Activated carbon is indispensable for industrial wastewater treatment

With the rapid development of industry, a large number of sewage is produced. More and more attention has been paid to the efficient treatment and recycling of these sewage. Industrial wastewater mainly comes from printing and dyeing, oil refining, petrochemical, pharmaceutical, coking, pharmaceutical and other industries. The composition of wastewater is complex, and the corresponding wastewater treatment methods are quite different

In the treatment of industrial wastewater, activated carbon can be used in the first, second and third treatment processes. For the industrial wastewater with complex pollution components, in most cases, several treatment processes need to be combined for treatment, and activated carbon is often used in the final advanced treatment of the combined process. In addition, activated carbon can be combined with different materials to form a new process technology, so as to achieve better treatment effect.

In the first-class physicochemical treatment process of wastewater, activated carbon is mainly used as flocculant, adsorption and separation agent to adsorb or assist flocculation of some organic pollutants that are difficult to biodegrade or toxic to microorganisms. The most typical application technology is the powdered activated carbon process. Adding a proper amount of powdered activated carbon in petrochemical, printing and dyeing, coking industrial wastewater can remove the non biodegradable chroma and odor in the wastewater, avoid the foaming phenomenon in the aeration tank, at the same time, it can make the coagulation flocs or biological flocs grow rapidly and precipitate, and also remove the heavy metal ions and their complexes in the wastewater

For printing and dyeing and petrochemical wastewater with high COD and BOD content, activated carbon can also be used in secondary treatment combined system. In the secondary biochemical degradation process, activated carbon is mostly used as biofilm carrier filler in various new high load biochemical reactors, which can enrich organic matters, improve the biochemical degradation rate and final conversion rate, and also improve the impact of high load water quality and quantity in the reactor. At the same time, as the carrier of biofilm, activated carbon can also form biological activated carbon, which greatly extends the service life of activated carbon.

The advanced treatment and reuse of industrial wastewater is a main way to solve the problem of water shortage in China. In general, industrial wastewater can be discharged up to standard after primary physicochemical and secondary biochemical treatment. However, if it is necessary to reuse the treated wastewater, it needs tertiary advanced treatment. In the three-stage treatment process, the activated carbon is mainly used to adsorb and remove the residual refractory organic pollutants (POPs, including heterocyclic, polycyclic compounds and ~ some long-chain aliphatic hydrocarbons) in the water, so that the water quality can meet the requirements of production and reuse. At this time, the activated carbon mainly plays two roles: one is common adsorbent, the other is biofilm carrier, forming the biological activated carbon.

The functions of the coal like carbon and the powdered carbon used for water treatment are the same, but the coal like carbon is not easy to be lost, easy to be regenerated and reused, which is suitable for the water treatment process with light pollution and continuous operation, while the powdered carbon is not easy to be recovered at present, which is generally used for one-time use, and generally used for the water treatment process with heavy intermittent pollution.

Application of activated carbon in drinking water

Due to its large specific surface area and developed pore structure, activated carbon has become an ideal habitat for microorganisms in water while adsorbing and removing pollutants in water. Under suitable temperature and nutrition conditions, when it is used in water treatment, it can play a dual role of activated carbon adsorption and microbial biodegradation, which is called biological activated carbon. The adsorbate on the activated carbon can provide a stable living environment for microorganisms, and the presence of microorganisms also provides a biological regeneration function for the activated carbon. The overall effect is to transform the unstable adsorption process with penetration into a quasi-stable process.

The activated carbon used for water treatment includes powdered activated carbon and granular activated carbon. Powdered activated carbon is generally used to directly throw into raw water to remove the abnormal smell and peculiar smell of seasonally produced corn, as well as to remove surfactants and pesticides. It can also be used as an emergency treatment measure in case of chemical pollution accident of water source. The use of powdered activated carbon for water treatment is mostly intermittent operation. According to the different water sources, attention should be paid to the control of feeding proportion, mixing contact time and the selection of feeding point. Granular activated carbon is used for water treatment, generally fixed bed or moving bed is used for continuous operation, and the activated carbon needs to be regenerated regularly. Granular carbon and powdered carbon have the same function, but the granular carbon is not easy to lose, easy to regenerate and reuse. It is suitable for water treatment process with light pollution and continuous operation. At present, powdered carbon is not easy to recover, generally used for one-time use, and used for water treatment process with heavy intermittent pollution.