Effect of lignocellulose/montmorillonite immobilized Bacillus sp. on monosodium glutamate wastewater.

ABSTRACT

A group of Bacillus sp. was extracted from monosodium glutamate wastewater. Lignocellulose/montmorillonite composite was selected as the carrier. Lignocellulose/montmorillonite composite immobilized Bacillus sp./calcium alginate microspheres were prepared by immobilized microorganism techniques. The microspheres were used to treat monosodium glutamate wastewater with significantly reduced ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) concentrations. The optimum preparation conditions of microspheres in the treatment of NH3-N and COD of monosodium glutamate wastewater were studied. The concentration of sodium alginate was 2.0 wt%, lignocellulose/montmorillonite was 0.06 wt%, Bacillus sp. was 1.0 wt%, CaCl2 solution was 2.0 wt%, coagulation time was 12 h, and the removal capacities of NH3-N and COD were 44832 and 78345 mg/L, respectively. The surface structure, element content, functional group change, and crystal structure of the microspheres were characterized by SEM, EDS, and other methods. The results showed that the -COOH in lignocellulose/montmorillonite and the -OH in the Bacillus sp. form intermolecular hydrogen bonds. The Si-O and Al-O bonds in lignocellulose/montmorillonite reacted with sodium ions in sodium alginate. New crystal structures appear inside the material after crosslinking, and the microspheres was formed. Thus, the study has shown that the microspheres were successfully prepared and contributes to the treatment of NH3-N and COD in monosodium glutamate wastewater. This work can provide an interesting strategy for the removal of COD and NH3-N in industrial wastewater by reasonably combining bio-physicochemical processes.