A survey of waste management practices in Victorian dairy factories

This paper reviews the waste management practices of 24 of the major dairy processing factories in Victoria, Australia. The identified total annual costs associated with waste management for the factories was more than AUD$36,760,000, which included the use of more than 11,000 t/year of cleaning-in-place (CIP) alkali and 3,000 t/year CIP acid cleaners at a cost of more than AUD$16,700,000. The total amount of water consumed annually by the factories was more than 10.5 GL, 78% of which was potable water. The recycling and reuse of water was common practice for pre-rinsing, CIP make-up, plant washdown, boiler feed/steam production or membrane washing. The relatively low cost of water and the ease of effluent disposal were found to be disincentives for factories attempting to use less water. The most common biological process for wastewater treatment was aerobic or facultative treatment in ponds or lagoons. Some 10 GL of wastewater was annually discharged in the following approximate proportions: surface-waterway 13%, land 44% and sewer 43%. The corresponding figure for sodium discharge was in the order of 3,400 t/year distributed thus: surface-waterway 8%, land 60% and sewer 32%. For factories providing enough data to conduct a reliable sodium balance (6), total sodium entering as CIP chemicals ranged from 21-64%, while sodium entering as raw material (e.g. milk) and salt varied from 19-67% and 1-57%, respectively. Of the sodium leaving these same factories, 29-64% was in the wastewater. Sodium analyses of many waste streams were not provided. Some waste streams, such as whey, sludges and product rejects, were reused or recycled as stockfeed to piggeries, while some were sent off-site for composting. The main concerns for these wastes were associated with the lack of long-term sustainable options for reuse and recycling.