A novel aerated surface flow constructed wetland using exhaust gas from biological wastewater treatment: Performance and mechanisms

Xinwen Zhang,Zhen Hu,Jian Zhang,Jinlin Fan,Huu Hao Ngo,Wenshan Guo,Chujun Zeng,Yiwen Wu,Siyuan Wang

doi:10.1016/j.biortech.2017.08.172

Xinwen Zhang, Zhen Hu + Show 7 more

Open Access

https://doi.org/10.1016/j.biortech.2017.08.172

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Journal: Biomass	Publication Date: Sep 18, 2017
Citations: 14	License type: cc-by

Affiliation: Shandong University, University of Technology Sydney

Abstract

In this study, a novel aerated surface flow constructed wetland (SFCW) using exhaust gas from biological wastewater treatment was investigated. Compared with un-aerated SFCW, the introduction of exhaust gas into SFCW significantly improved NH4+-N, TN and COD removal efficiencies by 68.30 ± 2.06%, 24.92 ± 1.13% and 73.92 ± 2.36%, respectively. The pollutants removal mechanism was related to the microbial abundance and the highest microbial abundance was observed in the SFCW with exhaust gas because of the introduction of exhaust gas from sequencing batch reactor (SBR), and thereby optimizing nitrogen transformation processes. Moreover, SFCW would significantly mitigate the risk of exhaust gas pollution. SFCW removed 20.00 ± 1.23%, 34.78 ± 1.39%, and 59.50 ± 2.33% of H2S, NH3 and N2O in the exhaust gas, respectively. And 31.32 ± 2.23% and 32.02 ± 2.86% of bacterial and fungal aerosols in exhaust gas were also removed through passing SFCW, respectively.

Highlights

Over the last few decades, rapid urbanization and economic growth has caused a series of severe environmental issues such as river pollution and water blooms in lakes, especially in developing countries
The DO concentrations of SFCWs B and C increased from 1.51 to 2.38 mg/L and 1.35 to 2.25 mg/L over the first 0.5 h aeration time (0-30min), respectively, which was primarily attributed to the excess power of the compressor used for air and exhaust gas injection
The DO was 1.12 ± 0.05 mg/L in SFCW A due to atmospheric reaeration (AR), which caused an anaerobic environment in SFCW and may result in poor nitrification

Summary

Introduction

Over the last few decades, rapid urbanization and economic growth has caused a series of severe environmental issues such as river pollution and water blooms in lakes, especially in developing countries. Considering the stringent discharge guidelines and standards for conventional wastewater treatment plants (WWTPs), WWTPs still face challenges in removing excess nutrients effectively from wastewater in an economical way, resulting in negative environmental consequences (Wu et al, 2016). On the other hand, constructed wetlands (CWs), which are regarded as a tertiary treatment process, have offered the greatest potential for secondary effluent treatment owing to their good efficiency, low costs and low maintenance (Vymazal, 2010). Pollutant removal within CWs is a complex process that primarily includes substrate adsorption, plant absorption and microbial degradation.

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