The isolation, identification of sludge-lysing thermophilic bacteria and its utilization in solubilization for excess sludge

Abstract

A novel strain of thermophilic bacteria with a highly efficient sludge dissolution performance was isolated from garden soil at 65 degrees C in this study. The colony morphology, physiological and biochemical characteristics of the strain were investigated. The results showed that the strain was Gram-positive, small rod-shaped, sporulating and secreted extracellular enzymes (protease and amylase). The 16S rDNA analysis demonstrated that this strain had not been previously reported. Therefore, it was labelled Bacillus thermophilic bacteria AT07-1 (registration number: FJ231108). To evaluate its capability for excess sludge solubilization, a pure culture of the strain was used in sludge solubilization tests; an enhanced solubilization process was subsequently obtained. After 36 h digestion, the protease activity in the inoculated system reached 0.37 U/ml, an increase of 0.16 U/ml compared with the non-inoculated system (0.21 U/ml). The solubilization rate for volatile suspended solids reached 46.45% in 48 h after inoculation with Bacillus thermophilic bacteria AT07-1, which was 10.24% higher than the non-inoculated system, and which could meet the standard of sludge stability suggested by the US Environmental Protection Agency.

Highlighting the cathodic contribution of an electrooxidation pretreatment study on waste activated sludge disintegration

“…Different mechanical, chemical (acid 13 and alkaline thermal pretreatment), 14 physical (microwave), 5 and biological (enzymatic, microbial, or biosurfactant) 15 pretreatment methods are available for the disintegration of WAS 16 . Besides, the electro‐oxidation (EO) process is used as a pretreatment method for the disintegration of WAS.…”

“…10 Disintegration increases the availability of the organic matter by breaking down the extracellular polymeric substances (EPS) layer liberating the trapped intracellular and organic substances promoting, in turn, the AD process. 1,11,12 Different mechanical, chemical (acid 13 and alkaline thermal pretreatment), 14 physical (microwave), 5 and biological (enzymatic, microbial, or biosurfactant) 15 pretreatment methods are available for the disintegration of WAS. 16 Besides, the electro-oxidation (EO) process is used as a pretreatment method for the disintegration of WAS.…”

“…0 A and a hydrolysis time of 20 min, increased concentrations of Na 2 SO 4(5,10,15, and 20 g/L) were evaluated for their effects on WAS disintegration. The results are presented in Figure2, showing the variation trend in the percentage of DD COD and the concentration of COD S .…”

Impact of Adding Biopreparations on the Anaerobic Co-Digestion of Sewage Sludge with Grease Trap Waste

“…Biological pretreatment is aimed at intensification by enhancing the hydrolysis process in an additional stage prior to the main digestion process [2]. Biological pretreatment can be classified into 2 categories: (1) adding industrial [9] or endogenous enzymes prior to anaerobic digestion processes; (2) adding specific bacteria which can release certain enzymes [10,11]. They have been shown to improve degradation, dewatering properties of the sludge and to increase methane production, and have been widely researched in laboratory and full-scale plants [12].…”