HJ 2002-2010Technical specifications for electroplating industry wastewater treatment (English PDF)

4.1 Classification of electroplating wastewater

Electroplating wastewater is generally classified according to the type of pollutants contained in the wastewater or the type of heavy metal ions, such as acid-base wastewater, cyanide-containing wastewater, chromium-containing wastewater, Contains heavy metal wastewater, etc. When the wastewater contains more than one type of pollutant (such as cyanide cadmium, both cyanide and cadmium), it is still generally A classification of pollutants; when there are several methods for the same plating, it can be subdivided into small categories according to different processes, such as copper pyrophosphate wastewater and sulfur.

Acid copper plating wastewater, etc. The wastewater in which different plating species and different pollutants are mixed together is collectively referred to as electroplating mixed wastewater.

4.2 Main pollutants and concentration ranges

The main pollutants of electroplating wastewater and their mass concentration range can be referred to Appendix A.

4.3 Design water quantity and design water quality

4.3.1 The design water quantity and design water quality of the new electroplating wastewater treatment project shall be based on the approved environmental impact assessment documents and consider certain the design margin is determined.

The measured water quality can also be measured data, wherein the designed water volume can be determined according to the measured value of 110% to 120%. No actual test strip for analogy, the analogy data can be used; when there is no analog data, it can be estimated as 85%~95% of the total water consumption of the electroplating workshop (production line).

The amount of water treated. For the absence of water quality data, refer to the range of major pollutant concentrations given in Table 1.

4.3.2 The influent concentration of wastewater entering the treatment facility shall meet the design influent requirements. If the requirements are not met, pretreatment shall be carried out.

4.3.3 After the wastewater treatment, the water quality requirements for the reuse process should be met. Wastewater discharge should comply with GB 21900 or local discharge the standard stipulates or meets the requirements of the environmental impact assessment approval document.

5.1 General provisions

5.1.1 Electroplating enterprises should promote clean production, improve cleaning efficiency, and reduce the amount of wastewater generated. Conditional enterprises should return after wastewater treatment use.

5.1.2 New electroplating enterprise (or production line), its wastewater treatment project should be designed, constructed and invested simultaneously with the main project.

use.

5.1.3 The construction scale of the electroplating wastewater treatment project shall be determined according to the designed water volume of the wastewater; the process configuration shall be coordinated with the production system of the enterprise;

The construction of the phased construction should meet the requirements of the overall planning of the enterprise.

5.1.4 Electroplating wastewater should be collected and separated. Among them, the pollutants that are regulated in the discharge port of the workshop or production facility shall be in the vehicle.

Collecting and disposing of the discharge port of the production facility; the pollutants specified in the total discharge port shall be collected and treated at the total discharge port of the wastewater. Cyanide Waste water and chromium-containing wastewater should be collected and treated separately. The filter residue generated after the plating solution is filtered and the discarded plating solution shall not enter the wastewater collection and Processing facilities.

5.1.5 During the construction and operation of the electroplating wastewater treatment project, measures such as fire protection, noise prevention and earthquake resistance shall be taken. Treatment facility, construction (building) Materials, etc. should take measures such as anti-corrosion, anti-leakage and anti-seepage according to the nature of the contact medium.

5.1.6 The total discharge port of the wastewater shall be installed with an on-line monitoring system and comply with the requirements of HJ/T 353, HJ/T 355 and HJ/T 212.

5.1.7 Electroplating sludge is a hazardous waste and should be sent to a qualified unit for recycling or disposal as required. Electroplating sludge in the enterprise Storage should be in accordance with GB 18597.

5.1.8 Electroplating wastewater treatment station should be equipped with an emergency accident pool. The volume of the emergency accident pool should be able to accommodate 12 to 24 hours of wastewater.

5.1.9 The electroplating wastewater treatment project construction project shall comply with the requirements of this specification and the environmental impact assessment approval document, and shall also comply with the state.

The capital construction procedures and the relevant national standards, norms and planning regulations.

5.2 Engineering composition

5.2.1 The electroplating wastewater treatment project mainly includes. wastewater treatment structure (construction) and equipment, auxiliary engineering and supporting facilities.

5.2.2 Wastewater treatment structure (construction) and equipment include. wastewater collection, regulation, upgrading, pretreatment, treatment, reuse and discharge, and pollution Mud concentration and dehydration and preparation of chemicals, automatic detection and control.

5.2.3 Auxiliary works include. roads, fences and green spaces in the plant (station) area; independent power supply and water supply and drainage works, for compression Gas; dedicated laboratories, control rooms, warehouses, maintenance workshops, temporary sludge storage sites, etc.

5.2.4 Supporting facilities include. office, lounge, bathroom,, etc.

5.2.5 Wastewater treatment stations shall be equipped with standard discharge outlets in accordance with relevant national and local regulations.

5.3 Project site selection and overall layout

5.3.1 The site selection of wastewater treatment project should meet the planning requirements and have good engineering geological conditions; it should be close to the electroplating production workshop, and the wastewater can be Self-flow into the wastewater treatment station; easy to construct, maintain and manage; the treated wastewater has good discharge conditions.

5.3.2 The layout of the wastewater treatment station shall meet the functions and treatment process requirements of each treatment unit, and the spacing between the construction (construction) and facilities shall be Compact and reasonable, and meet the requirements of construction and installation; all kinds of pipeline connections should be simple and avoid mutual interference; the channel setting should be convenient for maintenance pipe Treatment of chemicals and sludge.

5.3.3 The process equipment of the wastewater treatment station should be arranged according to the treatment process and the nature of the wastewater. The equipment and equipment are neatly arranged and easy to operate.

And repair. In cold areas, outdoor pipes and installations should be insulated.

5.3.4 Materials, pharmaceuticals, etc. used in wastewater treatment should not be stacked in the open air. The storage place should be set as needed, and the wastewater treatment station should be equipped with sludge.

Temporary stacking sites, take appropriate measures such as anti-corrosion, anti-seepage, rain-proof, and comply with the provisions of GB 18597.

5.3.5 The wastewater treatment station shall be provided with a collection system for ground flushing water and equipment leakage water, and discharged into the wastewater regulating tank.

5.3.6 The architectural shape of the wastewater treatment station should be simple and beautiful, and coordinated with the surrounding environment. Greenery should be around the wastewater treatment station.

6.1 Acid and alkali wastewater

6.1.1 The treatment of acid and alkali wastewater should firstly neutralize the natural neutralization of acid or alkali wastewater itself or use acid, alkali waste liquid, waste residue, etc.

deal with.

6.1.2 After the acid and alkali wastewater in the electroplating pretreatment process is mixed, it is generally acidic, and it is preferable to neutralize the acid. Treat acidic wastewater when there is no when alkaline waste is available, it can be neutralized with an alkaline agent or filtered and neutralized. When the wastewater contains a variety of metal ions, it should be used in the medicament.

with.

6.1.3 Neutralization reactions produce large amounts of sediment and should be removed by precipitation. When the amount of sediment is small, vertical flow sedimentation tank and continuous flow can be used.

When the amount of sediment is large and gravity drainage is difficult, a flat flow sedimentation tank can be used, and the sediment is discharged by a suction machine.

6.1.4 The amount of dry sludge produced after neutralization of acid and alkali wastewater should be determined by experiment. When unconditionally tested, it can be treated as wastewater Estimated from 0.1% to 0.25% of volume.

6.2 Cyanide-containing wastewater

6.2.1 General regulations

6.2.1.1 Cyanide-containing wastewater should be treated separately. Do not mix with other wastewater before treatment.

6.2.1.2 When the mass concentration of cyanide ion in wastewater is less than 50 mg/L, it should be treated by alkaline chlorination method; the concentration of cyanide ion in wastewater is greater than at 50 mg/L, electrolytic treatment should be used. Ozone treatment of cyanide-containing wastewater, there is no limit to the concentration of cyanide ions in the influent, but contains complexation the cyanide ion wastewater should not be treated with ozone.

6.2.1.3 Treatment of cyanide-containing wastewater should avoid the incorporation of iron and nickel ions.

6.2.1.4 After the cyanide-containing wastewater is treated, the free cyanide can enter the mixed wastewater treatment system to remove heavy metal ions after reaching the control requirements.

6.2.1.5 A small amount of CNCl gas may be generated during the treatment, so it should be operated under closed and ventilated conditions and protective measures should be taken. collected the gas should be treated and discharged through the exhaust.

6.2.2 Alkaline chlorination treatment technology

6.2.2.1 If the amount of wastewater treatment is small and the water quality concentration does not change much, intermittent first-stage oxidation treatment should be adopted; wastewater treatment capacity is large, water If the concentration of the material changes greatly, and the requirements for the discharge water quality are high, continuous secondary oxidation treatment should be adopted.

6.2.2.2 For chlorine-containing oxidants, sodium hypochlorite, chlorine dioxide, liquid chlorine, etc. should be used. Choosing oxidants requires both economics and safety.

Fullness.

6.2.2.3 When using alkaline chlorination to treat cyanide-containing wastewater, the basic process shown in Figure 1 should be used.

Primary oxidation treatment of wastewater containing cyanide wastewater treatment tank into secondary wastewater treatment system Alkali oxidant acid oxidant

Figure 1 Basic process of alkaline chlorination treatment of cyanide-containing wastewater

6.2.2.4 When using alkaline chlorination to treat cyanide-containing wastewater, the following technical conditions and requirements shall be met.

a) The amount of oxidant input should be determined by experiment. When unconditionally tested, the input amount should be based on the weight ratio of cyanide ion to active chlorine.

Be sure. The weight ratio is preferably 1.3 to 1.4 when the first oxidation treatment is performed, and is preferably 1.7 to 1.8 during the second oxidation treatment. One the oxidant required for the oxidation and secondary oxidation should be added in stages, and the dosage ratio is 1.1;

b) pH control and reaction time. the pH value of primary oxidation should be controlled at 10-11, and the reaction time should be 10-15 min;

The pH value should be controlled at 6.5 ~ 7.0, and the reaction time should be 10 ~ 15 min;

c) The dosage of available chlorine can be automatically controlled by oxidation reduction potential (ORP). Primary treatment, reaction when ORP reaches 300 mV Basically completed; secondary treatment, ORP needs to reach 650 mV;

d) The temperature of the wastewater should be controlled at 15 to 50 °C. The residual chlorine in the wastewater after the reaction should be in the range of 2 to 5 mg/L.

6.2.3 Ozone oxidation treatment technology

6.2.3.1 Ozone Oxidation When treating cyanide-containing wastewater, the basic process flow shown in Figure 2 should be used.

Cyanide-containing wastewater Emission after exhaust gas purification Reuse or discharge Ozone (O3) Clear water pool reaction pool Add alkali to adjust pH

Figure 2 Basic process flow of ozone-containing wastewater treatment by ozone oxidation

6.2.3.2 Ozone Oxidation When treating cyanide-containing wastewater, the following technical conditions and requirements shall be met.

a) Ozone dosage. the theoretical dosing mass ratio of primary oxidation reaction is m(CN-).m(O3)=1.1.85; theoretical oxidation of secondary oxidation reaction the mass ratio is m(CN-).m(O3)=1.4.61. The actual drug-to-drug ratio is larger than the theoretical value and should be determined according to the experiment;

b) For free cyanide, when the removal rate is 97%, the contact time should not be less than 15 min; when the removal rate is 99%, the contact time should not be less in 20 min. The reaction tank tail gas should be collected and discharged after being absorbed by the alkali solution;

c) pH should be controlled between 9 and 11;

d) If cuprous ion is used as a catalyst, the reaction time can be shortened.

6.2.4 Electrolytic treatment technology

6.2.4.1 The basic process flow shown in Figure 3 should be used for electrolytic treatment of cyanide-containing wastewater.

Cyanide-containing wastewater Sodium hypochlorite solution Air agitation Sludge dewatering sludge Reuse or discharge clear pool sedimentation tank electrolytic cell conditioning pool Lye

Figure 3 Basic process of electrolytic treatment of cyanide-containing wastewater

6.2.4.2 The electrolytic treatment of cyanide-containing wastewater should meet the following technical conditions and requirements.

a) The pH of the wastewater should be controlled at 9-10, which can be adjusted with NaOH solution;

b) The dosage of NaCl can be estimated from 30 to 60 times the concentration of cyanide;

c) The net pole distance of the electrolytic cell should be 20~30 cm;

d) the anode current density should be controlled at 0.3 ~ 0.5 A/dm2, the tank voltage should be 6 ~ 8.5V;

e) using air agitation, the gas volume is 0.1-0.5 m3/(min·m3), and the air pressure is (0.5-1.0)×105 Pa;

f) When the precipitation of the precipitate formed is difficult, a coagulant may be added.

6.3 Chromium-containing wastewater

6.3.1 General requirements

6.3.1.1 The chromium-containing wastewater shall be collected and treated separately, and other wastewater shall not be mixed. After reducing hexavalent chromium to trivalent chromium, it can be combined with other heavy metals.

It is a mixed wastewater treatment.

6.3.1.2 After dewatering of the sludge, it should be packed in plastic bags to prevent environmental pollution due to leakage, dripping or scattering.

6.3.1.3 Treating chrome-plated cleaning wastewater by ion exchange, the hexavalent chromium ion mass concentration should not be greater than.200 mg/L; black chrome plating and fluorine-plated chrome plating the cleaning wastewater should not be treated by ion exchange.

6.3.2 Sulfite reduction treatment technology

6.3.2.1 For the treatment of chromium-containing wastewater by sulfite reduction, the basic process shown in Figure 4 should be used.

Sulfite H2SO4

NaOH

Chromium-containing wastewater conditioning tank Sludge dewatering Reaction cell sedimentation tank sludge Sludge release water Reuse or discharge Chromium hydroxide sludge

Figure 4 Basic process of sulphite reduction treatment of chromium-containing wastewater

6.3.2.2 Sulfate reduction treatment of chromium-containing wastewater shall meet the following technical conditions and requirements.

a) Batch and continuous treatments can be used. When u...