Environment industries archive
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Bayer Australia Limited formulates agricultural and veterinary products for the Australian and New Zealand markets at its Agricultural Operations Centre at Wong in NSW. Due to the nature of the materials the company has adopted a vigorous approach towards monitoring the quality and minimising the quantity of the waste it generates.
In January 1992 the company launched a waste minimisation program aimed at reducing its hazardous waste generation rate from 14 kg per tonne to 5 kg per tonne of product by 1996. Implementation of the program involved identifying all the waste streams, investigating the cause of waste generation and developing reduction strategies.
A waste assessment identified waste from the effluent treatment process as the most significant contributor to the total site waste generation. The effluent treatment plant utilised a carbon adsorption process to remove pesticides and other organic materials followed by a biological digestion stage to reduce chemical oxygen demand (COD). The waste activated carbon constituted more than 50 per cent of total site waste by weight. Other significant sources of waste included cleaning operations and contaminated packaging.
The strategy chosen to reduce spent activated carbon generation was the introduction of a secondary wastewater treatment process. The primary water treatment process now uses activated carbon as a crude treatment only and allows the bulk of the contamination removal to be performed by a specialised secondary biological digestion system, the Biotower. In this way the amount of activated carbon used in the primary process is reduced while maintaining the quality of the finished treated effluent.
The Biotower is essentially a trickling filter treatment system that involves trickling the effluent over a medium that supports colonies of bacteria. These colonies digest the organics within the water and convert it to additional biological material and respiration products - carbon dioxide and water. The wastewater treatment process is shown below.
Wastewater treatment process flow diagram
Overloading of the Biotower is prevented by:
In addition the Biotower is currently operating at approximately 25 per cent of the design capacity.
Biosolids from the tower are removed and fed into the activated carbon treatment process. The biosolids are then collected in the filter press and disposed of with spent carbon.
The regeneration of the spent activated carbon was investigated but not adopted due to:
The introduction of the Biotower and subsequent reduction in activated carbon usage was linked to a number of other cleaner production initiatives within the plant, namely:
Since commencing operation of the Biotower in mid 1994 there was an 80 per cent reduction in spent activated carbon, as shown in the following graph. Had the reduction in spent carbon generation not occurred it is estimated that an additional $80,000 would have been incurred in the purchase and disposal of carbon in 1996. The capital investment in this project was $163,000 and the additional operational costs are minimal. This provided a payback of just over two years.
Reduction in carbon spent over time
The total site waste was also reduced to the target level of 5 kg per tonne of production as a result of the cleaner production initiatives.
The Biotower technology was chosen on the basis that the system worked in other plants around the world. The transfer of technology from Bayer's plants in France and Italy to Bayer Australia facilitated the project.
No barriers were experienced by Bayer in identifying, installing and running the Biotower, due to the fact the technology is widely utilised on a number of similar sites.
The Bayer Agricultural Operations Centre has continued to benefit from this cleaner production initiative, one of many environmental initiatives by Bayer.
Mr S Bordignon
Bayer Australia Limited
Agricultural Operations Centre
16 Lucca Road
PO Box 561
Wyong NSW 2259
Ph: 61 2 4352 4200
Fax: 61 2 4353 3092