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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time.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.

Monroe Australia Pty Ltd
Cleaner Production - Waste Minimisation Strategy

The company has implemented a major waste minimisation strategy that has enabled it to process liquid waste, reduce water usage, reduce chemical and waste disposal costs, and eliminate pollution. It installed new equipment which treats wastewater to remove emulsified fats and oils, grease, heavy metals and all forms of suspended, colloidal and some dissolved solids. Mains water usage has been reduced by over 10ML per annum and wastewater discharge to sewer reduced by 50 percent. The new technology has produced a saving of $250,000 per annum with a payback period of 2 years.


Monroe Australia is a leading Adelaide based manufacturer of shock absorbers and strut suspension units for the automotive industry. The company has a staff of 450 and a turnover of $100 million. A significant percentage of the company's total production is exported to Asia, North America and Europe.

The Process

The process of manufacturing shock absorbers and strut suspension units involves various chemicals which contribute to the liquid waste stream.

Waste discharged to sewer arises from two sources: as rinse water from the hard chromium electroplating process; and from the metal pre-treatment process before the finished product is painted. Total discharge flow was 45kL per day.

Waste treated for disposal arises from oily waste streams comprising metal turning, cutting and grinding lubricants and coolants from the machining centres with a daily volume of 10,000 litres. Regular removal and replacement of chemical solutions amounted on average to 2000 litres per day.

In 1994, over 70ML of water was used in the production process with almost 15ML being generated as liquid waste. Excess water cost in 1994 was more than $50,000 with wastewater streams of 52ML. 12ML of purified water was used per annum for processing purposes.

Water in all forms - clean, treated or contaminated - represented a significant volume and cost burden on the company's operations. The effluent contained a mixture of amines, olamines, amides, surfactants and wetting agents (generally organic in nature), refined mineral oils and synthetic machining and grinding fluids, plus a high content of heavy metals such as chromium, zinc, copper, aluminium, and iron, as well as oil and grease.

The total cost of disposal of non-sewerable liquid waste in 1995 was approximately $403,000.

Cleaner Production Initiative

The company put in place a major waste minimisation strategy, which involved the installation of a Microsep wastewater treatment plant and ancillary equipment; a reverse osmosis pure water generation unit; and water recycling pumps and piping.

Purchase of the new equipment was facilitated by an interest free loan of $50,000 from the South Australian Environment Protection Agency under its Cleaner Industries Demonstration Scheme.

The Microsep unit, which is a combination of chemical reactor and clarifier within a single plant, is able to treat many forms of liquid waste. The plant pre-treats chemicals when necessary, then allows the resultant solids, including gelatinous precipitates, oils and grease to rapidly settle out. The plant can also filter previously unfilterable solids for disposal.

Waste water treatment facility

Waste water treatment facility

Non-sewerable wastewater streams are blended with rinse water (which was previously discharged to the sewer) to provide a homogenous feed to the Microsep facility. The products from this processing step are sludge and clean water. The sludge is then fed to a filter press to yield approximately 7 tonnes of dry cake in 7-10 days, and further clean water. The clean water is used directly instead of mains water for rectifier cooling and overflow rinses in the paint shop and chromium plating areas. Excess clean water is drained into the sewer and is the only water discharged in the process.

Water treatment and recycling process

Water treatment and recycling process

Advantages of the Process

Mains water usage has been reduced by over 10 ML per annum by reusing treated water. Direct discharge of wastewater has been reduced by 50 percent from 10.8 ML per annum to 5.4 ML per annum.

All liquid waste is now processed on site. The water discharged direct to the sewer is very much cleaner and lower in volume, placing less load on the municipal sewerage system. Solid contaminant loadings are 20 times lower than previously, with the level of contaminants per discharge well below the limits set in South Australia for trade waste. Level of contaminants, particularly chromium, zinc, oil and grease, and suspended solids, have been reduced substantially. Chromium content has been reduced by 96 percent, while total suspended solids after Microsep treatment are below 10 parts per million.

The volume of solids and sludge previously disposed to landfill has been greatly reduced. Further measures being considered include mixing the dry cake with garden soil to enhance nutrient levels.

Total Outlay:
Annual Savings:
Mains water usage
Liquid waste transport and off-site treatment
Chemical costs of pure water generation

Less Annual Operating Costs:
Microsep processing costs (water treatment)
Landfill costs (cake disposal)

Net Savings (p.a.)
Payback Period
2 years

Cleaner Production Incentive

The company undertook the initiative with a view to reducing all forms of waste generation and conserving water. It was particularly concerned to ensure that employees had a healthy work environment and that it was contributing to an improved environment for the surrounding community.


No significant problems or obstacles were encountered.

Further Developments

The initiative is still in use and continues to generate savings for the company. Monroe have recently become signatories of the Greenhouse Challenge and will seek accreditation to ISO14001 in mid-2001.


Bob Bond
Senior Engineer - Process and Environment
Monroe Australia Pty Ltd
1326 South Road
Clovelly Park SA 5042
Ph: (08) 8374 5222
Fax: (08) 8276 1653

Casestudy implementation: 1995
Casestudy initially prepared: August 1998 by the South Australian Environment Protection Agency in association with the Environment Management Industry Association of Australia (EMIAA)

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Last modified: May 2001