Eastern Treatment Plant, Melbourne: Sewage Treatment and Environment

This report provides an overview of the Eastern Treatment Plant (ETP) located in Melbourne, Australia. It details the plant's structure, operation, and environmental impact. Commissioned in 1975 as a secondary treatment plant, it was upgraded to an advanced tertiary treatment facility in 2013, handling over 45% of Melbourne's sewage. The report outlines the sewage treatment process, including primary, secondary, and tertiary stages, which results in Class A quality recycled water. It describes the construction of the upgraded plant, the equipment involved, and the effects of the plant on the environment, such as reduced levels of pollutants, improved disinfection, and renewable energy generation through biogas. The report also discusses water recycling efforts and the plant's contribution to environmental management in Melbourne. The plant's impact on the marine environment is discussed in detail, including measures taken to reduce ammonia levels and improve water quality. The report concludes by highlighting the ETP's significance in water management and its positive contributions to the environment.

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Eastern Treatment Plant, Melbourne
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1Eastern Treatment Plant, Melbourne
Introduction
The Eastern Treatment Plant is located approximately 35 km on the Southern region of
Melbourne City. The treatment plant was initially a secondary treatment plant with a secondary
treatment process of sewage. It was commissioned for operation in 1975, covering an area of
1000 hectares. Furthermore, it was upgraded into an advanced tertiary treatment plant in 2013
and it treats over 45 % of sewage in Melbourne. 1 The following reflective journal will discuss
the plant structure, how it works including the process of sewage treatment and its effects to the
environment.
Construction of the newly upgraded plant involved installation of vital equipment in
infrastructure such as ozone production and ozone injection buildings, ultraviolet light,
biological media filters, chlorine contact basins, pump stations, pipelines and communication
cables. In addition to that, the plant has internal access roads, treated water storage basins that
are covered with ancillary tanks, storage facilities and chemical dosing tanks. The initial sewage
treatment provided a Class C type of water but the upgrade improved it to a Class A. The
recycled water is discharged to Boags Rocks. 5
How the plant works.
Sewage includes unwanted material that goes down from various places such as the
laundry, the kitchen, toilet flush and bathroom sink. The following steps define the treatment
process that is used at the Eastern Treatment Plant in Melbourne. Sewage in the plant undergoes
three different treatment stages leading to a Class A quality of recycled water. The three stages
include the primary, secondary and tertiary stages. 1

2Eastern Treatment Plant, Melbourne
Sewage treatment process.
The primary treatment stage of effluent starts with filtration, large items such as cotton
buds or rubbish are filtered from the sewage using fine screens. Next, the sewage is aerated
which removes tiny particles such as sand. Finally, the primary process is completed with a
sedimentation where a layer known as sludge is formed after large solid items sink to the bottom
of tanks. The sludge is then pumped to larger tanks referred to as digesters where decomposition
by bacteria takes place. 1
Secondary treatment of sewage entails the action of bacteria. Various types of bacteria
co-exist and these include aerobic, anaerobic and facultative bacteria in that environment. The
bacteria remove nutrients and breaks down organic substances in aeration tanks. The water flows
though sedimentation tanks to allow for further settlement of sludge at the bottom of the tanks.
Finally, clear water is formed at the top after sedimentation, this is known as the secondary
effluent. The secondary effluent flows into holding ponds then to the tertiary stage of the sewage
treatment process. 4
In the first step of the tertiary treatment stage, secondary treated effluent enters the
advanced tertiary treatment plant using a pump station. The effluent is pumped by two steel pipes
that are stainless, moreover, within the entrance of these two pipes, ozone gas is added. The
tertiary treatment process of effluent begins with media filtration, which is done through ozone
or biological methods to reduce odour, colour and suspended solids within the effluent. This
filtration step is followed by secondary ozonation. Ozone is extracted from oxygen in the air by
ozone generators. The next part of the process is disinfection using UV radiation and chlorine. 5

3Eastern Treatment Plant, Melbourne
The third step is the biological media filtration where 32 concrete tanks that act as
biological media filters allow the flow of treated water within them. The treated water flows to
produce filtered water through the filtration method. The surface of the filter media has certain
bacteria that enhance the water. In addition to that, the bacteria break down organic compounds
and reduce the ammonia content in treated water. These stages form sludge that is removed
through a backwash process, the sludge is thickened and sent to the available digesters that
convert the sludge into biogas. Water used during backwash is further reused by sending it to the
initial steps of the treatment process. 4
The fourth step involves water treatment in ozone for a second time, the water is then
sent to concrete channels. The fifth step comprises of seven UV reactors that are used in
disinfection using UV light. The final stage in the treatment process involves the use of chlorine
to disinfect water hence ensuring that the water is completely treated. The treated water is finally
passed on to an outfall pump station. 5
Effects of the plant to the environment.
The expansion project in Eastern Treatment Plant has led to environmental effects such
as a higher quality of recycled water at the Boags Rocks it is eventually discharged, hence a
substantial reduced impact on the marine environment. Moreover, there are more specific
improvements in the water discharged into the marine environment that include reduced levels of
oils, solids and grease deposited in the marine environment, improved disinfection of water and
reduction in litter. In addition to that, other improvements include a reduced amount of water that
is discharged into the marine environment, reduction in odour, water colour, foam and ammonia.
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4Eastern Treatment Plant, Melbourne
The amount of ammonia produced by the plant has had adverse effects to the marine
environment. The plant has undertaken measures to reduce the levels of ammonia in the effluent
through upgrading six tanks used in aeration at the secondary treatment process in order to
achieve an 85% reduction in ammonia levels annually. The plant has further built four extra
aeration tanks to reduce the levels of ammonia. Excess ammonia in the marine environment
harms the organisms that live in that environment therefore the plant has undertaken measures to
reduce the levels. 3
Water recycling.
The Eastern Treatment Plant produces class A quality of water, a portion of it is used in
the treatment process. The plant also supplies recycled water to customers who use it for non-
drinking purposes such as firefighting, laundry use, watering sports grounds or gardens and
irrigating various food crops. Recycling water reclaims water that has various uses and it
satisfies most of the environmentally water demands. This recycled water meets the standards set
by the Department of Health in Melbourne and it is approved to be safe for the non-drinking
purposes. 6
Renewable energy is obtained though biogas. In the final treatment stage, methanogenic
bacteria produce methane gas that is stored in large tanks. Methane gas runs seven generators
that provide 40 % of electricity needs in the plant and it is used to run the heat pipes therefore, it
saves on the electricity that would otherwise be imported from the grid. Moreover, it reduces the
amount of methane gas produced to the environment, which is a major effect in reducing global
warming through the reduction of greenhouse gases that deplete the ozone layer. 1

5Eastern Treatment Plant, Melbourne
Conclusion
The Eastern Treatment plant has undergone an early upgrade to a tertiary treatment of
sewage. The tertiary treatment process has led to many benefits such as improvement of the
quality of recycled water and more benefits to the marine environemt. Furthermore, the plant has
had its effect to the environment such as reduced odour, release of renewable energy from
biogas, reduction in the levels of ammonia and treatment of sewage for better recycled products.
The plant is an important factor in management of water in Melbourne.

6Eastern Treatment Plant, Melbourne
Reference List
1. Water M. Eastern Treatment Plant Water M. Eastern Treatment Plant Upgrade; Information
in support of work , Approval Application. Melbourne: Melbourne Water.; 2007.
2. Water. M. Eastern Treatment Plant; Environmental Improvement Plan. Update report.
Melbourne: Melbourne Water, Water management; 2012.
3. Water M. Community and environmental behefits. [Online].; 2017 [cited 2017 September 13.
Available from:
https://www.melbournewater.com.au/whatwedo/treatsewage/etp/Pages/Community-and-
environmental-benefits.aspx.
4. Water M. Sewage Treatment Process. [Online].; 2017 [cited 2017 September 12. Available
from: https://www.melbournewater.com.au/whatwedo/treatsewage/etp/Pages/Sewage-
treatment-process.aspx.
5. Technology W. Eastern Treatment Plant Tertiary Upgrade. [Online].; 2013 [cited 2017
September 12. Available from: https://www.melbournewater.com.au/what
wedo/projectsaroundmelbourne/Pages/Eastern-Treatment-Plant-Tertiary-upgrade.aspx.
6. Water M. Using Recycled Water. [Online].; 2016 [cited 2017 September 14. Available from:
http://www.melbourne.water.com.au/whatwedo/recyclewater/Pages/Using.recycled-
water.aspx.
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