Calcium ions-effect on performance, growth and extracellular nature of microalgal-bacterial symbiosis system treating wastewater

Cong-Cong Tang; Xin-Yi Zhang; Rong Wang; Tian-Yang Wang; Zhang-Wei He; Xiaochang C Wang

doi:10.1016/j.envres.2021.112228

Calcium ions-effect on performance, growth and extracellular nature of microalgal-bacterial symbiosis system treating wastewater

Environ Res. 2022 May 1:207:112228. doi: 10.1016/j.envres.2021.112228. Epub 2021 Oct 16.

Authors

Cong-Cong Tang¹, Xin-Yi Zhang², Rong Wang², Tian-Yang Wang², Zhang-Wei He³, Xiaochang C Wang⁴

Affiliations

¹ Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China. Electronic address: cctang0820@xauat.edu.cn.
² Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
³ Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China. Electronic address: zwhe@xauat.edu.cn.
⁴ Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an, 710055, China.

PMID: 34662574
DOI: 10.1016/j.envres.2021.112228

Abstract

Microalgal-bacterial symbiosis (MABS) system treating wastewater has attracted great concern because of its advantages of carbon dioxide reduction and biomass energy production. However, due to the low density and negative surface charge of microalgae cells, the sedimentation and harvesting performance of microalgae biomass has been one limitation for the application of MABS system on wastewater treatment. This study investigated the performance enhancement of microalgae harvesting and wastewater treatment contributed by calcium ions (i.e., Ca²⁺) in the MABS system. Results showed that a low Ca²⁺ loading (i.e., 0.1 mM) promoted both COD and nutrients removal, with growth rates of 11.95, 6.53 and 1.21% for COD, TN and TP compared to control, and chlorophyll a was increased by 64.15%. Differently, a high Ca²⁺ loading (i.e., 10 mM) caused removal reductions by improving the aggregation of microalgae, with reduction rates of 34.82, 3.50 and 10.30% for COD, NH₄⁺-N and TP. Mechanism analysis indicated that redundant Ca²⁺ adsorbed on MABS aggregates and dissolved in wastewater decreased the dispersibility of microalgae cells by electrical neutralization and compressed double electric layer. Moreover, the presence of Ca²⁺ could improve extracellular secretions and promoted flocculation performance, with particle size increasing by 336.22%. The findings of this study may provide some solutions for the enhanced microalgae biomass harvest and nutrients removal from wastewater.

Keywords: Calcium ion; Microalgae growth; Microalgal-bacterial symbiosis system; Nutrient removal; Wastewater treatment.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomass
Calcium
Chlorophyll A
Ions
Microalgae*
Symbiosis
Wastewater

Substances

Ions
Waste Water
Calcium
Chlorophyll A