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Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

The Smith's Snackfood Company Limited
Cleaner Production - Reducing Solids in Effluent

A consultancy study of company operations involved staff at all levels of the organisation and led to greater environmental awareness and significant cost savings and environmental benefits. Initial projects focused on reducing solids in effluent to eliminate overloading of the wastewater treatment plant servicing the potato and corn processing lines. The initiatives taken have resulted in cost savings of $130,000 per annum and have reduced bore water consumption by 20 ML per annum. Further reductions in water use of 50 ML per annum are planned.

Background

The Smith's Snackfood Company is the largest snackfood manufacturer in Australia with operations in Adelaide, Brisbane and Perth. The Adelaide site processes potatoes and corn to produce a variety of products including brands such as Smith's Potato Chips, Ruffles, Lites, Doritos and Twisties.

The Process

The company's water use has increased by 19.5 percent since 1993, rising from 264 ML per annum (47 percent mains water and 53 percent bore water) to 315 ML per annum in 1997 (61 percent mains water and 39 percent bore water) without an increase in production.

A substantial volume of water is used to wash potatoes: the amount and type of soil on the potatoes governing the actual volume of water. The manufacturing process includes several washing stages to meet stringent quality requirements. If the soil is not removed in the initial stage by the rod washer, more water must be used in subsequent stages.

The effluent generated contained 10 percent solids and was directed to the wastewater treatment plant where solids were removed by sucker trucks at a cost of $130,000 per annum. The plant was often stopped when the build-up of solids caused flooding.

There was no routine monitoring of water use and of wastes generated.

Cleaner Production Initiative

A consultancy study into the environmental aspects of company operations was undertaken with the assistance of a $15,000 grant from the South Australian Environment Protection Agency under its Cleaner Industries Demonstration Scheme. The company also contributed to the project by providing $30,000 for equipment and $20,000 in kind for staff and analytical time.

The consultancy brought together staff from different levels of the organisation and involved them in the decision making process. This has led to greater questioning and understanding of the plant's operation and a smoother running plant.

Measures implemented initially focused on equipment and process changes, installation of hydrocyclone technology to reduce water use and improve solid waste disposal, and staff training.

Hydrocyclones have been installed on both the potato and corn lines. The concentrated solid effluent streams from washing processes are directed to the hydrocyclones, where strong centrifugal forces separate the solids from the effluent. The underflow is collected in sludge bins, allowing separation of soil and the draining out of water. Cleaner water from the cyclones, containing minimal solids, is collected in a holding tank for recycling back into the system. A process flow diagram is set out below.

Water use, both from the mains and the bore, is now monitored daily. Water meters have been calibrated and installed at various locations within the plant to monitor the water used by individual production processes. The water meters are read on a daily basis by production crews. Water use is charted weekly and any rise that cannot be accounted for is investigated.

Advantages of the Process

Recycling of solids-minimised water from the hydrocyclone has reduced water consumption from the rod washer by more than 80 percent.

Process flow diagram

Process flow diagram

The recovered solids are in cake form and are no longer entering the wastewater treatment plant. Waste disposal costs have fallen as a consequence from $144 per tonne to $40 per tonne, providing a saving of $130,000 per annum.

Total outlay

$30,000

Annual saving

$130,000

Payback period

5 weeks

Additional hydrocyclones have been ordered for installation on the potato peeler and the potato slice washer. These initiatives could further reduce water consumption by up to 150 ML per annum.

Various measures are being investigated for disinfecting soil and potato peel that is currently deep buried as an anti-nematode measure. Such measures could save the company $55,000 per annum in deep burial costs and allow the material to be used as a mulch or agricultural additive.

Commercial uses for corn sludge are also under investigation.

Incentive

The company's motivation in undertaking the initiatives was to improve competitiveness by reducing environmental costs.

Barriers

No barriers were encountered.

Further Developments

The Company has changed ownership since the project was initiated. The new owner of the Company has a considerably different process of production compared with the one mentioned in the above casestudy. Reducing solids in effluent is still an objective of the Company. However, the method discussed in this casestudy is no longer relevant.

Contact

Ming Yue
Engineering Manager
The Smith's Snackfood Company Ltd
553-567 South Road
REGENCY PARK  SA  5064
Ph: 08 8208 5000
Fax: 08 8208 5185
Email: ming.yue@intl.fritolay.com

Implementation: 1997
Casestudy initially prepared: June 1998 by South Australian Environment Protection Agency and Environment Management Industry Association of Australia (EMIAA)

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Last modified: June 2001