At present, the sustainable utilization of water resources and water resource management has become a key contradiction in human production and life. The exploitation of oil has led to extensive pollution of water resources, and there is still a lack of mature, reliable and effective equipment for efficient treatment of oily wastewater. In view of the oily wastewater and other general pollution of water compared with both difficult to degrade, easy to emulsify the characteristics of the conventional treatment process can not achieve the desired results dish. This paper briefly introduces the proposed coagulation-ultrafiltration treatment process for oily wastewater.
Ultrafiltration treatment of oily wastewater principle analysis
The key to the ultrafiltration process is to select the appropriate ultrafiltration membrane, under the action of external pressure, the liquid to be treated will be passed through the ultrafiltration membrane of a certain aperture, so that the inorganic ions and low molecular weight substances in the solution will be passed through the ultrafiltration membrane, while other high molecular weight and macromolecule substances will be retained on the side of the ultrafiltration membrane, and finally the separation and concentration of wastewater will be realized. Through the analysis, the main mechanism of oily wastewater treatment based on ultrafiltration membrane can be summarized as follows:
(1) Pollutants are adsorbed on the surface of ultrafiltration membrane;
(2) In order to avoid the ultrafiltration membrane being blocked, the pollutants on the surface of the ultrafiltration membrane are removed in time;
(3) The pollutants retained on the surface of the ultrafiltration membrane can be screened to achieve the purpose of reuse.
In general, the main factors affecting the treatment effect of ultrafiltration membrane include the flow rate of the liquid to be treated, the size of the external pressure, the operating temperature, the operating time, the concentration of the liquid to be treated, and the effect of the pretreatment of the liquid to be treated. Among them, the flow rate of the liquid to be treated based on the ultrafiltration membrane is generally controlled at 1m/s ~ 3m/s; the size of the pressure given by the outside world is related to the nature of the boundary layer of the selected ultrafiltration membrane; as for the processing temperature, it is generally related to the physical, chemical, and biological properties of the liquid to be treated and carried out at higher temperatures as far as possible. The so-called operating time is related to the flux parameters of the ultrafiltration membrane, for different ultrafiltration membranes should be cleaned after one cycle of operation. According to the different characteristics of the liquid to be treated, the maximum concentration allowed varies; in order to enhance the treatment effect of the contaminated liquid to be treated, it is generally necessary to carry out pretreatment, and common pretreatment methods include filtration, chemical flocculation, pH adjustment and activated carbon adsorption.
Coagulation - ultrafiltration combined process for treatment of oily wastewater
Coagulation-ultrafiltration combined process refers to the coagulation pretreatment of oily wastewater before it passes through the ultrafiltration membrane. From the theoretical analysis, it can be seen that the coagulation pretreatment of oily wastewater can improve its permeability in the ultrafiltration membrane, thus reducing the contamination of the ultrafiltration membrane, which is specifically manifested in the following points:
(1) The coagulation treatment of oily wastewater can reduce the amount of pollutants at the pores of the ultrafiltration membrane;
(2) The coagulation treatment of oily wastewater can effectively improve the characteristics of the sedimentary layer on the surface of the ultrafiltration membrane;
(3) The coagulation treatment of oily wastewater can increase the reverse transport velocity of the particles, thus increasing the permeate flux.
In order to ensure the final treatment effect of oily wastewater treatment, it is necessary to ensure the pretreatment effect of oily wastewater. The main factors affecting the effect of coagulation pretreatment of oily wastewater, in addition to adding different types of coagulants, but also with the water temperature, PH value, the impurity composition of the liquid to be treated, as well as hydraulic conditions and other related.