All membrane method and treatment of electroplating heavy metal waste water reuse

With the rapid development of electronic industry, as one of the foundation of the electronics industry ─ ─ electroplating, at a rate of 10% ~ 20% growth each year, become one of the important industries in the electronics industry, but its complex process need to consume large amounts of water and produce many waste [ 1] 。 In recent years, the tap water price rising, and with the improvement of people environmental protection consciousness and more strict environmental protection laws and regulations, water and environmental protection has become a problem on the electroplating business, coupled with the introduction and implementation of ISO14000 international certification, electroplating factory must make more contributions to environmental protection. Save water and waste water treatment is the key of the electroplating factory environmental protection. Therefore, electroplating factory on the one hand must maintain wastewater emission standard; And, on the other hand, want to consider the water treatment cost saving and reduce the dosage of raw water from, strengthen water reuse. In electroplating wastewater treatment and water reuse process existing problems, the author put forward the whole membrane and recycling process, implement short electroplating heavy metal waste water treatment and reuse of process system, energy conservation and emissions reduction provides a new choice for electroplating industry. This paper, taking a comprehensive wastewater and electroplating enterprises in hangzhou complex wastewater as treatment object, using the membrane technology for processing, quality of water production reached back to the water after treatment, at the same time the strong water quality GB21900-2008 'electroplating pollutants emission standards' requirements. 2. Hangzhou some electroplating enterprise of water quality and quantity of wastewater effluent from daily amount is 500 m3, which integrated wastewater and complex wastewater and total cyanide wastewater emissions of 400 m3 / d, the water quality and water quantity as shown in table 1. 3. Electroplating wastewater treatment process and illustrate the traditional heavy metal waste water treatment and recycling process, generally by ion exchange method, chemical precipitation + filtration + reverse osmosis, or chemical precipitation + filtration + ultrafiltration + reverse osmosis process. Ion exchange method is characteristic of good water quality, making machine is simple, operation is easy to control, easy saturation or poisoning, but resin regeneration cycle is short, high operation cost. Chemical precipitation + filter + reverse osmosis and chemical precipitation + + ultrafiltration + reverse osmosis has mature technology, simple process, convenient operation, low cost, settling dehydration performance is good wait for an advantage, but the high cost of reagents, cause secondary pollution of sludge containing heavy metal ions, processing is not complete. The membrane process is simple, system stability, cover an area of an area small, high degree of automation, good water quality, high return powerusageeffectiveness, but the disadvantage is that large initial investment. Hangzhou some electroplating enterprise has a set of sewage treatment system, sewage treatment after discharging standard. With the improvement of production capacity and environmental requirements, the company plans on the original sewage treatment system upgrading, but because of the lack of empty lots available within an enterprise, cannot be carried out in accordance with the traditional process upgrading, therefore chose to cover an area of an area small integrated membrane process full of wastewater and complexing waste water processing, the original treatment facilities is converted to organic wastewater treatment system and water treatment systems. The process is shown in figure 1. First to break the cyanide bearing cyanide wastewater into comprehensive wastewater after adjusting pool, comprehensive wastewater and complex wastewater discharged into separate adjusting pool, through the pump to the reaction tank for reaction, at the same time to the reaction tank additive NaOH, complex agent and coagulant, and then the flow into the circulation water tank, and maintain the pH controller in 9 of the pH value of the circulating water in the box. Around zero, to ensure that all the heavy metal ions from wastewater formation of precipitation. Then waste water after the reaction with a circulating pump pressure to Duraflow companies in the United States production of DF for mud separation membrane. DF membrane device adopts the cross-flow filtration method, and through the big flow to prevent the accumulation of pollutants in the membrane surface. After DF membrane device is filtered to produce water into the DF water tank, DF membrane device of water back into the circulating water in the box. Circulating water in the sewage concentration in the process of circulation will be rising, run after a certain period of time by opening the valve discharge must concentrate, in order to maintain the concentration of the circulating water tank not too high. Concentrate into the sludge pool, pressure after working through filter press to entrust a qualified unit for processing. 3. 1 integrated wastewater adjusting pool comprehensive wastewater by 8 m3 / h capacity design, adjust pool effective volume of 76. Hydraulic residence time (8 m3, HRT） 9. 6h。 Adjust pool set liquid level controller, control comprehensive wastewater of lift pump start-up. 3. 2 complex wastewater adjusting pool complex wastewater by 11 m3 / h capacity design, adjusting pool effective volume of 95. 7 m3, HRT is 8. 7h。 Adjust the pool also set the liquid level controller, start-stop control complex wastewater lift pump. 3. 3 tank reaction tank is divided into three modules: the first cell through online pH meter control sodium hydroxide measuring dosing pump, regulating tank pH at nine. 0 ~ 10. Within the scope of 0; The second unit through online ORP ( Oxidation reduction potential) Instrument control Na2S dosing pump; The third unit dosing polyaluminium chloride ( PAC） And FeSO4. Each unit of HRT for 30 min. 3. Circulation circulation water tank for DF 4 membrane device to provide a stable source of water, and acceptance of DF concentrate membrane device, the design flow of 19 m3 / h, sodium hydroxide of circulating water control through online in the pH meter measuring dosing pump, adjust the circulating water pH at 9 in the box. About 0. Circulating water box set liquid level controller, the control of circulating water pump stop. Reverse osmosis water treatment machine, liquid detergent production machine, laundry detergent washing powder production machine production factory house, the previous: electroplating, cyanide, such as acid wastewater containing cadmium making machine