Performance of a Trickling-Bed Biocathode Microbial Electrochemical System Treating Domestic Wastewater and Functional Microbial Community Characteristics

Haiman Wang,Guiqiang Wang,Zhuang Miao,Yafeng Li,Lei Chao

doi:10.3390/app10092989

Haiman Wang, Guiqiang Wang + Show 3 more

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https://doi.org/10.3390/app10092989

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Journal: Applied sciences	Publication Date: Apr 25, 2020
Citations: 2	License type: CC BY 4.0

Affiliation: Shenyang Jianzhu University

Abstract

Biocathode microbial electrochemical systems (MESs) that remove nitrogen compounds out of wastewater are of special interest for practice. High energy-input for aeration is one of the barriers that hinder their application on a wider scope. A trickling-bed biocathode MES (TB-MES) was developed by integrating biotrickling filters with a biocathode MES. By recirculating the catholyte and sprinkling it through a spray nozzle, the system was able to achieve a reoxygenation process, which could facilitate the creation of an aerobic and anoxic environment. At an optimal recirculation rate of 200 mL min−1, the TB-MES removed 87.2 ± 2.7% of ammonium nitrogen and 79.7 ± 2.5% of total nitrogen (TN), and simultaneously achieved a maximum power density of 3.8 ± 0.3 Wm−3. Comparable performances were achieved when treating domestic wastewater, which were 84.6 ± 2.4%, 70.1 ± 4.2%, and 3.2 ± 0.2 W m−3 for ammonium nitrogen removal, TN removal, and maximum power density. Pyrosequencing analysis revealed Nitrosomonas was more abundant in the upper portion of the carbon fiber brush biocathode (CFBup, 20.4%) and Azoarcus was more abundant in the lower portion (CFBbottom, 12.6%), which was probably caused by the difference in dissolved oxygen concentration in different parts of the biocathode. The TB-MES shows great promise for domestic wastewater treatment by employing biotrickling filters for oxygen supply in biocathode MES.

Highlights

Recovering useful energy from wastewater represents a promising way to transform traditional wastewater treatment processes from energy consumers to energy producers [1]
The TB-microbial electrochemical systems (MESs) was operated at a fixed HRT of 48 h during the start-up phrase, when the external resistor was gradually reduced from 500 Ω to 10 Ω (500, 200, 100, 50, 10 Ω)
In order to enhance this reoxygenation process, as well as to improve the agitation and mixing of substrates, the stable, and results showed that current density gradually increased from 6.2 ± 2.8 A m–3 to 19.6 ± 4.6 catholyte was circulated back to the spray nozzle by a peristaltic pump at a flow rate of 50, 200, and

Summary

Introduction

Recovering useful energy from wastewater represents a promising way to transform traditional wastewater treatment processes from energy consumers to energy producers [1]. Among recently developed treatment approaches, microbial electrochemical systems (MESs) are capable of simultaneous wastewater treatment and electricity production through the catalytic activity of exoelectrogens [2]. Having achieved great progress in MES research and development with numerous bench-scale systems tests, more research has been carried out in scaling up MESs [3,4,5,6]. Biocathode MESs, using a microorganism catalyst instead of a chemical catalyst to promote the cathodic reaction, have drawn considerable attentions in pilot-scale MESs, due to their advantages in relatively low cost and long-term sustainability for wastewater treatment [7,8,9]. Because of the variety of in situ accumulated functional microorganisms, the biocathode exhibits as a potential approach to produce.

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