Contribution of Acid Additive to Co-Composting of Chicken Manure: Gas Emission Reduction and Economic Assessment
2025
Wentao Xue | Mao Li | Ling Zhang | Qinping Sun | Shanjiang Liu | Hao Sun | Rong Wu | Guoyuan Zou | Na Duan
Acidic additives have garnered significant attention due to their ability to reduce ammonia (NH<sub>3</sub>) emissions, enhance nitrogen retention, and balance function with cost-effectiveness. This study aimed to investigate the potential of oxalic acid (OA) in reducing gas emissions, promoting compost humification, and enhancing nutrient retention during the co-composting of chicken manure. Moreover, the comparative analysis of the effects and the economic benefits was conducted among OA groups with varying concentrations (OA1: 0.03 mol·kg<sup>−1</sup>, OA2: 0.10 mol·kg<sup>−1</sup>, and OA3: 0.15 mol·kg<sup>−1</sup>) and a sulfuric acid (SA) group (SA1: 0.03 mol·kg<sup>−1</sup>). The results indicated that the addition of OA can extend the thermophilic phase to some extent and achieve the required composting maturity. As the amount of OA increased, the NH<sub>3</sub> emissions (<i>p</i> < 0.05) and the total nitrogen loss rate was decreased; however, this also increased the cost. No significant difference in the total nitrogen loss rate was observed between SA1 and OA1 (<i>p</i> < 0.05). It is worth noting that the addition of SA increased the SO<sub>4</sub><sup>2−</sup> content, leading to an increase of 113.52% in H<sub>2</sub>S emissions. In contrast, the addition of OA resulted in a reduction in H<sub>2</sub>S emissions by 29.92–45.90%. In terms of economic analysis, OA1 was the most effective (OA1 > OA2 > OA3 > SA1). Thereby, OA was proved to be a good alternative for SA in the co-composting of chicken manure, and 0.03 mol·kg<sup>−1</sup> OA is recommended.
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