Real stone paint wastewater treatment process

Real stone paint is a kind of paint that resembles marble and granite. The paint has the characteristics of waterproof, fireproof, non-toxic, acid and alkali resistance, and strong anti-oxidation ability. It has been fully used in modern exterior wall decoration, and gradually replaces marble and granite. and other traditional stone. In recent years, with the rapid development of the real estate industry, the amount of real stone paint has gradually increased.

The real stone paint wastewater belongs to high organic matter and high suspended solids wastewater. The wastewater contains cellulose, plasticizers, thickeners, film-forming aids, emulsions and other substances. The wastewater is directly discharged into the natural environment without treatment, which will be harmful to the natural environment. Cause fatal damage, how to effectively treat the wastewater has become the top priority of the development of the industry.

With the increase in the amount of real stone paint in the world, many professional environmentalists have begun to explore the treatment methods of real stone paint wastewater to reduce its impact on the surrounding environment.

Experimental part

1.1 Experimental instruments and reagents

Plate and frame filter press device, coagulation sedimentation device, anaerobic reactor device, aerobic reactor device, ozone catalytic oxidation device, thermometer, beaker, COD constant temperature heater, COD bottle, 250mL conical flask, 1000mL conical flask , pipette, electronic balance, shaker, constant temperature heating rod, 100mL graduated cylinder;

Sodium hydroxide, potassium dichromate solution, sulfuric acid-silver sulfate solution (Ag2SO4-H2SO4 solution), ferrous ammonium sulfate standard solution, test ferrous spirit indicator, mercury sulfate.

1.2 Test indicators and test methods

1.3 Experiment processing process roadmap

In view of the high COD load of wastewater and the difficulty of degradation, the experimental study takes “serving engineering applications” as the starting point. Explore the feasibility and economy of wastewater treatment, and provide rich and reliable reference data for future engineering design and operation.

Determine the experimental process as follows:

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1.4 Sources and characteristics of wastewater

The water used in the experiment comes from the waste water of a real stone paint workshop of a paint enterprise in Shandong. The waste water has the characteristics of high suspended solids and high COD. The waste water is neutral, and the color is lavender and turbid. The COD concentration reaches 12000mg/L, and the SS content reaches 2000mg/L.

正在翻译…

(1) Take 2L of real stone paint waste water for plate and frame filter press experiment, collect waste water after filter press, and monitor the changes of SS and COD of waste water.

(2) Take 1.5L of wastewater after plate and frame pressure filtration, add PAC to the wastewater, observe the relationship between SS, COD and the amount of PAC in the wastewater supernatant after coagulation and sedimentation, and find the optimal amount of PAC to be added. .

(3) Take the wastewater after coagulation and sedimentation and put it in the anaerobic reactor, observe the degradation trend of COD in the anaerobic reactor, and find the best anaerobic reaction time.

(4) Take the anaerobic wastewater and put it in the aerobic reactor, observe the degradation trend of COD in the aerobic reactor, and find the best anaerobic reaction time.

(5) Conduct an ozone catalytic oxidation experiment on the aerobic wastewater to explore the relationship between ozone catalytic oxidation time, ozone amount and wastewater COD, explore the optimal ozone dosage and ozone reaction time, and lay the foundation for subsequent engineering applications.

Experimental results and discussion

2.1 The effect of plate and frame filter press on the removal of COD and SS from wastewater

During the experiment, two treatment modes were selected to filter the wastewater by plate and frame. One was to add PAM coagulant to increase the size of flocs in the wastewater to explore the effect of plate-and-frame filter press; the other was to directly filter. Observe the removal of the plate frame. The experimental results are as follows:

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It can be seen from the above table that the content of COD and SS in the wastewater after adding PAM filter press is obviously better than that without adding PAM.

The removal rate of COD and SS reached 51.7% and 92% in the wastewater with PAM added; the removal rate of COD and SS was 82.5% without PAM.

The main reason is that PAM is a coagulant aid, which can effectively increase the flocs of suspended solids in wastewater, reduce the permeability of filter cloth, and improve the removal effect of suspended solids in wastewater.

It can also be seen from the analysis that although the effect of adding PAM to the removal of COD and SS in wastewater is significantly enhanced, it is found through data comparison that the difference in the size of COD and SS in wastewater after adding PAM and without adding PAM is small, and adding PAM The filter press sludge cannot be reused in the production process, and needs to be disposed of as solid waste, and the disposal cost is relatively high.

For this reason, this process section selects the treatment process without PAM to pretreat the wastewater, and reuses the sludge after filtration to the production process, so as to reduce the impact of solid waste on the surrounding environment as much as possible, and realize the comprehensive utilization of waste, reduce the production cost of the enterprise.

2.2 The effect of coagulation and sedimentation on the removal of COD and SS from wastewater

During the experiment, different amounts of PAC were added to explore its influence on the coagulation and sedimentation removal effect of wastewater, so as to explore the best dosage of PAC. Introduce as few other substances as possible to reduce the impact on subsequent biochemistry. The experimental results are shown in Figure 1 and Figure 2.

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It can be seen from the above Figures 1 and 2 that with the increase of the dosing amount, the COD and SS in the wastewater gradually decreased, and the decrease range was gradually increased at first and then gradually decreased until it became stable.

When the amount of PAC added to the wastewater is 60 mg/L, most of the systems in the wastewater have been flocculated, and the flocculation point is the optimal flocculation point. With the increase of the agent, the suspended solids and COD in the wastewater remain basically unchanged. .

It can also be found from Figure 2 that when PAC was added at the beginning, the suspended solids index in the wastewater increased. At this time, the suspended solids in the wastewater were not agglomerated into agglomerates. Suspended solids content increased. It can be seen from Figure 1 and Figure 2 that when the amount of PAC added in the wastewater is 60 mg/L, the flocculation effect of the wastewater is the best at this time.

2.3 Influence of anaerobicity on COD removal from wastewater

The anaerobic temperature is controlled to be mesophilic anaerobic (about 35 ℃), the pH of the wastewater is controlled within the range of 7~8, and the anaerobic sludge is filtered by the sludge from the domestic sewage treatment plant. By observing the difference between the anaerobic reaction time and the COD of the wastewater Change the curve to explore the optimal anaerobic reaction time. The experimental results are shown in Figure 3.

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It can be seen from Figure 3 that with the change of time, the COD in the wastewater first increases and then decreases. When the COD in the wastewater becomes 1400-1500 mg/L, the anaerobic effect basically tends to be stable, and the anaerobic effect is stable. The removal efficiency can reach 67%.

It can be seen from the chart that in the early stage of the anaerobic reaction, the COD content in the wastewater gradually increased. The reason is that the sludge comes from the sludge of the municipal sewage plant. Adaptation, part of the sludge died or was lost, resulting in an increase in the organic matter content of the wastewater, and an appropriate increase in the COD concentration of the wastewater.

With the increase of time, the sludge in the wastewater is gradually domesticated into anaerobic sludge. At this time, the anaerobic effect is getting better and better. Through the biochemical action of anaerobic bacteria, the organic matter in the wastewater is converted into inorganic matter, reducing the COD of the wastewater. content.

With the increase of time, the COD content in the wastewater gradually tends to a stable state, because the substances that are easily consumed by anaerobic biochemistry have been basically digested at this time, and the remaining substances cannot be consumed by anaerobic microorganisms, so anaerobic microorganisms are formed. stable state.

It can be seen from the above figure that when the anaerobic time is 35~45h, the anaerobic state tends to be stable.

2.4 The effect of aerobic aerobic on COD removal from wastewater

Aerobic treatment is an indispensable treatment idea in the wastewater treatment process, mainly through the action of aerobic bacteria micelles to remove organic matter in wastewater.

During the experiment, 1.5L of anaerobic wastewater was taken into the aerobic processor, and the wastewater was oxygenated by means of fish pump oxygenation. The dissolved oxygen in the wastewater was controlled at 2~3mg/L, and the MLSS of the sludge was controlled at 4000mg/L. L. Water samples were taken every 12 hours to detect the concentration of COD in the wastewater. The experimental results are shown in the figure below.

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It can be seen from the above figure that with the increase of time, the COD content in the wastewater gradually decreases, and the reduction range of the wastewater COD is first increased and then decreased. When the wastewater COD concentration tends to be about 300mg/L, the wastewater COD tends to be stable. .

The main reason is that the aerobic bacteria micelles first adsorb the organic matter in the wastewater into the bacteria micelles through the adsorption of microorganisms, and then through the biochemical action of microorganisms, part of them are converted into raw materials required for the growth of microorganisms.

Another part is converted into CO2 and water, and another part of the organic matter is stored in the sludge in the form of sludge. With the increase of time, the organic matter in the sludge is discharged in the form of excess sludge.

With the increase of time, the organic matter in the wastewater is gradually consumed, and the remaining matter is the organic matter that is extremely difficult to be utilized by microorganisms.

2.5 The effect of ozone catalytic oxidation on COD removal from wastewater

Ozone catalytic oxidation is one of the processes of chemical treatment of wastewater. It mainly oxidizes organic matter in wastewater into inorganic matter, CO2 and water through the strong oxidation of ozone. This method has been widely used in advanced wastewater treatment in recent years. .

During the experiment, by changing the production amount and reaction time of the ozone generator, the change curve of COD in the wastewater was observed with the change of the reaction amount. The experimental results are shown below.

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It can be seen from the above figure that with the gradual increase of the amount of ozone, the COD content in the wastewater also gradually decreases, and the degradation curve of the wastewater COD is very stable. It can be seen from the analysis of the above figure that the ozone oxidation ability is extremely strong, which can effectively oxidize the organic matter in the wastewater, and can oxidize most of the organic components, and the oxidation process is extremely fast.

Conclusion

(1) It is found through experiments that the use of plate and frame filter press-coagulation sedimentation-anaerobic-aerobic-ozone oxidation can effectively remove organic matter in wastewater, and the COD of effluent reaches below 50mg/L.

(2) The use of the plate and frame filter press can effectively remove the suspended solids in the wastewater, the COD removal rate in the wastewater can reach more than 47.5%, and the SS removal rate can reach more than 82.5%. Adding PAM or not adding PAM has no obvious effect on the filter press of the plate and frame.

(3) The dosage of PAC in the coagulation and sedimentation process is 60 mg/L, the COD of the wastewater after coagulation is about 4300 mg/L, and the SS is about 120 mg/L.

(4) The COD effluent of wastewater treated by anaerobic process is 1500mg/L, and the anaerobic time is 72h, and the effect is the best.

(5) After the anaerobic wastewater is treated by the aerobic process, the COD effluent of the wastewater is about 300mg/L, and the best effect is when the aerobic time is 60h. At this time, the effluent can meet the discharge standard of the sewage treatment plant in the park.

(6) After the aerobic wastewater is treated with ozone oxygen, the COD effluent of the wastewater is about 50mg/L, and the dosage of ozone is 400mg/L.

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