The Coca Cola Amatil (CCA) Northmead plant in Sydney was established in 1972 and manufactures a wide range of world recognised Coca-Cola trademark soft drink products, such as Sprite, Fanta, Lift and Coca-Cola.
The Northmead plant has one aluminium can line and two plastic PET bottle lines. It produced over 250 million litres of soft drink in 1995.
The manufacture of soft drinks requires large volumes of water. This is treated on-site to meet product quality requirements before being used in the production process.
The Northmead plant treats an average of 1.5 million litres of municipal water daily using a conventional flocculation plant. This can operate at a rate of 200,000 litres per hour (using one older water treatment plant at 100,000 litre/hour and one new water treatment plant at 100,000 litres/hour). Three types of filters are used - sand, carbon and polishing filters.
The company cleans the 10 sand and carbon filters on a daily basis by forcing water back through the filter - a process known as back washing. The new water treatment line allows for the back washing process to incorporate air (known as air sparging) to reduce the amount of water required.
The generation of backwash water is dependent on production levels, but is estimated to reach up to 200 kilolitres a day. The backwash water is disposed to the sewer.
Cleaner Production Initiatives
The cleaner production initiative that CCA implemented involved recycling the backwash water through the treatment plant, allowing it to be reused in the manufacturing process. The recycled water must meet strict quality standards, and can only be used in the ratio of 10-20% with non-recycled water to ensure that there is no compromise in final product quality.
Efforts are also being made to reduce the amount of material that contributes to the high BOD (biochemical oxygen demand) levels entering the effluent system. This includes the addition of a PIG (pipe cleaning system) that physically forces residual syrup out of the pipework and into the production process, thus reducing the amount that is discharged to sewer during cleaning. This will result in cost savings from reduced syrup wastage, and reduced trade waste fees.
Advantages of the Process
The installation of a backwash recovery tank, pipework and additional filter was $150,000. This compares with the annual savings of $100,000 from reduced municipal water consumption.
The initiative has also resulted in a 25 per cent reduction in trade waste discharged to sewer. Now the only source of wastewater generation is from equipment cleaning.
Under current trade waste regulations the trade waste discharge agreement is based on the concentration of the waste, not the total load. Such a significant reduction in the volume of essentially clean water going into the trade waste system has resulted in an increase in the contaminant concentration levels - particularly for BOD. This will mean that in the short term the Northmead plant will be charged an increased amount to dispose of its trade waste. This is estimated to cost an additional $15,000-20,000 per annum.