Test Research On The Treatment Of Emulsified Oil Wastewater By Electrocoagulation

Emulsified oil wastewater has a very wide range of sources such as petrochemical industry, machine-building industry, iron and steel industry, food producing industry and so on. These industries all can produces emulsified oil wastewater. It will have a significant impact on the natural environment and ecological system if not disposed of properly.At present, the commonly used emulsified oil waste water treatment methods, such as membrane separation, flocculation and flotation method, has some effect on emulsified oil wastewater treatment. But more or less has some problems, such as large investment, easy to cause the secondary pollution, the treatment effect is not stable and so on. Electrocoagulation as a kind of water treatment technology, has some advantages such as simple equipment, no additional agents, small secondary pollution, easy and flexible operation etc., provides a new way to emulsified oil wastewater treatment.Respectively using DC and pulse electrocoagulation to treatment emulsified oil wastewater, the influence of various parameters on the treatment effect is studied, process parameters optimization design was carried out. The quantitative relationship between the treatment effect and the impact parameters was studied, the corresponding mathematical model was established. The economical efficiency and electrode passivation of DC and pulse electrocoagulation to treatment emulsified oil wastewater was analyzed. Explore the mechanism of how the pulse power to saving the energy and slow the electrode passivation. The results are as following:(1) DC electrocoagulation was applied to treat emulsified oil wastewater. The results show that removal efficiency is optimal when the current density is 11.90 mA/cm2(corresponding to the slot voltage of 7.8 V), the electrical flocculation time is 50 min, plate spacing is 2.5cm, raw water pH value is 3. Under this condition, the oil content of emulsified oil wastewater and CODCr removal rate were 95.69% and 94.04% respectively. Each index effect on the removal rate of oil content level in the order: current density > raw water pH > electrical flocculation time > plate spacing.(2) Pulse electrocoagulation was applied to treat emulsified oil wastewater. The results show that removal efficiency is optimal when the current density is 7.94 mA / cm2(corresponding to the cell voltage of 6.4V), the electrical flocculation time is 40 min, plate spacing is 2.5cm, the raw water pH value is 3, duty ratio is 70% and pulse frequency is 600 Hz. Under this condition, the oil content of emulsified oil wastewater and CODCr removal rate were 95.69% and 94.04% respectively. Each index effect on the removal rate of oil content level in the order: current density, duty ratio, electric flocculation time, pulse frequency, raw water pH and plate spacing.(3) Established the mathematical model of the dc and pulse electrocoagulation treatment of emulsified oil wastewater which is the form of quadratic polynomial, and the accuracy of the model is verified by test, point prediction error within 10.2% for the most part. It provides a theoretical basis for the subsequent development of electrical engineering practice and flocculation device.(4) Under the optimal conditions, pulse electrocoagulation compared with direct current electrocoagulation, the energy consumption was reduced by 56.40%, aluminium consumption was reduced by 46.70%, the water treatment cost was reduced by 52%, has achieved good energy saving effect.(5) Through continuous batch test and sem photos, discusses the mechanism of how the pulse electrocoagulation slowdown the electrode passivation. Through the formula of unit electrolysis voltage analysis and electrode weighing test shows that under the same condition pulse electrocoagulation compared with DC electrocoagulation has lower cell voltage. Pulse electrocoagulation has high current efficiency, which can significantly reduce the power consumption.