Conve Rsion And Utilization Of Slowly Biodegradable Organic Matter

The distribution characteristics of carbon source were studied by long-term analysis for biodegradabilities and speciation of organics in some Xi'an municipal wastewater treatment plants. Particulate organics accounted for 65% COD and slowly biodegradable organics was the main part of raw water. 20% to 30% of the organic carbon were removed in the primary sedimentation tank, which slowly biodegradable organics reduced about 30%.The conversion and utilization of slowly biodegradable organics was analyzed by scientific pilot test. Results showed that slowly biodegradable organics could be hydrolyzed at both aerobic and anaerobic conditions. Their utilization could reached to 58% and 65% respectively in eight hours. Under the anaerobic conditions, the transformation of slowly biodegradable organics were obvious.The first hour was the rate- limiting stage and the rate was significantly increased in next three hours and then began to flatten. Fluorescnce analysis showed that the main hydrolysis products of slowly biodegradable organics were protein- like, VFAs and polysaccharides which were easily used substances. At the same time, some humic acid were also produced, but its chemical structure could be changed gradually to be more bioavailable due to long biological effects. The UV results showed that aldehydes and ketones compound, unsaturated compounds and aromatic compounds were produced during hydrolysis of slowly biodegradable organics. These materials will be degraded or transform into new substance over the time. FTIR spectra we can see that hydrolysate of slowly biodegradable organics contained more oxygen-containing functional groups. Combined with the molecular weight distribution, the study shown that humic substances and aromatic compounds would be converted to other molecular substances, long biological effects could increased the proportion of small molecules. Molecular weight of protein- like had a broad molecular weight distribution, and showed a decreasing trend.slowly biodegradable organics and its utilization situation in sewage treatment system was analyzed, all rapid biodegradable organics in anaerobic phase used to release phosphorus, and 3.15 mg/L of slow biodegradable organic also used to release phosphorus, all required denitrification carbon were provided by slow biodegradable organics. In anoxic phase, hydrolysate of slow biodegradable organics could be used to remove 0.72 mg/L nitrogen and absorb 5.26 mg/L phosphorus which hold 65% of the total amount of phosphorus. About 12.5 mg/L hydrolysate of slow biodegradable organics oxidized in aerobic phase.