Conversion and utilization of slowly biodegradable organic matter

The distribution characteristics of different carbon sources were studied by long-term analysis of speciation and biodegradability of organics in Xi'an. Particulate organics accounted for 65% of the COD. Slowly biodegradable organics constituted a majority of the carbon source. The conversion and utilization of slowly biodegradable organics was analyzed. Our findings showed that the slowly biodegradable organics could be hydrolyzed under both aerobic and anaerobic conditions. Carbon utilization of 58% and 65% were recorded under aerobic and anaerobic conditions, respectively, over a period of 8 h. The first hour was the rate-limiting stage for the degradation of the slowly biodegradable organics. The rate significantly increased over the next three hours and then began to plateau. Volatile fatty acids (VFAs), polysaccharides, and proteins were the main hydrolysis products of the slowly biodegradable organics. In addition, humic acid was produced, the chemical structure of which can be gradually changed to be more bioavailable.