What Is Granular Microfiltration?

Granular microfiltration, also called granular microporous filtration, is alias high-efficiency microfiltration. It uses nano-composite particles as the filtration medium. Granular microfiltration can intercept particles between 0.1 and 2 microns. Granular microfiltration allows macromolecules and dissolved solids (inorganic salts) to pass through, but intercepts suspended solids, bacteria, and large-molecular-weight colloids. The operating pressure of granular microfiltration is generally 3-6 bar. Granular microfiltration is a technology developed and promoted in the microfiltration application field over the past ten-plus years, using natural or synthetic nano-composite compounds as the filtration material. For granular microfiltration, its separation mechanism is mainly sieving interception. And 'filtration is the operation in which the liquid (or gas) in a suspension (or gas containing solid particles) passes through a medium under a driving force or other external force, and solid particles and other substances are intercepted by the filter medium, thereby separating the solids and other substances from the liquid (or gas) [2] [2]'—this new microfiltration process is an effective supplement to traditional single microfiltration-membrane filtration, placing microfiltration between coarse filtration and ultrafiltration, true to its name.

Granular microfiltration can intercept particles between 0.1 and 2 microns; nano-composite particles allow macromolecular organics and inorganic salts to pass through, but can block the passage of suspended solids, bacteria, some viruses, and large-scale colloids. The surface porosity is high, generally reaching above 70%, and is at least tens of times faster than a filter membrane of equivalent interception capacity.

(7) Install the make-up water pipe and the water-distribution filament tube.

It belongs to precision filtration and features high efficiency, convenience, and economy. [1]

(1) Drawing design: according to the raw-water quality and quantity, design the equipment dimensions and structure, etc.

(2) Perforate the water-distribution plate; weld the holes to the water distributor, or alternatively use threaded connections for convenient future replacement. Also open the support-leg holes. Weld the branch pipe to the lower head, mainly used to support the water-distribution plate.

(3) The branch pipe passes through the water-distribution plate and is welded. The water-distribution plate is welded to the lower head, requiring double-sided welding on both faces;

(4) Roll the plate and weld the main body to the lower head.

(6) Open holes in the tank body: upper manhole (can also share the packing hole), lower manhole (determined by the distance between the lower head and the water-distribution plate), discharge hole, vent hole, water-inlet and water-outlet holes, and backwash air-inlet hole.

Nano-composite particles are a high-hardness continuum; during filtration no medium detaches, so no secondary pollution is caused, yielding high-purity filtrate.

(8) Weld the tank support legs and lifting lugs.

(9) Mirror-polish and grind.

(10) Internal and external anti-corrosion and rust prevention.

(11) Weld the external water-pipe of the cylinder.

(12) Arrange in a grid pattern: the water-inlet pipe, sewage-drain pipe, and water-outlet pipe, with 5 valves distributing the water flow.

Granular microfiltration has four filtration principles: sieving, filter-cake-layer filtration, deep-bed filtration, and adsorption. It is generally believed that the separation mechanism of granular microfiltration is the sieving mechanism, with the physical structure of the particles playing the decisive role. In addition, factors such as adsorption and electrical properties also affect the interception rate. Its effective separation range is particles of 0.1-10 um, and the operating static pressure difference is 3-6 MPa.

According to the interception position of suspended particles in the microfiltration process, they can be divided into 3 interception mechanisms: sieving, adsorption, and bridging; their microfiltration principles are as follows:

(1) Sieving: microporous filter particles intercept particles larger than or comparable to the membrane pore size, also called mechanical interception.

(2) Adsorption: suspended particles are adsorbed by the filter particles through physicochemical adsorption. Suspended matter smaller than the particle pores can also be intercepted.

(3) Bridging: suspended particles pile up and push against each other, causing many particles to be unable to enter the particle pores or to be stuck in the pores, thereby completing interception.

(1) Water treatment industry: removal of suspended solids, fine particles, and bacteria from water; pre-treatment for reverse osmosis and nanofiltration processes.

(2) Electronics industry: terminal treatment of ultrapure water for the semiconductor industry and cleaning water for integrated circuits;

(3) Pharmaceutical industry: medical pure-water bacteria removal, pyrogen removal, and drug sterilization;

(4) Medical industry: removal of bacteria from various solutions such as tissue fluid, antibiotics, serum, and plasma proteins;

(5) Food industry: removal of suspended matter, microorganisms, odor impurities, yeast, and mold from foods such as beverages, alcoholic drinks, soy sauce, and vinegar, and clarification filtration of fruit juice.

(6) Chemical industry: filtration and clarification of various chemicals. [3 [3]]

(7) Removal of algae and particulate impurities from surface water such as reservoirs, lakes, and rivers.

(8) Filter membrane modules for household water dispensers.