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I. Development prospects of ozonation of water and wastewater
1. Prospects for the development of ozonation with wastewater
The development of ozone treatment technology can be seen from two aspects: one is the combined use of ozone as a pre-treatment or post-treatment with other treatment methods, such as flocculation, air flotation, biochemical, etc .; the second is the development of the ozone treatment unit itself, such as photocatalysis. , Metal catalytic oxidation.
There are many forms of the combined process of ozone and other treatment methods, such as: ① O3 + biochemical (activated sludge, biological activated carbon method); ② O3 + flocculation + membrane treatment; ③ O3 + membrane treatment; ④ O3 + air flotation (blowing off); ⑤ O3 + activated carbon adsorption; ⑥ O3 + flocculation + O3. The ozone treatment unit itself has the following forms: ① O3; ② O3 / H2O2; ③ O3 / H2O2 / UV; ④ O3 / UV; ⑤ O3 / solid catalyst (solid catalyst such as activated carbon, metal and its oxide).
2.Ozone / Activated Carbon Technology
In the reaction, activated carbon may act like OH- in alkaline solution to accelerate the decomposition of ozone to generate free radicals such as OH. As a catalyst, the reaction of activated carbon and ozone to degrade trace organic pollutants is the same as other reactions involving ozone generation and OH (such as increasing the pH value, adding H2O2, and UV radiation), which belongs to advanced oxidation technology.
3, the role and application of ozone biological activated carbon
The removal of organic matter by ozone bioactive carbon includes three processes: ozone oxidation, activated carbon adsorption and biodegradation. That is, in the removal of organic matter, first use the strong oxidizing ability of ozone to oxidize the organic matter into biomolecular small-molecule organic matter, then use the good adsorption performance of activated carbon to adsorb it, and then adsorb it by the biological pair adsorbed on the activated carbon. The organic matter is biodegraded, and the oxygen generated after the decomposition of ozone increases the dissolved oxygen in the water, so that the dissolved oxygen in the water is usually in a saturated state or near a saturated state, and provides the necessary conditions for the biological degradation in the activated carbon treatment. The ozone biological activated carbon water purification process (BAC method), which combines ozone with granular activated carbon filters, is generally placed in the conventional place of water purification to remove organic matter in the water, and due to the application of biotechnology, the operation period of activated carbon is greatly extended.
Ozone oxidation treatment of industrial wastewater
Regardless of whether it is drinking water or wastewater, ozone reacts with simple or complex organic compounds to obtain some of the same products: acetaldehyde, carboxylic acid, aliphatic, aromatic and other oxides. These products are easily biodegradable and have no significant toxicity.
Ozone can not only oxidize inorganic substances in water, such as CN-, NH3, etc., but also oxidize organic substances, such as aromatic compounds, which are difficult to biodegrade. There are two ways of ozonation: one is that ozone directly participates in the reaction through nucleophilic or electrophilic effects; the other is that ozone reacts with pollutants through active free radicals under the action of alkali and other factors. Ozone can react with many organic substances or functional groups: C == C, C ≡ C, aromatic compounds, heterocyclic compounds, carbocyclic compounds, == N—N, == S, C ≡ N, C--N, C-- Si, —OH, —SH, —NH2, —CHO, —N == N—, etc. The effects of ozone destruction and removal of pollutants in wastewater have been extensively studied, and some studies have been conducted on the products of ozonation of organic matter. Studies have shown that ozonation products are mainly mono-aldehydes, di-aldehydes, uronic acids, mono-carboxylic acids, and di-carboxylic acids.
3. Ozone treatment of hospital sewage
Ozone has a strong killing power on almost all bacterial propagules, buds, fungi, fungus, and protozoa such as Pseudomonas aeruginosa, Escherichia coli, Aureus, Vibrio cholerae, Mycobacterium tuberculosis and worm eggs. Hospital sewage conditions are complicated, and pre-treatment should be done before disinfection. Generally, the ozone dosage of the first-stage treatment effluent is 30-50mg / l, and the ozone dosage of the second-stage effluent is 15-20mg / L. After treatment, disinfect with ozone.
The main advantages of ozone disinfection:
1, high efficiency: uniform diffusion, good tolerance, overcoming the shortcomings of ultraviolet sterilization, which can be quickly and efficiently disinfected in all directions; strong sterilization ability, fast effect, sterilization speed 600--3000 times faster than chlorine Can kill viruses and buds with strong antioxidant properties.
2. It is less affected by sewage PH value and water temperature.
3, can remove the color, odor, smell and phenol cyanide in the water, increase the dissolved oxygen in the water, and improve the condition of the water quality.
4. It can decompose the organic matter and three substances which are difficult to biodegrade, and improve the biodegradability of water.
5, high cleanliness. Ozone has the characteristics of natural decomposition, there is no residue after disinfection, no secondary pollution, and no halogenated organic matter with carcinogenic effect.
6. The preparation of ozone requires only air, oxygen, and electricity, and does not require any auxiliary materials and additives. There is no transport and storage problem of raw materials.
Fourth, other sewage ozone treatment
1. Textile printing and dyeing wastewater
Adopting advanced ozone + ultrasonic enhancement + biochemical treatment process, the azo dye removal effect is good, the organic matter removal rate is high, and the high-concentration PVA desizing wastewater can be effectively treated.
2. Tanning wastewater
Aiming at the characteristics of high concentration of organic matter in tannery wastewater, the physical and chemical + biochemical treatment method is adopted, and the biochemical section adopts the AO process, which has a good treatment effect on this type of wastewater.
For chemical wastewater containing benzene, phenol, cyanide and other toxic substances, the ozone treatment process is used to effectively remove these harmful substances.
4. Food sewage
The AO process is used to treat food sewage, with simple operation, small footprint, and good treatment effect.URL of this article: http://tjbg022.com/show.asp?id=86