Ultrafiltration – a technology of membrane water purification, which, due to the small pore size (0,02 – 0,03 microns) is able to hold a large number of impurities at low operating pressure.

These include:

  • pathogenic microorganisms: bacteria (E-coli, Salmonella, Campylobacter Coli, etc.).), protozoa (Giardia intestinalis, Cryptosporidium), worm eggs and fungi;
  • natural organic substances causing chromaticity – humic and fulvic acids;
  • colloidal particles of clay, oxidized iron, algae.
drinking water

System design

The element is a bundle of hollow fibers made of hydrophilic PVDF material with a nominal pore size of 0.03 ┬Ám. Outer diameter of the fibers is 1.3 mm and inner diameter is 0.7 mm.

productivity membrane

A bundle is fastened in the two bases of the membrane element body.

productivity membrane element

Depending on the production capacity of the plant, the prefabricated membrane elements in the required quantity (depending on the capacity) are placed on the frame and connected to the distribution system of the fluid streams.

hollow fibers

How it works?

The diaphragm plant operation can be described in several steps.

Operating mode

During the filtration process, water at a pressure of 2-3 bar is fed through the bottom distributor to the outside of the housing and seeps through the thickness of the capillary. Contaminants remain in the external volume, and the purified water is usually diverted to the next stages of purification or to the process.

productivity membrane element

Current Washing

When productivity of a membrane element drops, the following operations are carried out.

productivity membrane element

  1. Backwashing with pre-cleaned water at 1.5 bar. It passes through the interior of the fibers in a few minutes and washes contaminant particles from the exterior surface by seeping outward.
  2. Compressed air blow-off to loosen contaminants from the diaphragm surface.
  3. Rapid direct rinsing with clean water.
  4. Ongoing chemical backwashing with reagent solution (CEB). This is necessary to wash impurities, organic and silicate impurities, which are difficult to remove from the surface of the hollow fibers.

This cycle takes an average of 40 to 60 minutes. Since the operation of modern plants is fully automatic, the operator does not have to spend time near the equipment at all times, which results in a higher productivity of the membrane element.

Periodic Chemical In-Place Backwashing (CIP)

Produced approximately once a month in order to fully restore the characteristics of the membrane element. This process takes from 60 minutes.

Alkaline and acidic reagents are used for flushing. The task of the alkaline reagent is to dissolve impurities such as silicates, organic deposits, biofilm and sludge. Acidic reagents remove deposits of hardness salts, iron, manganese and aluminum.

productivity membrane element

You can see in detail how the membrane is washed in this video.

Scope of application

1. Ultrafiltration due to its advantages has replaced traditional schemes of water treatment of centralized municipal water supply in particular in processes of groundwater post-treatment.

productivity membrane element

Ultrafiltration (UF) operation and Back washing/Flushing Steps

The picture shows the Ceyran Batan drinking water plant, which supplies the Azerbaijani cities of Baku and Apsheron Peninsula with drinking water.

pore size

2. Surface water treatment before industrial reverse osmosis systems in industry and sea water desalination plants.

water treatment

The picture below shows the water treatment scheme at Arcelor Mittal Kryvyi Rih.best-store-us.com.

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