Home


WATER TREATMENT SYSTEMS AND TECHNOLOGY

NG Shtukarin

LLС "Ekotehnica-M", Krasnoyarsk, Russia
 
The growing natural water contamination determines the search for innovative, more efficient and environmentally friendly methods of cleaning and disinfection of  water supply and sanitation. The ozone-UV (OUF) treatment combined with froth flotation (FF) meets all the requirements to the quality of potable and waste water treatment.
 
The existing flotation processes fail to separate flotation products. A positive feature of the flotation process is the formation of the heterophasic system (foam) in the whole volume of water to be treated, while it should be noted that the FF products make up 1% or 5% maximum of the total volume.  Possible chemical reactions in the flotation process are complete resulting in  high yield, which is defined by a huge surface (foam) of the reaction volume. The ability to produce foam in aqueous solution containing no added foaming agent is caused by the presence in natural water of: ion metal hydroxides formed by oxidation with atmospheric oxygen, organic compounds such as: humic acids, herbal zooplankton, air carbon dioxide and alkaline medium, maximum mechanical air dissolving in water. Generally, the use of air as a blowing agent is optimal for two reasons: sufficient solubility in water and oxygen and carbon dioxide containing in its composition. These components have remarkable properties: oxygen is an oxidizer and has the ability to transform into another modification – ozone - 60-time exceeding chlorine by oxidative properties. Carbon dioxide, when dissolved in water, forms carbonic acid solution, ultimately changing the pH value (pH) to the acidic side.
The high degree of dissolution in the air can be reached by its pulsed input when the water stream under saturation is subjected to compression and expansion pressure, while it is  unnecessary to use high-pressure.
Thus, for example, by gravity sewage flow the oxygen concentration reaches as high as 8 mg/dm3. Air or ozone-air mixture used as a blowing agent does not provide the generation of high-expansion and stable foam, therefore, its separation from the water should take place immediately after foaming. Such conditions may be implemented in special hydrodynamic equipment called hydrodynamic separators (HDS).
 UV ozone water treatment is carried out in BT-W equipment simultaneously: ozone-air mixture obtained from the atmospheric oxygen photopolymerization exposed to ultraviolet (UV) rays is ejected in the treated water to form foam, where foam is subjected to UV irradiation. UV-radiation, when interacting with foam, acts as a catalyst for ozone-oxidation reaction to generates hydroxyl groups of the water. The effectiveness of this treatment may be indicated by the following parameters: the ozone concentration to 0.3 dm 3 - (hygienic parameter of residual ozone concentration in drinking water) and simultaneous UV exposure is equivalent to ozonization (comparing oxidative properties) with an ozone dose of 0.5 - 1 g/.dm3.
At this stage of BT-W chemical oxidation does not stop and continue in HDS, where the foamed water is multiple-pulsed by compression and expansion. Mechanical foam, both formed by acidification and ozone oxidation products, is evacuated from the HDS under excessive pressure and, simultaneously, in the pressure mode purified water is separated. In the HDS with filter the purified water is filtered by the sorbent or other acceptable loading. By no means exhausted possibilities of the systems offered here for water purification  can be significantly enhanced by cooperation.