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PCB board wastewater treatment process principle

2019-04-22     By: H.C.C.

According to the designed diversion standard, the wastewater is diverted into the wastewater storage tank of each treatment system after being diverted from the production workshop and then lifted into the various treatment processes by the wastewater pump of each treatment system. The wastewater will pass through the communicating device or through the transfer pump. Processing is performed in each processing system function pool. (PCB board wastewater treatment process principle)


(1) General mixed wastewater W1: This type of wastewater has a large amount of water and a low concentration of CODCr. It is mixed with small-scale acid-base wastewater and copper-containing wastewater and then enters the integrated wastewater treatment system (1# system) for treatment. Metal ions and a small amount of organic matter, the treatment process is flocculation → precipitation → sand filtration → pH adjustment. The treatment process is as follows: firstly adding ferrous sulfate (which can be used for displacement and coagulation), and then adjusting the pH to about 10, and removing heavy metal ions (Cu2+) in the wastewater to form a hydroxide; then the wastewater is added to the flocculation tank. The flocculant PAM is flocculated, and the treated wastewater enters the inclined plate sedimentation tank for sedimentation mud water separation; the upper layer of clean water overflows into the clean water tank, and then passes through the pump into the sand filter for filtration treatment, further reducing the suspended matter content in the effluent. The filtered wastewater enters the final pH adjustment tank and is discharged after pH adjustment to 6-9. (PCB board wastewater treatment process principle)


(2) High concentration organic wastewater W2: The concentration of CODCr in this wastewater is high. The pretreatment process is acidification→precipitation. The treatment process is as follows: adding an acidifying agent to adjust the pH value to about 5, adding poly ferric chloride, so that the only organic matter in the wastewater is condensed into large particle particles capable of solid-liquid separation, and then adding an appropriate amount of high-molecular flocculant PAM, The solid-liquid components are separated by pressure filtration, and the pressure filtrate is quantitatively and averagely added to a general organic wastewater pretreatment facility (2# system) and mixed with general organic wastewater for advanced treatment. (PCB board wastewater treatment process principle)


(3) General organic wastewater W3: mainly from the process of developing, de-filming and other cleaning wastewater, the concentration of CODCr in the wastewater are relatively high. The general organic wastewater is mixed with the pretreated high-concentration organic wastewater for further treatment, and the deep treatment process is acidification→Fenton oxidation. The oxidation process uses hydrogen peroxide as a high-efficiency oxidant and ferrous sulfate as a catalyst. Under acidic conditions, the ferrous salt decomposes hydrogen peroxide to form free hydroxyl radicals. The hydroxyl radicals have strong oxidation properties and ultimately the organic matter in the wastewater. Oxidation to carbon dioxide and water. After the reaction was completed, the pH was adjusted to 10 to 11, and then added to the 1# system by a pump to be further processed. (PCB board wastewater treatment process principle)


(4) Acid-base wastewater W4: The acid-base waste liquid mainly comes from the washing tank of the production line. The main pollution factors are pH, CODCr, etc. After the acid-base wastewater is collected separately, it is added to the 1# system and the generally mixed wastewater for further treatment.


(5) Wastewater containing copper W5: mainly from micro-etching, pickling, browning, pickling and other processes, the copper content of wastewater is relatively high, the main pollution factors are total copper and CODCr. The wastewater with high copper content in the micro-etching process is separately subjected to copper recovery treatment, and the wastewater after copper recovery is quantitatively pumped to the 1# system for further treatment; and the processes of pickling, browning, pickling, etc. contain less copper. Direct metering is then pumped to the 1# system for processing.


(6) Complex wastewater W6: mainly from the copper sinking process, the process uses a certain amount of complex copper, the wastewater contains a strong metal ion complex (such as EDTA), and the complex wastewater pollution factor is total copper. The pretreatment process of CODCr etc. is displacement→flocculation→precipitation→sand filtration. The treatment process is as follows: firstly adjust the pH to 3 to 4, and then add ferrous sulfate, which can effectively displace the metal ions in the form of a complex, and add sodium hydroxide to adjust the pH to about 10, which will be soluble. Complex copper