| Title |
Biochemical Methane Potential of Chemically Enhanced Primary Treatment Sludge for Energy-Independence of Sewage Treatment Plants |
| Authors |
천민선 ( Minsun Chun ) ; 김형호 ( Hyoungho Kim ) ; 배효관 ( Hyokwan Bae ) |
| DOI |
https://doi.org/10.15681/KSWE.2020.36.4.322 |
| Keywords |
Anaerobic Digestion; Biochemical Methane Potential; Chemically Enhanced Primary Treatment; Energy-positive Sewage Treatment; Salinity |
| Abstract |
By introducing chemically enhanced primary treatment (CEPT) in the first stage of sewage treatment, organic matter in sewage can be effectively recovered. Because CEPT sludge contains a high biodegradable organic matter in volatile solids (VS), it is feasible to convert the collected CEPT sludge into energy through anaerobic digestion. This study examined the properties and biochemical methane potential (BMP) of the CEPT sludge obtained from a sewage treatment plant located in an ocean area. The CEPT sludge contains a VS content of 37,597 mg/L, which is higher than that of excessive sludge (ES), i.e., 33,352 mg-VS/L. In the methane generation reaction, the lag period was as short as 1 to 2 days. The BMP for the CEPT sludge was 0.57 m3-CH4/kg-VSremoved which is better than that of ES, i.e., 0.36 m3-CH4/kg-VSremoved. Unfortunately, the CEPT sludge showed a high salinity as 0.56∼0.75% probably due to the saline sewage. Due to the salinity, repeated BMP testing in a sequencing batch reactor showed significantly low methane production rates and BMPs. Also, the ES showed a strongly reduced BMP when the salinity was adjusted from 0.20 to 0.70% by NaCl. The ES mixture with higher CEPT content showed a better BMP, which is suitable for co-digestion. Besides, anaerobic digestion for 100% CEPT sludge can be a considerable option instead of co-digestion. |