In the treatment of drinking water, disinfection is said to kill most pathogens in tap water and to make the water’s microbial quality meet human health requirements.
Disinfectants such as ozone, halogens and halogen compounds inactivate disease entities by destroying the basic physiological functional units of the pathogen such as enzymes, coenzymes and hydrogen carriers. Comparison of killing effect and stability of several disinfectants:
Killing efficiency: ozone> chlorine dioxide> chlorine gas> chloramine
Stability: Chloramine> Chlorine Dioxide> Chlorine> Ozone
Redox potential: 2.07 volts 1.50 volts 1.3 volts
Therefore, ozone has a strong oxidizing effect. Ozone is easily digested into oxygen, and oxygen does not remain in the water, causing harm to the human body. However, due to its high cost, it is basically not used in large water plants and is often used for advanced water treatment due to its high oxidation level.
The main characteristics of activated carbon are large specific surface area and pore structure. The surface area of each gram of carbon can reach 1,000 square meters, most of which are the tiny pore surfaces inside the particles. Because adsorption is the concentration of impurities dissolved in water on the surface of carbon particles, the specific surface area of carbon is an important factor affecting adsorption performance. Due to the large surface area of activated carbon, it exhibits good adsorption performance.
Most larger organic molecules, aromatic compounds, halogenated hydrocarbons, etc. can be firmly adsorbed on the surface or pores of activated carbon, and have obvious removal effects on humic substances, synthetic organic matter and low molecular weight organic matter. Practice has proved that activated carbon can reduce the total organic carbon of the total organic carbon, the total organic carbon of the total organic carbon, the total organic carbon of the total organic carbon, and the total organic carbon of the total organic carbon.
Biological activated carbon: refers to a water treatment process combining ozonation and activated carbon adsorption.
The biological activated carbon method is characterized by the conversion of NH4 -N to NO4 after the completion of biological nitrification; the biological oxidation of dissolved organic matter can remove the dissolved organic carbon and trihalomethane generation potential at a concentration of mg / l, and Organic matter.
The purpose of adding a small amount of oxidant (usually O3) to water is to convert the dissolved colloidal organic matter into more biodegradable organic matter, and oxidize some humic substances with larger molecular weight to lower molecular weight and easily biodegradable substances to become carbon. A source of nutrients for the microbes in the bed. In the activated carbon bed, organic matter is adsorbed on the surface of carbon particles and small pores, and microorganisms grow in large pores on the surface of carbon particles. Some organics are degraded under the action of cellular enzymes, so the removal of organics has the dual effects of adsorption and biodegradation.
Pressure-driven membrane separation technologies include reverse osmosis, nanofiltration, ultrafiltration, and microfiltration.
The feature of membrane separation technology is to provide stable and reliable water quality. Since the main principle of membrane separation of impurities in water is mechanical screening, the quality of the effluent water is very stable, which is based on the pore size of the membrane and has nothing to do with the quality of the raw water and the operating conditions.