Recognition of the key chemical constituents of sewage sludge for biogas production

Abstract

One of the key factors hindering the application of anaerobic sludge digestion is the lower biogas production (BP). In this paper, the main constituents of sewage sludge (SS) and model sludge (MS) were reconsidered and a biochemical methane potential assay of sludge was conducted with the effect of different key chemical constituents. It was found that the humic matter, metal ions (such as Fe, Ca, and Al), silts were the main differences of constituents between SS and MS, and the interactions between them and easily biodegradable organic matter (EBOM) were the main factors for limiting the BP. Further research indicates that the apparent activated energy of sludge organic solubilisation could be used to suggest the strength of the interactions between non-biodegradable matter and EBOM, and the biodegradability of the EBOM in sludge particulate can be indicated by surface site density. This study can provide a new path for enhancing the BP per unit of organic matter and enlighten environmental scientists to develop more effective methods for improving the anaerobic sludge digestion.