The treatment of high-concentration garlic processing wastewater by UASB-SBR.

The treatment of garlic processing wastewater was investigated in a UASB-SBR system. The experimental results showed that UASB was successfully started up after 64 days of continuous operation with COD removal rate of 45%. SBR start-up phase went through 60 days and the COD removal rate achieved 96%. UASB ran under optimal conditions (HRT of 45 h, pH of 7.5, and temperature of 35 ± 2°C) for 14d and performed well in organic matter treatment. SBR played a major part in nitrogen and phosphorus removal when running under optimal conditions (cycle time of 12 h, temperature of 25°C, organic loading of 0.72 kgCOD/(m·d), and COD of 6000 mg/L) for 18d. Secondly, the microbial community structure indicated that the abundance of β-Proteobacteria and α-Proteobacteria in the sludge reached 30.05% and 47.57%, respectively, and played a crucial part for the organic matter, nitrogen and phosphorus removal in the SBR. After UASB-SBR system had been stabilised with influent COD of 9800 mg/L, the average COD, TP, NH-N and TN removal rates were 99%, 94.82%, 87.07% and 94.87%, respectively, which were 3%, -2%, 1% and 3.5% higher than SBR running alone under optimal conditions. UASB coupled with SBR process had an excellent performance for high-concentration garlic processing wastewater.