The quality of raw wastewater inflows to Melbourne’s Eastern (ETP) and Western (WTP) Treatment Plants is of particular interest, as it is vital to the success of efforts at those locations to recycle water and to mine waste water for a variety of end uses. Work in this project assessed a variety of industrial sources of sewage contaminants, their contribution to overall waste water quality and identified possible remedial action for some industrial sites. The specific pollutants addressed were colour, cadmium, copper, zinc, mercury and boron. These are all priority contaminants in the Melbourne sewerage system.
The fundamental objectives were:
- to evaluate the sources of critical contaminants
- to assess practicable industry based measures to reduce their discharge.
Water quality at Melbourne’s treatment plants was not found to be dominated by any particular industrial source.
A number of sewage components from industrial sources limit reuse and recycling of treated effluent and biosolids. These were identified and selected as key contaminants for study as follows:
- Metals – Cadmium, Mercury,
- Copper, Zinc
- Metalloids – Boron
- Biodegradable Colour – UV Spectrometry & Transmittance
A literature and data review of existing approaches to monitoring contaminants and their sources was conducted.
Investigations were undertaken to find the individual industrial sites that are the main sources of these contaminants in trade waste water being discharged to Melbourne’s Sewerage System. This included assessment of pollutant loads from the highest ranked industrial sites as a portion of the total load in the inflows to the ETP & WTP plants and included a two week composite sampling program at ten industrial sites across Melbourne for each contaminant.
Completion of this monitoring program was only possible with the participation of four of Melbourne’s Water authorities, government agencies and the assistance of private companies. URS appreciates the cooperation and support received from all these organisations.
While water quality at Melbourne’s treatment plants was not found to be dominated by any singular industrial source or industry. A number of sites were identified as having sufficiently high loads that pollution reduction measures should be considered. This recommendation applies to:
- Industrial Waste Treatment Sites: Boron reduction (three sites),
- Cadmium and Zinc reduction (one site each)
- Inks and Dyes : Cadmium Reduction (one site)
- Leather Processing: Boron (one site)
- Glass Manufacturing Zinc (one site)
- Landfill: Boron reduction (one site) and Zinc (one site)
- Metal Finishing Plant: Copper (one site),
- Boron and Zinc (one site)
Sites assessed for production of colour contamination were limited, however the textile industry generally was found to be a candidate for colour contaminant reduction measures. Application of these measures together would result in improvement in the quality of water inflows to Melbourne’s ETP and WTP treatment plants.