Performance and microbial community evaluation of full-scale two-phase anaerobic digestion of waste activated sludge

Temperature Staging and Biological Phasing ('TSBP) is an improved two-phase anaerobic digestion (AD) technology. This technology hydrolyzes waste activated sludge (WAS) at 45 degrees C and converts methane at mesophilic temperature (35-38 degrees C), with hydraulic retention times of 3-5 d and 14-17 d, respectively. In this study, the performance and microbial community dynamics of full-scale TSBP-based sludge anaerobic digestion system were studied, and the technology was evaluated by energy balance and ecological benefit analysis. The stable operation for 390 d showed that the cumulative biogas yield was about 349,041 m(3), the maximum biogas yield rate was 563.68 L/kg VS, and the VS degradation rate of organic matters in the sludge was 47.19%. Proteobacteria and Firmicutes were found to be the dominant bacteria in both thermophilic and mesophilic reactors. Methanobacterium and Methanosarcina were the two most abundant methanogenic genera in the AD samples. The aceticlastic methanogenesis was likely the predominant production pathway of methane in AD processes based on metagenomics. The TSBP system operated stably, and the recovered energy could achieve energy self-sufficiency, which provided technical reference for the anaerobic treatment of sludge.

Automated summary

Temperature Staging and Biological Phasing (TSBP) is an improved anaerobic digestion technology for treating waste activated sludge. The stable operation of TSBP system showed significant biogas production and organic matter degradation. Microbial community analysis revealed the dominance of Proteobacteria and Firmicutes, and aceticlastic methanogenesis was identified as the major pathway for methane production in this system.