OZONE SEWAGE WASTEWATER DISINFECTION
Ozone sewage wastewater disinfection became popular after its widespread use in the 1970s and 1980s. The reason why it is popular; is due to improved equipment reliability and low cost; However, the main reason for the increase in the use of ozone in the sector is the economic benefits offered by ozone, as well as the increased secondary benefits that create an economic advantage.
Among the secondary benefits of ozone; there is colour removal in wastewater, odour control, removal of micropollutants and reduction of total suspended solids (TSS).
The use of ozone for wastewater disinfection is gaining popularity due to strict regulations on faecal coliform and other pathogens. As chemical costs increase, ozone becomes a more cost-effective solution for wastewater disinfection. Ozone can be produced on-site using oxygen in the ambient air. Only electrical power is required for the process.
When discharge limits on pathogens are reduced, the natural solution is to add additional chemicals to meet these new limits. Adding more chemicals to the wastewater stream for disinfection may seem an easy solution at first; However, in most cases, these chemicals must be removed from the wastewater prior to discharge due to limitations on these chemicals.
For example, if chlorine is used to reduce E.coli, the removal of chlorine is required before the discharge of wastewater. If 20% more chlorine is required to meet the new wastewater discharge limits, 20% de-chlorination should be applied to this water. This application increases the costs very much over time.
Ozone sewage water application is a green solution for wastewater disinfection. Ozone is produced on-site and is completely natural, it consists only of oxygen. No by-products or waste products are formed in the formation of ozone.
– The use of ozone eliminates the need to move chemicals into the field.
– With the use of ozone, the need to store chemicals is eliminated.
– After ozone dissolves in water, it does not leave residue in water; it returns to its original form, oxygen.
|PROCESS IN WASTEWATER
|Oxidation Potential (Volts)
|Disinfection of Bacteria
|Disinfection of Viruses
Ozonation of wastewater effluents has many advantages, such as increased dissolved oxygen, reduced chemical oxygen demand, and improved aesthetic properties due to reduced turbidity and colour. Chlorination and UV radiation do not provide these benefits. Ozonation, which has been successfully applied for many years, is a mature technology used in some of the largest cities for municipal wastewater treatment all over the world.
- Ozone is more effective than chlorine in destroying viruses and bacteria.
- Ozonation has a short contact time (10 to 30 minutes).
- There are no harmful residuals that need to be removed after ozonation because ozone decomposes rapidly.
- There is no regrowth of microorganisms, except for those protected by the particulates in the wastewater stream, after ozonation.
- Ozone is generated onsite, so 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 stream.
The Following Chemicals and Compounds are Disinfected by Ozone in Water and Wastewater
Because of its efficiency, residual qualities, and low cost, chlorine has traditionally been used to disinfect wastewater treatment plants.
Disinfection by-products (DBPs) such as trihalomethanes and haloacetic acids are formed when free chlorine combines with organics. Because of their carcinogenic qualities, these DBPs could have a negative impact on public health and aquatic life.
Fish kills were also experienced in water bodies receiving municipal wastewater disinfected with chlorine. Researchers have discovered many more chemicals and compounds in water and wastewater in concentrations that can be a cause of various other ecological concerns.
These more recently discovered pollutants of concern are commonly being grouped as contaminants of emerging concern( CECs).
The CECs are usually unregulated and consist of:
- Pharmaceutically active compounds
- Personal care products
- Endocrine disruptive chemicals
- Fire retardants
- Industrial and Household Chemical