Advanced treatment technology for electroplating sewage

Abstract

The invention discloses an advanced treatment technology for electroplating sewage, which comprises the following steps: (A) sewage division; (B) pretreatment of wax-containing sewage; (C) pretreatment of sewage containing pyrophosphoric acid and the like; (D) pretreatment of cyanogen-containing sewage; (E) pretreatment of chromium-containing sewage; and (F) heavy metal removal treatment. Compared with the prior art, the technology disclosed by the invention has the advantages that by adopting the treatment technology, the indexes after the electroplating sewage treatment far exceed the national emission standard, for example, the total chromium content is less than or equal to 0.004mg / L, the total copper content is less than 0.05mg / L, the ammonia nitrogen content is less than 0.8mg / L, the phosphide content is less than 0.3mg / L, and the COD content is less than 20mg / L; the operation cost of the sewage treatment system is low, and the system is stable and reliable; and a factory is willing to accept the technology and can strictly execute the operation process, and the daily effluent completely reaches the standard.

Description

Technical field [0001] The invention relates to a sewage treatment process, in particular to an electroplating sewage treatment process. Background technique [0002] At present, all electroplating plants only divide cyanide-containing sewage and chromium-containing sewage into two water treatments. Among them, chromium-containing sewage includes surface water, copper-containing sewage, zinc-containing sewage, degreasing and dewaxing water, and copper pyrophosphate-containing sewage The treatment process is to introduce the cyanide-containing sewage to the dosing reaction tank, and add NaClO and NaOH. When the pH=10-11, ORP=300MV, the sewage flows into the next tank, and then NaClO is added to make the pH=8, ORP=600 After ~620MV, at the same time, put H in the chromium-containing sewage 2 SO 4 Or HCl, make pH=3, then put in Na 2 S 2 O 5 Make ORP=280~300MV, and then introduce the above-mentioned cyanide-containing sewage into the pH adjustment tank to mix, put in lime to make the ...

AI Technical Summary

Problems solved by technology

[0003] The weak point of above-mentioned traditional processing method is: 1, the reaction time is unstable, such as the two-stage reaction of cyanide-containing sewage, the volume of the dosing reaction tank is fixed, and the water inflow varies slightly, and the cyanide breaking time cannot be guaranteed; 2 , Although the dosage is controlled by potential, because the reaction pool is generally small, for example, the reaction pool of a certain factory is only 1.5 cubic meters, but the water inflow reaches 20 cubic meters per hour, and the pH and potentiometer are fixed in a certain part of the reaction pool for dosing. In one position, often the instrument has not responded or the local value has reached the requirement and the other parts of the drug dose is not enough, the sewage has flowed into the next pool, so the drug dose can not be appropriate, and the time for breaking cyanide is insufficient, the two channels of water enter the pH After adjusting the pool, such as Na 2 S 2 o 5 Excessive, cyanide will be reduced, such as excessive NaClO, Cr 3+ Oxidized to Cr 6+ ; 3, due to NaClO, Na 2 S ， o 5 The amount of medicine is added according to the demand, and the reaction when the two channels of water enters the pH adjustment tank is more complicated. There is the possibility of cyanide and total chromium not reaching the standard, and phosphide, copper, nickel, and zinc cannot be guaranteed. To meet the standard, if copper, nickel and zinc are to meet the standard, 250-300g of heavy metal scavenger such as DDTC should be added to each ton of sewage. Calculated on the basis of a commercially available 12 yuan / liter metal scavenger with a content of 30%, the dosage is 0.8-1kg Only the heavy metals can reach the standard, not only the cost is high, but also the phosphide and COD still exceed the standard

Due to the high cost, some factories are unwilling to self-consciously use enough medicines, which often results in substandard discharge of heavy metals. When the environmental protection department conducts spot checks, they use the medicines to deal with spot checks.