Bayer Australia Limited formulates agricultural and veterinary products for the Australian and New Zealand markets at their Wyong Formulation Plant 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 has 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.
Cleaner Production Initiatives
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 ëcrudeí 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.