CN1327039C - Technology for treating electroplating effluent by biochemical process - Google Patents

Abstract

The process of treating electroplating wastewater by this biochemical method is to use BM functional bacteria composed of Desulfovibrio, Desulfurococcus and Desulfuria annulus to treat electroplating comprehensive wastewater, introduce electroplating wastewater into the regulating pool, adjust its water volume, and homogenize the water quality; The electroplating wastewater passes through the first-stage static mixer, and BM functional bacteria are added to the first-stage static mixer. , carry out the primary biological reaction, stay for 1-2.5 hours, pass the electroplating wastewater after the primary biological reaction through the second static mixer, add 30% sodium hydroxide solution, adjust the pH value to 7.0-8.5, or at the same time Add BM functional bacteria, the amount of which is 1-3‰ of the electroplating wastewater flow rate, carry out secondary reaction precipitation filtration, and stay for 2.5-4 hours; the electroplating wastewater after secondary biochemical reaction precipitation filtration will meet the national sewage comprehensive discharge standard The primary standard in GB8978-1996.

Description

Treatment of electroplating wastewater by biochemical method

technical field

The invention relates to a process for treating electroplating sewage by using BM functional bacteria group.

Background technique

Environmental governance engineering is a major event that benefits the country and the people. Heavy metal wastewater is directly discharged into water bodies without treatment, which will cause water pollution and affect the ecological balance of water bodies.

At present, the most widely used method to treat electroplating wastewater in China is chemical treatment, which removes various heavy metals through precipitation and flocculation to make wastewater meet the standard. The discharge of chromium-containing wastewater must be treated separately, and a large amount of chemical agents need to be invested, which not only has high operating costs, but also produces a large amount of sludge, which is likely to cause secondary pollution;

Electrolytic treatment of electroplating sewage is to use the principle of redox to reduce Cr ⁶⁺ to Cr ³⁺ and remove Cr ³⁺ in wastewater. However, mixed wastewater cannot be treated, and there are certain restrictions on the concentration and water volume of a single heavy metal;

The ion exchange method is used to treat electroplating sewage, the operation is complicated, the resin is saturated quickly, the regeneration needs to consume a lot of acid and alkali, and the operating cost is too high;

The iron filing method treats electroplating sewage, and its stable operation time is short. As time goes by, the effluent water quality is poor and the purification rate is low;

Microbial treatment of electroplating wastewater is more effective than the aforementioned treatment methods. For example, the new technology of microbial treatment of electroplating wastewater provided by patent CN1096769A can significantly remove Cr ⁶⁺ , but it cannot fully meet the standards for comprehensive electroplating wastewater treatment, especially nickel and zinc in wastewater. . Due to the limitations and instability of its technology, it cannot be popularized and applied to large-volume, high-concentration electroplating wastewater.

purpose of invention

In view of the current status of various treatment of electroplating wastewater, the purpose of the present invention is to develop a treatment of electroplating wastewater using microorganisms to provide a high-efficiency, technically stable, impact-resistant load and low operating cost, suitable for large water volumes and high concentrations. The process of treating electroplating wastewater by biochemical method.

The biochemical method for treating electroplating wastewater is characterized in that the electroplating wastewater is treated by using BM functional bacteria group, and the processing steps are as follows:

1) Introduce the electroplating wastewater into the regulating tank to adjust the water volume and homogenize the water quality;

2) Pass the electroplating wastewater in the regulating tank through the first-stage static mixer, and add BM functional bacteria into the first-stage static mixer at the same time, the amount added is 1/50-200 of the flow rate of the electroplating wastewater in the first-stage static mixer , enter the BM reactor or pool, carry out the first-order biological reaction, and stay for 1-2.5 hours;

3) Pass the electroplating wastewater after the primary biological reaction through the second static mixer, add 30% sodium hydroxide solution, the amount depends on the acidity of the electroplating wastewater, adjust the pH value to 7.0-8.5, or add at the same time BM functional bacteria, the amount added is 1-3‰ of the electroplating wastewater flow rate, and the secondary biochemical reaction is precipitated and filtered, and the residence time is 2.5-4 hours;

4) The electroplating wastewater after secondary biochemical reaction sedimentation and filtration reaches the first-level standard in the national sewage comprehensive discharge standard GB8978-1996;

5) Collect the sediment from the two-stage biochemical reaction to the sludge drying tank for drying or pressure filtration after concentration to recover heavy metals.

The above optimal process conditions for treating electroplating comprehensive wastewater are: the pH value of the wastewater is 3.0-8.0, and the reaction temperature is 10-50°C.

The above-mentioned process of treating electroplating wastewater by biochemical method refers to the BM functional bacteria composed of Desulfovibrio, Desulfococcus, and Desulfurized Cyclobacterium. The growth conditions are anaerobic growth, the temperature is 20-40°C, and the growth time is 12-24 hours. .

BM functional bacteria have undergone long-term screening and cultivation, and there are three levels of mutual cooperation among them: chemistry, physics, and biology. Therefore, the BM bacteria group has five functions of electrostatic adsorption, valence transformation, complexation, flocculation and pH buffering. It enriches the heavy metal ions in the wastewater on the surface of the BM bacteria, separates the solid and liquid, and then enters the secondary biochemical reaction precipitation. After filtering, the electroplating wastewater can be discharged up to the standard. The advantages of the present invention are:

1. The wastewater treatment project will completely solve the problem of environmental pollution caused by the production wastewater of the enterprise.

2. The electroplating wastewater after biochemical treatment can be completely reused in places with strict water quality requirements, and the reuse is generally not less than 50%.

3. Compared with the traditional treatment process—chemical method, it can save a lot of operating costs and maintenance costs. If the discharge is strictly in accordance with the national first-level standard, the chemical method usually costs 3-8 yuan to treat 1 ton of wastewater, while the biochemical method only costs about 1.2 yuan, and the difference between the two is about 2.0 yuan or more.

4. The amount of sludge is small, the metal can be recycled, and there is no secondary pollution. BM bacteria will form the heavy metal ions in the electroplating wastewater through adsorption and other actions to form granular sediments, and the amount of slag is very small. Due to the high content of heavy metals in sludge, centralized treatment of sludge can recover heavy metals or chemical raw materials. After extraction, the residual amount of sludge is less, and the residual amount of heavy metals is lower, thus effectively avoiding secondary pollution.

In summary, the present invention uses BM functional bacteria to treat electroplating comprehensive wastewater, overcomes the deficiencies of existing chemical methods, electrolytic methods, and ion exchange methods, and combines chemical methods, electrolytic methods, ion exchange methods, and microbial methods to treat electroplating. The advantages of wastewater, with unique technical advantages, can handle comprehensive electroplating wastewater, and has strong processing capacity, high efficiency, less bacteria, stable effluent quality, impact load resistance and low operating cost, easy operation and management, and is suitable for processing large amounts of water , High concentration electroplating wastewater.

Explanatory drawings

Fig. 1 process flow chart of the present invention

Detailed ways

Example 1:

An electroplating factory in Chongqing discharges 400 tons of comprehensive electroplating wastewater per day, and the raw water index: (monitoring and acceptance data of the local environmental protection bureau)

PH Cr6 ⁺ TCr Ni ²⁺ CODcr Petro 3.05 77.1 127 4.89 124 5.68

Wastewater flow rate is 20 tons/hour, temperature 25 ℃, add the BM functional bacteria of 400 liters/hour and enter BM reactor through the first stage static mixer to carry out the first stage biological reaction after 1.0 hour, add 30% sodium hydroxide solution, will Adjust the pH value to 7.0, and carry out the second-stage biochemical reaction, sedimentation and filtration for 2.5 hours through the second-stage static mixer. The result of the effluent is:

(Monitoring and acceptance data of the local environmental protection bureau)

PH Cr6 ⁺ TCr Ni ²⁺ CODcr Petro 7.72 0.102 0.296 0.108 38.5 1.04

The first-level standard in the National Comprehensive Wastewater Discharge Standard (G88978-1996):

PH Cr6 ⁺ TCr Ni ²⁺ CODcr Petro 6--9 0.5 1.5 1.0 100 5

The effluent fully meets the national sewage comprehensive discharge standard.

Example 2:

An electroplating factory in Dongguan discharges 1,000 tons of comprehensive electroplating wastewater per day, and the raw water index: (monitoring and acceptance data of the local environmental protection bureau)

PH Cr6 ⁺ Cu ²⁺ Ni ²⁺ CODcr Petro 3.0 58.06 2.51 5.7 51.1 1.3

The wastewater flow rate is 50 tons/hour, the temperature is 50°C, add 250 liters/hour of BM functional bacteria, and enter the BM reactor through the first-stage static mixer for 2.5 hours of primary biological reaction, then add 30% sodium hydroxide solution, Adjust the pH value to 8.0, and carry out the secondary biochemical reaction, precipitation and filtration for 4.0 hours through the second-stage static mixer, and the result of the effluent is:

(Monitoring and acceptance data of the local environmental protection bureau)

PH Cr6 ⁺ Cu ²⁺ Ni ²⁺ CODcr Petro 7.0 0.05 not detected 0.1 49.5 0.4

The first-level standard in the National Comprehensive Wastewater Discharge Standard (GB8978-1996):

PH Cr6 ⁺ Cu ²⁺ Ni ²⁺ CODcr Petro 6-9 0.5 0.5 1.0 100 5

The effluent fully meets the national sewage comprehensive discharge standard.

Example 3:

An electroplating factory in Suzhou discharges 100 tons of comprehensive electroplating wastewater per day, and the raw water indicators are:

(Monitoring and acceptance data of the local environmental protection bureau)

PH Cu ²⁺ Ni ²⁺ CODcr 8.0 11.25 12.351 69

The wastewater flow rate is 10 tons/hour, the temperature is 10°C, 100 liters/hour of BM functional bacteria is added into the BM reactor through the first-stage static mixer for 1.5 hours of primary biological reaction, and 30 liters/hour of BM functional bacteria and 30% sodium hydroxide solution, adjust the pH value to 8.5, carry out the secondary biochemical reaction, precipitate and filter for 2.5 hours through the second-stage static mixer, and the result of the effluent is:

(Monitoring and acceptance data of the local environmental protection bureau)

PH Cu ²⁺ Ni ²⁺ CODcr 7.0 0.017 0.248 20.0

The first-level standard in the National Comprehensive Wastewater Discharge Standard (GB8978-1996):

PH Cu ²⁺ Ni ²⁺ CODcr 6-9 0.5 1.0 100

The effluent fully meets the national sewage comprehensive discharge standard.

Example 4:

An electroplating factory in Chongqing discharges 700 tons of comprehensive electroplating wastewater per day, and the raw water indicators are:

(Monitoring and acceptance data of the local environmental protection bureau)

PH Cr6 ⁺ Ni ²⁺ CODcr 3.5 65.5 30.0 102.0

The wastewater flow rate is 30 tons/hour, the temperature is 15°C, 300 liters/hour of functional bacteria are added into the BM reactor through the first-stage static mixer for 1.5 hours of primary biological reaction, and 90 liters/hour of BM functional bacteria and 30 % sodium hydroxide solution, adjust the pH value to 8.5, carry out the secondary biochemical reaction, precipitate and filter for 2.5 hours through the second-stage static mixer, and the result of the effluent is:

(Monitoring and acceptance data of the local environmental protection bureau)

PH Cr6 ⁺ Ni ²⁺ CODcr 7.0 0.012 0.045 76.0

The first-level standard in the National Comprehensive Wastewater Discharge Standard (GB8978-1996):

PH Cr ⁸⁺ Ni ²⁺ CODcr 6-9 0.5 1.0 100

The effluent fully meets the national sewage comprehensive discharge standard.

Claims (2)

1, a kind of biochemical process is administered electroplating wastewater technology, it is characterized in that utilizing the BM function cenobium of being made up of desulfovibrio, desulfurization coccus, desulfurization band bacterium that electroplating sewerage is carried out Two-Stage Biochemical and handles, and treatment step is as follows:

1), electroplating wastewater is introduced equalizing tank, regulates its water yield, homogenizing water quality;

2), with the process of the electroplating wastewater in equalizing tank first step static mixer, in first step static mixer, add the BM function yeast simultaneously, add-on is the 1/50-200 of electroplating wastewater flow in the first step static mixer, enter BM reactor or pond, carry out the one-level biological respinse, stopped 1-2.5 hour;

3), will carry out electroplating wastewater behind the one-level biological respinse through second static mixer, adding content is 30% sodium hydroxide solution, add-on is decided on electroplating wastewater acidity, adjust pH value to 7.0-8.5, or add the BM function yeast simultaneously, its add-on is the 1-3 ‰ of electroplating wastewater flow, carries out the secondary biochemical reaction precipitation and filters, and stops 2.5-4 hour;

4), the electroplating wastewater after will filtering through the secondary biochemical reaction precipitation promptly reach the primary standard among the national sewage comprehensive emission standard GB8978-1996;

5), the throw out with two-stage reaction is collected into mummification of sludge drying pond or press filtration after concentrating, recyclable heavy metal; The optimum process condition of above-mentioned steps is: the waste water pH value is 3.0-8.0,10～50 ℃ of temperature of reaction.

2, administer electroplating wastewater technology according to the described biochemical process of claim 1, it is characterized in that the BM function yeast be made up of desulfovibrio, desulfurization coccus, desulfurization band bacterium, growth conditions is an anaerobic growth, 20～40 ℃ of temperature, and growth time is 12-24 hour.