Recycling Grey Water in Continuous Batch Washers

The Challenge

Large Continuous batch washing businesses have the potential to use water more efficiently when properly assessed and assisted to identify these opportunities. Recycling 'grey water' at Warragul Linen Service (WLS) presented as one of those key water efficiency opportunities.

Warragul Linen Service (WLS) is a business unit of the West Gippsland Healthcare Group and is operated as a State Government commercialised organisation. The service supplies linen requirements to public health facilities located in the West and South Gippsland region in Victoria.

WLS consumes considerable quantities of fresh water to achieve the levels of cleanliness and sterility required to meet the needs of its customers.   As a result, water savings initiatives are an important part of the operating strategy of WLS.

The Project

In this project, modifications were made to two large commercial washers, Continuous Batch Washers (CBW), to recycle grey water.  This project aimed to verify modifications made to two the CBWs, as these modifications allowed grey water that was captured from the press cycle to be recycled into the rinse zone of the machines.  This is a process that is standard in newer CBWs, however rinse water in the older CBWs is sourced entirely from incoming potable water lines.  Recycling a proportion of this rinse water from the press tanks was expected to reduce water consumption by around 10 – 11 megaliters (ML) per year (approximately a 20 per cent saving).  As around 95 per cent of incoming water is discharged to sewer, a reduction of up to 9 ML per year in sewage discharge was also expected.

Water usage was metered at each individual washing machine and recorded on a weekly basis, so changes in water consumption following commissioning were recorded. Cost modelling established a payback period of nine months for these modifications at 2010/11 water prices.

The Outcome

The reduction in water usage immediately following commissioning of these machines was significant.

For the six month period prior to commissioning, the collective average water consumption through both machines was 9.37 litres per kilogram (Lt/kg) washed. For the eight month period post commissioning (ending April 2011), the average water consumption was reduced to 6.12 Lt/kg, approximately a 35 per cent reduction. This represents an annual potable water saving of 17.8 ML, and a saving of almost 17 ML in waste discharge to sewer was achieved.  These results far exceeded the project targets while maintaining the required cleanliness standards.

Significant water savings are available to the commercial laundry industry via the adoption of this relatively inexpensive modification to existing equipment.  There are dozens of older style CBWs in use throughout Victoria and Australia.  The payback period of nine months demonstrated in this project should make this modification an attractive proposition for other commercial laundry operators.

Project Information

  • Project Round:
    2012
  • Project Status:
    Completed
  • Research Organisation:
    Warragul Linen Service
  • Project Number:
    72R - 7025
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