Carbon dioxide emission control of a vermicompost process using fly ash

Abstract

Composting and vermicomposting generate a valuable product rich in plant nutrients and at the same time, reduce environmental pollution. However, along with these processes and in relation to the metabolism of the microorganism and the worms present in the vermicomposting, CO₂ is emitted to the atmosphere, contributing to the greenhouse effect. Taking these issues into account, different masses of fly ash were used to study the control of the CO₂ of the gas coming from a vermicomposting process and to evaluate the possibility of using the adsorbent as fertilizer in the culture of lettuce Lactuca sativa. Along the vermicomposting process, an increase in the concentration of CO₂ emissions was observed, with a maximum level of emission at the day 20 of the process and an average of 770 mg/L in air. After the adsorption process, the CO₂ concentration was lower due to the effect of the fly ash that was able to trap the emitted gas. The percentage of CO₂ adsorption shows maximum values of 55.5, 58.1 and 63.8% with 0.5, 1 and 1.5 kg of fly ash, respectively. The CO₂ uptake capacities of the different loads of fly ash used were 3.39, 7.03 and 6.84 mmol CO₂/g sorbent with 0.5, 1 and 1.5 kg of fly ash, respectively. After five weeks of sowing L. sativa, it was observed that when no fly ash was used in the soil, the length of the stem was 10.2 cm. Then, the length of the stem was 22 cm, and 16 cm when 10% of fly ash was applied and not applied in the adsorption process, getting a significant correlation between the load of fly ash and the length of the stem. The r when fly ash was used in the adsorption process was 0.9817 and 0.9811 when no ash fly was used in the process.

Keywords: CO(2) capture; Fertilizer; Fly ash; Vermicompost.