Expanded granular sludge blanket reactor treatment of food waste at ambient temperature: Analysis of nitrogen compositions and microbial community structure.

The influent and effluent nitrogen compositions of an expanded granular sludge blanket (EGSB) reactor employed for treating food waste (FW) operated under ambient temperature was evaluated. Additionally, dynamic changes in the bacterial community structures and its metabolic functions were investigated. Results show that the EGSB reactor had a good effect on FW disposal and well resistance to variations in the organic loading rate. Furthermore, the COD concentration in the influent increased to about 10,000 mg/L and the COD removal rate stabilized at about 95%. The dissolved ammonia nitrogen (d-ammonia) content was the largest, accounting for approximately 70-80% of the dissolved nitrogen in the effluent. The amount of particulate organic nitrogen (PON) decreased by about 25%-33%. Amino acid, carbohydrate and lipid metabolism decreased at high organic loading rate (OLR). Meanwhile, the abundance of Methanothrix increased from 30.82% to 70.25%, whereas Methanobacterium decreased from 66.14% to 14.49%.