On the morning of October 11th, an excursion was made to the Yarra Valley Water Sewage Treatment Plant, located east of Melbourne. This facility treats raw sewage and discharges the treated water into the Yarra River and surrounding wetlands. The service area of Yarra Valley Water covers approximately 4,000 square kilometers, maintaining
over 20,000 kilometers of water and sewer mains. The plants incoming water is mostly coming from households and the plant operates 24/7 and processes wastewater from around 10,000 properties.

The tour began with an explanation of the wastewater treatment process. Yarra Valley Water, one of three companies supplying water to Melbourne, is responsible for treating
the sewage in this area. Before the plant’s construction, wastewater was stored in concrete basins, which eventually started leaking into the river, necessitating the need
for a proper treatment facility. However, establishing the plant was challenging due to local resistance, as no one wanted an industrial treatment facility in their backyard. Stakeholder participation played a significant role in reaching a compromise. Consultations were necessary, there were concerns about water quality, aerial quality, impact on cattle, and even the WWF was involved. It was placed in a quite remote area, and to reduce its visual impact, the plant was designed to look like a farmhouse, and the area around it was landscaped with raised barriers and trees.

Eventually the plant started operating in 1997.
The first step in the treatment process is the removal of phosphorus from the wastewater. Aluminum sulfate is added to react with the phosphorus, forming a solid material that can be filtered out. The water then passes through a screen to catch metals and plastics, which are collected and disposed of in the same manner as medical waste, due to the potential presence of hazardous chemicals. The next stage involves biological treatment in two reactors. These reactors use
bacteria to break down the organic material in the water. The process is split into two 30-minute cycles: the first involves aeration, where oxygen is introduced to help bacteria that need oxygen to digest the waste, this is what looks bubbling. This is mainly to get out the urine. The second cycle is anaerobic, where bacteria that do not require oxygen remove ammonia from the water, converting it to nitrogen gas, which is released into the air, and this is where the water is still. Nitrogen capturing is mostly done at water treatment plants, but since this treatment plant is quite small it is not beneficial
to do so. The bacteria in the water will basically ‘eat’ the toilet paper and other organics. This cycling process is repeated several times to ensure a thorough treatment.

Some sludge, composed of dead bacteria and other waste, is periodically removed from the bottom of the tanks and sent to a dewatering facility. Here, water is extracted, and the remaining sludge is sent to the Eastern Treatment Plant for further use. Meanwhile, partially treated water continues to sand filters, which remove finer contaminants like liquid plastics. The most common elements to be found and captured by the sand filters are fruit labels and glue. The colour of the water is quite grey, but this is due to the
bacteria and not due to organics or other defecation. Since the sand filters can clog over time, retaining basins are used to hold the water temporarily in case of emergencies. The extra retaining basins get sprayed water on continuously over time for it to not grow any algae in it. The final stage of treatment involves disinfecting the water using UV light to kill
pathogens, such as E. coli. The treated water is then discharged into the Yarra River and wetlands, ensuring that it meets the necessary environmental standards.

Solar panels have been installed at the plant in recent years, although they only contribute partially to the energy required for the purification process. Nevertheless, these panels help reduce the plant’s reliance on external power sources, contributing to its self-sufficiency. The plant is committed to expanding its use of green energy wherever possible.
One notable insight from the tour was that only about 5% of the incoming wastewater is composed of solid materials like toilet paper and other substances, indicating high water usage. This suggests that people tend to use more water than necessary, especially as they grow older or achieve financial stability, leading to less mindfulness about their environmental impact. To address this, Yarra Valley Water has launched campaigns and educational programs promoting water conservation, including the installation of rainwater tanks for more sustainable reuse of rainwater. Another insight
was the experience required of staff working at the plants. Nowadays everything is computerized, but back in the day highly experienced staff could smell if something was
not going well in the process.

As with many companies and organizations in Australia, Yarra Valley Water acknowledges the traditional custodians of the land—the Aboriginal people. Although only 3% of the current Australian population identifies as Aboriginal, these communities have historically taken excellent care of the land, passing down knowledge about sustainability and caretaking from generation to generation. Women played a significant
role as caretakers of both the land and children. Cultural practices such as controlled burning was employed to encourage the growth of specific plants like orchids.
The placement of the treatment plant faced significant resistance from residents and farmers, who feared it would negatively impact the landscape and their quality of life.
However, the poor water quality in the region made the facility necessary. After consulting with stakeholders, the plant was built with careful attention to blending into the rural landscape, designed to resemble a barn with a small house. Today, the plant is well-hidden, and most people driving by would not even notice it.

During the tour, the guide, Karen, provided interesting information about the local wildlife and plants. Brush-tailed possums and foxes were introduced to the area in the
past. The possums were brought to halt fur hunting, while foxes were introduced to control the rabbit population—though the latter strategy proved unsuccessful. Karen
even had pelts in the back of her car to illustrate her point. There was also mention of flying squirrels with long tails that inhabit the area. The wetlands in the area have been
made to re-introduce ecology and certain animals such as platypuses.

In conclusion, the Yarra Valley Water Sewage Treatment Plant serves a vital role in maintaining the region’s water quality while blending into the surrounding landscape. The facility’s treatment process, sustainability efforts, and community involvement shows the balance between modern infrastructure and environmental responsibility.