Study On Treating Oil-wastewater With Electro-coagulation Flotation Technology

With the improvement of economy and industry in our country, the industrial pollution is more and more serious. People do lots of research, exploration and engineering practice especially in recently, many new technologies which are more available than the tradition method emergence. Despite some progress, in some extent, in practice, there are many problems. So we need urgently to study and popularize the applied new technology for processing waste water, and impel the continuous improvement of protecting environment. In this work, the object of study is oil-waste water. Oil-wastewater is a kind of wastewater which is liable to cause serious environmental pollution to the industry and our life. Its source is wide and composition is complex, oil-wastewater treatment is especially attended by people at home and abroad.This paper mainly expound processing the oil-waste water by the method of electro-coagulation flotation,it includes the research of the petroleum ether that it used to extract oil in the water; the research of choosing electrode; the research of choosing the parameter that can influence the result. Finally,An experimentation of the waste water disposal,according to orthographic experimental method,is arranged. The data obtained on orthogonal experiment were analysis by range analysis and variance analysis to verify the reliability of the results and analysis the oil removal influence of waste water technological parameter. The content is:(1) To determine the oil concentration in the waste water, the traditional method of UV spectrophotometry is a common one. When the incoming wavelength is 225 nm, the transmittance of the petroleum ether must be more than 80%. However, the petroleum ether supplied in the market can not achieve this standard, so the process of removal of the aroma is necessary. In this work, we take contrast experiment. Taking concentrated sulfuric acid, activated carbon, potassium permanganate and redistilling respectively, these methods not only can enhance the transmittance of the petroleum ether but also make transmittance exceed 80%. The experiment result is that taking concentrated sulfuric acid treated petroleum ether is better than other methods.(2) In this paper, the object of study is self-made emulsifying oily wastewater in the laboratory. We combined with aluminum electrodes and pulse electro-coagulation flotation technology to treat waste water. Firstly, taking Single-factor experiment to treat oil-waste water, identify the main factors affect the degreasing effect and scope of various factors. Pulse electro-coagulation flotation was used to treat oil-wastewater with high oil content. Different operational conditions were examined, which included current density, reactive time, electrode distance, pH value and pole switching time.(3) Orthogonal tests were carried out to identify the optimal operational conditions for this technique. Considering the treatment cost and efficiency together, the optimal operational conditions turned out to be as follows: an electrode distance of 3.3 cm, pH value of 4, current density of 49.38mA.cm^-2, reaction time of 15 min and pole switching time of 10 s. The removal efficiency of oil-wastewater under normal conditions reached up to 96.21%.The influences of different factors on removal efficiency are in the following decreasing sequence: pH value> current density > pole switching time > reactive time > board distance.(4) The data obtained on orthogonal experiment were analysis by range analysis and variance analysis to verify the reliability of the results. The verified experiments show that electro-coagulation flotation is found effective in treating emulsion wastewater, with the advantages of less energy consumption and treatment time and so on. And the experimental devices not only switch electrode, but also can set the time of electrode. This result is equivalent to imposing a pulse signal on the device, the pulse signal make the electrode reaction intermittent, and is conducive to the proliferation of more favorable between metal ions and colloidal flocculation, and can reduce the concentration polarization, preventing electrode been passivation so that this effect is to reduce energy consumption. Therefore, pulse electro-coagulation floatation technology is wide applicability in wastewater, and can be well applied in treating emulsified oil wastewater.