In late 1995, Australian National Railways (ANR) commissioned consultants to undertake a program of environmental audits of its locomotive maintenance workshop facilities in South Australia, Western Australia, Northern Territory and Tasmania. The audits were conducted primarily to identify potential environmental liabilities for ANR that could be addressed prior to the sale of its assets as part of a privatisation process.
During these audits, various problems with wastewater and effluent treatment systems on several ANR sites were identified. A review of ANR sampling records in South Australia showed that the coalescing plate separators (typically used to remove oils from effluent generated on the sites to allow discharge to sewer) failed to meet South Australian Water Standards for Discharge to Sewer in terms of oil and grease and suspended solids concentrations. Additional sampling and analyses confirmed that the treatment systems were performing poorly.
Further investigations of effluent treatment systems were conducted at several ANR facilities, with the aim of improving the performance of existing systems or recommending appropriate replacement systems to meet the required standards for discharge to sewer.
Prior to the cleaner production initiative, there was no control over chemical use on any of the ANR sites. About 20 different chemicals were being used in the cleaning yards, which were discharged into the effluent system.
The oils, solvents and degreasers formed a highly stable emulsion, making it impossible for the coalescing plate separators to function. This was because plate separator technology relies on oil droplets coalescing to form larger droplets, which then separate out due to density difference. If a stable emulsion is present the drops do not coalesce and separation will not occur.
Cleaner Production Initiatives
Over a period of several months, three major ANR operational sites were comprehensively studied in terms of effluent generated at each site. This involved the detailed analysis of the components of the effluent and volumes, as well as the activities undertaken on the sites producing effluent requiring treatment.
The studies revealed a diverse range of cleaning, degreasing and hydrocarbon-based chemicals being used on all of the sites. While manufacturers of many of these chemicals characterised them as quick emulsion breaking types (ie. emulsions destabilise to allow oil droplets to coalesce and separate out),the effluent 'cocktail' produced prevented the coalescing plate separators from breaking down the emulsified oil.
To maintain the quick breaking characteristics of cleaning chemicals, a rationalisation of cleaning chemicals used on ANR sites was required. Trials were conducted therefore with replacement cleaners on two ANR sites, including Dry Creek in metropolitan Adelaide.
It was found that two quick breaking emulsion type compatible chemicals could be used to replace the 20 previously in use.
Advantages of the Process
Trial assessments indicated that the replacement cleaners improved cleaning efficiency, reduced operating costs by approximately 20 percent,and allowed effluent to be more readily treated using coalescing plate separator technology.
The measures introduced allowed the sites to improve sewer discharge quality. Environmental performance and cleaning efficiencies have therefore been improved, reportedly at reduced operational cost.
Cleaner Production Incentive
Failure to meet the South Australian Water Standards for Discharge to Sewer was a strong incentive for the cleaner production measures.
However, the obligations on ANR to identify and address potential environmental liabilities prior to the sale of its assets as part of a privatisation process was a critical inducement.
The introduction of the measures was met with some resistance from site management and staff, reflecting the low priority given to the effluent aspect of operations.
However, the consultants had strong allies in ANR's senior management and its Environment Manager, who recognised that there was a serious problem in complying with the trade waste licence.
After the success of the trials in Adelaide, similar measures were adopted in other yards in South Australia and Tasmania.
Case study coordinated by the Environment Management Association of Australia (EMIAA), April 1998.