The Cleaner Production Demonstration Project (the Project) was an initiative of Environment Australia -The Environment Protection Group (EPG). The aim of the Project was to raise the awareness of Australian industry and actively promote cleaner production issues. This was to be achieved by conducting ten successful cleaner production demonstration projects in industry around Australia, documenting the benefits and experiences of the project, and publicising the results to wider industry. Dames & Moore, assisted by Energetics, were engaged as technical consultants on the project. The project commenced in June 1994, and ran for 27 months.
Bonlac Foods' Stanhope facility in Victoria was selected as one of the ten companies to participate in the project. This case study represents a record of progress of the Bonlac project, and any problems or lessons which may have been encountered. The case study demonstrates the application of Cleaner Production to the dairy foods processing industry.
Bonlac Foods, Australia's largest manufacturer of dairy products, is committed to producing high quality dairy products with minimal impacts to the environment. When producing cheese and milk powder, Bonlac is faced with the problem of preventing small particles of cheese entering its waste water drainage system. These particles represent a loss of product and add an unnecessary load onto the waste water treatment facility.
In addition, Bonlac must ensure that all process equipment, pipes and tanks are kept clean and free of unwanted micro-organisms. This is achieved with a periodic chemical flushing process called, Cleaning In Place (CIP), and involves the use of both alkaline solutions and acid detergents. These chemicals ultimately discharge to the waste water treatment facility and increase the load on the system.
The cleaner production demonstration projects that were initially identified were as follows:
- changeover to Stabilon® detergent in the CIP process;
- diversion of waste water to landfarm treatment/disposal;
- capture of solids from cheese room waste water;
- and alternative disposal of soap stock.
Alternative CIP Cleaning Process/Solution
The use of Stabilon ® was expected to reduce the use of an acid cleaning solution in the dairy CIP process. It was also expected to reduce the total volume of waste water and phosphorous levels in the effluent being discharged to the waste water treatment facility. Change over to Stabilon®; detergent was found to reduce the cycle time of the CIP process, providing more time to produce cheese. This resulted in an income net benefit of about $310.00 per day.
Diversion of Waste water to Land Filtration
Some of the less contaminated waste water streams were to be diverted to a farm for spray irrigation thus reducing the biological and hydraulic load on the effluent treatment facility. The diversion to farm is limited to the drier months. Soil which is too wet cannot effectively handle the additional waste water.
Results of a ten day trial indicated a 30% reduction in the waste water volume discharged to the waste water treatment facility. The diversion will recommence on a regular basis in the next cheese production season.
Solids Screening, Cheese Room Waste water
Appreciable quantities of cheese solids are lost to the drain in the cheese room operations during normal production, daily wash down and the CIP process.
Bonlac aims to capture these solids and reduce the organic load on the waste water treatment facility. Two methods were proposed to deal with this issue. The first involves installing screens at the points where the large losses occur. The second method involves installing two large settling tanks in the whey room to capture cheese fines in the process rinse water. The impact of the project was to be assessed by monitoring the total suspended solids levels in waste water discharge from the cheese room.
Overall levels of suspended solids in the water was immediately noted as a results of the project implementation. The reduction was not as significant as expected but this is largely attributed to only one settling tank being commissioned. In addition, insufficient time was available to properly tune the tank to operate at optimum design conditions. This is believed to have reduced the effectiveness of the settling tank in removing the solids from in the waste water discharge. However, Bonlac will have both tanks operational and fully tuned for the next cheese production season. It is expected that the TSS level in the waste water discharge will show a significant reduction.
The total cost for the works to capture the cheese fine was about $30,500 The budget recovery of the fines was monitored by Bonlac Stanhope on a monthly basis. The recovery is expected to translate as $100,968 Therefore, the payback period for this project is less than 4 months.
Alternative Disposal of Soap Stock
Soap stock is a by-product of anhydrous milk fat production. It is basically a mixture of caustic soda and free fatty acids, and is approximately 5 % solids. It is normally disposed to landfill at a property owned by Bonlac. An opportunity was identified to sell the product to commercial soap manufacturers, however the natural composition of the soap stock was found to vary beyond the specifications imposed by the soap manufacturer and the project was postponed indefinitely.
A key lesson from this Cleaner Production demonstration project is that the process of compiling the environmental and process data in itself plays an important role in the identification of Cleaner Production initiatives. Other important lessons which emanated from demonstration project include the importance of commitment from management, ideas are encouraged in teams commissioned to assess specific parts of the operation, and that opportunities do not have to involve large capital costs.
Cleaner Production initiatives have been implemented at Bonlac Foods (Stanhope) with significant improvements. This has provided Bonlac with incentive for other Cleaner Production opportunities to be investigated and implemented.