Microalgae-derived hydrogels/membranes for phosphorus removal and recovery from aquaculture tailwater: Waste utilization and phosphorus recycling

• Published in: Bioresource technology 2024-10, Vol.409, p.131246, Article 131246
• Main Authors: Zhang, Aihua, Fang, Shihao, Ge, Mengni, Zhang, Jianfeng, Xi, Huan, Xu, Yidan, Gao, Zhuofan, Huang, Zhuo, Liu, Mu
• Format: Article
• Language: English
• Subjects: adsorption; aquaculture; Aquaculture tailwater; biochar; Euglena gracilis; Haematococcus pluvialis; hydrogels; magnesium; microalgae; Microalgae cultivation; Microalgae-derived hydrogels; Microalgae-derived membranes; phosphates; phosphorus; Phosphorus recycling; poly(vinyl chloride); sodium alginate; technology; total phosphorus; waste utilization; wastes
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131246

[Display omitted] •Phosphorus was recovered from aquaculture tailwater using microalgae biochars.•Microalgae biochars were derived from waste after high-value utilization.•Phosphorus-saturated hydrogels could be applied for microalgae cultivation.•Microalgae biochar-based membranes could be used for microalgae harvesting. Efficient removal and recovery of phosphorus from aquaculture tailwater is challenging due to increasing strict water environment restrictions. This study presents a sustainable approach by using microalgae-waste-derived hydrogels/membranes for phosphorus adsorption and microalgae cultivation. Waste from Euglena gracilis (or Haematococcus pluvialis), modified with magnesium, was converted into biochars (abbreviated as MEBC or MHBC). This biochars were then combined with sodium alginate to fabricate hydrogels and with polyvinyl chloride to create membranes. Due to the almost 100 % phosphorus removal of MEBC (or MHBC) biochar, the as-obtained hydrogels/membranes demonstrated excellent phosphate adsorption, reducing total phosphorus in real aquaculture tailwater from 11 mg/L to 0. Additionally, the phosphorus-saturated hydrogel served as a phosphorus source for microalgae cultivation, while the membranes facilitated microalgae harvesting with a water flux over 40 L/m2/h. This study provides an eco-friendly solution for using microalgae-waste-derived materials to effectively address phosphorus removal and recovery challenges in aquaculture tailwater.