Effect of cation binding agents on sludge solubilization potential of bacteria

The aim of the present study is to increase sludge solubilization potential of bacteria by the addition of cation binding agents. During the study, three strains of bacteria B1, B2 and B3 were isolated from waste activated sludge acclimatized to a thermophilic condition (55℃). Using these strains the mixed liquor suspended solids degradation was 67, 59, and 33% and the chemical oxygen demand solubilization enhancement was 71, 62, and 36% compared with the control. Cation binding agents such as citric acid, ethylenediaminetetraacetate and sodium tripolyphosphate were added to enhance the sludge solubilization further. Among these, citric acid along with B1 was more effective in solubilization with the mixed liquor suspended solids degradation of 110% and the chemical oxygen demand solubilization enhancement of 115%. 16s rRNA technique was used to identify the bacterial species B1 and it was found to be Bacillus licheniformis. It was also observed that mixed liquor suspended solids reduced rapidly when more soluble chemical oxygen demand was released, thereby increasing sludge solubilization.