Study on Inactivation of Escherichia coli by Ultra-macroporous Sponge-like Biochar

Developing efficient disinfection technology is of great significance to control environment biological pollution of agricultural products. Traditional disinfection technologies have problems of low stability, low sustainability, producing disinfection by-products and high cost. Herein, a new disinfection method based on ultra-macroporous sponge-like biochar was developed, and the performance and mechanism were investigated. Results show that operation conditions have significant influence on disinfection effects. With the increase of ultra-macroporous sponge-like pomelo peel biochar dosage and sulfate concentration, the inactivation efficiency of bacteria increased. Rapid inactivation could be achieved (99.81% inactivation in 1 hour and 99.97% inactivation in 2 hours) when dosage of pomelo peel biochar was 4 g·L^-1 and sulfate concentration was 50 mmol·L^-1. Bactericidal effects and pore size distribution of pomelo peel biochar system, pomelo peel system and coconut shell biochar system were compared. It was found that the ultra-macroporous structure in pomelo peel biochar is irreplaceable, which is compatible with bacteria size and could trap bacteria well or kill the captured bacteria by contact. Moreover, comparisons between pomelo peel biochar system, sulfate-free system, chlorine salt system and filtrate system suggest that mixture of pomelo peel biochar and sulfate solution would generate chemicals with bactericidal effect such as aromatic phenols or ketones, which further improved the bactericidal efficiency. This study can provide methodological support for technology innovation of efficient disinfection for soil biological pollution.