Pilot-Scale Airlift Bioreactor with Function-Enhanced Microbes for the Reduction of Refinery Excess Sludge

Hongyan Mu, Min Zhang, Shanshan Sun, Zhaozheng Song, Yijing Luo, Zhongzhi Zhang and Qingzhe Jiang
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Hongyan Mu: State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249, China
Min Zhang: State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249, China
Shanshan Sun: State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249, China
Zhaozheng Song: State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249, China
Yijing Luo: State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249, China
Zhongzhi Zhang: State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249, China
Qingzhe Jiang: State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249, China

IJERPH, 2021, vol. 18, issue 13, 1-12

Abstract: A pilot-scale airlift bioreactor (ALBR) system was built and operated continuously for refinery excess sludge (RES) reduction. Combined ALBR and function-enhanced microbes (composed of photosynthetic bacteria and yeast) were integrated into the system. The pilot-scale ALBR was operated for 62 days, and the start-up time was 7 d. Continuous operation showed that the sludge reduction efficiency was more than 56.22%, and the water quality of the effluent was satisfactory. This study focused on investigating the effects of hydraulic retention time (HRT) on the stability of the system and the effect of sludge reduction. Under different HRT conditions of 40, 26.7, 20, and 16 h, the sludge reduction rates reached 56.22%, 73.24%, 74.09%, and 69.64%, respectively. The removal rates of chemical oxygen demand ( COD ) and total nitrogen (TN) decreased with decreasing HRT, whereas the removal rate of NH 4 + -N increased. The removal rate of total phosphorus (TP) was approximately 30%. Results indicate that the ALBR and function-enhanced microbe system can reduce sludge and treat sewage simultaneously, and the effluent is up to the national emission standard. Addition of function-enhanced microbes can promote the degradation of petroleum hydrocarbon substances in the sludge, especially alkanes with low carbon numbers. This study suggests that the optimal HRT for the system is 16 h. The total operation cost of the ALBR combined with the function-enhanced microbe system can be reduced by 50% compared with the cost of direct treatment of the RES system.

Keywords: refinery excess sludge; sludge reduction; function-enhanced microbes; airlift bioreactor (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2021
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