Minimization of hazardous sludge production using a bioelectrochemical system supplied by an alternating current...

In the present study, minimization of hazardous bio-sludge production was investigated using a bioelectrochemical system supplied by an alternating current electric field and supplemented with phenol as a cabon source. The experiments were conducted in an air-conditioned bioreactor and at neutral pH value. Moreover, steel wool and carbon cloth were utilized as electrodes in the bioelectrochemical system. The experiments were operated in an air-conditioned bioreactor at 25 ℃ and a neutral pH value with carbon to nitrogen (C/N) ratio of 0.5-6. The results obtainedshowed that complete phenol electro-biodegradation occurred at a C/N ratio ofa frequency of 5 Hz, and 0.4 peak-to-peak voltage (Vpp) over 2 h.Besides, sludge production and sludge yield were obtained at the C/N ratio of 0.5-6 by 200-382 mg VSS/g COD and 82-89.4 mg TSS/g COD, respectively. Ultimately, the C/N ratio of 1 seemed to be optimum for microbial growth with the phenol biodegradation efficiency of 99.9% as well as the lowest sludge production. These results demonstrated that the proposed bioelectrochemical system supplied by low-frequency and low-voltage electric current could reduce hazardous sludge production.