What Are the Process Standards for Chemical Laboratory Wastewater Treatment?
2024.12.23
In chemical laboratories, which are at the forefront of scientific research exploration and teaching practice, a wide variety of wastewater with complex compositions is generated every day. If this wastewater is discharged directly without proper treatment, it will cause incalculable harm to the environment. As Guangzhou Cleanroom Construction Co., Ltd., a professional manufacturer specializing in the purification field, today we will take you to have an in-depth understanding of the process standards for chemical laboratory wastewater treatment.
I. Analysis of the Sources and Hazards of Wastewater
The wastewater in chemical laboratories mainly comes from the discharge of waste liquid after various chemical reactions, the water used for cleaning instruments and equipment, and the discarded liquid generated during sample pretreatment. Its components include heavy metal ions such as mercury, cadmium, and lead. These heavy metals are highly bio-toxic and will accumulate through the food chain after entering the water body, ultimately threatening human health. There are also organic pollutants, such as various organic solvents, phenols, and aldehyde compounds. They are difficult to degrade and will pollute the soil and water for a long time, destroying the ecological balance. In addition, acid-base substances, if discharged in excess, will change the pH value of the water body, causing aquatic organisms to lose their suitable living environment.
II. Pretreatment: The Key Beginning of Wastewater Treatment
1. Classification and Collection
This is the foundation of pretreatment. According to the composition and properties of the wastewater, it is divided into different categories such as organic wastewater, inorganic wastewater, and heavy metal wastewater. For example, chromium-containing wastewater should be collected separately because its subsequent treatment method is completely different from that of ordinary acid-base wastewater. Classification and collection can effectively prevent the mixture of wastewater with different components from generating more complex and difficult-to-treat substances, laying a solid foundation for subsequent precise treatment.
2. pH Adjustment
The pH value of most chemical laboratory wastewater fluctuates greatly. Use acid-base neutralizing agents to adjust the pH value of the wastewater to a range suitable for subsequent treatment, generally between 6 and 9. This can not only prevent strongly acidic or strongly alkaline wastewater from corroding treatment equipment but also enable some heavy metal ions to form precipitates under specific pH conditions, preliminarily removing some pollutants.
III. The Core Treatment Stage: Tackling Pollution from Multiple Aspects
1. Coagulation and Sedimentation
Add coagulants such as polyaluminum chloride and ferrous sulfate to the wastewater. The colloidal particles formed after the hydrolysis of the coagulants can adsorb the fine suspended particles, colloids, and some dissolved organic substances in the wastewater. Through the processes of coagulation and flocculation, they gather into larger flocs and settle down, taking away a large number of impurities and effectively reducing the turbidity of the wastewater and the content of some organic pollutants.
2. Oxidation-Reduction Treatment
For pollutants with oxidizing or reducing properties in the wastewater, corresponding oxidation-reduction methods are adopted. For example, for cyanide-containing wastewater, oxidants such as sodium hypochlorite are added to oxidize the highly toxic cyanide ions into non-toxic nitrogen gas and carbon dioxide for discharge. For wastewater containing heavy metal ions such as hexavalent chromium, reducing agents such as ferrous sulfate are used to reduce them to trivalent chromium, which is easier to remove during the subsequent sedimentation process, greatly reducing the risk of heavy metal pollution.
3. Advanced Filtration
After the wastewater has been treated through the previous steps, there may still be a small amount of fine particles and incompletely settled colloids remaining. At this time, advanced filtration technologies such as ultrafiltration and reverse osmosis are adopted. The ultrafiltration membrane can intercept macromolecular organic substances and colloids, while the reverse osmosis membrane, with its extremely small pore size, can block almost all dissolved salts and heavy metal ions, further purifying the wastewater so that it approaches or meets the discharge standards.
IV. Post-treatment and Monitoring: Ensuring Discharge up to Standards
1. Disinfection Treatment
Before the treated wastewater is discharged, it needs to be disinfected to kill the pathogenic microorganisms it may carry. Commonly used disinfection methods include ultraviolet disinfection and chlorine dioxide disinfection. Ultraviolet light inactivates microorganisms by destroying their DNA structure, while chlorine dioxide relies on its strong oxidizing property to oxidize the key enzymes in microorganisms, ensuring that the wastewater will not cause public health problems after discharge.
2. Compliance Monitoring
A strict monitoring system should be established. According to the relevant national discharge standards, key indicators such as COD (Chemical Oxygen Demand), BOD (Biochemical Oxygen Demand), heavy metal content, and pH value of the treated wastewater should be regularly tested. Only when all indicators meet the standards can the wastewater be safely discharged. This is the last line of defense for environmental protection.
As a professional manufacturer of purification equipment, Guangzhou Cleanroom Construction Co., Ltd. has developed and produced a series of professional equipment suitable for chemical laboratory wastewater treatment based on these strict process standards. Our equipment is integrated with an advanced automatic control system, which can accurately regulate each treatment link and efficiently and stably purify laboratory wastewater, helping laboratories achieve green development.
If you have any questions about chemical laboratory wastewater treatment or want to learn more about purification solutions, please feel free to contact us. Let's work together to safeguard the cleanliness of laboratories and the health of the environment.
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