source,the better the effect of denitrification.The denitrification rate was0.732mgN/gMLSS·h when the size of particulate carbon source range from180to830μm.The denitrification rate was1.276mgN/gMLSS·h when the size of particulate carbon source is less than61μm.The greater the particle size, the less the microbial growth.Because the Hydrolysis rate of the larger particles is slow.and the more carbon source is just used to keep microbial cells living. The smaller the particle size, the greater the chances the microbial cells grow and the more the consumption of carbon source required to reduce nitrate nitrogen.The theoretical COD consumption to reduce lmg/L of Nitrate nitrogen is5.61mg/L when the size of particulate carbon source range from180to830μm.The theoretical COD consumption to reduce1mg/L of Nitrate nitrogen is8.17mg/L when the size of particulate carbon source is less than61μm.