An evolved native microalgal consortium-snow system for the bioremediation of biogas and centrate wastewater: Start-up, optimization and stabilization

Shuang Qiu; Ziwei Yu; Yanbing Hu; Zhipeng Chen; Jianhua Guo; Wenhao Xia; Shijian Ge

doi:10.1016/j.watres.2021.117038

An evolved native microalgal consortium-snow system for the bioremediation of biogas and centrate wastewater: Start-up, optimization and stabilization

Water Res. 2021 May 15:196:117038. doi: 10.1016/j.watres.2021.117038. Epub 2021 Mar 10.

Authors

Shuang Qiu¹, Ziwei Yu², Yanbing Hu², Zhipeng Chen², Jianhua Guo³, Wenhao Xia², Shijian Ge⁴

Affiliations

¹ Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China; Department of Biology, Queen's University, Kingston, ON, Canada K7L 3N6.
² Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China.
³ Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia.
⁴ Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China. Electronic address: geshijian1221@njust.edu.cn.

PMID: 33751972
DOI: 10.1016/j.watres.2021.117038

Abstract

It is necessary to develop sustainable technologies for centrate wastewater (CW) and biogas treatment from sludge anaerobic digestion (AD) systems in an environmentally friendly and economical manner. The microalgae-based bioremediation approach presents a competitive alternative due to its capacity for nutrient recovery and carbon sequestration. However, process instabilities and operating challenges limit its development and implementation largely due to the complexities in the CW and biogas. In this study, the evolved native microalgal consortium (ENMC) was firstly developed using the gradual stress increase method to enhance their adaptation in high ammonium condition. The supplementation of local snow (with Ca²⁺ and Mg²⁺) and biogas into CW significantly enhanced ENMC growth through batch tests. Subsequently, an integrated ENMC-snow (ENMCS) system was proposed consisting of a hydrolysis-acidification reactor (HAR), biogas upgrade reactor, and photobioreactor (PBR). The ENMCS system was systematically investigated under both batch and semi-continuous operations, by adjusting primary process parameters including the fill ratio, feeding time, hydraulic retention time (HRT), wastewater pretreatment, and PBR type. It was eventually optimized as a 24 h, 70% fermented CW diluted with 30% snow water, semi-continuous feeding system with a fill ratio of 50% and HRT of 6 d in an open-PBR. Long-term operation (310 days) showed superior biomass yield (0.3059 ± 0.0039 g/(L•d)) and nutrient removal efficiencies (95.6 ± 0.13% and 90.8 ± 0.44% for NH₄⁺-N and PO₄^3--P removal). Meanwhile, biogas was upgraded with an 82.2% CO₂ reduction. The economic and environmental analysis further demonstrated the ENMCS system as an effective alternative for the bioremediation of AD effluents while simultaneously producing value-added biomass, especially applicable to snowy regions.

Keywords: Biogas; Centrate wastewater; Gradual stress increase; Microalgal consortium; Snow.

MeSH terms

Biodegradation, Environmental
Biofuels / analysis
Biomass
Microalgae*
Snow
Wastewater

Substances

Biofuels
Waste Water