Study on factors affecting the remediation of DDT-contaminated soil using the Biosoil bio-preparation

Abstract

This study evaluates the remediation potential of the bioproduct Biosoil containing Bacillus subtilis for DDT-contaminated soil and identifies factors affecting treatment efficiency. Two field soil samples with initial DDT concentrations of approximately 80 mg/kg (MĐ-TXL-01) and 120 mg/kg (MĐ-TXL-02), exceeding the limits specified in QCVN 03:2023/BTNMT, were investigated. Experiments were conducted with straw supplementation to improve soil porosity, while the effects of temperature, product dosage, and treatment time were assessed. Isothermal conditions showed higher efficiency; however, variable-temperature conditions were selected for practical application. A 3% product dosage was optimal in terms of both technical performance and cost. DDT concentrations decreased rapidly within the first 5÷20 days, followed by a slower degradation rate. After 20 days of treatment with 3% Biosoil under variable-temperature conditions, MĐ-TXL-01 achieved concentrations below the permissible limit, while MĐ-TXL-02 remained above the threshold. The results demonstrate the potential of Bacillus subtilis-based Biosoil for DDT soil remediation; however, additional measures such as nutrient supplementation, soil turning, or supporting technologies are needed for highly contaminated soils.