Water futures

Barriers 4 and 5 - Ultraviolet light disinfection and advanced oxidation

By this stage the water is already more than pure enough to drink, but ultraviolet (UV) light disinfection and advanced oxidation will provide additional layers of protection by passing the water through intense light, similar to the cleansing rays of the sun but hundreds of times stronger.

UV disinfection irradiates drinking water killing pathogens such as bacteria and viruses, and inactivating Cryptosporidium and Giardia. Advanced oxidation will break down and destroy any remaining organic chemicals or contaminants.

Barrier 6 - Cooby Dam

The recycled water is then blended with Lake Cooby’s surface water.

The water from Cooby Dam is naturally hard and contains dissolved organic matter. In the days before Toowoomba found other water supplies hardness was a major water quality issue for Toowoomba. Hardness destroys soap and leaves a calcium carbonate buildup around tap fittings. Bore water and dam water both pick up minerals through the ground. Water that has been processed through RO is soft And so the water that will come through the Advanced Water Treatment plant will improve the quality of Cooby Dam’s water.

Barrier 7 - Mount Kynoch Water Treatment Plant

At the Mt Kynoch Water Treatment Plant, where our current drinking water is already processed, Toowoomba's water is treated to meet the health and aesthetic requirements of the National Health and Medical Research Council’s Australian Drinking Water Guidelines. This process does not change with the advent of Water Futures - Toowoomba: it is something we have always done.

Turbidity is taken out of the water in a large settling tank and multi-media filters (crushed coal, sand and gravel) remove the remainder of the turbidity. To settle and filter small particles, a specialised treatment chemical (coagulant) is added that makes the particles larger (flocculate). The larger particles (flocs) containing the dirt settle and become sludge that is removed. The smaller flocs are trapped in the filters.

Under conditions where the raw dam water is relatively clean, the settling stage is not needed, and the plant can be operated in what is called “contact filtration”.

Nuisance minerals such as iron and manganese are removed through adding chlorine prior to filtration. Chlorine oxidises these metals, bringing them from solution into suspension so that they may then be filtered out. Adding chlorine in the treated water also destroys microorganisms, not trapped by the filters, and a sufficient quantity of chlorine is added to ensure some is present at the consumer tap, to prevent bacteriological re-growth in the pipes.

The science advocated through the Water Futures - Toowoomba recycling project is not new it is, however, a first for Australia. Our city has a unique opportunity to lead this country in responsible water conservation with the adoption of a technique of water purification I believe will soon be commonplace throughout the world. It is time Australians took responsibility for the environment we leave to future generations and had the courage and commitment to make it a world of which we can be to be proud.