Search

Melbourne Water finds an energy-saving solution

We are an online community created around a smart and easy to access information hub which is focused on providing proven global and local insights about sustainability

04 Jun, 2024

This post was originally published on Sustainability Matters

Sewage and wastewater treatment is a highly energy-intensive process, presenting a challenge for water utilities seeking to meet net zero goals.

Melbourne Water’s Eastern Treatment Plant (ETP) treats almost half of all Melbourne’s sewage, an average of 330 million litres a day. Located in the Melbourne suburb of Bangholme, approximately 19 miles south-east of the city centre, the 1000 ha site was upgraded in 2012 to treat sewage to an advanced tertiary standard, producing Class A recycled water.

Shooting for net zero

Since opening in 1975, the ETP has always generated energy from sewage gas, and the site houses seven power generators that are capable of running solely on biogas — produced through the anaerobic digestion of sludge during the first and second phases of water treatment.

In 2020, Melbourne Water began a project with John Holland-KBR Joint Venture to upgrade the biogas handling system at the Eastern Treatment Plant to make it more efficient, resilient and futureproof. The project aimed to expand capacity, prevent corrosion and sedimentation, and extend the working life of equipment — with specific requirements to remove liquid droplets and moisture and to minimise the size and cost of any necessary cooling system.

Sewage transfer and treatment are responsible for about 85% of Melbourne Water’s total greenhouse gas (GHG) emissions, so contributing to the company’s net zero commitment was a main target for the project. “However, with existing assets nearing the end of their service life, ensuring that the new asset can service future production growth and plant upgrades was also essential,” said Nick Fung, Senior Project Manager at Melbourne Water.

Increasing reliability for the operations team onsite and improving safety across both operation and maintenance were further aims.

Selecting an energy-saving solution

The HRS BDS formed part of a wider upgrade to the biogas handling equipment at Melbourne Water’s Eastern Treatment Plant.

Biogas contains hydrogen sulfide (H2S) gas, which condensates out to form a highly corrosive liquid. Including a system to remove most of the moisture from the gas was therefore essential to minimise the amount of corrosion and degradation of the power station generators, while also limiting operational downtime and reducing the need to import electricity from the grid.

HRS Heat Exchangers was one of five companies invited to tender for the moisture removal equipment in the project. The HRS Biogas Dehumidification System (BDS) removes water from biogas, protecting combined heat and power (CHP) engines and generator sets from corrosion and cavitation. According to HRS, it condenses more than 90% of the water present in biogas by reducing the temperature to leave a clean gas. The addition of heat regeneration technology means the cold biogas produced can be used to pre-cool the incoming warmer biogas. This reduces the load on the final cooling heat exchanger and saves valuable energy.

The BDS supplied for the project has a maximum capacity of 4161 m3/h (4710 kg/h), while the inclusion of an energy recovery section subsequently reduces the eventual chiller load by 30%. This BDS consists of two heat exchangers, a regeneration unit and a final cooler, supplied on two skids. One skid — located in a hazardous area zone — contains the heat exchangers, a condensate knockout pot, a condensate drain line and all the relevant IECEx-rated instrumentation. The second skid contains a buffer tank, standby and duty glycol pumps, and all the relevant glycol line process control valves and instruments.

HRS also supplied an additional chiller and detailed process control descriptions, enabling the joint venture engineers to provide overall control and automation systems for the client.

Overcoming complex design parameters

The HRS BDS at Melbourne Water’s Eastern Treatment Plant incorporated some complex design elements.

The BDS needed to meet the requirements of two different operational stages, each of which contains four duty requirements. This meant a complex thermal design process was necessary to make sure that the supplied unit could meet all eight of the potential design scenarios.

Ella Taghavi, Project Manager and Technical Lead at HRS Heat Exchangers, explained: “Designing the BDS for the Melbourne Water project posed a significant challenge as it needed to cater to both current and future demands, with two very different conditions in each phase.

“The current first phase uses biogas supplied by the compressors and aftercoolers at an average pressure of 66 kPa. In the second (future) scenario, the gas is supplied following a number of additional treatments at an average pressure of 5 kPa and then supplied to the compressors. We therefore had to deal with two very different inlet conditions.

“The addition of heat regeneration added further complexity in terms of design. However, thanks to our cutting-edge technology, not only were capital costs reduced as a smaller chiller could be specified, but regeneration is also helping to lower ongoing operational costs.”

An efficient result

From being awarded the contract in July 2021, it took less than 12 months for HRS to install the bespoke BDS onsite, with commissioning completed in June 2022.

The John Holland-KBR team noted that of the five tendered solutions, the technology of the HRS BDS stood out, including the excellent technical support it provided to help develop the project further with Melbourne Water.

“Our experience in project management, construction and logistics enabled us to overcome early design challenges and respond to necessary changes during the design and construction process. As a result, we were able to deliver a high-quality product that has performed to specification since its installation,” Taghavi said.

The upgrade project has improved the quality of the biogas supply to the power station at ETP, providing more confidence in its ability to deliver more than 36,000 MWh (approximately 130 TJ) of thermal energy for process heating. This means a reduced reliance on natural gas, cutting down on emissions and making the operation more self-sufficient.

Top image caption: The HRS Biogas Dehumidification System (BDS) is specifically designed to improve the operating life and energy efficiency of biogas engines. Images courtesy of HRS Heat Exchangers.

Pass over the stars to rate this post. Your opinion is always welcome.
[Total: 0 Average: 0]

You may also like…

Taking the electronic pulse of the circular economy

Taking the electronic pulse of the circular economy

In June, I had the privilege of attending the 2025 E-Waste World, Battery Recycling, Metal Recycling, and ITAD & Circular Electronics Conference & Expo events in Frankfurt, Germany.

Speaking in the ITAD & Circular Electronics track on a panel with global Circular Economy leaders from Foxway Group, ERI and HP, we explored the evolving role of IT asset disposition (ITAD) and opportunities in the circular electronics economy.

The event’s focus on advancing circular economy goals and reducing environmental impact delivered a series of insights and learnings. From this assembly of international expertise across 75+ countries, here are some points from the presentations that stood out for me:

1. Environmental impact of the digital economy

Digitalisation has a heavy material footprint in the production phase, and lifecycle thinking needs to guide every product decision. Consider that 81% of the energy a laptop uses in its lifetime is consumed during manufacture (1 tonne in manufacture is equal to 10,000 tonnes of CO2) and laptops are typically refreshed or replaced by companies every 3–4 years.

From 2018 to 2023, the average number of devices and connections per capita in the world increased by 50% (2.4 to 3.6). In North America (8.2 to 13.4) and Western Europe (5.6 to 9.4), this almost doubled. In 1960, only 10 periodic table elements were used to make phones. In 1990, 27 elements were used and now over 60 elements are used to build the smartphones that we have become so reliant on.

A key challenge is that low-carbon and digital technologies largely compete for the same minerals. Material resource extraction could increase 60% between 2020 and 2060, while demand for lithium, cobalt and graphite is expected to rise by 500% until 2050.

High growth in ICT demand and Internet requires more attention to the environmental footprint of the digital economy. Energy consumption of data centres is expected to more than double by 2026. The electronics industry accounts for over 4% of global GHG — and digitalisation-related waste is growing, with skewed impacts on developing countries.

E-waste is rising five times faster than recycling — 1 tonne of e-waste has a carbon footprint of 2 tonnes. Today’s solution? ‘Bury it or burn it.’ In terms of spent emissions, waste and the costs associated with end-of-life liabilities, PCBAs (printed circuit board assembly) cost us enormously — they generally achieve 3–5% recyclability (75% of CO2 in PCBAs is from components).

2. Regulating circularity in electronics

There is good momentum across jurisdictions in right-to-repair, design and labelling regulations; recycling targets; and voluntary frameworks on circularity and eco-design.

The EU is at the forefront. EU legislation is lifting the ICT aftermarket, providing new opportunities for IT asset disposition (ITAD) businesses. To get a sense, the global market for electronics recycling is estimated to grow from $37 billion to $108 billion (2022–2030). The value of refurbished electronics is estimated to increase from $85.9 billion to $262.2 billion (2022–2032). Strikingly, 40% of companies do not have a formal ITAD strategy in place.

Significantly, the EU is rethinking its Waste Electrical and Electronic Equipment (WEEE) management targets, aligned with upcoming circularity and WEEE legislation, as part of efforts to foster the circular economy. A more robust and realistic circularity-driven approach to setting collection targets would better reflect various factors including long lifespans of electronic products and market fluctuations.

Australia and New Zealand lag the EU’s comprehensive e-waste mandated frameworks. The lack of a systematic approach results in environmental degradation and missed positioning opportunities for businesses in the circular economy. While Australia’s Senate inquiry into waste reduction and recycling recommended legislating a full circular economy framework — including for imported and local product design, financial incentives and regulatory enforcement, New Zealand remains the only OECD country without a national scheme to manage e-waste.

3. Extending product lifecycles

Along with data security and digital tools, reuse was a key theme in the ITAD & Circular Electronics track of the conference. The sustainable tech company that I lead, Greenbox, recognises that reuse is the simplest circular strategy. Devices that are still functional undergo refurbishment and are reintroduced into the market, reducing new production need and conserving valuable resources.

Conference presenters highlighted how repair over replacement is being legislated as a right in jurisdictions around the world. Resources are saved, costs are lowered, product life is extended, and people and organisations are empowered to support a greener future. It was pointed out that just 43% of countries have recycling policies, 17% of global waste is formally recycled, and less than 1% of global e-waste is formally repaired and reused.

Right to repair is a rising wave in the circular economy, and legislation is one way that civil society is pushing back on programmed obsolescence. Its global momentum continues at different speeds for different product categories — from the recent EU mandates to multiple US state bills (and some laws) through to repair and reuse steps in India, Canada, Australia and New Zealand.

The European Commission’s Joint Research Commission has done a scoping study to identify product groups under the Ecodesign framework that would be most relevant for implementing an EU-wide product reparability scoring system.

Attending this event with the entire electronic waste recycling supply chain — from peers and partners to suppliers and customers — underscored the importance of sharing best practices to address the environmental challenges that increased hardware proliferation and complex related issues are having on the world.

Ross Thompson is Group CEO of sustainability, data management and technology asset lifecycle management market leader Greenbox. With facilities in Brisbane, Sydney, Melbourne, Canberra, Auckland, Wellington and Christchurch, Greenbox Group provides customers all over the world a carbon-neutral supply chain for IT equipment to reduce their carbon footprint by actively managing their environmental, social and governance obligations.

Image credit: iStock.com/Mustafa Ovec

0 Comments