Petrochemical is a series of organic processing processes based on petroleum as raw material, mainly based on cracking, refining, fractionation, reforming and synthesis. The wastewater generated in the production has complex components, large fluctuations in water quality and quantity, high concentration of pollutants and is difficult to degrade. Most of the pollutants are toxic and harmful organic matter, which seriously pollutes the environment. With the increasing tension of water resources and the strengthening of people’s awareness of environmental protection, the treatment technology of petrochemical wastewater has gradually become a hot topic of research, and new treatment technologies and processes are constantly emerging.
Petrochemical is a pillar industry of the national economy and plays a pivotal role in my country’s modernization construction. Petrochemical enterprises are large water users, and a considerable number of my country’s petrochemical enterprises are located in arid or water-scarce areas. Insufficient water supply has become one of the limiting factors for petrochemical enterprises to expand production. On the other hand, with the rapid development of my country’s economy, oil consumption has continued to rise, the production scale of domestic petrochemical enterprises has continued to expand, and the processing depth has continued to increase. The quality of petrochemical wastewater shows a trend of increasing types of pollutants and complex water quality. With the increasing tension of water resources and the strengthening of people’s awareness of environmental protection, the treatment of petrochemical wastewater has attracted more and more attention.
Overview of petrochemical wastewater
1. Characteristics of petrochemical wastewater quality
Petrochemical is a series of organic processing processes based on petroleum as raw material, mainly based on cracking, refining, fractionation, reforming and synthesis. The production process of petrochemical products is long, with many production equipment and a large amount of wastewater. Typical petrochemical wastewater contains conventional pollutants such as petroleum, CODCr, ammonia nitrogen, sulfur, phenol, cyanide, etc. At the same time, due to different products, different companies also produce wastewater containing a variety of characteristic pollutants related to their organic chemical products, such as polycyclic aromatic hydrocarbons, aromatic amine compounds, heterocyclic compounds, etc., which makes the wastewater not only complex in water quality, but also contains many toxic substances. In addition, production fluctuations such as the start-up, shutdown, maintenance, and changes in raw material sources of enterprises will cause changes in the amount of wastewater and the content and nature of pollutants, increasing the impact load of wastewater treatment facilities.
2. Sewage flow and treatment process
(I) Physical treatment technology
1. Floating oil isolation technology
The sewage generated during the development of petrochemical enterprises is relatively complex. There will be more particulate dirt and biological films floating on the surface of the sewage. These dirt and films will carry more floating oil with low density, floating on the water surface, isolating the water and air. The organisms that need oxygen in the water cannot survive, which ultimately leads to unsatisfactory sewage purification effect of petrochemical plants. In order to solve this problem, floating oil isolation technology has emerged. With the support of floating oil isolation technology, the floating objects on the water surface will be removed in time when the sewage passes through the oil separator, and the pollutants in the water body will be blocked in time, reducing the interference of pollutants on aerobic organisms.
2. Suspended matter adhesion technology
The quality of petrochemical wastewater treated by the oil separator is improved, but there will inevitably be some floating objects and floating oil in the wastewater. In order to better deal with these floating oil and floating objects, it is necessary to further introduce suspended matter adhesion technology in sewage treatment work, and strengthen the treatment of suspended floating oil in wastewater under the action of suspended matter adhesion technology. When implementing the operation, dispersed and small bubbles are used to adsorb suspended matter in the water body on the surface of the wastewater, and then these suspended matter are treated on the surface of the wastewater to completely separate the floating oil and water in the emulsified oil.
3. Adsorption technology
Adsorption technology uses porous materials such as activated carbon to adsorb impurities in wastewater to the surface of the water body, thereby achieving the purpose of removing toxic and harmful substances in wastewater. However, from the actual operation point of view, the cost of activated carbon is relatively large. If the secondary treatment work is not done well in this process, it will induce secondary pollution. Therefore, in the process of using adsorption technology, petrochemical enterprises need to have sufficient financial support to effectively treat particulate impurities in sewage with the reserve of funds.
(II) Salt balance test
The composition of pollutants in petrochemical wastewater is relatively complex. If you want to reduce the harm of sewage to the surrounding environment, you must conduct a scientific and rational analysis of the sewage and adopt effective methods to improve the sewage treatment effect. Nowadays, the increasingly serious water resource problem has become a bottleneck restricting the economic and social development of our country, and it has become inevitable to achieve zero sewage discharge. Through the salt balance test, the water quality can be made safe, stable and good, so as to reduce the wastewater discharge and achieve zero discharge.
The salt balance test is based on ensuring the quality of water used by each unit, that is, to control the salt content in the user’s water at a reasonable value, so as to achieve the balance of the salt content in the entire factory water system, so as to avoid the accumulation of salt in the water system and prevent the impact on the user’s water quality. On this basis, through the salt balance analysis of the equipment, the optimal water balance analysis of the equipment is realized, so as to ensure the rationality and feasibility of the water balance analysis of the entire system. Using water quality analysis as a means to understand the salt content of various water used by petrochemical enterprises, and using salt balance calculation, analyze and calculate the source and destination of salt in petrochemical wastewater.
(III) Biological treatment technology
1. Anaerobic biological treatment technology
Using microbial aerobic respiration, the entire sewage environment can be organically decomposed, so as to achieve precise control of harmful organic matter in sewage. Under the guidance of aerobic biological treatment technology, a new type of membrane bioreactor is established and optimal removal is performed. According to the current development situation, anaerobic biological treatment technology has high practical value, and this mature technical content and technical advantages can be used to achieve efficient utilization of macromolecular organic matter.
2. Application of comprehensive treatment technology
In practical applications, anaerobic biological treatment technology can be organically combined with aerobic biological treatment technology according to the complex characteristics of wastewater components. For example, when demonstrating aerated biological filtration technology, suitable fillers can be selected and covered inside the biofilm. After petrochemical wastewater is filtered, organic matter in the wastewater will be absorbed into microorganisms, accelerating the decomposition of organic matter and improving the efficiency of petrochemical wastewater treatment.
With the continuous development and progress of science and technology and economy, petrochemical processes and wastewater treatment technologies have also achieved innovation and optimization. Different industrial fields and different process flows may have different wastewater treatment needs and specific solutions. Therefore, when implementing the zero discharge plan for wastewater, it is necessary to analyze the specific situation in detail and design solutions in a targeted manner. Smart Jinma has long served petroleum refining companies, providing one-stop services and solutions from basic data collection of pipeline networks, intelligent management to smart factories, helping to improve industrial water efficiency and promote its long-term development.
3. Hazards of petrochemical wastewater
Petrochemical wastewater contains a large amount of toxic and harmful substances, especially some of its components can be closely combined with phosphorus and nitrogen elements in the soil, which leads to a serious lack of phosphorus and nitrogen elements in the soil, thus causing serious adverse effects on the normal growth of plants.
Petrochemical wastewater also contains a large amount of heavy metal elements, such as arsenic, chromium, nickel, beryllium, etc. Once they enter the human body with water, they will greatly increase the incidence of cancer and have a very serious impact on people’s health.
Untreated petrochemical wastewater discharged into the river will also cause a significant decrease in the oxygen content in the water, which will have an adverse effect on the normal growth and development of aquatic plants and animals. In addition, when the microorganisms in the water degrade the organic matter in the petrochemical wastewater, they will consume a large amount of oxygen dissolved in the water, thereby destroying the balance of dissolved oxygen in the water, which is not conducive to the long-term development of plants and animals.
4. Wastewater detection in the petrochemical industry
I. Monitoring items
Petroleum wastewater monitoring mainly includes the following items:
1. Petroleum substances: This is the core content of monitoring. By detecting the content of petroleum substances in wastewater, the degree of pollution of wastewater can be directly reflected.
2. Chemical oxygen demand (COD): An indicator to measure the degree of organic pollution in wastewater. A high COD value indicates that the organic content in wastewater is high.
3. Biochemical oxygen demand (BOD): Reflects the content of biodegradable organic matter in wastewater and is an important indicator for evaluating the biological treatment effect of wastewater.
4. Suspended solids (SS): Solid matter insoluble in water in wastewater, whose content affects the treatment effect of wastewater.
5. pH value: Reflects the acidity and alkalinity of wastewater, which is of guiding significance for the selection of wastewater treatment process.
6. Heavy metals: Some heavy metals are toxic to the environment and organisms, and their content in wastewater needs to be strictly controlled.
2. Detection methods
There are many methods for detecting petroleum wastewater, and the following are commonly used:
1. Gravimetric method: Although the operation is cumbersome and the accuracy is low, it is still one of the classic detection methods.
2. Infrared spectrophotometry: fast and accurate, but the detection cost is high, suitable for occasions with high detection accuracy requirements.
3. Gas chromatography: high sensitivity and good selectivity, but requires professional technicians to operate, suitable for quantitative analysis of complex samples.
In addition, there are many detection methods such as ultraviolet spectrophotometry and fluorescence photometry. The appropriate method can be selected according to specific needs and conditions.
3. Recommended instruments for analyzing petroleum wastewater
1. Lianhua Technology Multi-parameter Water Quality Meter, using spectrophotometry, one instrument integrates 50+ detection indicators, supports the detection of chemical oxygen demand (COD), ammonia nitrogen, total phosphorus, total nitrogen, suspended solids, chromaticity, turbidity, heavy metals, organic pollutants and inorganic pollutants in wastewater, etc., can quickly obtain results, simple operation, and equipped with complete reagents and accessories.
2. Lianhua Technology’s infrared oil tester supports the detection of oil and grease. It has a built-in computer and a high-definition touch screen. It can be used immediately after it is turned on without connecting to a computer or tablet. The spectrum is intelligently displayed. The measured values are displayed intuitively, and the operation method is unified, which reduces the learning cost and allows for quick start.
3. The BOD tester adopts the mercury-free differential pressure method detection principle, which is simple to operate. 0-4000mg/LBOD can be directly measured, 6 samples can be independently timed for detection, and 0-30 days of detection settings can be selected.
Post time: May-27-2025
