Enhancing Soil Bioremediation: Microbial Composting Strategies for the Degradation of Chlorpyrifos Ethyl in Agricultural Soils

¹ Faculty of Environmental Sciences, University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam.
² Ministry of Natural Resources and Environment, 10 Ton That Thuyet, Nam Tu Liem district, Hanoi, Vietnam
³ Institute for Environment and Resources, Vietnam National University Ho Chi Minh City (VNU- HCMC), Ho Chi Minh City, 70000, Vietnam.
⁴ Research and Development Institutes Advanced Agrobilogy, Nguyen Tat Thanh University, Ho Chi Minh City, 700000, Vietnam.

^* Email: tthanh@ntt.edu.vntthanh@ntt.edu.vn

Abstract

The study investigates the decomposition of Chlorpyrifos Ethyl (CE) in tea-growing soils using Biomix under varied conditions, aiming to enhance the safety of agricultural products. Biomix 1 demonstrated a significant capability for degrading CE, particularly at higher temperatures and an optimal pH of 6. It showcased higher microbial density for lignindecomposing organisms at 4.68×10⁵ CFU/g for cellulose decomposition, 3.6×10⁵ CFU/g for hemicellulose, and 2.5×10⁵ CFU/g for lignin, indicating robust biodegradation potential. An intriguing outcome was Biomix 2’s improved performance with nitrogen supplementation, reaching over 96% degradation efficiency for CE at a concentration of 150ppm. Temperature fluctuations within the composting bins pointed to the thermophilic nature of the degrading microbes, with an initial increase to 35°C and subsequent stabilization, suggesting a vigorous decomposition phase followed by a plateau due to substrate depletion. These findings indicate that microbial composting at optimized moisture (60%) and pH levels can significantly degrade CE, with a higher degradation rate observed at 37°C compared to 25°C. Biomix amendments and maintained conditions reflect the practical application potential, aligning with the common agricultural CE concentrations of 120-150ppm. This study underlines the viability of using microbial composting as a sustainable and effective strategy for the bioremediation of pesticide-contaminated agricultural soils, with promising implications for environmental safety and public health.