OZONE APPLICATION FIELDS
Drinking Water Treatment
Ozone applied in drinking water
Drinking Water Treatment
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Overview of Drinking Water Bottling Industry
The water bottling industry, juice and beverages is increasingly reliant on ozone, which clean and disinfect quickly and effectively the bottles from bacteria andviruses such as Escherichia coli and Cryptosporidium. Ozone also disinfects thebottling equipment and bottle caps, thus creating a sterile environment, while reducing the steps of rinsing with potable water without excessive use ofwater. Any bad smell is removed. Its action concerns the sterilization of tanks and storage tanks, disinfection of bottles prior to bottling, the waste watertreatment plant and the areas used for processing and bottling.
Due to its oxidizing power, ozone inhibits the presence of heavy metals such asiron and manganese, and hydrogen sulfide tannins, with longer quality of the bottled product.
Ozone is also used to sterilize the inside of containers intended for food,pharmaceutical and industrial use: it is able to disinfect areas difficult toaccess by other components, and does so at low cost, very quickly, without using any chemical and leaves no toxic residue.
Ozone is used for disinfection of bottled water since 1982. Nowadays many cities take advantages from installations that provide drinking water taken from the rivers and treated with ozone.The treatment of drinking water is certainly one of the most traditional uses of ozone, which has generally proved more effective than other methods of disinfection, especially those using chlorine,because it sterilize more successfully bacteria (such as Escherichia Coli, andStreptococcus Sthaphylococcus), cysts of protozoa (Giardia lamblia) and spores.
European legislation of drinking water treatment let use ozone-enriched waterfor the separation of iron, manganese, sulfur and arsenic: the residues of thetreatment should not exceed the limits and must be exposed the label"water subjected to an oxidation technique allowed ozone-enrichedair."
Due to its oxidizing power, ozone is widely used in drinking water treatment inthe three phases of pre-oxidation, interim oxidation and final disinfection.
Ozone can beused in water treatment for the following purposes:
1.Removal of fine and colloidal solids
Fine and colloidal solids consist ofparticles 1-30 microns (m m) and 0.001-1 m m respectively. The small size ofthe particles enables the solids to remain in suspension and avoid most mechanical methods of separation. The accumulation of fine and colloidal solidscan impair biofilter nitrification efficiencies and stress fish stocks.
Ozone removes fine and colloidal solidsby causing clumping of the solids (microflocculation), which facilitatesremoval by foam-fractionation, filtration and sedimentation.
2.Removal of dissolved organic compounds
Dissolved organic compounds (DOC’s) orrefractory organics, give the water a characteristic tea-coloured stain. DOC’sare non-biodegradable and accumulate according to feed input, water exchange rate and the rate of solids removal. High levels of DOC’s can stress fish and reduce nitrification efficiencies of the biofilter.
Ozone removes dissolved organics by:
· oxidation into products that are more readily nitrifiedin the biofilter;
· including precipitation, which enables removal of waste particles by conventional filtration or sedimentation.
3.Removal of Nitrite
Nitrite can accumulate as production intensifies and organic loadings on the biofilter increase. Bacteria that process ammonia into nitrite (Nitrosomonasspp) operates more efficiently under high organic loadings than bacteria that process nitrite to nitrate (Nitrobacter)and levels of nitrite rise accordingly.
High levels of nitrite can be toxic tofish. Data available for silver perch, Bidyanusbidyanus indicates levels of nitrite as low as 2.8 parts per million(ppm) can reduce growth of fingerlings by 5%.
Ozone removes nitrite by:
·direct oxidation to nitrate;
·reducing organic loading, which improves biofiltration efficiency and nitrification.
The high stocking densities, associated fish stress and increased nutrient loads found in RAS create an ideal environment for fish pathogens. An important step in reducing the risk of disease outbreaks in RAS is the use of standard quarantine procedures for any fish introduced. Facilities using surface waters, including RAS and flow-through hatchery systems, are also interested in reducing the pathogen load introduced via the source water. The disinfection of effluent waters before introduction to the environment is also crucial to prevent the translocation of exotic diseases.
Ozone can effectively inactivate a rangeof bacterial, viral, fungal and protozoan fish pathogens. The effectiveness of ozone treatment depends on ozone concentration, length of ozone exposure(contact time), pathogen loads and levels of organic matter. If high levels of organic matter are present, the demand created by oxidising the organic matter can make it difficult to maintain enough residual ozone for effective disinfection.
Capacity of ozone treatment units
The ozone dose required will vary according to water quality,but a typical ozone dose is 1.0 to 2.0 milligrams per liter, which is sufficient to kill most bacteria and control tastes and odors. The capacity ofthe storage tank determines how much water is available for use. The amount ofstorage required depends on household water use.
1#: Ozone is used for stable system (stable water quality and stable water flow). Need to adjust the ozone dosage on time when the system changed. It will be certain difficult to adjusting timely in actual production.
2#: Another question must be considered is the content of organic matter in water. When the turbidity of the water is less than 5mg / L, the consequent of ozone sterilization will be very small. Basically, the disinfection consequent will be affected when the turbidity increased. Meanwhile, the ozone consumption will rise if the organic content in water is high, and the disinfection ability will decreased.Because of ozone consumed in the organic matter firstly, but not kill bacteria aspects. Therefore, many foreign pharmaceutical industries install the (TOC)monitoring control project when treat the waste water treatment.
In many applications, both ozone and chlorine are as disinfectant, their advantages are complementary. Ozone has a rapid bactericidal effect and inactivated virus, and good result for the odour removal, taste and color removal. Chlorine is lasting, flexible, can be controlled for bactericidal effect, can be used continuously in the pipe network system; Therefore, combine both ozone and chlorine in water treatment system will be an ideal disinfectant.
At present in the world, pure water, natural water (mountain spring water, mineral water, ground water is filtered and other steps), has been widely adopted ozone gas for disinfection. In tap water purification, the international standard for 0.4mg/L dissolve degrees for 4 minutes, the CT value is1.6. The reference value as following:
Ozone dissolved in water