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 companyís total production is exported to Asia, North America and Europe.
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 45 KL 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 70 ML of water was used in the production process with almost 15 ML being generated as liquid waste. Excess water cost in 1994 was more than $50,000 with wastewater streams of 52 ML. 12 ML 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 companyís 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.