Silicate mediated simultaneous in-situ CO₂ sequestration and nutrients removal in anaerobic digestion.

He Liu, Linlin Gong, Yan Zhang, Qianqian Jiang, Minhua Cui, Jie Zhang, Bo Fu, Hongbo Liu   全文下载

School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China

Jiangsu Key Laboratory of Anaerobic Biotechnology, Wuxi 214122, China

Jiangsu Collaborative Innovation Center of Water Treatment Technology and Material, Suzhou 215011, China

ABSTRACT:This study investigated the reactions among CO₃²⁻ , PO₄³⁻, NH₄⁺, Mg²⁺, and Ca²⁺, under different CO₃²⁻ concentration and Mg²⁺/Ca²⁺ ratio, and conducted sludge anaerobic digestion (AD) with silicate addition to achieve in-situ CO₂ sequestration and nutrients removal. High CO₃²⁻ concentration facilitated the formation of MgNH₄PO₄, and Mg²⁺/Ca²⁺ ratio of 1:1 achieved best CO₃²⁻, PO₄³⁻, and NH⁴⁺ removal in simulated anaerobic digestate. Supplementation of 40 g/L magnesium silicate combined with 20 g/L wollastonite decreased CO₂ content in biogas from 28.2% to 19.0%, and removed PO₄³⁻ and NH₄⁺ by 61.8% and 21.2%, respectively, in AD. Simultaneous in-situ CO₂ sequestration and nutrients removal was achieved by directed precipitation of PO₄³⁻ , NH₄⁺ , and CO₂ with silicate released Mg²⁺ and Ca²⁺, to form MgNH₄PO₄ and CaCO₃. Meanwhile, methane production was improved by 51.2% with silicate supplementation. This study provides an attractive measure for CO₂ and nutrients removal as well as methane production enhancement of sludge AD.

KEYWORDS:Anaerobic digestion; Mineral carbonation; CO₂ sequestration; Nutrients removal; Silicates;

GRAPHIC ALABSTRACT：

JOURNAL:Bioresource Technology

SOURCE:Elsevierjournal

DOI:10.1016/j.biortech.2019.03.004

YEAR:2019

PAGES:125-132

PUBLISHER:Elsevier Ltd