Improving algal growth in an anaerobic digestion piggery effluent by fungal pretreatment: Process optimization, the underlying mechanism of fungal decolorization, and nitrogen removal

Hanwu Song; Jun Li; Mi Zhou; Hongwu Li; Liangliang Fan; Peilun Xu; Shengxi Shao; Jingjing Li; Chengyu Xu; Wenguang Zhou; Jun Qian

doi:10.1016/j.chemosphere.2023.139416

Improving algal growth in an anaerobic digestion piggery effluent by fungal pretreatment: Process optimization, the underlying mechanism of fungal decolorization, and nitrogen removal

Chemosphere. 2023 Oct:337:139416. doi: 10.1016/j.chemosphere.2023.139416. Epub 2023 Jul 4.

Authors

Hanwu Song¹, Jun Li¹, Mi Zhou², Hongwu Li³, Liangliang Fan¹, Peilun Xu¹, Shengxi Shao¹, Jingjing Li¹, Chengyu Xu¹, Wenguang Zhou⁴, Jun Qian⁵

Affiliations

¹ Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, and School of Resources & Environment, Nanchang University, Nanchang, 330031, China.
² Xinjiang Rao River Hydrological and Water Resources Monitoring Center, Shangrao, 334000, China.
³ Faculty of Science and Engineering, Soka University, Tokyo, 1928577, Japan.
⁴ Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, and School of Resources & Environment, Nanchang University, Nanchang, 330031, China. Electronic address: wgzhou@ncu.edu.cn.
⁵ Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, and School of Resources & Environment, Nanchang University, Nanchang, 330031, China. Electronic address: qianjun504@ncu.edu.cn.

PMID: 37414296
DOI: 10.1016/j.chemosphere.2023.139416

Abstract

Anaerobic digestion piggery effluent (ADPE) shows high chromaticity and ammonium levels, severely inhibiting algal growth. Fungal pretreatment has great potential for decolorization and nutrient removal from wastewater, which coupled with microalgal cultivation may be a reliable strategy for sustainable ADPE resource utilization. In this study, we selected and identified two locally isolated eco-friendly fungal strains for ADPE pretreatment, and fungal culture conditions were optimized for decolorization and ammonium nitrogen (NH₄⁺-N) removal. Subsequently, the underlying mechanisms of fungal decolorization and nitrogen removal were investigated, and the feasibility of using pretreated ADPE for algal cultivation was explored. The results showed that two fungal strains were identified as Trichoderma harzianum and Trichoderma afroharzianum, respectively, presenting good growth and decolorization performance for ADPE pretreatment. The optimized culture conditions were as follows: 20% ADPE, 8 g L^-1 glucose, initial pH 6, 160 rpm, 25-30 °C, and 0.15 g L^-1 initial dry-weight. ADPE decolorization was mainly caused by fungal biodegradation of color-related humic substances through manganese peroxidase secretion. The removed nitrogen was completely converted into fungal biomass as nitrogen assimilated, ca. 90% of which was attributed to NH₄⁺-N removal. The pretreated ADPE significantly improved algal growth and nutrient removal, demonstrating the feasibility of developing an eco-friendly fungi-based pretreatment technology.

Keywords: Algal growth; Anaerobic digestion piggery effluent; Fungal pretreatment; Mechanistic investigation; Parameter optimization.

MeSH terms

Ammonium Compounds* / metabolism
Anaerobiosis
Biomass
Denitrification
Microalgae* / metabolism
Nitrogen / metabolism
Wastewater

Substances

Nitrogen
Wastewater
Ammonium Compounds