Check the advantages and disadvantages of different coal based activated carbon in water purification application

1 raw coal crushed granular activated carbon

In the 1990s, the manufacturer used the block high-quality Jurassic bituminous coal in Datong, Shanxi Province to produce raw coal broken granular activated carbon through the process of block coal crushing carbonization activation crushing screening, which was applied to the water purification process in some water plants in some areas.

Raw coal crushed granular activated carbon is an amorphous granular activated carbon product, which is applied to the advanced purification treatment of drinking water. It can meet a certain particle size range, and the particle size is usually 8 × 30 mesh or 12 × 40 mesh.

Raw coal crushed carbon has the advantages of simple process and low cost. However, raw coal crushed carbon has the disadvantages of rapid strength decline, low regeneration yield, high floating rate, and difficult to control pore structure and surface characteristics. In addition, with the widespread application of fully mechanized coal mining, the output of block Jurassic bituminous coal has decreased significantly, resulting in less and less output of high-quality raw coal crushed granular activated carbon. Therefore, it is no longer the mainstream for municipal waterworks to use raw coal broken granular activated carbon as purification material.

2 coal based columnar activated carbon

In the 1980s, through the application experience of coal columnar granular activated carbon in the field of gas phase adsorption, 1.5 mm coal columnar granular activated carbon for liquid phase adsorption was developed and applied to the ozone activated carbon advanced treatment process of major Waterworks in Beijing and surrounding areas.

Around 2000, ozone activated carbon advanced treatment technology began to be popularized in urban water purification plants in coastal areas. Relevant activated carbon manufacturers and waterworks further improved the existing 1.5 mm coal columnar granular activated carbon and developed columnar broken carbon. By rolling the columnar granular activated carbon into amorphous particles with smaller particle size, the surface film hanging capacity, adsorption performance and filtration performance of columnar activated carbon were effectively improved, Good application results have been achieved.

Coal based columnar activated carbon has good adsorption and regeneration performance, and its strength can meet the requirements of water purification. However, as a shaped activated carbon, the surface of columnar granular activated carbon is smooth, the ability of biofilm is limited, and tar / asphalt and other binders need to be added in the processing process, which increases the manufacturing cost. Moreover, the additives may bring some harmful substances in the process of use, which is easy to cause adverse effects on the purified water products of municipal waterworks. Therefore, the application of columnar granular activated carbon in water purification has increasingly highlighted its limitations.

3 coal based powdered activated carbon

Coal based powdered activated carbon is a by-product in the production of coal based granular activated carbon. It is made from sieved activated carbon particles by grinding, and its price is usually low.

The advantages of powdered activated carbon are low equipment cost, fast adsorption rate, fast dosing and response to sudden or short-term water quality changes, and low price. However, due to its physical characteristics, powdered activated carbon can only be used once and can hardly be regenerated. It will produce solid pollutants after use, with high disposal cost, and carbon loss is easy to occur in the process of water treatment and backwashing. Therefore, powdered activated carbon is generally used for short-term seasonal water treatment, and less for long-term deep purification treatment.

4 coal briquette crushed granular activated carbon

Coal briquette crushed granular activated carbon is a product that further improves the advanced purification performance of activated carbon water based on the research, production and application of raw coal crushed granular activated carbon and columnar granular activated carbon. Briquetted crushed carbon is an activated carbon product prepared by blending and milling high-quality weakly viscous coal, bituminous coal and other raw coal, using the coal's own cohesive briquette, carbonization and activation processing, and finally crushing as required.

Compared with columnar granular activated carbon, briquetting crushed granular activated carbon is formed by using the self binding briquette of raw coal. It does not need to add binder, and has high reaction activity. It is easy to develop micropores and mesopores. At present, only the weak binding Jurassic bituminous coal in Datong and Xinjiang is suitable for briquetting crushed granular activated carbon in China.

Compared with raw coal granular activated carbon, crushed granular activated carbon can be produced through coal blending, which is convenient to adjust the pore structure and strength of activated carbon products, and is conducive to the purification application of activated carbon.

The briquetted activated carbon product has low floating rate and high strength, which is more suitable for liquid phase treatment. Moreover, the briquetted activated carbon product has stable and controllable quality, mature process, good adsorption performance, regeneration performance and low production cost. It has become the best choice for the advanced purification treatment process of municipal waterworks at present.