Alkali pretreatment as a game-changer in enhancing methane production from cattle manure and reshaping microbial landscape: A comparative analysis of NaOH, KOH, and Ca(OH)2

IF 3.7 3区生物学 Q2 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Biochemical Engineering Journal Pub Date : 2025-09-10 DOI:10.1016/j.bej.2025.109931

Wenjun Yan , Zhixuan Yin , Lingying Kong , Qian Zhang , Changqing Liu

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Abstract

The presence of refractory organic substances in cattle manure significantly impedes its biogas recovery potential through anaerobic digestion. To address this challenge, this study explored the application of three different types of alkaline agents—NaOH, KOH, and Ca(OH)₂—for pretreatments to optimize methane production from cattle manure. The results demonstrated that pretreatment with various alkaline agents could notably accelerate the conversion of insoluble organics in cattle manure into more digestible soluble forms, with varying degrees of effectiveness. NaOH/KOH pretreatments of cattle manure elevated the soluble chemical oxygen demand (SCOD) by 7.6 times, reaching approximately 38,000 mg/L. This enhancement led to a 50 % increase in the methane yield during subsequent anaerobic digestion, achieving a rate of 150 mL/g VS·d. Despite the low solubility of Ca(OH)₂ and the formation of Ca-precipitates hindering hydrolysis during pretreatment, the methane yield still increased by 31 %. High-throughput sequencing further revealed that alkaline pretreatments reshaped the microbial communities. Specifically, by enhancing hydrolysis and increasing the availability of H₂/CO₂, NaOH/KOH pretreatment shifted the methanogenesis pathway from acetotrophic to polytrophic by enriching hydrogenotrophic Methanobacterium and polytrophic Methanosarcina. However, Ca(OH)₂ pretreatment maintained the dominance of acetoclastic methanogenesis by preserving the inherent characteristics of the cattle manure.

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碱预处理在提高牛粪甲烷产量和重塑微生物景观中的作用：NaOH、KOH和Ca(OH)2的比较分析

牛粪中难降解有机物的存在严重阻碍了其通过厌氧消化的沼气回收潜力。为了解决这一挑战，本研究探索了三种不同类型的碱性剂——naoh、KOH和Ca(OH)2的应用，以优化牛粪的甲烷产量。结果表明，不同碱剂预处理能显著促进牛粪中不溶性有机物转化为更易消化的可溶性有机物，且效果不同。牛粪的NaOH/KOH预处理使可溶性化学需氧量（SCOD）提高了7.6倍，达到约38,000 mg/L。在随后的厌氧消化过程中，这种增强导致甲烷产量增加50 %，达到150 mL/g VS·d。尽管预处理过程中Ca(OH)2的溶解度较低且Ca沉淀物的形成阻碍了水解，但甲烷产率仍提高了31% %。高通量测序进一步显示，碱性预处理重塑了微生物群落。具体而言，NaOH/KOH预处理通过增强水解和增加H2/CO2的可用性，通过丰富氢营养型甲烷菌和多营养型甲烷菌，将甲烷生成途径从乙酰营养型转变为多营养型。而Ca(OH)2预处理通过保留牛粪的固有特性，保持了醋酸破酯产甲烷的优势。

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来源期刊

Biochemical Engineering Journal 工程技术-工程：化工

CiteScore

7.10

自引率

5.10%

发文量

380

审稿时长

34 days

期刊介绍： The Biochemical Engineering Journal aims to promote progress in the crucial chemical engineering aspects of the development of biological processes associated with everything from raw materials preparation to product recovery relevant to industries as diverse as medical/healthcare, industrial biotechnology, and environmental biotechnology. The Journal welcomes full length original research papers, short communications, and review papers* in the following research fields: Biocatalysis (enzyme or microbial) and biotransformations, including immobilized biocatalyst preparation and kinetics Biosensors and Biodevices including biofabrication and novel fuel cell development Bioseparations including scale-up and protein refolding/renaturation Environmental Bioengineering including bioconversion, bioremediation, and microbial fuel cells Bioreactor Systems including characterization, optimization and scale-up Bioresources and Biorefinery Engineering including biomass conversion, biofuels, bioenergy, and optimization Industrial Biotechnology including specialty chemicals, platform chemicals and neutraceuticals Biomaterials and Tissue Engineering including bioartificial organs, cell encapsulation, and controlled release Cell Culture Engineering (plant, animal or insect cells) including viral vectors, monoclonal antibodies, recombinant proteins, vaccines, and secondary metabolites Cell Therapies and Stem Cells including pluripotent, mesenchymal and hematopoietic stem cells; immunotherapies; tissue-specific differentiation; and cryopreservation Metabolic Engineering, Systems and Synthetic Biology including OMICS, bioinformatics, in silico biology, and metabolic flux analysis Protein Engineering including enzyme engineering and directed evolution.