O3 Greentech Applications – Waste-water Treatment

Why Ozone for Waste-Water Treatment?

3,000 times more germicidal than chlorine

160 times more bactericidal than sulphur dioxide

37 times more bactericidal than formaldehyde

1.7 times more bactericidal than hydrocyanic acid

Application of Ozone in Waste-Water Treatment

Oxidation of Organic Waste	Cyanide Destruction	Ground Water Petrochemical Oxidation
Heavy Metal Precipitation	Pulp and Paper Effluents	Textile Mill Effluents
Textile Dye and Starch Elimination	Pesticide, Herbicide and Insecticide Elimination	Fat, Oil and Grease (FOG) Elimination
Secondary Treatment of Municipal Waste-Water	Mining Heavy Metal Precipitation	BOD Reduction of Domestic Waste

Issues of Waste-Water Treatment

Notes: Would be better to present in the form of slides. Otherwise it will become a long read.

Colour Removal Problem: Decaying vegetation in the waste-water releases compounds like fumic, huvic and tannic acids These compoundscause coloration in the surface waters. Science Behind This: The compounds released are made of conjugated carbon-carbon double bonds. As the series of these double bonds increases, the colour becomes more and more visible in the spectrum Role of Ozone: Ozone is naturally attracted towards these double bonds. When these compounds react with Ozone, the double bonds break. The more the double bonds break, the more the colour disappears from the water. About 2-4 ppm of Ozone is sufficient to decolorize surface water.

Removal of Heavy Metal Problem: Common heavy metals are Arsenic (in presence of iron) Cadmium Chromium Cobalt Copper Lead Manganese Nickel Zinc Role of Ozone: Ozone oxidises the transition metals to their higher oxidation state in which they usually form less soluble oxides. These compounds are easy to filter. For example, when Ozone reacts with iron, it creates ferrous oxide which can be filtered. At Ozone levels above 4 ppm, Manganese converts from soluble Permanganate, showing up as a pink colour.

Water Treatment and Algae Removal: Problem: Ozonated water can be used to treat fruits, vegetables, meat, poultry as certified by as GRAS by the USA FDA Ozone treats water from bacteria and algae to make it suitable for drinking and air conditioning Many bottling companies have also started using Ozone to purify drinking water. Role of Ozone: Typically, a concentration of Ozone between 1 and 10 ppm is sufficient for treating water, and in that the most common amount used is 2 ppm. The concentration of Ozone in watervaries on the function of Feed Gas Concentration (over 1% or 10,000 ppm of Ozone) and Water Temperature (Colder the water, more the concentration). The effectiveness of Ozone in washing water may reduce with increased Biological Oxygen Demand (BOD). In that case, the water should first be treated to reduce the BOD. This can be done by reducing the organic contamination in the water. Algae Removal: When algae-contaminated water is oxidised with Ozone, the metabolic by-products of algae are also oxidised resulting in cleaner water and less undesirable odour and taste.

Improved Coagulation and Turbidity Removal (AKA Pre-ozonisation): Role of Ozone: When certain dissolved materials are oxidised by Ozone, they form polar and charged molecules. These molecules react with Polyvalent Aluminium or Calcium to form precipitates. Treating surface water with up to 0.5 ppm of Ozone has the following results: Decrease in turbidity Improved settleability Reduced number of particles Result: This treatment destabilizes the colloid with a resultant reduction of the amount of coagulant needed to produce a clear filtrate.