OZONE FOR WATER & WASTE WATER TREATMENT
The use of Ozone for the disinfection of water post filtration is an accepted technology.
- Ozone is fast acting and there is no risk of chemical residual or "aftertaste".
- There is no measuring out of chemicals nor time consuming mixing.
- Because of its high oxidation potential, Ozone is far more effective than conventional sanitizers.
- Ozone oxidises Iron & Manganese.
- Dosing is done by venturi or airstone. A venturi is fitted into the pipeline and connected to the Ozone generator. The flow of water past the venturi sucks in Ozone. An airstone is placed into a tank and Ozone is bubbled into the tank via the airstone.
- Ozone is produced on site by the Ozone generator and requires little servicing or maintenance.
- Cost effective - initial investment in the Ozone generator system then no further "monthly" orders.
The ozonation of wastewater effluents has several other advantages such as an increase in dissolved oxygen, decrease in chemical oxygen demand, and improvement in aesthetic characteristics due to reduction in turbidity and color. Chlorination and UV radiation do not provide these benefits.
- Ozone is more effective than chlorine in destroying viruses and bacteria.
- The ozonation process utilizes a short contact time (approximately 10 to 30 minutes).
- There are no harmful residuals that need to be removed after ozonation because ozone decomposes rapidly.
- After ozonation, there is no regrowth of microorganisms, except for those protected by the particulates in the wastewater stream.
- Ozone is generated onsite, and thus, there are fewer safety problems associated with shipping and handling.
- Ozonation elevates the dissolved oxygen (DO) concentration of the effluent. The increase in DO can eliminate the need for reaeration and also raise the level of DO in the receiving stream.
Ozone is used to remove harmful micro-organisms from water after reverse osmosis or filtration. A residual Ozone concentration of 0.1ppm to 0.5ppm would be sufficient to maintain the water free of bacteria. Ozone leaves no possible after taste and is more powerful than conventional chemical chemicals. Ozone can be dosed via an in-line venturi or an airstone inside a tank.
BOREHOLE WATER DISINFECTION
The water from boreholes is not always as microbiologically clean. It has been subject to millions of years underground and the soil above it has been subject to contamination. there may be chemical elements that are in the water that could be harmful. Ozone will remove all unwanted bacteria and heavy metals such as Iron and Manganese.
Ozone will reduce the COD content of waste water. The amount of Ozone required to reduce COD's is apporximately 3 - 5 mg/l Ozone per 1 mg/l COD. The addition of hydrogen peroxide in conjunction with Ozone will increase the COD removal efficiency.
Ozone can be used to replace biocides in the treatment of cooling tower water. It has a broader kill spectrum and would remove potentially harmful bacteria.
Soluble Iron Fe(II) is called ferrous iron. Ferrous Iron Fe(II) is oxidized to Ferric Iron Fe(III) by ozone. This Ferric Iron Fe(III) will then hydrolyze to form Fe(OH)3 which is a particulate and can be removed by standard filtration. The reaction of Ferrous Iron Fe(II) to Ferric Iron Fe(II) consumes 0.43 mg of ozone per mg of Fe(II). Iron can also be oxidized by oxygen. Due to the oxidation of iron by oxygen, an ozone system for iron removal may be more efficient than the calculated ozone demand of 0.43 mg ozone per mg iron.
Soluble Manganese Mn(II) is oxidized by ozone to form manganese dioxide MnO2 which is a particulate and can be easily removed by standard filtration. This process consumes 0.88 mg of ozone per mg of Manganese Mn(II). However, over oxidation of manganese will form soluble permanganate MnO4. While permanganate will normally return to manganese dioxide MnO2 over time (20-30 minutes), it is best to design a manganese removal system with the proper ozone dosages and integrated controls to prevent over oxidation.
REMOVAL OF HYDROCARBONS
Research has been done on using Ozone to oxidise hydrocarbons in conjunction with UV or Hydrogen Peroxide.
REMOVAL OF PHENOLS
Ozone is a viable alternative for industrial wastewater pre-treatment. This would be a preferred treatment where the toxicity of the water and pollutant content is not conducive for biological treatment.
Ozone is capable of removing cyanide from wastewater in conjunction with Hydrogen Peroxide.