The typical service life of sewage treatment equipment varies depending on type, material, and maintenance, but generally ranges from 10 to 50 years. Underground equipment lasts approximately 15 years or more, while stainless steel or fiberglass structures can last up to 50 years. Core components such as reverse osmosis require regular replacement.

The treatment method for industrial wastewater is selected based on the type and concentration of pollutants and the specific characteristics of the industry. Physical, chemical, biological, or a combination of processes is typically used.

The selection of a wastewater treatment chemical requires comprehensive consideration of water quality characteristics, treatment processes, cost-effectiveness, and environmental requirements. High-quality chemicals should exhibit high efficiency (low overall consumption), high treatment efficiency (high pollutant removal limits), not introduce new pollutants, be harmless to humans, and not damage biochemical systems or equipment.
Heavy metal removal: A precipitant (such as sodium sulfide or sodium hydroxide) is added to form a poorly soluble precipitate.
Nitrogen and phosphorus removal: Targeted phosphorus removal agents (such as ferric chloride or lime) or denitrifiers are used.
Refractory organic matter: Advanced oxidants (such as ozone) can be used to break down its structure.

The price of an MVR evaporator varies greatly depending on factors such as processing scale, material, and configuration. Please contact our customer service directly for details.
Material: Titanium is over 50% more expensive than stainless steel, but it is more corrosion-resistant.
Configuration: The compressor brand, energy efficiency rating, and intelligent control system significantly influence the price.
Processing scale: The larger the scale, the higher the cost.

An evaporator is a device that vaporizes and removes the solvent from a solution through heating, resulting in a concentrated solution or solid. Evaporators can be categorized into various types based on their structure, operating principle, and application. These include tubular evaporators, plate evaporators, scraped film evaporators, multi-effect evaporators, MVR evaporators, and low-temperature evaporators.

Generally speaking, when the environment and resources are damaged and the ecological balance is disrupted, it takes decades, sometimes even hundreds of years, for the system to recover, and sometimes it is impossible to recover at all.

The ISO 14000 series of standards is an environmental management standard developed by the International Organization for Standardization's Technical Committee on Environmental Management. Its guiding principle is "comprehensive management, pollution prevention, and continuous improvement," representing an innovation in environmental management thinking and methods. ISO 14000 has very strict standards and regulations, with corresponding verification standards for every production process and management link, from the purchase of raw materials to the delivery of finished products. This system strictly prevents the generation of pollutants during the production process and ensures their effective management. Wastewater treatment is only one component of the ISO 14000 series of standards. Currently, pilot programs and implementation of the ISO 14000 series are underway in some major cities and large enterprises in China. ISO 14000 environmental quality certification is known as a "green passport" recognized by the international market. Certification grants undeniable access to international markets. Many countries have announced that imports of goods and products without environmental management certification will be subject to quantity and price restrictions. Therefore, as we gradually integrate with the international market, ISO14000 environmental quality certification is being fully implemented in all domestic enterprises, just as ISO9000 (quality management standards). Thus, from the perspective of environmental management standards, we must not only strive to ensure effective wastewater treatment at the end of the pollution source, implement scientific environmental management, and ensure that treated effluent meets discharge standards; we must also vigorously implement clean production management at the source to prevent and reduce pollution.

Protecting the environment has become a basic national policy for the sustainable development of my country's economy. Therefore, wastewater treatment should comply with my country's environmental protection laws, regulations and policies. In the planning and design of environmental protection, it is necessary to combine production perspectives with ecological concepts and environmental protection, and to combine wastewater treatment with improving production processes and implementing clean production. Through systematic analysis and verification, a more reasonable treatment plan can be sought. The main principles of environmental management can be summarized as follows:
(1)Eliminate unreasonable products. For some traditional, low-value, and waste products with extremely difficult wastewater treatment, we should be determined to replace them with high-value, high-tech products. If the annual profit of a product is not enough to cover the annual wastewater treatment costs, such products should be determined to stop production and replaced with products that are less polluting and easier to treat.
(2)Strengthen management and reduce pollution. Enterprise management is also an important factor in preventing and controlling pollution. For example, the leakage of equipment; production accidents or product scrapping caused by failure to follow operating procedures, which lead to the generation of large amounts of high-concentration wastewater; the use of large amounts of water to wash equipment and the ground, which increases the amount of wastewater; the failure to separate cooling water and production wastewater into "clear and turbid" streams, all of which increase the amount of wastewater and the difficulty of wastewater treatment.
(3) Establishing regional small-scale sewage treatment plants For areas where factories are concentrated, it is not necessary to apply the principle of "whoever pollutes, whoever cleans"; instead, it is necessary to strengthen the relationship between enterprises and comprehensively consider pollution control measures. If necessary and possible, the wastewater of each factory can be centrally treated and a unified sewage treatment plant can be established to implement the "whoever pollutes, whoever pays" treatment method. Because the wastewater quality of each factory is different due to different products, for example, some factories' wastewater is acidic, while some factories' wastewater is alkaline. Treating them together can reduce the treatment cost of neutralizing agents; some factories discharge high-salt and low-COD wastewater, while some factories' wastewater is high-concentration and easily biodegradable. If treated separately, they are all difficult to treat. However, if they are treated together for biochemical treatment, the improvement of water quality conditions can not only reduce the difficulty of wastewater treatment, but also improve treatment efficiency.
(4) Improve the recycling rate of water
In order to reduce the amount of wastewater, we should first do more work at the source of wastewater generation. For example, we can consider recycling water or reuse it multiple times to improve the recycling rate of water and minimize the amount of water discharged. In foreign countries, the recycling rate of water in some advanced enterprises has reached more than 96%, while the recycling rate of water in Shanghai production enterprises is still at a low level of 20-30%, and there is still great potential to be tapped. Improving the recycling rate of production water can not only reduce environmental pollution, but also reduce the amount of fresh water replenishment, and to a certain extent, it can alleviate the increasingly tense water resource problem. When treating wastewater, we should also try to consider the recycling of treated water.
(5) Recycling and comprehensive utilization
The pollutants in wastewater are raw materials, semi-finished products, finished products and reaction media (such as solvents) that enter the water during the production process. In particular, some chemical reactions in fine chemical production are often not very safe, and the product separation process cannot be very thorough. Therefore, there is often a certain amount of useful substances in the wastewater, especially in the reaction mother liquor. Discharging these pollutants will pollute the environment and cause harm. However, if it is recycled or comprehensively utilized, waste can be turned into treasure and harm can be turned into benefit; or waste can be treated with waste, the strengths of the waste can be made up for the weaknesses, and comprehensive management can be carried out to save the cost of water treatment.

To address the current mismatch between environmental protection enforcement and management and public complaints, Shanghai has launched an environmental emergency hotline, 62863110, known as "Environmental Protection 110." This number will be simplified to 63110 (a homophone of "Green 110"). This is the first "Environmental Protection 110" in the national environmental protection system. As environmental protection efforts intensify, environmental emergency hotlines will be implemented across the country.
The Environmental Emergency Hotline's responsibilities include: accepting and responding to reports of major pollution incidents occurring citywide; accepting reports of illegal pollution discharges by polluting units, such as illegal and direct discharges; accepting and handling incidents caused by environmental issues that could potentially cause social instability; and assisting relevant departments in handling major incidents that may impact the environment. For other environmental pollution issues that do not require on-site response, the Environmental Emergency Hotline is available 24 hours a day to receive complaints from the public within the aforementioned areas.
For polluting units, the launch of Environmental Protection 110 is both a source of pressure and motivation. Only by diligently managing and controlling pollution can we withstand the scrutiny of environmental law enforcement agencies and the public.

Wastewater and the pollutants therein are products of the production process. Therefore, reforming the production process and implementing clean production are fundamental measures to eliminate or reduce the hazards of wastewater. Through the reform of processes and equipment, wastewater can be eliminated in the production process, which can not only improve the utilization rate of raw and auxiliary materials, but also reduce the cost of wastewater treatment. This work should be completed by the production process engineers and environmental engineers in cooperation. It should be recognized that protecting the environment is not just the job of environmental engineers, but it is necessary to control the pollution source, so that wastewater can be truly managed. Therefore, when designing processes and trial-producing products, it is necessary to consider possible environmental pollution problems in the future. When choosing a synthesis route, try to use pollution-free or less pollution-free production processes, choose the route with the highest raw material utilization rate, do not use or use less biodegradable substances or toxic and harmful substances in the production process, including raw and auxiliary materials and solvents, and strengthen the recovery and comprehensive utilization of solvents and by-products. The specific methods are roughly as follows:
(1)Adopting new processes, new technologies, and new routes Adopting new processes, new technologies, and new routes. First, the ratio of ingredients in the production process can be verified. Raw materials with high pollution and exceeding the theoretical ratio should be reduced to increase the utilization rate of raw materials and the treatability of wastewater. In chemical production, new routes are sometimes adopted, which can not only improve production levels but also solve wastewater treatment problems. For example, in the past, the raw material of anti-tuberculosis drug isonicotinic acid needed to be prepared by electrolytic oxidation using sulfuric acid as an electrolyte. The amount of acidic wastewater generated in the process was large and difficult to treat. Now, the new technology of air catalytic oxidation is used to carry out the reaction in a fluidized bed. The amount of wastewater is also small, and the pollution problem is easier to solve.
(2)Replacement of raw and auxiliary materials This is a common method, such as replacing highly toxic or extremely toxic raw materials with non-toxic or low-toxic raw materials, and replacing biodegradable substances with biodegradable substances. In addition, it is necessary to avoid or use less restricted substances specified in the emission standards, especially some substances with strict requirements, so as to reduce the burden of wastewater treatment. For example, there are now stricter requirements for the concentration of ammonia nitrogen in wastewater, which requires the use of as little ammonia water or liquid ammonia as possible in production. For example, in the past, when adjusting the pH of wastewater, some treatment processes used ammonia water to adjust, which would greatly exceed the ammonia nitrogen content in the effluent, and increase the difficulty of biochemical treatment of wastewater. Based on the same principle, we should use less potassium dichromate as an oxidant and less nitro compounds and chlorinated hydrocarbons as solvents. When selecting a solvent, in addition to meeting the requirements of the production process, the biodegradability and toxicity of the solvent must also be considered.
(3)Select a new post-treatment process to reduce or eliminate pollution in the production process. This method is very useful for technicians engaged in chemical production. For example, in the organic synthesis industry, the method of adding water to dilute the reaction materials (water separation) is often used to precipitate the reaction products from the reaction organic solvent. The mother liquor produced by water separation has a large amount of water, and the organic solvent (such as methanol, ethanol and other water-soluble solvents) in it is difficult to recover, which is carried into the wastewater flow and causes pollution. If most of the solvent is recovered by distillation before dilution and then diluted with water, the content of organic matter in the wastewater can be significantly reduced. In order to ensure the quality of the resulting products, reaction products or intermediates often need to be washed to remove impurities entrained in the products. Whether the washing operation is reasonable has a considerable impact on the degree of wastewater pollution. However, if new post-treatment technology is adopted, the washing wastewater can be completely eliminated during the process operation, achieving zero pollution discharge. Too high a salt content in the wastewater will inhibit the growth and reproduction of microorganisms and affect the effect of biochemical treatment. We can also adopt a new post-treatment process to solve this difficulty in wastewater treatment. For example, a factory reacts p-nitrochlorobenzene with sodium hydroxide in a methanol solvent to prepare p-nitroanisole. The original post-treatment operation process is to use water washing to remove the NaCl salt in the reaction materials. The result of this operation is a large amount of wastewater with a high salt content, which makes subsequent biochemical treatment difficult. Later, the plant improved the post-treatment process, first filtering out the NaCl in the reaction material (organic phase), then washing with water and precipitating p-nitroanisole. The improved process not only reduced the amount of wastewater by 50%, but also recovered 97.4% of the salt in the wastewater, reduced the organic load of the wastewater by 58.7%, and greatly improved the biodegradability of the wastewater.
(4) Strengthening solvent recovery work In most chemical raw material production plants, the proportion of solvents used in raw materials and auxiliary materials is quite high. It can be said that the organic load in many production wastewaters basically comes from solvents. Therefore, paying attention to and doing a good job in solvent recovery is not only an important measure to prevent and reduce pollution, but also an important way to reduce costs, increase efficiency and improve profits, with dual environmental and economic benefits. For example, a pharmaceutical factory in Shanghai that produces hormones has a total daily organic load (COD) emission of 8 tons, making it a major polluter in the region. The plant's environmental management first started with solvent recovery. The mother liquor wastewater containing the same solvent was collected and recycled. As a result, the total daily discharge of organic load in the wastewater was reduced from 8 tons to 3 tons. The income from solvent recovery exceeded the operating costs of the wastewater treatment plant.

Wastewater contains numerous organic substances, often containing dozens, even hundreds of them. Qualitative and quantitative analysis of each organic substance in wastewater is both time-consuming and chemically intensive. So, is it possible to use a single pollution indicator to represent all organic substances in wastewater and their quantities? Research by environmental scientists has revealed that all organic substances share two common characteristics: first, they are composed of at least one carbon and hydrogen; second, the vast majority of organic substances can be chemically oxidized or microbially oxidized, with their carbon and hydrogen reacting with oxygen to form harmless carbon dioxide and water, respectively. Whether chemically or biologically oxidized, organic substances in wastewater consume oxygen. The greater the amount of organic matter in the wastewater, the greater the oxygen consumption, and the two are directly proportional. Environmental scientists therefore refer to the amount of oxygen consumed when wastewater is oxidized with chemicals as chemical oxygen demand (COD), and the amount of oxygen consumed when wastewater is oxidized with microorganisms as biological oxygen demand (BOD). Because COD and BOD comprehensively reflect the amount of all organic matter in wastewater and are relatively simple to analyze, they are widely used in wastewater analysis and environmental engineering.
In fact, COD does not only indicate the organic matter in the water, it also indicates the inorganic substances with reducing properties in the water, such as sulfide, ferrous ions, sodium sulfite, and even chloride ions. For example, if the ferrous ions in the effluent of the iron-carbon pool are not completely removed in the neutralization tank, the COD of the effluent from the biological treatment may exceed the standard due to the presence of ferrous ions.

Chemical oxygen demand (COD) refers to the amount of oxygen required by oxidizable substances in wastewater when oxidized by a chemical oxidant, measured in milligrams of oxygen per liter. It is currently the most commonly used method for measuring the organic matter content in wastewater. Common oxidants used in COD analysis include potassium permanganate (manganese method CODMn) and potassium dichromate (chromium method CODCr), with the potassium dichromate method currently being the most commonly used. Organic matter is oxidized by heating the wastewater with strong acid under boiling reflux conditions. Using silver sulfate as a catalyst can increase the oxidation rate of most organic matter to 85-95%. If the wastewater contains high concentrations of chloride ions, mercuric sulfate should be used to screen the chloride ions to reduce interference with COD determination.

Biochemical oxygen demand (BOD) can also indicate the extent of organic contamination in wastewater. The most commonly used measure is the 5-day BOD, expressed as BOD5. It indicates the amount of oxygen required for wastewater to biodegrade in the presence of microorganisms over a 5-day period. We will frequently use the 5-day BOD5 in the future.

Some organic matter can be biodegraded (such as glucose and ethanol), others can only be partially biodegraded (such as methanol), and some cannot be biodegraded and are toxic (such as ginkgo biloba, ginkgolic acid, and certain surfactants). Therefore, organic matter in water can be divided into two components: biodegradable organic matter and non-biodegradable organic matter.
COD is generally considered to represent essentially all organic matter in water. BOD, on the other hand, represents biodegradable organic matter in water. Therefore, the difference between COD and BOD represents the non-biodegradable organic matter in wastewater.

B/C stands for the ratio of BOD5 to COD, which indicates the biodegradability of wastewater. If CODNB represents the non-biodegradable portion of COD, then the proportion of organic matter in wastewater that is not biodegradable by microorganisms can be expressed as CODNB/COD.
When BOD5/COD ≥ 0.45, non-biodegradable organic matter accounts for less than 20% of the total organic matter. When BOD5/COD ≤ 0.2, non-biodegradable organic matter accounts for over 60% of the total organic matter.
B/C is of great importance and practical significance in environmental engineering.

pH is actually a method of expressing the acidity or alkalinity of an aqueous solution. We often express the pH of an aqueous solution as a percentage, such as a 1% sulfuric acid solution or a 1% alkaline solution. However, when the pH of an aqueous solution is very low, expressing it as a percentage is too cumbersome. In such cases, pH can be used instead. The pH range is 0-14. When the pH is 7, the water is neutral; when the pH is less than 7, the water is acidic, and the lower the pH, the more acidic it is. When the pH is greater than 7, the water is alkaline, and the higher the pH, the more alkaline it is.
All living things in the world cannot live without water, but the pH range suitable for survival is often very narrow. Therefore, the National Environmental Protection Agency strictly regulates the pH value of treated water to be between 6 and 9.
The pH value in water is often tested using pH test paper, but it can also be measured using instruments such as pH meters.

Generally speaking, the concentrations of organic and inorganic substances in wastewater are very small, making it cumbersome and inconvenient to express them as percentages or other concentrations. For example, a ton of wastewater often contains only a few grams, tens of grams, hundreds of grams, or even a few kilograms of pollutants. The unit used is grams per ton (g/T). Converting tons to liters yields milligrams per liter (mg/L). For calculations, refer to the following conversion table:
1 mg/L = 1 part per million
1,000 mg/L = 1 part per thousand
10,000 mg/L = 1 percent

Preprocessing is generally referred to as treatment prior to biochemical treatment. Because biochemical treatment is relatively inexpensive and stable, it is generally used for industrial wastewater treatment and is the primary method of wastewater management. However, wastewater contains certain organic substances that are inhibitory or toxic to microorganisms. Therefore, Preprocessing is necessary before wastewater enters the biochemical tank. The goal is to minimize or remove these inhibitory or toxic substances to ensure the normal functioning of the microorganisms in the biochemical tank.
Preprocessing has two goals: first, to minimize and remove these inhibitory, toxic, or inhibitory substances in the wastewater, or to convert them into substances that are harmless or beneficial to microorganisms to ensure the normal functioning of the microorganisms in the biochemical tank; second, to reduce the COD load during the Preprocessing process to alleviate the operational burden of the biochemical tank. The Preprocessing process is iron-carbon micro-electrolysis and Fe2+/Fe3+ reduction-oxidation method. The countless tiny iron-carbon primary cells formed are conducive to the redox reaction, which can destroy and remove toxic and harmful substances in the wastewater. During the neutralization and precipitation process, the active flocs formed by divalent iron and trivalent iron under alkaline conditions can adsorb organic matter in the wastewater to reduce the COD load and ensure the normal operation of the subsequent biochemical treatment system.

A wastewater collection tank collects, stores, and balances the quality and quantity of wastewater. The volume and quality of wastewater discharged from various workshops are generally uneven. There is wastewater during production, but not during periods of inactivity. This can even fluctuate significantly within a single day or between shifts. This is particularly true for wastewater from the fine chemical industry. If clear and turbid wastewater are not separated, the quality and quantity of concentrated and less polluted process wastewater can vary significantly. This variability is detrimental to, and even harmful to, the proper operation and treatment effectiveness of wastewater treatment facilities. Therefore, before wastewater enters the main sewage treatment system, a wastewater collection tank of a certain capacity must be installed to store and homogenize the wastewater to ensure the proper operation of wastewater treatment equipment and facilities.

Many suspended impurities with a specific gravity greater than 1, large particles, and easily settling suspended solids in wastewater can be removed by natural sedimentation, centrifugation, and other methods. However, suspended particles with a specific gravity less than 1, tiny particles that are even invisible to the naked eye, are difficult to settle naturally. For example, colloidal particles are particles with a size of 10-4 to 10-6 mm. They are very stable in water and have an extremely slow sedimentation rate. It takes 200 years of tillage to settle 1 meter. There are two reasons for the slow sedimentation: (1) Generally speaking, colloidal particles have a negative charge. Because like charges repel each other, the colloidal particles are prevented from contacting each other, and cannot be bonded to each other and suspended in water. (2) There is also a layer of molecules tightly surrounding the surface of the colloidal particles. This hydration layer also hinders and isolates the contact between the colloidal particles, and cannot be bonded to each other and suspended in water.

To precipitate colloidal particles, they must be brought into contact with each other, forming larger particles. This means they aggregate, causing their specific gravity to exceed 1, leading to precipitation. There are many methods available, and commonly used engineering techniques include coagulation, flocculation, and coagulation.

When a coagulant containing positive ions is added to wastewater, the presence of a large number of positive ions between the colloidal particles eliminates the electrostatic repulsion between them, causing the particles to agglomerate. This process of agglomerating colloidal particles by adding positive ion electrolytes is called coagulation. Commonly used coagulants include aluminum sulfate, ferrous sulfate, alum, and ferric chloride.

Flocculation involves adding a polymer coagulant to wastewater. Upon dissolution, the polymer forms polymers. This polymer has a linear structure, with one end of the line pulling on a tiny particle and the other end pulling on another tiny particle, acting as a bridge between the two distant particles. This acts as a bond, causing the particles to gradually grow larger, ultimately forming large flocs (commonly known as alum flocs), which accelerate particle settling. Commonly used flocculants include polyacrylamide (PAM) and polyferric ion (PE).

During the coagulation process, polyferric iron forms ferric hydroxide flocs, which have a strong ability to adsorb organic matter in wastewater. Experimental data shows that polyferric iron flocculation and adsorption can remove approximately 10%-20% of the COD in wastewater, significantly reducing the operating burden of the biochemical tank and facilitating the treatment of wastewater that meets discharge standards. Furthermore, polyferric iron pretreatment can remove trace substances in wastewater that are toxic or inhibitory to microorganisms, ensuring the normal functioning of microorganisms in the biochemical tank. Among various coagulants, polyferric iron is relatively inexpensive (25-300 yuan/ton), resulting in relatively low treatment costs and making it suitable for pretreatment of process wastewater.
Polyferric iron is an acidic substance and highly corrosive, so treatment equipment should be properly treated with corrosion protection.

Coagulation is the combined process of coagulation and flocculation. Coagulation is frequently used in experiments and engineering. For example, ferrous sulfate and other chemicals are first added to water to eliminate the electrostatic repulsion between colloidal particles. Polyacrylamide (PAM) is then added to gradually enlarge the particles, forming visible flocs, which ultimately cause sedimentation.

Adsorption is the process of using porous solids (such as activated carbon) or flocculent materials (such as polyferric iron) to adsorb toxic and harmful substances in wastewater onto the surface or within the micropores of the solids or flocs, thereby purifying the water. The adsorbed substances can be either insoluble solids or soluble substances. Adsorption treatment is highly efficient and produces high-quality effluent, making it a common method for advanced wastewater treatment. Adsorption can also be incorporated into biochemical treatment units to improve their efficiency (e.g., the PACT method).

The iron-carbon treatment method, also known as the iron-carbon micro-electrolysis method or the iron-carbon internal electrolysis method, is an application of metallic iron wastewater treatment technology. Using the iron-carbon method as a pretreatment technology is uniquely effective in treating toxic and hazardous wastewater with high COD concentrations. The treatment mechanism of the iron-carbon method is not yet fully understood, but a generally accepted explanation is that under acidic conditions, countless microcurrent reaction pools are formed between the iron and carbon, where organic matter is reduced and oxidized by the microcurrent. The iron-carbon effluent is then neutralized with lime or lime milk, resulting in the formation of Fe(OH)2 colloidal flocs that have a strong flocculating and adsorbing capacity for organic matter. Therefore, the iron-carbon method combines the reducing properties of iron, the electrochemical properties of iron-carbon, and the flocculating and adsorbing effects of iron ions. It is the combined effects of these three properties that enable the iron-carbon method to achieve excellent treatment results. The disadvantages of the iron-carbon method are: (1) Iron filings tend to form lumps after being immersed in an acidic medium for a long time, causing blockages and channeling, making operation difficult and reducing treatment efficiency;
(2) Iron dissolves a large amount of iron under acidic conditions, and a large amount of sludge is produced after neutralization with alkali.

After the wastewater is adjusted to a pH of 2 with sulfuric acid and treated with iron-carbon, the sulfuric acid becomes ferrous sulfate, and the pH value of the wastewater increases from 2 to 5-6. So why is lime powder still needed to neutralize the iron-carbon effluent? Or can less lime powder be added during the neutralization process? The effluent from the iron-carbon treatment plant contains a large amount of ferrous sulfate. If not removed, it will affect the growth and reproduction of microorganisms in the subsequent biochemical tank. Therefore, lime must be used to raise the pH of the wastewater from 5-6 to above 9. This converts the water-soluble ferrous sulfate into insoluble ferrous hydroxide and calcium sulfate. These are then precipitated through coagulation and sedimentation to ensure that the wastewater entering the biochemical tank is ferrous sulfate-free.