Dairy wastewater treatment using immobilized bacteria on calcium alginate in a microbial electrochemical system

The present study was conducted to assess the effect of immobilized Pseudomonas aeruginosa at calcium alginate beads for improving protease and lipase production as the main biocatalysts for dairy wastewater treatment in a microbial electrochemical system. A single-chamber cylindrical bioreactor with adequate volume of 3 L equipped with circular steel mesh and carbon cloth as the cathode and anode electrodes was utilized for the experiments. The main operating variables, including percent of alginate beads, pH, concentration, current density, and time were studied. The obtained results showed that the maximum production of protease and lipase in pH = 6.0 and induced current of 8.0 mA were 193.81 and 47.89 IU/L, respectively. The best precentage of calcium alginate in the bioreactor were obtained 40%. Moreover, the enzyme production time compared to the non-alginate reactor decreased from 12 to 4 h. According to the obtained results, the immobilization of Pseudomonas aeruginosa on calcium alginate along with the electrical stimulation of the bacteria increases the enzyme activities and thus reduces the time of treatment of dairy wastewater in the microbial electrochemical system.