Source：Jiangsu Envset Time:19 October 2020
Surfactants have good washing, wetting, emulsifying and solubilizing properties. There are many sources of surfactant wastewater. For example, household kitchen wastewater, hotel wastewater, and laundry wastewater contain anionic surfactants (LAS). Washing, chemical, textile and other industries also produce a large amount of surfactant-containing wastewater. Next, we will introduce you to the hazards and treatment methods of surfactant wastewater.
1. Hazard of surfactant wastewater
After the surfactant is used, most of the emulsified colloidal substances are eventually discharged into nature with the waste water. After the primary pollutant LAS enters the water body, it combines with other pollutants to form colloidal particles with a certain degree of dispersibility. Anionic surfactants have the effect of inhibiting and killing microorganisms, and also inhibit the degradation of other toxic substances. At the same time, the surfactants foam in the water to reduce the rate of reoxygenation and the degree of oxygenation in the water, and make the water quality worse. If it is not treated Direct discharge into water bodies will cause eutrophication problems in lakes, rivers and other water bodies; LAS can also emulsify other pollutants in the water body, increase the concentration of pollutants, and increase the toxicity of other pollutants, thereby causing indirect pollution. Surfactant production wastewater, kitchen wastewater, bathing wastewater, laundry wastewater and other wastewater containing LAS have a greater chronic toxicity to animals, plants and humans.
2. Treatment method
1) Coagulation-biochemical treatment of surfactant wastewater
The waste water enters the adjustment tank after intercepting the debris through the grille, and is lifted by the submersible pump to the coagulation reaction tank. The inorganic coagulant PAC and the organic flocculant CG-A are pumped by the metering pump into the lifting pipe to effectively mix with the waste water and coagulate. The reactor adopts the flat plug flow type, and the cross-sectional area of the reaction channel gradually increases to realize the gradual reduction of coagulation. Then the wastewater enters the sedimentation tank to complete the solid-liquid separation. The clear liquid is adjusted to pH between 8-9 by adding alkali according to the water quality before entering the hydrolysis and acidification tank. After hydrolysis and acidification, contact oxidation, sand filtration, the water is discharged.
The biological contact oxidation tank adopts a two-stage contact oxidation process with plum-shaped three-dimensional fillers. The two aerobic tanks can be connected in parallel and in series, depending on the water quality and effluent standards.
2) Foam separation method
The foam separation method refers to the process of introducing air into the wastewater to generate bubbles, so that the LAS in the wastewater is adsorbed on the surface of the bubbles, rising to the surface of the water and enriched to form a foam layer, removing the foam layer, and concentrating and separating LAS from the wastewater. The foam separation method has been industrialized in our country and is running well. The separated foam can be removed with defoamer such as silicone, vacuum or mechanical defoamer, and the concentrated liquid can be reused or further processed. At present, the removal rate of COD by foam separation is not high, only about 50%, so it needs to be connected with other methods.
3) Membrane separation method
Membrane separation method refers to the use of the membrane's high permeability selectivity to separate the solvent and solute in the solution. The ultrafiltration and nanofiltration technologies in membrane separation can be used to treat LAS wastewater. When the LAS in the wastewater mainly exists in the form of molecules and ions, the treatment effect of nanofiltration technology is better.
The adsorbent of the adsorption method mainly includes activated carbon, adsorption resin, diatomaceous earth, kaolin and so on. At room temperature, the treatment of surfactant wastewater by activated carbon has a better effect. The adsorption capacity of activated carbon for LAS can reach 55.8mg/g, and the adsorption of activated carbon is in accordance with the Freundlich formula. However, the energy consumption of activated carbon regeneration is large, and the adsorption capacity after regeneration is also reduced to varying degrees, which limits its application.
Jiangsu Envset is a supplier of high-quality surfactant wastewater treatment equipment. We provide customers with the most suitable sewage treatment solutions and after-sales service. If you are interested in surfactant wastewater treatment methods, please contact us.
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