Application of talc in sewage treatment

Talc is a magnesia silicate with a special layered structure, with stable chemical properties, unique pore structure and large specific surface area. Powdered talc has lipophilic hydrophobicity and excellent adsorption properties. Talc powder manufacturers have abundant reserves and low cost. In recent years, talc powder has been successfully applied to the field of sewage treatment. It has been used as a coagulant, coagulant, Research on filter aids, adsorbents and oil absorbents. The main component of talc is hydrated magnesia silicate, its structure is a 2:1 monoclinic crystal system composed of two layers of silicon-oxygen tetrahedron sandwiched by a layer of brucite octahedron, the chemical formula is Mg3(Si4O10) (OH ) 2, its composition is MgO 31.72%, SiO2 63.52%, H2O 4.76%...talc powder manufacturers

At present, domestic and foreign methods of sewage treatment mainly include physical method, chemical method and biological treatment method. Among them, adsorption method is widely used because of its simple process, low cost and good effluent quality. Other methods have complicated operation and operating costs. problems such as high or secondary pollution. At present, the most widely used adsorbent is activated carbon, but its high price and relatively slow purification effect restrict its wide application. Talc is a natural clay mineral, and talc powder is made of talc blocks by air separation, crushing, grinding, washing and drying. Therefore, more and more domestic and foreign scholars use talc to treat water pollution.

talcum powder

1. Treatment of papermaking wastewater

Papermaking wastewater mainly comes from the pulping and papermaking production processes in the papermaking industry. The main components are lignin, cellulose, volatile organic acids, etc., which have the characteristics of high pollutant concentration, large emission, refractory degradation, and poor biodegradability. , is one of the more difficult industrial wastewater treatment. In recent years, gratifying progress has been made in the application of talc as a coagulant, coagulant, and filter aid in the treatment of papermaking wastewater.

1.1 Treating papermaking wastewater as a coagulant

Under coagulation conditions, that is, when the amount of talc mixed with polyferric sulfate (PFS), polyaluminum chloride (PAC), and polyaluminum sulfate (PAFS) is 0.8~1.0, 1.2, 0.4~0.5g/L, respectively , the removal rate of CODcr was increased by 3.0%, 4.0% and 2.5%, and the removal rate of suspended solids (SS) was increased by 27.1%, 29.4% and 26.5%, respectively. The experimental results show that the superfine talcum powder (SFT, with an average particle size of 12 μm) as a coagulant and PAC or PFS has a significant effect on the treatment of papermaking wastewater. Polyacrylamide (PAM), the cost is reduced by about 23%. One of the reasons why talc is used as a coagulant is that it has more surface hydroxyl groups, and these active functional groups can participate in the migration of surface protons to generate surface complexation reactions and adsorb pollutants.

1.2 Treatment of papermaking wastewater as filter aid

Membrane bioreactor (MBR) is a new type of water treatment technology that combines membrane separation unit and biological treatment unit. It has the characteristics of simple operation and strong adaptability, and has been used to treat papermaking wastewater [11], but the problem of membrane fouling needs to be solved urgently. The papermaking wastewater is treated by adding talcum powder to MBR. The results show that the removal rate of CODcr can reach more than 90% when the dosage of talc is 1.2g/L (screened out by a 0.1mm aperture screen), and the addition of talc filter aid reduces the membrane fouling resistance by 68.5%. The filter cake resistance decreased by 91.1%, which slowed down the membrane fouling and extended the service life of the membrane. Since the filter aid talc powder has strong adsorption, the sludge flocs are easier to aggregate, and the viscosity is correspondingly reduced, which reduces the membrane fouling resistance. New Direction.

Talc, a non-metallic mineral, has been widely used and has significant social and economic benefits, which increasingly shows its feasibility in the field of environmental protection. The advantages and disadvantages of talc in various wastewater treatment are now compared as follows, see Table 1. Although talc powder has some shortcomings in wastewater treatment, talc powder also has considerable application prospects in water treatment technology due to its advantages of large reserves, wide distribution, low cost, and low pollution.