Study On Degradation Characteristics Of High Salinity Wastewater Using Microbial Fuel Cells

Purposes of this experiment were to study the electricity generation of microbial fuel cells, explore the relationship between COD and voltage and make a construct biosensor.Basic model: MFCs had double chamber configuration, the anode chamber and the cathode chamber, with a proton exchange membrane between them; Anode chamber and the cathode chamber were made of plexiglas, three high of 5.0 X5.5 X6.5 cm. The effective volume was 150 ml, the effective volume was 130 ml in experiment. The anode chamber had two 5 mm holes. Anode chamber was anaerobic continuous flow, with small magnetic beads, we used peristaltic pump put mustard wastewater to the anode chamber with 0.748 ml/min. Cathode chamber changed the solution once a week, we used the vacuum pump put the air to the cathode chamber with 40-60 ml/min. Proton exchange membrane was CEM,(Ultrex CMI7000, Membranes International Inc., USA), the effective area was 5.5 X5.5 cm. Electrode using carbon cloth, width of 5 x4. 5 cm, the effective area of 20.25 m2, electrodes were not daub catalyst. We used mustard wastewater as nutrient solution of the anode chamber and the cathode chamber. We regard electrode and wire and external resistance and the voltage acquisition as a perfective aspect. The external resistance was 500. The voltage acquisition system once every 1.5 min record data.This experiment was divided into two parts, batch and continuous flow, microbial fuel cells were observed contrast of the COD, ammonia nitrogen, the salinity of mustard wastewater. Batch flow: the removal rate of COD was 88%, the removal rate of ammonia nitrogen was 9.8%. Salinity changed little. The maximum voltage of batch flow was 380 mv. Continuous flow was divided into nine stages, each stage used different concentrations of mustard wastewater as fuel, each phase of the COD removal rate was about 20%, the highest was 31.7% in the ninth stage; Ammonia nitrogen removal rate was 0.5%, the highest was 3%; Salinity almost had no change; The first phase to phase six, the voltage was about 161-172 mv, the highest was 172 mv. Current density was 160-169.88 m A/m2, the highest was 169.88 m A/m2. Power density was 25.92-29.22 m W/m2, the highest was 29.22 m W/m2. Seventh stage to the ninth stage, because the COD concentration can’t meet the demand of microbes, voltage value gradually reduce, from 132 to 45. Current density from 130.37 to 44.44 m A/m2. Power density decreased from 17.21 m W/m2 to 2 m W/m2.We established the mathematical relationship between the voltage and COD. Model based on the experiment, when COD concentration was less than 300 mg/L, there was the almost linear relationship between voltage and COD, y = 0.51 x, the y was the value of voltage, the x was the value of COD concentration.