Case study INdustRIaL

Melbourne WaterEastern Treatment PlantConnecting you to a more sustainable future

Case Study / Melbourne Water eastern treatment Plant pg 2

Power from the people

The Eastern Treatment Plant, in Bangholme in Melbourne’s south-east, is a vital part of Melbourne’s infrastructure. Operated by Melbourne Water, the plant treats around 41 percent of Melbourne’s sewage and services roughly 1.5 million people in Melbourne’s south-eastern and eastern suburbs. In 2008/09 the plant treated an average of 312 million litres of sewage per day. Some treated wastewater is recycled and the rest flows via the 57km South Eastern Outfall pipeline to the Mornington Peninsula, where it is discharged into Bass Strait at Boags Rocks, under an EPA Victoria licence. When the Eastern Treatment Plant opened in 1975 it was a world leader in the secondary treatment of sewage. Ongoing improvements to the plant over the years have continued to serve the community well. Recently, a number of upgrades at the plant have been/are being undertaken to ensure that plant performance continues to meet community expectations. Two of these developments involve the upgrade of the existing power station and the construction of a new Odour Control Facility (OCF).

Part 1 – Power Station

Under a comprehensive plan titled the Eastern Green Energy Project (EGEP), pumps that were previously powered by a combination of diesel and biogas have been converted to run on electricity. Now the biogas – a by-product of the plant, and which is 60 percent methane - provides the electricity for the pumps by powering seven new generators.

The old engines, installed when the Eastern Treatment Plant was constructed in 1975, consumed some 1.3 million litres of diesel per year. Eliminating diesel usage in this way is the equivalent to removing about 600 diesel-powered cars from the road.

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By upgrading the existing power plant, which was used to power vital equipment during maintenance and in the case of emergencies, the Eastern Treatment Plant now produces 34.4GWh (gigawatt hours) of renewable electrical energy from sewage each year. This is enough electricity to supply about 5,000 households, but is also about 40 percent of the total amount the plant needs to function fully.

Through the use of technology, biogas is captured and harnessed to use as fuel in seven modern spark ignition engines.

Melbourne Water Team Leader – Mechanical and Electrical Asset Management, Julian Morton says: “The $46 million project reduces greenhouse gas emissions in two ways – by reducing waste and by using renewable energy to power the treatment processes.

“The revamped power station, commissioned in 2007, reduces electricity imported from the grid by 34,400MWh per year and reduces greenhouse gas emissions by about 40,800 tonnes a year,” he says.

Waste not …

Julian adds that EGEP is a key part of Melbourne Water’s pledge to reduce net greenhouse gas emissions to zero by 2018. Melbourne Water is among the top 20 energy users in the State, but has made significant inroads into emissions reductions and renewable energy usage since 2000-01. Emissions are significantly lower than the 2000-01 baseline.

“The modern equipment provides the opportunity to maximise the use of this renewable energy source,” says Julian. “It also provides the heat energy for the process to create biogas, in addition to the heating and cooling in buildings and offices at the site year round.”

Powering ahead

“The control of the engines is to match the production of the biogas in the process. The biogas is a fairly ‘dirty’ gas so maintenance of the engines is paramount. After maintenance, the engines are started on natural gas and then mixed across to biogas. This ensures the gas used by the engines does not exceed the volume being produced by the process so that the system is always at positive pressure,” says Julian.

“The EGEP power station provides positive outcomes for the environment through the beneficial use of sewage and provides the plant with heat and power. It is a key part of Melbourne Water’s commitment to sustainability and our greenhouse emissions target.”

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Fast facts

• 40,800 tonnes of CO2 eradicated;• Creation of 34,400 megawatt hours of renewable electricity per year;• More than 95 percent sludge gas utilised for power and heat, supplemented

with natural gas when required• Eliminating 1.3 million litres of diesel per year;• Over 100 billion litres of Class A recycled water produced for a range

of applications.

Part 2 – Odour control

A less than pleasant by-product of a sewage treatment plant is, naturally, the odour. The Eastern Treatment Plant must meet environmental performance targets that specify no offensive odours are to be discharged beyond the plant boundary. “In 2009 a new Odour Control Facility (OCF) was commissioned at the plant. The facility is the first of a three-stage strategy designed to achieve significant odour reductions,” says Team Leader, ETP Planning, Colin Hughes.

“The new facility is a biofilter used to treat foul air from the incoming sewer and inlet works. Prior to the new installation, the foul air was transferred to extraction fans and vented without treatment.”

The biofilters, which rely on bacteria held in crushed bark for their success, are able to reduce levels of hydrogen sulphide (the ‘rotten egg’ smell) from 24 parts per million to just 0.1 parts per million.

A significant part of the new OCF included extensive electrical engineering and contracting works and was undertaken by Nilsen. Founded in Victoria in 1916, Nilsen remains a family-owned business to the fourth generation.

Works at the Eastern Treatment Plant included 24V DC control and monitoring of odour control humidifiers and odour extraction fan motors.

It also included external lighting and general power around the new facility.

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“Nilsen’s works at the Eastern Treatment Plant were carried out to our usual level of technical excellence in equipment manufacturer, supply and installation.

“We knew that this new facility would have a positive impact on the environment so we were proud to be involved,” says Project Manager Wayne English.

“One area where our technical expertise enhanced the project beyond the contract’s specifications was that we built the switchboards rather than purchasing them from a supplier,” he says.

“This enabled us to provide ready access to the experts in our switchboards division to address technical questions and to discuss any potential or perceived problems.

“If this service had been provided by a third party switchboard manufacturer, there would have been significant additional costs,” he says.

Nilsen also carried out a range of low-level infrastructure engineering design work around the new facility to meet the design intent of items such as control panels, stands, and light poles/fittings.

Environment and energy-efficiency

As a business principle, Nilsen’s commitment to the environment and energy-efficiency is a priority.

The company aims to minimise adverse environmental effects of its work by using sustainable management processes and mitigation controls that comply with the client, legislative and regulatory requirements.

“By using low current 24V DC monitoring and control equipment, not installing excessive or unnecessary lighting and using the latest energy-efficient motors we have helped reduce the plant’s carbon footprint.

“We also identified environmental risks associated with the delivery of the works. We undertook and formulated strategies and processes to achieve low-

impact environmental outcomes,” says Wayne.

“All the equipment supplied complies with the latest electrical standards and is fit-for purpose.”

Wayne outlines that on the site construction zone, separate bins for metal and cardboard recycling and mixed bins for other types of waste were provided. “Plus we recycled our own copper wiring and cable drums,” Wayne adds.

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Scope of works

The works began with the modification of an existing main switchboard to accommodate two new 2500A power supplies. These new supplies were reticulated 250m from the existing switchroom in the chlorination building to the new OCF, where the modern switchboards and Motor Logic Centres (MLCs), which enable the operation of the new facility, would be housed.

Optic fibre and control cables were also extended from the existing network control centre to the new facility to integrate it into the plant’s overall control and monitoring network.

In the OCF, Nilsen installed five new switchboards of varying sizes, manufactured in the company’s Heidelberg West plant. The switchboards covered MLCs, PLCs (Programmable Logic Controls), VSDs (Variable Speed Drives) and the main switchboard.

A 250kVA uninterrupted power supply (UPS) as back-up, power was also installed.

Underground power and control cabling was installed to three humidifiers, five biofilter odour foul air tanks, four 130kW extraction fans and the drainage pumping station.

At each location, stainless steel control panels were installed for the termination of incoming cables. “It’s important to use stainless steel as the harsh environment of the plant corrodes mild steel,” says Wayne.

From these local control panels, the cables were installed to the pumps, motors, and instruments.

“Once the installation of the equipment was completed, there was an extensive commissioning process, where everything was tested and carefully integrated into the existing systems and networks,” says Wayne.

“We then undertook some significant modifications to the new switchboards, at Melbourne Water’s request, but still finished the project on time.

“We believe that by installing the latest electrical equipment, combined with our knowledge of energy efficiencies, we have provided the Melbourne Water Eastern Treatment Plant with a sustainable solution to its OCF,” he says, proudly.

“The use of quality products, the creation of our switchboards built for the specific needs of this unique site and the implementation of stainless steel fittings allows Melbourne Water to take full advantage of its own power generation to run the OCF for many years to come.”

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suMMaRy OF WORKs uNdeRtaKeN By NILseN

• Supply and installation of 2x 2500A busway electrical supplies for extension of biofilter MLC control boards;

• Installation of underground sub-mains to new biofilter SAP building control room;

• Manufacture and installation of control building main switchboards, PLC, MLC and VSD switchboards;

• Supply and installation of underground services for the 4W treatment switchboards and associated control cabling;

• Supply and installation of underground services for the site drainage pumping station switchboard;

• Supply and installation of UPS in the biofilter control room;• Installation of underground reticulation conduit system to the biofilter odour

foul air tanks;• Supply and installation of all power and control cables to service the

instruments on the biofilter odour foul air tanks and humidifiers; • Supply and installation of all exterior lighting for foul air tanks and

associated areas;• Supply and installation of all stainless steel local control panels to service

instruments, motors and pumps’• Supply and installation of optic fibre backbone and profibus

backbone system;• Supply and installation of power cabling to 132kW exhaust extraction

fan motors;• Supply and installation of general light and power to new control rooms;• Complete commissioning of the new installation and integration into the

existing site network.