Application of BCXZM Composite for Arsenic Removal: EPS Production, Biotransformation and Immobilization of Bacillus XZM on Corn Cobs Biochar

SIMPLE SUMMARY: Biological techniques are environmentally friendly for arsenic bioremediation; however, the practical applicability for these techniques requires some engineering additions. For instance, in the bacterial bioremediation of arsenic, after the bioaccumulation of arsenic, the bacterial biomass is easily suspended in the water and difficult to separate. To resolve this problem, the current research provides a simple approach. Arsenic-tolerant bacterium Bacillus XZM was immobilized on Biocahr and biofilm provided a filter layer for arsenic adsorption. This composite was able to bio-sorb and bio-accumulate 42.3 mg/g of arsenic, which implies that it required USD 6.24 for the bioremediation of 1000 gallons of drinking water (with 50 µg/L of arsenic). This research is beneficial and worthy as it provides a technological application of a biological technique for arsenic-free drinking water. Moreover, it is a clean, green and economical method as it generates no residual sludge and does not use any harmful chemicals. ABSTRACT: This study determined the effect of Bacillus XZM extracellular polymeric substances (EPS) production on the arsenic adsorption capacity of the Biochar-Bacillus XZM (BCXZM) composite. The Bacillus XZM was immobilized on corn cobs multifunction biochar to generate the BCXZM composite. The arsenic adsorption capacity of BCXZM composite was optimized at different pHs and As(V) concentrations using a central composite design (CCD)2(2) and maximum adsorption capacity (42.3 mg/g) was attained at pH 6.9 and 48.9 mg/L As(V) dose. The BCXZM composite showed a higher arsenic adsorption than biochar alone, which was further confirmed through scanning electron microscopy (SEM) micrographs, EXD graph and elemental overlay as well. The bacterial EPS production was sensitive to the pH, which caused a major shift in the –NH, –OH, –CH, –C=O, –C–N, –SH, –COO and aromatic/-NO(2) peaks of FTIR spectra. Regarding the techno economic analysis, it was revealed that USD 6.24 are required to prepare the BCXZM composite to treat 1000 gallons of drinking water (with 50 µg/L of arsenic). Our findings provide insights (such as adsorbent dose, optimum operating temperature and reaction time, and pollution load) for the potential application of the BCXZM composite as bedding material in fixed-bed bioreactors for the bioremediation of arsenic-contaminated water in future.