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Correct Treatment Of Laboratory Waste

Oct 17, 2018

First, the general method of waste collection

1. Classification and collection method: According to the nature and state of the waste, it is collected in different categories.

2, according to the amount of collection method: according to the amount of waste discharged during the experiment or the concentration of high-low collection.

3, similar classification collection method: nature or treatment methods, methods and other similar waste should be collected together.

4. Separate collection method: Hazardous waste should be collected and treated separately.

 

Second, the general principles of waste disposal

When it is proved that the waste is quite rare and safe, it can be discharged into the atmosphere or drain; concentrate the waste liquid as much as possible, make it smaller, and store it in a safe place; use distillation, filtration, adsorption, etc. Separate the material, and only discard the safe part; no matter whether it is liquid or solid, it can be burned safely, but the quantity should not be too large. Do not leave harmful gas or burnt residue when burning. If it can not be burned, choose safety. The site is landfilled and not exposed to the ground.

Generally, toxic gases can be removed through air ventilating cabinets or ventilation ducts after dilution with air. A large amount of toxic gases must be fully burned or adsorbed with oxygen before being discharged.

The waste liquid should be selected according to its chemical characteristics, and stored in a closed container. It should not be mixed and stored, indicating the type of waste, storage time, and regular treatment.

 

Third, the treatment of inorganic waste

1. Treatment of cadmium waste liquid

The cadmium ions were converted into a poorly water-soluble Cd(OH)2 precipitate by slaked lime. That is, adding slaked lime to the cadmium waste liquid, adjusting the pH value to 10.6-11.2, and placing it after thorough stirring, separating the precipitate, and detecting that there is no cadmium ion in the filtrate, the mixture can be discharged after being neutralized.

2. Treatment of hexavalent chromium waste

Mainly by ferrite adsorption method, that is, using hexavalent chromium oxidation by ferrite adsorption method, reducing it to trivalent chromium, and then adding slaked lime to the solution, adjusting the pH to 8-9, heating to about 80 degrees, placing Overnight, the solution turned from yellow to green and discharged the waste.

3. Treatment of lead-containing waste liquid

The principle is to convert the divalent lead into insoluble lead hydroxide with Ca(OH)2, and then use the aluminum salt to remove lead, that is, adding slaked lime to the waste liquid, adjusting the pH to 11, and causing the lead in the waste liquid to form hydroxide. The lead is precipitated, and then aluminum sulfate is added to lower the pH to 7-8, that is, aluminum hydroxide and lead hydroxide are coprecipitated, placed, and fully clarified, and the filtrate is detected to be free of lead, the precipitate is separated, and the waste liquid is discharged.

4. Treatment of arsenic-containing waste liquid

Principle: Using the precipitation adsorption of hydroxide, arsenic removal by color magnesium salt, adding magnesium salt to the arsenic-containing waste liquid, adjusting the pH to 9.5-10.5, forming magnesium hydroxide precipitate, utilizing the new magnesium hydroxide and arsenic compound The adsorption, stirring, and standing overnight, separating the precipitate, discharging the waste liquid.

5. Treatment of mercury-containing waste liquid

Principle: using sodium sulfide to convert mercury into mercury-insoluble mercury sulfide, and then separating and removing it with co-precipitated ferrous sulfide, that is, adding 1:1 equivalent of sodium sulfide to the mercury-containing waste liquid, and then adding Ferrous sulfate is added to form ferrous sulfide, mercury ions are precipitated, the precipitate is separated, and the waste liquid is discharged.

6. Treatment of cyanide waste liquid

Because cyanide and its derivatives are highly toxic, they must be processed in a fume hood.

Principle: The cyanide ion is converted to a harmless gas by the oxidative properties of bleaching powder or sodium hypochlorite. That is, after adjusting the pH value of the solution to more than 11 with an alkali solution, sodium hypochlorite or bleaching powder is added, and the mixture is thoroughly stirred, and cyanide is decomposed into carbon dioxide and nitrogen gas, and discharged after being placed for 24 hours.

7. Treatment of acid-base waste liquid

Collect waste acid in a concentrated way, or use it to treat waste alkali, or filter the waste acid first with acid-resistant glass fiber, neutralize the filtrate with alkali, adjust the pH to 6-8, and discharge it. A small amount of filter residue is buried in the ground.

 

Fourth, the treatment of organic waste

1. Treatment with soluble solvent containing methanol, ethanol and acetic acid. Since these solvents can be decomposed by bacteria, they can be diluted with a large amount of water and discharged.

2, chloroform and carbon tetrachloride waste liquid: water bath distillation, collecting distillate, sealed storage, reuse.

3. Treatment of hydrocarbons and their oxygen-containing derivatives: The simplest method is adsorption with activated carbon. At present, the most widely and most effective treatment methods for organic pollutants are biodegradation method, activated sludge method and the like.

 

5. Precautions for waste disposal

1. With the composition of the waste liquid, in the process of treatment, it is often accompanied by toxic gases and the dangers of heat generation and explosion. Therefore, the nature of the waste liquid must be fully understood before treatment, and then a small amount of the added drugs must be added separately. Operate while watching.

2. Substances containing complex ions, chelates, etc., only one kind of elimination drug is added, and sometimes it can not be completely treated. Therefore, appropriate measures should be taken to prevent some untreated harmful substances from being discharged.

3. In the case where sodium hypochlorite is added to decompose cyanide, so that free residual chlorine is generated, and the waste liquid is treated by sulfide precipitation to produce a water-soluble sulfide, the treated wastewater is often harmful, and therefore, it is necessary to carry out reprocessing.

4. For large amounts of organic solvents, in principle, they should be recycled and their residues treated.