Clean and green water infrastructure

Australia is experiencing an evolution in water infrastructure. Desalination plants and water-recycling facilities are just some of the major water infrastructure projects being built across the country. For government and designers, the challenge is how to create water infrastructure that improves access to water while minimising environmental footprint.

Parsons Brinckerhoff (PB) is an engineering, planning and environmental company making water matter in a green way. Outlined below are some of the major water infrastructure projects where it is a contributing partner.

Dalby Stage 2 desalination plant

The Dalby Stage 2 desalination plant is a duplication of the existing Stage 1 desalination plant delivered in 2004. The new Stage 2 plant will treat alluvial bore water by reverse osmosis to produce 2.0 ML per day of drinking water. The $3.25m project is due for completion by the end of 2011.

The pressure vessels pictured above are in a two stage array of the reverse osmosis system at Dalby Stage 2 Desalination Plant.

The desalination plant allows the township of Dalby to maintain its demand for drinking water even though rainfall levels continue to diminish. The plant’s supporting infrastructure can be expanded if the demand for drinking water increases.

PB first worked on the project in 2004, designing Stage 1. The firm has continued its involvement with the project by designing the treatment process and supporting infrastructure for Stage 2.

The Stage 2 design determined the optimum treatment process. The design also allowed for the possible future installation of a brine-concentrating desalination plant. This installation would minimise the amount of brine disposal at the evaporation ponds and continue to reduce the plant’s environmental impact.

The water produced from the desalination plant is treated by a packed tower aerator to liberate carbon dioxide. It is then blended with a small proportion of raw water and trimmed by dosing chemicals. The treated water is non-corrosive and stable.

Dalby wastewater recycling scheme

Opened in June 2010, the $2.35m upgrade of the existing wastewater treatment plant now delivers Class A+ water to the Dalby biorefinery. This project reduces the biorefinery’s reliance on the town’s drinking water supply by 25% each day.

The submerged ultrafiltration system used in the delivery of Class A+ water at the Dalby Wastewater Treatment Plant.

Because alternative water supply sources surrounding Dalby were limited and unreliable, the Western Downs Regional Council needed a solution that preserved the town’s drinking supply and allocated water to the biorefinery.

PB designed a specific treatment process that was installed without altering the existing infrastructure or biological wastewater process. The design diverted treated outfall water prior to discharge to a balanced storage. This ensured that the upstream recycling plant would have supply during daily diurnal flows from the biological process.

By drawing on this under-utilised resource in a sustainable way, PB facilitated environmental and economic benefits for the community. The Dalby Wastewater Treatment Plant has reduced potable water demand and resource extractions by approximately 350 ML/year. The return of wastewater to the Murray Darling Basin was reduced by a similar amount.

In October 2010, the project won the Institute of Public Works Engineering Australia Queensland Award for Innovation in the Wastewater, Sewerage and Drought Management category (<$5m).

Gippsland Water Factory

The Gippsland Water Factory will treat up to 35 million litres of Gippsland’s residential and industrial wastewater each day. This wastewater will come from more than 19,000 households and businesses in the Gippsland region, and Australian Paper’s Maryvale mill.

The Gippsland Water Factory is comprised of two treatment plants in one, with the residential and industrial wastewater being treated separately. The residential wastewater will be further refined to meet the requirements of the Department of Health standards, producing about eight million litres of recycled water per day. In the coming months, this recycled water will be sold to Australian Paper for use in production processes at its Maryvale mill. The industrial stream will also receive a high level of treatment and will be delivered to the regional outfall sewer free of organics and odour.

By selling recycled water to industry, the Gippsland Water Factory will free up an equivalent amount of fresh water - about three billion litres annually - in the Moondarra/Latrobe system. The greater volume of water maintained in the Moondarra/Latrobe system will then be available for environmental flows in local rivers, drinking purposes, or to support future growth in the area. Three billion litres of potable water is enough to service a town of 40,000 people for an entire year.

The residential treatment component was commissioned in January 2010 and the residential wastewater now discharged to the regional outfall sewer is treated and odour free. An education and interpretative centre has been built in conjunction with the Gippsland Water Factory, showcasing the wastewater treatment process and technology to the local, Australian and international community.

The Vortex Centre is the education and interpretative centre built in conjunction with Gippsland Water Factory.

Bundamba Advanced Water Treatment Plant

In 2006, due to worsened drought conditions, the Queensland Government decided the Bundamba Advanced Water Treatment Plant would be designed and constructed just 12 months after a team had been announced. The recycled water produced is not only clean enough to drink; it is of a higher quality than most potable water reserves.

The microfiltration area of the Bundamba Advanced Water Treatment Plant. Photo courtesy of WaterSecure.

PB was engaged by the Thiess/Black & Veatch joint venture to work on the $360 million project. The primary objective of the plant was to provide recycled water for power station and industrial purposes, and reduce demand on the Wivenhoe-Somerset potable water-storage systems. The ultimate projected output of 282 ML/day represented a significant international water recycling project.

Previously, water recycling projects produced non-potable water for use in industrial processes.

The process for the new plant used a unique combination of technologies never before applied to a project of this scope. As water from the plant was initially used to supply power stations, the town’s water supply was untouched. Later, water was supplied for industrial use and eventually pumped directly into a water supply dam. From there, it was processed through the normal water supply treatment system.

PB designed the infrastructure for the process without any previous plants to use as examples.

Similarly sized projects in the US were simpler facilities but typically took more than one year to design and build. Delivering the plant and its complex facilities within the 12 month timeframe was a major challenge.

With the help of PB, the project features positive environmental impacts and innovative engineering solutions, as it utilised existing technologies for water treatment in ways not previously used. The waste discharged into river systems has been reduced by 82% and the plant recovers 15-20 tonnes of solid waste every day. Local industries can now maximise their use of recycled water in lieu of potable water supplies.

In 2008, Bundamba Advanced Treatment Plant was awarded Water Project of the Year at the Global Water Awards in London, UK.