Efficient Treatment and Simultaneous Energy Recovery from Cattle Wastewater by the Micro-Aerated UASB and SBR Coupled System

Thepresent study introduces a coupled system comprising an upflowanaerobic sludge blanket (UASB) and a sequencing batch reactor (SBR)to treat intensive cattle farming wastewater. The results confirmedthat the optimal conditions for UASB were an organic load rate of9.98 kg-COD m(-3)& BULL;day(-1), aC/N ratio of 22, and a hydraulic retention time (HRT) of 1.5 h. Forthe SBR reactor, the optimal conditions are a dissolved oxygen (DO)concentration of 6.08 mg L-1 and the S2 aerationmode. Under these optimal conditions, the study achieved anaerobicand aerobic sludge granules (0.25-0.5 and 0.5-0.75 mm)with excellent properties due to the cooperation of a functional microbialcommunity, including Synergistetes, Thermotogae, Acidobacteria, Proteobacteria, Chloroflexi, and Hyd24-12 in UASB and Paracoccus, Proteobacteria, Chloroflexi, and Acinetobacter in SBR. This hybrid system contributed 94% of chemical oxygen demand(COD), 90% of NH4 (+)-N, 90% of TN, and 61% ofTP. Additionally, it achieved 18% net energy recovery from the realcattle wastewater, indicating that the UASB-SBR-coupled systemholds potential as an approach for treating and recovering energyfrom cattle wastewater. Anovel system combining micro-aerated UASB and SBR processestreats cattle wastewater efficiently while recovering energy simultaneously.