Low-strength electronic wastewater treatment using immobilized cells of TMAH-degrading bacterium followed by activated carbon adsorption

An immobilized-cell process followed by activated carbon adsorption was developed to treat the tetra-methyl ammonium hydroxide (TMAH) containing low-strength electronic wastewater. The isolated TMAH-degrading bacterium (Mycobacterium sp. TMAH-W0418) and activated sludge were entrapped in polyethylene glycol cubes. The packing rate of 60% (v/v), biomass ratio between Mycobacterium and activated sludge of 2:3 (w/w), and total biomass of 7,000 mg/L were found to be optimal for removing dissolved organic carbon (DOC) and TMAH with the concentrations around 1 and 0.2 mg/L, respectively. Granular activated carbon was used to further decrease the DOC and TMAH in the effluent, and the concentrations of DOC and TMAH in the effluent of the combined system were below 1 mg/L and almost 0 mg/L, respectively. Scanning electron microscope results confirmed that cells were effectively immobilized in the polymer matrix. Thick biofilm on the surface of both polymer carriers and activated carbon granules was observe...