Today, I will explain to you the management and treatment methods of laboratory waste liquid in environmental monitoring stations. During the experimental operation, various strong acids, strong alkalis, and organic solutions are generated; cleaning various experimental utensils and equipment (various glass containers, Sample bottle, sample preparation equipment, etc.), waste liquid and equipment cooling device (such as various distillation cooling devices, equipment cooling devices, etc.) generated waste liquid.

We all know that the waste liquid of the experiment cannot be poured casually. It is neither environmentally friendly nor meets the requirements of laboratory accreditation, but it is not so easy to treat the waste liquid separately. Of course, there are also methods for treating wastewater with different compositions. The difference.

Some of the waste liquid can be recycled and reused of useful substances, and some can be directly discharged to the external drainage pipe network, and some can be treated by appropriate methods and then discharged into the external pipe network.

Today, the director will talk to everyone about the treatment methods of waste liquid and how to take different treatments according to its nature and composition.

Usually, the waste water produced in the laboratory includes excess samples, standard curve and sample analysis residual liquid, invalid storage and washing liquid, and a large amount of washing water. Almost all routine analysis projects have the problem of wastewater pollution to varying degrees.

Management and Treatment Methods of Laboratory Waste Liquid in Environmental Monitoring Stations

1. Common wastewater treatment methods

There are three common wastewater treatment methods, physical method, chemical method and biological method.

Physical method mainly uses physical action to separate suspended solids in wastewater;

The chemical method mainly uses chemical methods to treat dissolved or colloidal substances in wastewater;

Biological method is mainly to remove colloids and dissolved organic substances in wastewater.

2, processing method

incineration method

①Put the waste liquid of combustible substances in a combustion furnace to burn. If the quantity is small, put it in an iron or porcelain container and burn it in a safe outdoor place. When igniting, take a long rod, tie a rag with oil on one end, or use wood chips and other things, stand upwind to ignite and burn. And, it must be monitored until the burn is finished.

②For substances that are difficult to burn, it can be mixed with combustible substances for combustion, or sprayed into an incinerator equipped with a combustor for combustion. For hard-to-burn substances such as PCBs, some of the unburnt substances are often discharged, so be careful. For high-concentration organic waste liquid containing water, this method can also be incinerated.

③The waste liquid that produces harmful gases such as NO2 SO2 or HCl due to combustion must be burned in an incinerator equipped with a scrubber. At this time, the combustion exhaust gas must be washed with lye to remove harmful gases.

④For solid substances, it can also be dissolved in a flammable solvent and then burned.

solvent extraction

① The low-concentration waste liquid containing water is extracted with a volatile solvent such as n-hexane that is not mixed with water. After the solvent layer is separated, it is incinerated. Then blow in air to blow out the solvent in the water layer.

②Waste liquids that form emulsions cannot be treated by this method, but must be treated by incineration.

adsorption method

Use activated carbon diatomite bauxite layer sheet fabric polypropylene polyester sheet urethane foam plastic straw and sawdust which can absorb solvents well and make it fully adsorbed and burned together with the adsorbent.

oxidation decomposition method

In the low-concentration organic waste liquid containing water, the waste liquid that is easily oxidized and decomposed is oxidized and decomposed with H2O2 KMnO4 NaOCl H2SO4+HNO3 HNO3+HClO4 H2SO4+HClO4 and the mixed liquid of waste chromic acid. Then, treat it according to the inorganic experimental waste liquid treatment method.

hydrolysis

For organic acid or inorganic acid esters, and some organic phosphorus compounds that are prone to hydrolysis, sodium hydroxide or calcium hydroxide can be added to hydrolyze at room temperature or under heating. After hydrolysis, if the waste liquid is non-toxic, it can be discharged after neutralization and dilution. If it contains harmful substances, treat it with appropriate methods such as adsorption.

Biochemical treatment method

Use activated sludge or the like and blow in air for treatment. For example, this method can be used to treat dilute solutions containing ethanol, acetic acid, animal and vegetable oils, proteins and starches.

3. Various wastewater treatment methods

Organic wastewater treatment

Organic wastewater mainly includes some titrants, reaction solutions and metal digestion solutions including chloroform, carbon tetrachloride, sulfur dioxide, etc. Among them, the less toxic waste water can be directly discharged by dilution with water, while other toxic and harmful waste water can be treated by distilled water, recycling or other treatment methods.

Inorganic wastewater treatment

Inorganic wastewater mainly includes heavy metals such as mercury, zinc, copper, cadmium, nickel, heavy metal complexes, and waste liquid containing a large amount of acid and alkali.

Treatment of mercury-containing wastewater: adjust the pH value of mercury-containing wastewater to 8-9, add ferrous sulfate to produce iron sulfide, and iron sulfide precipitation can be used as a co-precipitating agent to accelerate the precipitation of mercury sulfide, and then the mercury precipitation is recovered by electrolysis and filtered. The supernatant is discharged after neutralization.

Treatment of chromium-containing wastewater: Add 10% ferrous sulfate solution to the waste liquid. At this time, iron ions can reduce hexavalent chromium to trivalent chromium, and then add nitrate lime to adjust the pH of the solution to 6-8. Heat to 80°C and leave overnight. After the filtrate is detected to be free of chromium, separation and precipitation are performed and the waste liquid is discharged.

Lead-containing wastewater treatment: It reacts with slaked lime, and when the pH is adjusted to 8-9, precipitation can be formed, and then the residual liquid remaining after precipitation and filtration can be neutralized and discharged.

Acid and alkaline wastewater treatment

For experimental wastewater containing acid or alkali, neutralization and post-treatment are generally carried out according to the principle of acid and alkali. In the process of processing, pay attention to the operation of a small amount of multiple times. When mixing, the two kinds of wastewater with different pH values are combined. Generally, the pH value of the solution can be adjusted to 7 for corresponding discharge.

Comprehensive wastewater treatment

The process of "water quality homogenization + neutralization filtration → neutralization coagulation → replacement internal electrolysis → biological adsorption tank → sedimentation tank and clear water tank" is used for treatment. In wastewater treatment, in order to protect the pH value online control system, neutralization and filtration technology is adopted to ensure that the acid-base wastewater can reach the standard stably and save chemicals.

Using combined fillers to achieve sludge immobilization; the disinfection treatment section uses advanced ozone generators for disinfection, and sludge digestion uses pulsed water distributors to distribute water to achieve sludge reduction. The process can decompose complex organic matter, and can stably treat the effects of chemicals produced in experimental wastewater on wastewater.

Special wastewater treatment

Waste water containing radionuclides can be classified into long life and short life according to the half-life of the nuclides. Long-lived radionuclides and high-concentration wastewater should be stored in several types. After a certain amount is reached, the purification method is used. Short-lived radionuclide wastewater should be treated by storage methods, and it must be disinfected. After treatment, it can meet the requirements of discharge standards before it can be discharged.

4. Matters needing attention

Try to recover the solvent and use it repeatedly if it does not interfere with the experiment.

In order to facilitate processing, the collection and classification are often divided into: a) flammable substances b) non-flammable substances c) aqueous waste liquid d) solid substances and so on.

A substance that is soluble in water, easily lost as an aqueous solution. Therefore, pay attention when recycling. However, solvents such as methanol, ethanol and acetic acid can be easily decomposed by bacteria. Therefore, the dilute solution of this kind of solvent can be discharged after being diluted with a large amount of water.

Waste liquid containing heavy metals is treated as inorganic waste liquid after the organic matter is decomposed.

If laboratory wastewater cannot be treated effectively and correctly, it will cause irreversible damage to the environment, and it will also harm ourselves relatively.

The treatment of laboratory waste liquid is a work that cannot be ignored to prevent pollution and protect the environment. The experimenters must lead by example and take effective measures to resolutely achieve the discharge of laboratory waste liquid.