Immobilization of enzymes for Klebsiella BOD sensor

Klebsiella sp. was isolated from the activated sludge of a wastewater disposal facility treating wastewater contaminated with highly concentrated lactose. A BOD probe loaded with Klebsiella sp. showed an improved performance for lactose detection, however, the sensitivity of the microbial BOD sensor toward glucose or fructose was still higher than that corresponding to lactose. Accordingly, an enzyme capable of hydrolyzing disaccharides or polysaccharides was immobilized and used together with Klebsiella sp. to correct the inclined selectivity of a BOD sensor towards monosaccharides. Furthermore, the possibility of using a microbial BOD sensor to obtain BOD values that correlated well with conventional BOD5 values was investigated, irrespective of the content of saccharides in dairy factory wastewater. Bovine serum albumin (BSA) was found to be the best for immobilizing β-galactosidase, invertase, amyloglucosidase, and α-amylase for BOD measurements of lactose, sucrose, maltose, and soluble starch, respectively. Although some improvement was achieved, the results were still far below satisfaction.