Effect of Zn2+ on the Performances and Methanogenic Community Shifts of UASB Reactor During the Treatment of Swine Wastewater

Tuo, Ye; Cai, Jianbo; Zhu, Duanwei; Zhu, Ying; Liu, Guanglong; Hua, Yumei; He, Jiajie

Effect of Zn2+ on the Performances and Methanogenic Community Shifts of UASB Reactor During the Treatment of Swine Wastewater

2014

Zn²⁺was added to one of the two identical bench-scale upflow anaerobic sludge blanket (UASB) reactors in steady-state period treating swine wastewater to evaluate the effects of Zn²⁺on performance and methanogenic population. Real-time quantitative PCR (QPCR) was used to quantify the 16S rRNA gene concentrations of the four methanogenic orders. In both reactors, the hydraulic retention time (HRT) was sustained at 48 h and the inner temperature was kept at 35 °C. Both promotion and inhibition of Zn²⁺on chemical oxygen demand (COD) removal, methane production and methanogens community were observed in accordance with different Zn²⁺dosages. COD removal rate and methane production reacted in the same way as methanogens, suggesting that the impact of Zn²⁺on the methanogenic community was the critical reason that caused the changes of UASB performance in treating swine wastewater with unstable Zn²⁺concentration. Among the methanogenic community, Methanomicrobiales (MMB) was the dominant group which got visibly impacted by the dosed Zn²⁺. Overall, lower concentration of Zn²⁺, e.g., less than 17.8 mg/L, was supposed to be advisable for a stable and high efficient treatment of swine wastewater by UASB reactor in practice.

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