Effects of biochar pyrolysis temperature on di-2-ethylhexyl phthalate (DEHP) removal performance and microbial community structure in coastal sediments

Abstract

Di-2-ethylhexylphthalate (DEHP) is a common plasticizer and widely detected in sediments, water and biota. For its strong reproductive toxicity, teratogenicity and poisonousness, many approaches are developed to remediate DEHP-contaminated soils. This study aimed to evaluate the roles of biochar in accelerating DEHP degradation, assess the impacts of biochar pyrolysis temperature on DEHP removal performance, and explore the underlying mechanisms. Biochar had a satisfactory performance in DEHP adsorption and followed a Freundlich isotherm, exhibiting proportional adsorption capabilities to pyrolysis temperature. Biochar amendment significantly accelerated soil DEHP degradation, and the degradation efficiency ranged from 61.4% to 82.2% and increased with biochar pyrolysis temperature. Biochar remarkably changed soil physiochemical properties by increasing soil pH, organic matter and humus. Soil bacterial community was altered with biochar amendment that the relative abundance of Nocardioides , Marinobacter , Rhodococcus and Gramella increased. Our findings suggested that biochar-assisted bioremediation has a huge potential in soil DEHP degradation and pyrolysis temperature is a critical factor affecting the performance. Our work characterize biochar at different pyrolysis temperatures and explored the underlying mechanisms of biochar-assisted DEHP bioremediation, offering both scientific and practical hints for DEHP bioremediation in coastal sediments. • Higher biochar pyrolysis temperature accelerated DEHP degradation in sediments. • Increased DEHP adsorption on biochar synthesized at higher pyrolysis temperature. • Soil pH, organic matter and humus increased with biochar pyrolysis temperature. • Altered microbial community structure in biochar-assisted DEHP degradation process.