CN101070215B - Electroplating wastewater recycling process - Google Patents

Abstract

The invention discloses a waste reduction and recycling process of circuit board wastewater, which comprises the following steps: a process for reclaiming electroplating sewage includes such steps as respectively introducing the sewage from electroplating workshop to mixing pool, reducing or oil-water separating, depositing, pre-treating by microfilter, ultrafilter and nanofilter, and reclaiming the water from recovering system; dewatering sludge in the sedimentation tank and then treating outside; the high COD waste water and the concentrated water of the first stage reverse osmosis system are discharged after reaching the standard through the waste water treatment system. After being uniformly mixed, the cyanogen series waste water enters an ion exchange system, and produced water is introduced into a neutralization pond; the regenerated liquid of the ion exchange system is subjected to sulfur ionization electrolysis to generate sodium hydroxide, then is introduced into a neutralization tank and neutralized by acid and copper pyrophosphate discharged in batches from an electroplating workshop, and then is conveyed to a wastewater recovery regulating tank after staying in a retention tank for a certain time. The electroplating wastewater treatment and reuse process system has the following advantages: high recovery rate, low operation cost, low cost of tap water and low cost of environmental maintenance.

Description

Electroplating Wastewater Reuse Process

technical field

The invention relates to a process for waste reduction and reuse of wastewater, in particular to a process for waste reduction and reuse of electroplating wastewater

Background technique

The electroplating industry is an important part of the cultural industry. Economic development and the improvement of the people's material and cultural living standards will inevitably require the electroplating industry to adapt to it. Many places have identified electroplating as an urban industry, which has enhanced the important position of electroplating in the regional economy; however, the environmental pollution caused by the electroplating industry is also very serious. According to incomplete statistics, there are more than 10,000 electroplating manufacturers in the country. , about 4.5 billion m ³ of electroplating wastewater is discharged every year, which is equivalent to the tap water supply of several large and medium-sized cities in China, making the shortage of water resources and water source pollution more serious, and the treatment of waste reduction and reuse of wastewater is very important .

Contents of the invention

The object of the present invention is to provide a waste reduction and reuse process for electroplating wastewater in order to solve the above-mentioned disadvantages.

The purpose of the present invention is achieved through the following technical solutions: electroplating wastewater recycling system process, each wastewater system in the electroplating workshop is separately introduced into each mixing tank, treated by reduction or oil-water separation, after precipitation, it passes through microfilter, ultrafilter, Nanofilter and other pretreatment filtration, and then through the recovery system, the effluent is reused to the workshop as production water; the sedimentation tank sludge is dehydrated and then outsourced; high COD wastewater is discharged through the wastewater treatment system to meet the standards; cyanide wastewater is mixed thoroughly and then enters In the ion exchange system, the produced water is introduced into the neutralization tank, and the regeneration solution of the ion exchange system is electrolyzed by sulfur ionization to generate sodium hydroxide, and then introduced into the neutralization tank and the acid and copper pyrophosphate discharged in batches from the electroplating workshop for neutralization, and then in the retention After staying in the pool for a certain period of time, it is transported to the recycling wastewater regulating pool; the oil-removing wastewater is separated from oil and water, then acidified and precipitated, and then introduced into the comprehensive mixing tank, and the sludge is dehydrated and treated outsourced; after the chromium-containing wastewater is mixed, the hexavalent chromium is reduced to three The valence chromium is introduced into the comprehensive mixing pool; the acidic wastewater is directly introduced into the comprehensive mixing pool after being thoroughly mixed; the copper, nickel, zinc and other wastewater is directly introduced into the comprehensive mixing pool from the electroplating workshop; , slow mixing, and sedimentation into the intermediate pool, and outsource the treatment after sludge dehydration; the wastewater from the intermediate pool after the previous corresponding treatment is pre-filtered and treated by microfilter, ultrafilter or nanofiltration, and then enters the recovery system and is recycled to the workshop for electroplating line with water. The process is as follows:

The following is a benefit assessment:

1. Wastewater type and water volume

1. Wastewater containing cyanide: 200m ³ /day, 2. Wastewater containing chromium: 50m ³ /day, 3. Other nickel, acid, alkali, etc.: 350m ³ /day total 600m ³ /day, 30m ³ /hr, operating time Based on 20hrs/day

2. Water recycling and treatment goals

1. Recovery rate: designed to be 75-80% of the waste water that can recover economic benefits.

2. Recycled water quality: the electrical conductivity is better than that of tap water, up to 20μs/cm, and can be recycled to the general water point of the process.

3. The amount of sludge generated is reduced by 1/3 to 1/2 compared with traditional chemical treatment.

Economic Benefit Assessment

Economic Benefits of Cyanide Treatment System

The amount of cyanide wastewater is 200CMD CN ^- the concentration is 100ppm => the daily discharge of CN ^- is 20kg

1. Traditional treatment plus bleaching water, liquid caustic soda, acid and other first oxidation and second oxidation treatment unit process

1. The cost of NaOCl is 20×150×1=3,000 yuan

2. NaOH is about 120 yuan

3. H ₂ SO ₄ is about 100 yuan

Total: 3,000 ⁺ 120 + 100 = 3,220 yuan/day

2. The cyanide treatment method adopting the new technology of TECO electroplating wastewater reuse

The operating cost is only 400 kwh/day x 0.8 yuan/kwh = 320 yuan/day

Economic benefits can save 3,220-320 = 2,900 yuan/da per day

Overall Assessment of Economic Benefits of Water Recycling

A. The water volume of the traditional treatment system is calculated at 600m ³ /day

Total operating cost of traditional processing system: 1 day operating cost 3,500 yuan/day [excluding electricity and maintenance fees]

B. Using electroplating wastewater recycling process system

A total of newly installed water recovery system: 1,975 yuan/day operating cost per day

Total one-year price difference (2,900+3,500-1,975) yuan/m ³ ×320 days/year≒1,416,000 yuan/year + saved follow-up pure water equipment costs and operating costs

The electroplating wastewater treatment and reuse process system has the following advantages:

1. Take water and recycle directly in the electroplating workshop, because although the water at the discharge port has reached the discharge standard, the amount of miscellaneous ions in the water has increased due to the addition of various chemicals in the wastewater treatment process, and its conductivity has also increased. Several times, the standard discharge water is generally around 10000us/ ^cm2 , while the conductivity of each series of wastewater in the workshop is generally below 3000us/ ^cm2 , which will increase the processing load in the recovery system at the back stage, and the membrane fouling will be blocked quickly, reducing recovery The life of the system, the filter membrane needs to be replaced in a few months, and the recovery cost has increased to an unacceptable level for users. Speaking again, there are repeated wastewater treatment costs and recycling costs for recycling water at the standard discharge outlet. This recycling process directly collects water and recycles items online in the electroplating workshop, which solves these problems.

2. The recovery rate is high. 75%-95% of the wastewater in the electroplating plant is recovered and the water quality is stable below 20μs/cm. It can be reused as water for electroplating processes to achieve the purpose of recycling water resources.

3. The lowest operating cost, the cost of tap water, and the cost of environmental maintenance are reduced, and the cost of recycling a ton of electroplating wastewater does not exceed 2.5 yuan.

4. It has good economic benefits, and the initial cost can be recovered within 1-3 years

5. The design life of the system is more than 20 years

The system developed in this project is mainly used to treat electroplating wastewater and reuse most of the wastewater after treatment. At present, the wastewater discharged by electroplating factories in my country is about 4.5 billion m3 every year. Conventional treatment methods such as chemical methods cannot fundamentally solve the pollution problem. Over the years, the government and enterprises have invested tens of billions in wastewater treatment projects. Both the government and enterprises have a strong desire to have a suitable electroplating wastewater treatment technology to solve the waste discharge problem that has plagued electroplating enterprises for a long time. Even if only 5% of the wastewater discharged by electroplating enterprises adopts TECO's electroplating wastewater recycling process, the market prospect is very promising. According to calculations based on the projects already built, the 600T/D electroplating wastewater of the whole plant reuses 450m ³ of the recycling system with a recycling rate of 75%. The investment is about 3 million yuan. Before the recycling system is set up, the wastewater treatment operation cost is It costs 6,400 yuan per day. After using the recovery system, the daily operating cost is 1,975 yuan. The daily price difference is 4,425 yuan/day×320 days/year ≈ 1,416,000 yuan/year. The initial cost can be recovered in about two years. Therefore, under the situation that the country puts a considerable emphasis on environmental protection, and under the situation that the country pays more attention to water conservation and the water price is increasing year by year, the enthusiasm of electroplating industrial wastewater to adopt this new wastewater reuse process will continue to increase. The new process technology of electroplating wastewater reuse will have a huge market in the process of recycling wastewater, recycling wastewater and reducing production costs, and its environmental and social benefits are very significant.

specific embodiment

The present invention will be further described below in conjunction with technology:

The wastewater from the electroplating workshop is separately introduced into the mixing tanks for treatment such as reduction or oil-water separation. After precipitation, it is pretreated and filtered by microfilters, ultrafilters, nanofilters, etc., and then passes through the recovery system, and the effluent is reused in the workshop. Production water; outsourced treatment of sedimentation tank sludge after dehydration; high COD wastewater and concentrated water from the first-stage reverse osmosis system are discharged through the wastewater treatment system up to standard. Cyanide wastewater, after being thoroughly mixed, enters the ion exchange system, and the produced water is introduced into the neutralization tank; the regeneration solution of the ion exchange system is electrolyzed by sulfur ionization to generate sodium hydroxide, and then introduced into the neutralization tank and the acid and coke discharged in batches from the electroplating workshop Copper phosphate neutralizes, and then stays in the retention tank for a certain period of time and then transports it to the recovery wastewater adjustment tank; the oil-removing wastewater is separated from oil and water, then acidified, and precipitated, then introduced into the comprehensive mixing tank, and the sludge is dehydrated and then treated outsourced; the chromium-containing wastewater is mixed thoroughly Finally, the hexavalent chromium is reduced to trivalent chromium and introduced into the comprehensive mixing tank; the acidic wastewater is directly introduced into the comprehensive mixing tank after being thoroughly mixed; the copper, nickel, zinc and other wastewater is directly introduced into the comprehensive mixing tank from the electroplating workshop; the wastewater in the comprehensive mixing tank is adjusted to PH After the value reaches neutral, it is introduced into the intermediate tank after fast mixing, slow mixing, and sedimentation, and the sludge is dehydrated and then outsourced for treatment; the wastewater in the intermediate tank after the previous corresponding treatment is pre-filtered and treated with microfilters, ultrafilters or nanofiltration , The recovery rate of entering the recovery system is about 75%, and the produced water can be reused to the water used in the electroplating line of the workshop. The conductivity is below 200us/cm ² , in order to ensure the quality of recycled water, it is generally treated with a two-stage reverse osmosis system, and the conductivity of the product water can be 20us/cm ² ; the concentrated water of the reverse osmosis system is discharged after being treated up to the standard.

Claims (1)

1. electroplating waste-water reutilizing process is characterized in that: by each waste water system of plating shop, separately introduce and respectively mix well the pond, reduction or oily water separation are handled, and post precipitation filters through the microfiltration systems pre-treatment, passes through recovery system again, and water of productive use is made in its effluent reuse to workshop; Committee is outer after the settling tank sludge dewatering handles; High-COD waste water is through the Waste Water Treatment qualified discharge; Cyanogen is waste water; After mixing well, get into ion exchange system; Produce water and introduce neutralization tank, the regenerated liquid of ion exchange system is also introduced the acid and the cupric pyrophosphate neutralization of neutralization tank and plating shop batch discharging after sulphur ionization electrolysis generates sodium hydroxide, after delaying basin stops certain hour, be delivered to the recovery wastewater equalization pond then; Oil removing waste water acidification reaction, post precipitation after oily water separation are introduced and are comprehensively mixed well the pond, and committee is outer after the sludge dewatering handles; Chromate waste water is after mixing well, and hexavalent chrome reduction becomes the trivalent chromium introducing comprehensively to mix well the pond; The pond is comprehensively mixed well in acid waste water direct introducing after mixing well; Cupric, nickel, zinc and other waste water are comprehensively mixed well the pond from the direct introducing of plating shop; The waste water adjustment pH value of comprehensively mixing well the pond to neutral after mix soon, mix slowly, post precipitation introduce in the middle of the pond, committee is outer after the sludge dewatering handles; Through the middle pond waste water after the handled of front; After the microfiltration systems pre-filtering is handled; The RO1 recovery machine that gets into first step r-o-in the recovery system through filtered water storage pond is handled; Product water after this RO1 recovery machine is handled gets into recycle-water storage pond; Recycle-water storage pond water outlet gets into accumulator tank through the RO2 water purification machine, and the water of 88%-92% reclaims so that workshop plating line water to be provided in the accumulator tank, and condensed water then gets into and reclaimed by RO3 seaization recovery system after RO1 concentrates tank; Obtain a part through RO3 seaization recovery system and produce in the water cycle entering recycle-water storage pond, and the RO3 of 8%-12% product water is handled qualified discharge through Waste Water Treatment together with the no economic benefit waste water in the electroplating wastewater.