Carbon Monoxide Production during Bio-Waste Composting under Different Temperature and Aeration Regimes

Abstract

Despite the development of biorefinery processes, the possibility of coupling the “conventional” composting process with the production of biochemicals is not taken into account. However, net carbon monoxide (CO) production has been observed during bio-waste composting. So far, O2 concentration and temperature have been identified as the main variables influencing CO formation. This study aimed to investigate CO net production during bio-waste composting under controlled laboratory conditions by varying aeration rates and temperatures. A series of composting processes was carried out in conditions ranging from mesophilic to thermophilic (T = 35, 45, 55, and 65 °C) and an aeration rate of 2.7, 3.4, 4.8, and 7.8 L·h−1. Based on the findings of this study, suggestions for the improvement of CO production throughout the composting process have been developed for the first time. The highest concentrations of CO in each thermal variant was achieved with an O2 deficit (aeration rate 2.7 L·h−1); additionally, CO levels increased with temperature, reaching ~300 ppm at 65 °C. The production of CO in mesophilic and thermophilic conditions draws attention to biological CO formation by microorganisms capable of producing the CODH enzyme. Further research on CO production efficiency in these thermal ranges is necessary with the characterization of the microbial community and analysis of the ability of the identified bacteria to produce the CODH enzyme and convert CO from CO2.

Effective Carbon Dioxide Mitigation and Improvement of Compost Nutrients with the Use of Composts’ Biochar

“…It was observed that emissions of CO increased with time and temperature (Supplementary Materials Figure S2), which was previously indicated with our own study [61]. This is an effect of the thermochemical reactions and biological activities of microorganism.…”

Development and Evaluation of Cow Dung Composting Equipment with Ventilation and Heating

“…On this basis, the heating box with the vent of the composting equipment is designed as a rectangle, and the size of the heating box refers to the structure of the fermentation tank. This paper describes the design of a heating box made of 304 stainless steel, with dimensions of 500 mm × 350 mm × 300 mm and vents [41]. The box consists of a top cover and a main structure, with an electric heating pipe installed in the middle of the top cover.…”

Optimization and Experiment of Livestock and Poultry Manure Composting Equipment with Vented Heating

“…Animal manure is both a rich source of organic matter and a potential environmental pollutant, containing pathogenic bacteria and nutrients which can contribute to water eutrophication and soil contamination if improperly treated [8,9]. Recognizing these challenges, China has outlined goals for agricultural sustainability to ensure the comprehensive utilization of livestock waste and crop straw by 2030 [9][10][11]. Given the urgency of harmless manure treatment, composting-a widely used method-transforms livestock and poultry manure into organic fertilizer, increasing agricultural yield and mitigating soil degradation from traditional fertilizers [12][13][14][15][16].…”