Problems and solutions in the process of electroplating wastewater treatment and reuse: At present, many electroplating enterprises generally treat electroplating wastewater with conventional chemical treatment, and directly discharge it after reaching the discharge standards, without recycling. Although the heavy metal ions are almost completely removed, the proportion of impurities such as non-heavy metal ions and soluble salts in the water is still very high. The measured conductivity of water is about 0.15 to 0.25 s / m. This kind of water is similar in nature to seawater, and can only be used for factory toilet flushing and limited water landscapes, and cannot even be used for long-term greening. As the country's requirements for reclaimed water are becoming more and more stringent, enterprises need to improve wastewater treatment technology and add advanced treatment equipment to achieve the reclaimed water reuse target. Inner Mongolia wastewater treatment currently uses reverse osmosis, ion exchange, Combined processes such as nanofiltration and ultrafiltration reduce the conductivity of the treated water to 0.035 ～ 0.045 s / m, which can only be reused for some rough washing processes before the pretreatment of the electroplating production line. The reuse rate of the water can generally reach 50% ~ About 60%. There are still many problems in the actual wastewater treatment and reuse process, and further improvement of the process and level is needed.
Wastewater shunting is incomplete: With the continuous development of electroplating technology, technology and product types, the types of pollutants in electroplating wastewater are becoming more and more complex. At present, electroplating enterprises generally divide wastewater into three categories: cyanide-containing wastewater, chromium-containing wastewater and comprehensive wastewater, which are separately treated and then comprehensively treated. From the perspective of cleaner production, this classification is unreasonable. Heavy metals in wastewater are not recovered, which increases the wastewater treatment load and treatment costs. The characteristics of various pollutants are different, and effective treatment measures are not taken according to the nature of the pollutants, which will increase the use of pharmaceuticals. And processing costs.
Large amount of alkali: When the enterprise adopts chemical precipitation to treat wastewater, a large amount of alkali is used, part of which is used for acid neutralization and part of which is used for heavy metal precipitation. In Inner Mongolia wastewater treatment , although the precipitation method itself requires a large amount of alkali, it also causes excessive use of alkali due to various reasons during the treatment of wastewater. The main reasons are as follows: ① The heavy metal content in the wastewater is too large and has not been recycled. Treatment, directly adding alkali precipitation, resulting in an increase in the amount of alkali required, and excessive sludge production; ② the use of acid to remove oil and rust during the electroplating process of plated parts, a large amount of acid, waste acid is not treated separately, directly Discharge into wastewater, increase wastewater treatment costs, and after treating a large amount of acid with alkali, the conductivity of the entire water quality will increase, thereby increasing the difficulty of subsequent reuse of reclaimed water; ③ dosing and processes of wastewater treatment stations in many enterprises The control still uses manual operation, and there is a problem of excessive or insufficient addition of chemicals (mainly alkali). In order to ensure the quality of the effluent water, most companies will invest too much medicine, which will cause waste of medicines and increase the cost of sewage treatment. In addition, manual operations will not be timely. It meets the requirements of wastewater quality and quantity change, and the work efficiency is low.
The sewage treatment process is not targeted, the treatment cost is high, and the reclaimed water reuse rate is low: At present, many enterprises have high sewage treatment costs, excluding reuse treatment costs. Inner Mongolia wastewater treatment costs are only 13-20 yuan / t if they meet the standard treatment requirements. Some of them are as high as 20-30 yuan / t, and the cost of adding alkali is 5-10 yuan / t. According to the analysis of the above situation, it is found that the most important reason for the high cost of sewage treatment is that the process is unreasonable and the wastewater is not treated according to the characteristics of the wastewater. However, in order to meet environmental protection requirements, companies have to invest in high-cost wastewater treatment to meet discharge standards. With the increasingly strict requirements for reclaimed water reuse, the discharge of wastewater in compliance with environmental standards can no longer meet environmental protection requirements. Enterprises need to invest more to increase the reclaimed water reuse rate. In order to achieve the target of reclaimed water reuse, some enterprises have added a series of "activated carbon adsorption-reverse osmosis-nanofiltration-ultrafiltration" processes in the advanced treatment stage.
From the analysis of economic benefits, although there are economic benefits in sewage treatment and recycling, compared with the cost of sewage treatment and investment funds, the economic benefits are very small. Almost all enterprises are for profit. Without the drive of profits, the enterprises have no incentive to do the sewage treatment work. All the pressures are based on the state's clear requirements for the environmental protection requirements of the electroplating industry. Therefore, regardless of the consideration of the state or the enterprise, the enterprise must transform the wastewater treatment station, improve the wastewater treatment process, achieve "separate treatment, classified recovery, and strict process", reduce wastewater treatment costs, and increase economic benefits as much as possible. .
New development trend of electroplating wastewater treatment industry: The electroplating industry is an industry related to the national economy and the people's livelihood, but also an industry with high pollution and high water consumption. If the wastewater produced by it is discharged without treatment, it will be discharged. Inner Mongolia wastewater treatment will cause great harm to the water body, which will endanger aquatic plants and livelihoods, crops, animals and humans. Although the treatment of electroplating wastewater in China has a history of more than 50 years, the relevant industry discharge standards were only introduced in 2008.
The treatment methods of electroplating wastewater are divided into physical methods, chemical methods, and biochemical methods. Inner Mongolia wastewater treatment For electroplating wastewater, a variety of treatment methods must be combined and separated to achieve the best treatment effect. Under the environmental protection theme of clean production, energy saving and emission reduction, the reuse of electroplating wastewater, heavy metal recovery and zero-emission technology have received more and more attention. Some environmental requirements have risen from meeting emission standards to micro-emissions and zero-emissions. However, how to properly process or reuse the relatively high salt content in the current process in this type of process is one of the current difficulties in reusing water. In addition, in many electroplating, such as precision electrical parts and high-end crafts, the plating of precious metals, such as gold plating, silver plating, etc., has produced gold cyanide wastewater, silver cyanide wastewater, etc. Recycling not only wastes valuable raw materials, but also increases the cost of wastewater treatment. Nowadays, most of them adopt a kind of resin which is specifically aimed at adsorbing gold and silver in wastewater, and its effective recovery can generate income for wastewater treatment systems. Inner Mongolia wastewater treatment is in line with the concept of circular economy.