Facilitating immobilization of functional bacteria and accelerating degradation of PAHs via modified biochar: Performance and mechanisms
Xiaoyi Xu, Xiaoyong Cao, Xiaobin Chen, Bin Wang, Jinlong Zhuang, Tianyin Huang, Bingdang Wu
Abstract
Enrichment of functional microorganisms is an effective strategy to degrade toxic polycyclic aromatic hydrocarbons (PAHs). Here, brewer's spent grain biochar was modified with MgCl 2 for the immobilization of the functional bacteria (SZ-3), and its microbial degradation of three PAHs (phenanthrene, fluoranthene , and pyrene) in sediments were investigated. Results showed that modified biochar has more hydrophilic functional groups and higher porosity, resulting in a maximum adsorption capacity of 955.13 nmolP·g −1 for SZ-3. Along with a stronger electron release capacity and charge capacity, the degradation rate of PAHs by modified biochar was enhanced. Compared to the free bacteria system, the highest degradation efficiency was increased 4.9 times (from 0.0088 d −1 to 0.0431 d −1 ) for the immobilized system. By detecting microbial species and analyzing enzyme activity , the mechanism of enhanced degradation of pollutants has been hypothesized that, Mg 2+ modification can protect the normal growth of functional bacteria and promoting the secretion and expression of biological enzymes. Especially for polyphenol enzyme and catalase activity, they were increased 2 and 1.6 times comparing with the free bacteria system. These results demonstrate that immobilized microorganisms have the potential to rapid degrade PAHs by increasing enzyme activity , thus shed lights on biodegradation and bioremediation.