oxygen (o 3) wastewater treatment technology was used in water treatment in 1905. with the progress of related technologies, the cost of ozonation method has been reduced, which is generally considered as a promising water treatment method. because of its technological and economic advantages, it has been widely used, and some research and engineering applications have been achieved. the following will introduce the principle of ozone deodorization, decolorization and cod reduction in sewage treatment process.
1. reduction of excess sludge by ozone
activated sludge process improves the daily treatment capacity of sewage and has been widely used as a common sewage treatment technology at home and abroad. however, the excess sludge generated in the process of sewage treatment has become a difficult problem. the cost of sludge treatment accounts for a large proportion of the total sewage treatment cost. among the technologies of sludge reduction, ozone reduction technology for sludge pretreatment has been relatively mature.
the sludge treated by ozone enters the aeration tank as part of the sewage and the target wastewater, which is digested by microorganisms and partially converted into carbon dioxide. after such a process of ozone pretreatment of sludge, the excess sludge is greatly reduced. ozone generator is needed in the field of ozone excess sludge reduction technology, which consumes a lot of energy. the development of high efficiency ozone generator and the utilization efficiency of ozone play an important role in reducing sewage cost.
in recent years, japan has been devoted to the development of high-efficiency ozonator. in order to improve the ozone utilization efficiency, the continuous ozone treatment sludge was changed to intermittent ozone treatment sludge, and the actual wastewater was used as a control experiment. it was found that the ozone required for the improved ozone sludge treatment was about one-fourth of the raw material. at the same time, the treatment water quality is better than that of continuous low concentration ozone treatment, which provides a possible way to reduce the cost of ozone sludge reduction wastewater treatment technology.
2. ozone deodorization of water
in the process of sewage treatment, the odors are mainly composed of carbon, nitrogen and sulfur.
only a few odor-producing substances are inorganic compounds, such as ammonia, phosphorus, hydrogen sulfide; most odor-producing substances are organic compounds, such as low molecular fatty acids, amines, aldehydes, ketones, ethers, etc. according to the analysis of the water inflow of my sewage treatment plant, 80% of the water inflow is domestic sewage, that is, the content of organic matter is very high, and the content of inorganic compounds is relatively small.
odor-producing substances are mostly organic compounds, such as low molecular fatty acids, amines, aldehydes, ketones, ethers, etc. these substances have active groups, which are prone to chemical reactions and are particularly prone to oxidation. ozone has the characteristics of strong oxidation, oxidation active groups, odor disappearance, so as to achieve the deodorization principle.
in addition to removing odor, ozone can also prevent odor re-production. this is because the gas produced by ozone generator contains a lot of oxygen or air, and the odor-producing substances are easy to cause odor under anoxic environment. ozone treatment can prevent odor re-production by forming an oxygen-rich environment while oxidizing and deodorizing. for the improvement of sewage treatment environment of municipal domestic sewage plant, the effect is relatively large.
3. decolorization of water by ozone
with the attention paid to the water source environment of tap water and the reuse of secondary treated sewer water, the decolorization of secondary treated water has attracted more and more attention.
as for the color and taste caused by humus, the average color of water quality is 10 degrees. the maximum is 20 degrees. such chromaticity can not meet the water quality standard for full removal by general condensation and sedimentation and sand filtration processes, and even may exceed the worst standard. after ozone treatment, the color can be reduced to less than 1 degree. generally, the reason of tap water coloring is the excessive content of iron and manganese. if these metals are in free state, they can be fully removed by conventional methods. if the raw water contains humus and sometimes forms chromium salts, it is very difficult to treat it by routine treatment. therefore, decolorization is also an important factor in ozone treatment.
4. principle of ozone action
decolorization mechanism of ozone: with the vigorous development of molecular biology, microecology has extended the ecosystem to the molecular level.
in fact, no matter protein or nucleic acid molecules are organic matter, they are composed of carbon, hydrogen, oxygen, nitrogen and phosphorus or sulfur (c, n, o, n, p or s). at the same time, the capsid of poisonous compounds is composed of many protein subunits, namely shell particles. each shell particle is linked by non-covalent bonds and intertwined symmetrically. proteins are composed of multiple chains and nucleic acids are composed of linked nucleotide chains.
source: polaris environmental protection network
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