This is a Smart Water Fund Project

Rainwater Harvesting for Re-use in Cooling Towers

Project Date: 31 December 2010
Project Status: Complete
Research Organisation: Nestle Foods
Project Number: 42M - 2072

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The Challenge

Nestlé Foods Pakenham factory is one of four major Nestlé factories in Victoria and manufactures shelf stable foods, frozen foods and ready-to-eat frozen meals. The factory has about 200 staff working on site.

As a global organisation, Nestlé has emphasised environmental sustainability and reduction of water use.

At a factory level, the organisation encourages sustainability initiatives by lowering the hurdles for implementing environmental programs. Nestlé aims to reduce water consumption by 5 per cent per tonne of product. Its Oceania operations have achieved a 24.8 per cent water reduction since 2003.

Two years ago, the Pakenham factory switched to mains water leaving two large water treatment tanks unused. The Pakenham Water Wise team, which is open to every factory employee, came up with the idea of using the 5,500 square metre factory roof for rainwater catchment. The group recognised that the 1.2 million litre capacity water tanks would be ideal for storing the rainwater.

Recycled water cannot be used in food processing for hygiene reasons, so the challenge for the Water Wise team was to devise an innovative use for the rainwater collected.

The Project

Commissioned in August 2007, the project captures rainwater from the rooftops of three factory buildings. A small transfer water tank is used to feed the two larger tanks, which have a total capacity of 1.2 million litres.

The project team initially planned to use the water in the factory's boilers and cooling towers. The project's scope was narrowed after modelling showed the amount of rainwater collected each year would not be sufficient for use in both systems. The rainwater now supplements mains water for the cooling towers, which are used for freezing ready-made meals and consume 11 million litres of water a year.

As water from cooling towers evaporates, the dissolved salts in the water become more concentrated. To reduce salt concentration, part of the water is regularly disposed of as trade waste and topped up with fresh water.

The project team estimates that because rainwater contains lower levels of dissolved solids than mains water, fresh water won't be needed as frequently to top up the cooling towers.

Factory manager Andrew Nooy estimates that around 5 million litres of rainwater will be collected per year, potentially cutting water consumption from the cooling towers by half. Reduction in water usage for the cooling towers will save around $6,000 per year in addition to reductions in disposal cost savings related to the reduction of trade wastewater generated.

The Outcome

Nestlé's Pakenham project shows the food manufacturing industry that while recycled water cannot be used in their primary source of production, substantial water savings can still be made.

Mr Nooy is quite passionate about reducing the amount of water use at the site and their experience show the benefits in 'grassroots' water savings that engage with all levels of staff. Initiatives by the Water Wise team resulted in a 21.2 per cent reduction in water use during the 2007 calendar year.

The factory manager said that flexibility in water savings projects is also required, as the scope of projects often changes, as is keeping up to date with the regulations for your industry.

"For example, because we are in the food industry, we had to build in a 'first flush system' into the project to ensure that cross contaminants from our roof don't flow into our tanks," he said.

For all Smart Water Fund Project enquiries please contact swfinfo@melbournewater.com.au

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