Preparation of Micron-Scale Activated Carbon-Immobilized Bacteria for the Adsorption–Biodegradation of Diesel Oil

Abstract

This paper investigated the micron-scale activated carbon (MAC) immobilized diesel-oil-degrading bacteria (bio-MAC) used as remediation materials for the removal of diesel-oil-contaminated water. The high-efficiency indigenous diesel-oil-degrading bacteria were firstly screened and enriched, then the MAC was used as a diesel oil sorbent and biocarrier for the immobilization of degrading bacteria to prepare the bio-MAC material. The removal performance of the bio-MAC was evaluated via a comparison with the freely degrading bacteria and MAC. The SEM results demonstrated that the diesel-oil-degrading bacteria were effectively immobilized and grew well on the surfaces of MAC particles. The concentration of MAC significantly influenced the growth and activity (DHA and LPS) of immobilized bacteria, and the MAC addition of 3.0 g/L was proven to be an optimum amount for the preparation of bio-MAC. The high-throughput sequencing analysis further indicated that the bacteria immobilized on MAC showed higher abundance levels and diversities index values compared to freely suspended bacteria, such as Pseudomonas, Rhodococcus, Bacillus and Microbacterium. The FTIR spectroscopy results showed that the bio-MAC could effectively degrade the aliphatic hydrocarbons, alkenes and aromatic compounds of diesel oil to carboxylic acids, esters, alcohols and other metabolites. When the concentration of diesel oil was 1 g/L, the removal efficiency for the diesel oil of bio-MAC reached 86.35% after 15 days, while only 23.82% and 70.97% of the diesel oil was removed using the same amount of free bacteria and MAC, respectively. The prepared bio-MAC showed a synergic effect of adsorption and biodegradation and efficiently removed diesel oil from wastewater.