Process flow + key technologies: one article to solve the problem of oily sewage treatment

Among them, water pollution is a complex issue with many pollution sources. In our country's water pollution treatment work, the treatment of oily sewage is also a very difficult task. We should Fully analyze the source of oily sewage, analyze its hazards, clarify the work flow of oily sewage treatment, and formulate scientific and reasonable treatment countermeasures.

This article conducts a detailed analysis and exploration of the sources and hazards of oily sewage, the process flow of oily sewage treatment, and the key technical methods of oily sewage treatment, so as to The oily sewage treatment work in my country is discussed in detail.

1.1 Analysis of the sources of oily wastewater

The sources of oily wastewater in my country are very wide, in steel refining, industrial production, oil extraction, pesticides and food Oily sewage will be produced during processing and production, and these oil pollutants mainly exist in four forms, namely dissolved oil, dispersed oil, floating oil and emulsified oil.

　 (1) Petrochemical industry. In my country's petrochemical industry, oily wastewater will be produced at almost any stage from initial extraction to final transportation and consumption. With the rapid development of my country's science and technology level, my country's tertiary oil recovery technology has also been widely used. , which improves the oil displacement effect, but also makes the composition of the sewage more complex.

　 (2) Chemical and pharmaceutical engineering. The main source is oily sewage from high-concentration processes. During the manufacturing process, a large amount of water and lubricating oil are used in the raw material reaction, product separation and raw material pretreatment stages, so a large amount of oily sewage will be generated in the later stage.

　 (3) Metal smelting industry. In the process of smelting metal, whether it is materials in contact with oil or equipment in contact with oil, we need to cool, clean and lubricate them, and the lubricating oil may also come into direct contact with them, so oily sewage will be formed. .

　(4)Food processing and production. In the process of food processing and production in our country, oily sewage will be generated in stages such as equipment cleaning and machine lubrication.

　1.2 Hazard analysis of oily sewage

　 (1) Oily sewage pollutes drinking water sources. If our daily drinking water source is contaminated by oily sewage, not only humans and animals will be infected with diseases, but it may even cause food poisoning, which is very harmful. In addition, oily sewage also contains a certain amount of carcinogens, so it may It will increase the incidence of cancer in areas contaminated by oily sewage;

　(2) Oily sewage is discharged into rivers and lakes. The density of oily sewage is smaller than that of normal pure water. Therefore, once the oily sewage is discharged into rivers and lakes, it will adhere to the water surface, and the gases in the atmosphere and water cannot exchange normally. The oxygen content in the water If the water content continues to decline, aquatic plants will not be able to grow normally, the quality of the water body will be seriously affected, and the utilization value of water resources will be greatly reduced;

　 (3) Oily sewage enters the soil. If oily sewage is used as irrigation water to irrigate the soil, then the oil stains will be deposited on the surface of the crops, the soil will not be able to effectively exchange with the outside air, and the metabolism of the soil will slow down, thus affecting the normal growth of crops and even causing The death of crops, if crops containing oil stains are eaten by humans, will also cause harm to our health.

Usually In the process of treating sewage containing sewage, the process flow is to first separate the oil and water from the oily sewage, and then further separate the oil and water through coagulation or flotation. At this time, we should add quantitatively PAM and PAC ensure the full occurrence of flocculation reaction and coagulation reaction. This process can avoid oil clogging of treatment devices, and at the same time, the oil removal performance of each device can be fully exerted.

When the oily sewage enters the combined air flotation, a large amount of SS and oil have been removed. At this time, we should measure the water quality first. If the water quality still does not meet the standards, Then we should use activated carbon filter tank or quartz sand filter tank to filter it to ensure that it meets the quality standards before it can be discharged.

The main purpose of our secondary oil-water separation is to reduce the emulsification degree of oily sewage. If the freezing point is high and the particlesFor oily sewage with a large density, insulation and heating equipment should be used during treatment. If it is oily sewage with a small specific gravity difference between oil and water, a filtering device should be used. When selecting materials for processing devices, we should fully consider the temperature parameter. When the combined air flotation scum is discharged to the sludge storage tank, it is driven by a pneumatic diaphragm pump to a chamber filter press for filtration and dehydration, and then is transported out for processing.

< strong>　3.1 Coagulation method. This method is mainly aimed at separating tiny suspended oil particles and colloidal oil particles in oily sewage. First, we should add a certain amount of chemicals to the oily sewage to allow a sufficient chemical reaction to occur, and then it will Gradually condense into floc or a relatively stable mixture.

Afterwards, we will add coagulant to the sewage, so that the original colloidal oil particles in the sewage are no longer negatively charged, but electrically neutral. Flocculated polymers or stable mixtures will slowly sink. In the actual treatment process, we often use coagulants such as ferric chloride, basic alumina, aluminum sulfate and ferrous sulfate, and accelerated clarifiers are usually used as structures.

　　3.2 Filtering method. The so-called filtration method refers to intercepting the particles in the oily sewage under the action of the filter membrane, thereby separating the oil and water to achieve the ideal purification effect. Generally speaking, the filtration method should be the next-level treatment method after the coagulation method and the flotation method. After forming a polymer or a stable mixture, the filtration method can be used to remove the colloidal oil stains in the sewage.

Using this treatment method, the oil content of the oily sewage after post-treatment does not exceed 10mg/l. Pressure filters and ordinary rapid filters are usually regarded as structures. The management process using the filtration method is somewhat difficult. Hot water backwashing or air reverse aeration should be performed, otherwise the problem of filter material clogging will easily occur.

　3.3 Air flotation method. This method is mainly used to remove emulsified oil and smaller oil particles in oily sewage. The oil content of the oily sewage treated by this method does not exceed 30mg/l. Its working principle is: first When a certain amount of air is poured into the oily sewage, a large number of bubbles will appear in the sewage, and the bubbles will also float. At this time, an uneven system composed of bubbles, water and oil will be formed. The bubbles will change with the density. For the approaching oil combination and gradual upward movement, which achieves the effect of oil-water separation. According to the different ways of generating bubbles, we can divide the flotation method into the following types:

　 (1) Dissolved air flotation method. This method achieves oil-water separation by precipitating bubbles from saturated oily sewage, adding oily sewage and air to the dissolved air tank and gradually pressurizing it to ensure that the air has been well dissolved in the sewage. The dissolution time is about for 4 minutes, and then send the sewage into the floating tank. When the air is suddenly decompressed, many tiny bubbles will appear, and the bubbles will float together with the oil particles. The biggest advantage of this method is that the sewage and air can be fully integrated;

　(2) Air distribution and air flotation method. The working principle of this method is to cut the air dissolved in water into pieces. Equipment such as impeller air flotation, water pump suction pipe suction flotation, diffusion plate aeration flotation, and jet air flotation are commonly used. This method is easy to operate and manage, and consumes a lot of energy. It can be reduced, but the degree of bubble fragmentation cannot be accurately controlled, and the floating effect may be affected;

　 (3) Electrical floatation. This method is also called electrolytic condensation flotation. Its working principle is to install a positive and negative electrode in the oily sewage. Under the action of direct current, electrolysis will occur and bubbles will be generated at the cathode. The oil particles will also interact with the bubbles. Gradually combine and float upward, and finally achieve oil-water separation of oily sewage.

Through the above discussion, we have The sources and hazards of oily sewage, the process flow of oily sewage treatment, and the key technical methods of oily sewage treatment were analyzed and discussed in detail.

With the rapid development of my country's socialist market economy, people's living standards have been greatly improved, but the environment we live in has been severely damaged, and our country is also actively With the implementation of the strategy of sustainable development, the awareness of environmental protection has gradually become deeply rooted in the hearts of the people, and the general public has paid more attention to our country's environmental protection work.

The treatment of oily sewage is a complex system project. We should analyze the sources and hazards of oily sewage in detail, constantly optimize the treatment process of oily sewage, and use oily sewage scientifically. The key treatment technology is to truly do a good job in the treatment of oily sewage.

　(Original title: Process flow + key technologies: one article to solve the problem of oily sewage treatment)