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Method for treating mixed waste water of electroplating industry

A technology of mixed wastewater and electroplating industry, applied in metallurgical wastewater treatment, aerobic process treatment, reduced water/sewage treatment, etc., can solve the problems of reducing wastewater treatment costs, large dosage of chemicals, high treatment costs, etc. Disposal cost, biological toxicity reduction effect

Inactive Publication Date: 2010-08-25
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the past, in the actual treatment process of some wastewater treatment stations, the reducing agent was often added first to remove chromium, and then the oxidant was added to remove cyanide. However, the chromium may not meet the standard at this time. At this time, the cyanide may not meet the standard. If the cyanide is not up to the standard, add the oxidant again, repeat several times, rely on the co-precipitation effect of adding a large amount of chemical agents, and finally barely make the heavy metals and cyanide reach the standard. The amount of sludge is large, the amount of sludge is also large, and the treatment cost is high
In addition, for electroplating industrial wastewater, a new requirement for COD treatment to meet the standard was proposed. Although heavy metals and cyanide have reached the standard with this treatment method, the COD value of the wastewater still cannot meet the standard.
[0004] In order to reduce the treatment cost of electroplating wastewater and improve the treatment effect, newly-built electroplating factories and electroplating industrial parks often require strict distinctions between different wastewaters, such as wastewater containing hexavalent chromium, wastewater containing cyanide, wastewater containing organic matter, and wastewater containing other heavy metals. The waste water is sent to the waste water treatment station separately, so that the treatment can reach the standard, and the cost of waste water treatment can also be reduced. However, for the electroplating industrial park that has been built, these waste waters are completely separated, and different types of waste water transmission pipelines that are completely separated are laid again. certain difficulty

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] In an electroplating industrial park, the influent water quality of mixed wastewater is shown in Table 1:

[0023] Table 1 Influent water quality (unit: mg / L, except pH)

[0024] water quality index

[0025] Add ferrous sulfate to the mixed wastewater, control the concentration of ferrous sulfate in the mixed wastewater to 2000mg / L, add lime 2000mg / L at the same time, control the concentration of lime in the mixed wastewater after adding ferrous sulfate to 2000mg / L, the pH value of wastewater is adjusted to more than 7 with lime, and 1.5 hours after the chemical precipitation, the water quality of the supernatant is as shown in table 2: this step is through the reduction of ferrous iron, Cr 6+ reduced to Cr 3+ At the same time, the precipitation is removed to ensure that the total Cr is discharged up to the standard. At the same time, ferrous ions can also form ferricyanide complexes with cyanides, and ferricyanide complexes can form ferricyanide complex ion...

Embodiment 2

[0036] In an electroplating industrial park, the influent water quality of mixed wastewater is shown in Table 5:

[0037] Table 5 Influent water quality (unit: mg / L, except pH)

[0038] water quality index

[0039]Add ferrous chloride in the mixed wastewater, control the concentration of ferrous chloride in the mixed wastewater to be 3000mg / L, add lime 2000mg / L at the same time, control the concentration of lime in the mixed wastewater after adding ferrous chloride The concentration is 2000mg / L, and the pH value of the wastewater is adjusted to 6.5-7 with lime. After 2 hours of chemical precipitation, the water quality of the supernatant is shown in Table 6:

[0040] Table 6 Water quality after pretreatment (unit: mg / L, except pH)

[0041] water quality index

[0042] The treated wastewater enters the aerobic biological fluidized bed reactor equipped with 3-5MM ceramsite, and the reaction residence time is 6 hours. After the biochemical reaction, the water...

Embodiment 3

[0050] In an electroplating industrial park, the influent water quality of mixed wastewater is shown in Table 9:

[0051] Table 9 Influent water quality (unit: mg / L, except pH)

[0052] water quality index

[0053] Add ferrous sulfate to the mixed wastewater, control the concentration of ferrous sulfate in the mixed wastewater to 4000mg / L, add lime 2000mg / L at the same time, control the concentration of lime in the mixed wastewater after adding ferrous sulfate to 2000mg / L, the pH value of waste water is adjusted to 7-7.5 with lime, after chemical precipitation 2 hours, the water quality situation of supernatant is as shown in table 10:

[0054] Table 10 Water quality after pretreatment (unit: mg / L, except pH)

[0055] water quality index

[0056] The treated wastewater enters the aerobic biological fluidized bed reactor equipped with 3-5MM ceramsite, and the reaction residence time is 8 hours. After the biochemical reaction, the water quality of the waste...

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Abstract

The invention discloses a method for treating the mixed waste water of the electroplating industry, which comprises the following steps of: firstly, reacting ferrous salt and the mixed waste water of the electroplating industry, then adding sodium hydroxide or lime, regulating the pH value to 6.5 to 7.5 and precipitating for 1.5 to 2h, wherein the concentration of the ferrous salt in the mixed waste water of the electroplating industry is 2000 to 4000mg / L; after precipitating the waste water, carrying out aerobic biochemical treatment on the obtained supernatant liquid by an aerobic biochemical treatment system filled with ceramsite with the detention time of 4 to 8h and removing the COD value and the residual cyanogen in the mixed waste water; and adding a chemical oxidant of sodium hypochlorite into the treated waste water, further oxidizing the cyanogen in the waste water, regulating the pH value of the waste water to 7 to 8.5 and precipitating again for 1.5 to 2h. The method has relatively low treatment cost, not only heavy metal and cyanide reach the standard, but also the COD value in the waste water can be obviously lowered, and the treated waste water reaches a novel discharge standard.

Description

technical field [0001] The present invention relates to a wastewater treatment method, in particular to a treatment method for electroplating industrial mixed wastewater, which is used for the treatment of mixed wastewater containing hexavalent chromium, copper, nickel and other heavy metals and cyanide in electroplating factories or electroplating industrial parks. After being processed by this method, it reaches the new discharge standard stipulated by the state. Background technique [0002] To treat oxidative hexavalent chromium wastewater, the reducing agent can reduce it to trivalent chromium, and then adjust the pH value of the wastewater to about 8, so that the trivalent chromium can form hydroxide precipitation and remove. To treat wastewater containing cyanide, a strong chemical oxidant can be added, generally using sodium hypochlorite solution (floating water), to remove the cyanide in the wastewater through secondary oxidation. For heavy metals in wastewater, s...

Claims

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Application Information

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IPC IPC(8): C02F9/14C02F3/02C02F1/70C02F1/76C02F103/16
CPCY02W10/10
Inventor 汪晓军顾晓扬简磊李达宁丛丛
Owner SOUTH CHINA UNIV OF TECH
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