Treatment of cutting and emulsifying wastewater by non-thermal plasma

The technology of non-thermal plasma was used to treat cutting and emulsifying wastewater and investigate the effect of initial pH value of wastewater, several kinds of inorganic salt or not, velocity of airflow, electrode distance, input voltage, discharge time on wastewater treatment ratio. The experiment results show: the effect of wastewater purifying ratio increases with prolonging the plasma discharge time, the effect of wastewater purifying tends to steady after discharge time exceeds 120min; acidic conditions of wastewater is benefit to improve purifying ratio then basic condition. Putting a little of inorganic salt can increase the effect of wastewater purifying ratio, in this experiment, the effect of CaCl₂ is better than Al₂(SO₄)₃, FeSO₄, NaCl. The distance between electrodes have more effects of wastewater treatment, the purifying ratio of gas phase discharge is better then liquid phase discharge and gas-liquid interface. Putting air into the wastewater can increase the effect of treatment, but when the velocity of airflow is too high the residence time will be short and then reduce the purifying ratio. The purifying ratio increases with the increasing of input voltage. In this experiment when the input voltage is 25kV, electrode distance 35mm, airflow 0.2L/min, CaCl₂ 1.6g/L, discharge time 30 min, the removal ratio of COD and turbidity could reach 90% and 92%, respectively.