In the process of chemical experiments, a lot of waste liquid is often produced, some of which are very harmful to the body. When we prove that the waste is quite rare and safe, it can be discharged into the atmosphere or drainage ditch; Concentrate the waste liquid as much as possible to reduce its volume and store it in a safe place; Use distillation, filtration, adsorption and other methods to separate hazardous substances, and only discard the safe part; Whatever liquid or solid can be safely burned, it shall be burned, but the quantity shall not be too large. When burning, it shall not be left with harmful gas or burning residue. If it cannot be burned, it shall be buried in a safe place instead of exposed on the ground.

Chemical waste liquid includes organic and inorganic waste water. Inorganic wastewater mainly contains heavy metals, heavy metal complexes, acids and bases, cyanide, sulfide, halogen ions and other inorganic ions. Organic wastewater contains commonly used organic solvents, organic acids, ethers, polychlorinated biphenyls, organic phosphorus compounds, phenols, petroleum and oils. In contrast, organic wastewater has a wider range of pollution than inorganic wastewater, and brings more serious harm. Different wastewater has different pollutant composition, treatment method and degree. The treatment of laboratory sewage is based on the principles of classified collection, on-site and timely in-situ treatment, simple operation, waste treatment and cost reduction

Treatment of chemical waste liquid

1. The waste acid produced in the chemical laboratory is collected into the waste liquid tank. The neutralization method is generally adopted for the treatment of acid waste liquid:

① Neutralize the acid waste liquid and alkali waste liquid to make their PH value reach 6-9

② The dosing neutralization method is adopted. The commonly used neutralizers are industrial soda ash, caustic soda, ammonia water and calcium carbonate.

1.1 Waste alkali produced in the chemical laboratory shall be collected into the waste liquid tank. The neutralization method is generally adopted for the treatment of alkaline waste liquid:

① Neutralize the alkaline waste liquid with the acid waste liquid to make its PH value reach 6-9

② The dosing neutralization method is adopted. The commonly used neutralizers are sulfuric acid, hydrochloric acid or nitric acid for industrial use.

2. Treatment of arsenic containing waste liquid.

Add quicklime into arsenic containing waste liquid, adjust and control the PH value to about 8, and then generate calcium arsenate and calcium arsenite precipitation. After the precipitation and separation, the filtrate can be directly discharged into the sewer.

3. Treatment method of waste liquid containing mercury:

Chemical coagulation deep sedimentation method: First, adjust the pH value of the mercury containing waste liquid to 8-10 with NaOH, add excessive iron sulfide to make it generate mercury sulfide precipitation, then add a certain amount of ferrous sulfate as flocculant, absorb the mercury sulfide particles that are difficult to precipitate in the water and precipitate together, and then stand still. After separation and filtration, the clear liquid can be discharged into the sewer. A small amount of residue can be buried underground, and a large amount of residue can be used to recover mercury by roasting,

4. Waste liquid containing heavy metal ions

Add alkali or Na2S to change heavy metal ions into insoluble hydroxide or sulfide and deposit them, so as to filter and separate. A small amount of residue can be buried underground.

5. Empty medicine bottles shall be collected by category, and shall be subject to acid washing or alkali washing and neutralization treatment before being disposed of as waste products.

What should be paid attention to in the treatment of chemical waste liquid:

(1) As the composition of waste liquid is different, the treatment process is often accompanied by toxic gas, heating, explosion and other hazards. Therefore, the nature of waste liquid must be fully understood before treatment, and then a small amount of drugs needed to be added must be added, and the operation must be conducted while observing.

(2) For substances containing complex ions, chelates and the like, only one elimination drug can be added, and sometimes it cannot be completely treated. Therefore, appropriate measures should be taken to prevent the discharge of some untreated harmful substances. See http://www.dowater.com More relevant technical documents.

(3) For sodium hypochlorite added to decompose cyanide, resulting in the generation of free residual chlorine, and water-soluble sulfide generated by sulfide precipitation of waste liquid, the treated wastewater is often harmful, so it must be re treated.