Integrated expanded granular sludge bed and sequential batch reactor treating beet sugar industrial wastewater and recovering bioenergy

Abstract

The exponential rise in energy demand vis-à-vis depletion of mineral oil resources has accelerated recovery

of bioenergy from organic waste. In this study, a laboratory- scale anaerobic (An)/aerobic (Ar) system comprising of ex- panded granular sludge bed (EGSB) reactor coupled to an

aerobic sequential batch reactor (SBR) was constructed to treat beet sugar industrial wastewater (BSIW) of chemical

oxygen demand (COD) 1665 mg L−1 while harnessing meth- ane gas. The EGSB reactor generated methane at the rate of

235 mL/g COD added, with considerably higher than previ- ously reported methane content of 86 %. Meanwhile, contam- inants were successfully reduced in the combined An/Ar sys- tem, realizing a removal rate of more than 71.4, 97.3, 97.7,

and 99.3 % of organic matter as total phosphorus, total nitro- gen, biological oxygen demand (BOD), and soluble COD,

respectively. Microbial community analysis showed that the bacterial genus Clostridium sp. and archaeal genus Methanosaeta sp. dominated the EGSB reactor, while

Rhodobacter sp. dominance was observed in the SBR. The ob- tained experimental results indicate that the integration of ex- panded granular sludge bed and sequential batch reactor in

treating BSIW obtained competitively outstanding performance.