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Application of membrane filtration in agricultural and sideline products

The wine, vinegar and soy sauce in agricultural and sideline products are fermented from starch such as grain. The filtration of these products is an important production process, and the quality of filtration directly affects the quality of products. Traditional filtration methods include natural sedimentation, active adsorption, diatomite filtration, plate and frame filtration, etc. These filtration methods have some problems in terms of time, operation, environmental protection and other aspects, so it is necessary to choose a more advanced filtration method. 

Hollow fiber can intercept 0.002 ~ 0.1μm of macromolecules and impurities, allowing small molecules and dissolved solids (inorganic salts) through, so that the filtered liquid to maintain its original color, fragrance, taste, while achieving the purpose of no heat sterilization. Therefore, using hollow fiber filter to filter wine, vinegar, soy sauce is a more advanced filtration method.

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 Polyethersulfone (PES) was selected as the membrane material. The hollow fiber ultrafiltration membrane produced by PES has high chemical properties and can be resistant to chlorinated hydrocarbons, ketones, acids and other organic solvents, and also stable to acids, bases, aliphatic hydrocarbons, oils, alcohols and so on. Good thermal stability, good resistance to steam and superhot water (150 ~ 160), fast flow rate, high mechanical strength. The filter membrane is easy to clean internal pressure hollow fiber membrane, and the membrane shell, pipe, valve adopts 304 stainless steel, sanitary and easy to clean.

Filtering way

For wine, vinegar, soy sauce is a variety of amino acids, organic acids, sugars, vitamins, organic material such as alcohol and ester and water mixture, and adopts the cross-flow filtration method, through the pump will be required to filter the liquid pipelines into the filtration membrane, the membrane filtered liquid for the finished product, not through the liquid to the concentrate pipe to return to the same place. Due to the discharge of concentrated solution, a large shear force can be formed on the membrane surface, thus effectively reducing membrane contamination. The ratio of the flow rate of the cross-flow filtration concentrate to the flow rate of the finished product can be adjusted according to the specific conditions of the filtration liquid to reduce the pollution of the membrane. The concentrate can be returned to its original place and re-filtered into the ultrafiltration system for filtration treatment.

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Cleaning system

The cleaning principle is that the cleaning liquid (generally filtered clean water) is fed into the hollow fiber filter membrane through the pipeline to wash away the impurities on the membrane wall, and the waste liquid is discharged through the waste pipeline. The cleaning system of the filter can be cleaned in two ways: positive and negative. Are washing (such as pressure flushing) particular way is close the filtrate outlet valve, open the water outlet valve, pump will start production membrane body fluid input, this operation make the hollow fiber is equal on both sides of the air pressure inside and outside, by the pressure differential adhesion in loose dirt on the surface of the membrane, increase traffic again flush surface, soft film on the surface of a large number of impurities can be removed. Backwash (reverse flushing), the specific method is to close the filtrate outlet valve, fully open the waste liquid outlet valve, open the cleaning valve, start the cleaning pump, the cleaning liquid into the membrane body, remove impurities in the membrane wall hole. When backwashing, attention should be paid to the control of washing pressure, backwashing pressure should be less than 0.2mpa, otherwise it is easy to crack the film or destroy the bond surface of hollow fiber and binder and form leakage. Although regular forward and back cleaning can maintain the membrane filtration rate well, with the extension of the running time of membrane components, the membrane pollution will continue to worsen, and the membrane filtration rate will also continue to decline. In order to restore the membrane filtration flux, chemical cleaning of membrane components is required. Chemical cleaning is usually pickling first and then alkali washing. Generally, 2% citric acid is used for pickling, and 1% ~ 2% NaOH is used for alkali washing.


Post time: Jun-07-2022