How Many Pollutants are Polluting the Flat Ceramic Filtration Membranes?

Some measures can be taken to prevent and control the fouling process of ceramic membrane in the filtration process, but the membrane fouling can not be completely avoided. With the extension of the operation time, the permeation flux of ceramic membrane decreases rapidly, and it can not meet the requirements. For a long period of time, the pollutants adhered to the membrane surface and existed in the pores, which may have chemical effects with the membrane and reduce its service life. Therefore, in order to restore the performance parameters of the membrane as much as possible, the ceramic membrane must be cleaned regularly.

Fistly, how many pollutants are polluting the Flat Ceramic Filtration Membranes?

1. Inorganic pollution

Under the pressure driven of membrane separation system, the concentration of components will occur on the membrane surface due to the retention of membrane in the system, which result in concentration polarization. For soluble components, it will form precipitation and scale on the surface and the membrane pore when the content of ions exceeds its solubility. The most important inorganic pollutant is the so-called scale layer, which is formed by sulfate and carbonate such as calcium and barium. In most cases, inorganic and organic pollutants promote each other and aggravate membrane pollution.

2. Organic pollution

Organic pollutants are mainly bacteria extracellular polymeric substances (EPS), proteins, peptides, fats and polysaccharides and other macromolecular substances. Macromolecules active groups may interact with metal ions such as Ca2+, Mg2+ and Ba2+, and form a gel layer on the surface of the membrane. It will reduce the flux of the membrane and increase the filtration resistance of the membrane.

3. Microbial pollution

Microbial pollution is mainly composed of microorganisms and their metabolites. The surface of the membrane is easy to absorb humus, polysaccharide and metabolites of microorganisms, which have the living conditions of microorganisms and easily form a biofilm, thus causing irreversible blocking of the membrane and reducing the water flux.

4. Colloid pollution

Algae, bacteria and organic matter may be in colloidal size, and these colloidal substances may adsorb on the membrane surface. Colloidal substances are from different places, and they produce very different membrane pollution. Colloidal materials are from abiotic processes, which include inorganic materials such as silt and clay. The attenuation of water flux caused by them and generally they are not thermodynamics irreversibly that can be adsorbed on the membrane surface; these types of colloids accumulated are easily removed by hydraulic cleaning (such as backwashing and air scrubbing) on the membrane surface. The colloidal substances are often permanently adsorbed on the surface of the membrane, produced by microbial metabolism. It results irreversible adsorption pollution. Colloidal contamination is classified as microbial contamination from microbial processes.

Therefore, how to control the membrane pollution?

The pretreatment and improvement of waste water have a great effect on the prevention and control of the ceramic membrane pollution. The feed liquid often contains impurities such as organic matters, organic matters, microorganisms and colloids, which have adverse effects on the ceramic membrane. Therefore, the feed liquid should be pretreated, and the corresponding pretreatment process should be added to remove the dominant pollutants, so as to minimize the pollution of the ceramic membrane.

How to improve the hydrophilicity of ceramic membrane. The results show that the hydrophilicity of the ceramic membrane has a great influence on the anti pollution performance, and the hydrophilic membrane is less affected by adsorption and can produce a greater membrane permeation flux. Optimize the operating conditions of ceramic membrane separation.

The operating conditions are closely related to ceramic membrane pollution. The operating conditions, such as ceramic membrane flux, operating pressure, cross flow velocity, hydraulic retention time, solid retention time and operating temperature, have a direct impact on ceramic membrane pollution. There are two basic modes of ceramic membrane filtration, namely cross flow filtration and terminal filtration. According to Doctor Sun and others, the energy of terminal filtration is fully utilized, but it is easy to cause rapid ceramic membrane pollution; cross flow filtration is proposed for the shortcomings of terminal filtration, but the energy consumption is large.