Wastewater Treatment Plant
1.3 Aerators: Four mechanical Aerators circulate air or oxygen through the water and help to make water flow around the lagoon. The chopping action of the Aerators also helps to physically break up blue algae on the surface of the wastewater, preventing algal bloom.
2. Secondary Treatment
2.1 Secondary Oxidation Lagoon: Wastewater remaining at the top of the Primary Lagoon contains less solids and is piped to the Secondary Oxidation Lagoon where further settling and removal of organic solids takes place. Bugs are also present in this lagoon, but in lower numbers, and need oxygen to survive.
3. Tertiary Treatment
3.1 Basic Wetland: Treated wastewater is trickled into a planted area called a 'Wetland'. Plants in the wetland act as a very basic filter, removing colour caused by algae present in the wastewater and also smaller solids which are suspended in the wastewater. Algae and solids get caught in the plants as the wastewater passes through the wetland and remain behind while cleaner wastewater continues its way to the Ultra Violet Irradiation system.
Wetlands are also thought to help remove pollutants present in wastewater, such as heavy metals (eg, mercury, lead and iron) and also nutrients such as Nitrogen and Phosphorus. Scientists are still learning about this and understanding how it works.
3.2 Ultra Violet (UV) irradiation: Wastewater is further treated by exposure to Ultra Violet light. This kills any bacteria and viruses remaining in the wastewater by destroying their genetic core (DNA). It is also effective against many protozoa.
The figure below shows a UV lamp cartridge taken out of the UV system for servicing.
The UV cartridge is slotted into the below UV system. Water flows through the system and is exposed to UV irradiation.
Discharge of Treated Wastewater to the Environment