|Cleaner Production in the Dairy Industry||New Zealand||1993||Full scale|
MANUFACTURE OF FOOD PRODUCTS AND BEVERAGES # 27
The New Zealand Dairy Group of businesses is the largest dairy business in New Zealand, with 3,500 staff and an annual turnover of $2 billion. The Anchor Products' plant at Hautapu produces a wide range of high quality and specialized dairy products for export. When the cheese factory was expanded for the start of the 1993-94 year, one of the objectives for the project was to maintain or reduce the wastewater from this plant.
Cleaner Production Principle:
Housekeeping, Recovery, reuse and recycle, New technology
Cleaner Production Application:
In its endeavor to reduce/ maintain the wastewater generated, following the expansion of the cheese factory, the following CP options were implemented:
Recovery of Separator Desludge
During the separation of milk into skim milk and cream, a volume is discharged from the machine to clear the bowl. This material was removed from the general waste and used as stock food.
Wash water recovery
The wash water used in casein manufacture, which contains diluted whey solids, had been irrigated on to the farms until 1993. The business decided to recover this material as stock food. A reverse osmosis plant was installed for the 1993/94 season to concentrate these solids and produce a clean water stream. The process uses high pressure pumps to force water through a tight molecular structure. Up to five times the original solids level can be concentrated.
Reuse Water Recovery
Typically milk contains over 85% water when it arrives on the Anchor Products' site at Hautapu. Milk products leave in a dry form. The recovery of this water by evaporation and reverse osmosis allows water to be reused. The potential reuse of water derived from milk has been identified as 2,500 m3 per day.
When further reverse osmosis processing capacity was installed on site, a large resource of clean water became available. A recovery system was installed with the goal of reusing up to 1000 m3 per day for cleaning.
WPC plant expansion and lactose recovery
The Whey Protein concentrate (WPC) plant was expanded with the objective of processing all the sweet whey on site and recovering all permeate for lactose. This allows the recovery of valuable milk solids on site.
Processing of sweet whey has increased by 57% and the recovery of permeate has increased by 254%. The increase in lactose recovery from this project is approximately 50-70 tons per day that was previously being lost.
Reverse osmosis is also used for purifying the water used in the laboratory.
Reduction in nitric acid use
Nitric acid is one of the cleaning agents used in the plant. An alternative acid cleaner has now been tried across the whole site.
Environmental and Economic Benefits:
The amount of wastewater from the site, and the pressure on the disposal system has been reduced. Recovering water for reuse will become increasingly important as more pressure is placed on the waterways. The benefits arising from each of the options discussed above are as follows:
|Due to recovery of separator desludge, the business recovers useful material and thus needs to dispose of less waste.|
|Washwater recovery results in recovery of a useful material and results in disposal of less waste.|
|The reuse of water has the benefit of displacing fresh water and reducing the clean water load which either goes to the river discharge or to the farm system. The amount of waste water from the site and the pressure on the disposal system has been reduced. Recovering water for reuse will become increasingly important as more pressure is placed on our water resources.|
|Expansion of the WPC plant and lactose recovery has led to a reduction in the amount of waste that has to be disposed off.|
|Reduction in nitric acid use has led to reduction in nitrate loads to the waste water irrigation farms.|
The economic benefits of the CP options implemented at the Hautapu Site are summarized in the following tables :
Table I : Reduction of Wastewater Volumes
|Project Area||Before||After||Saving per annum||Nitrogen reduction|
|Cheese factory expansion*||1250m3/d||1120m3/d||$20,000||130m3/d|
|Separator desludge farm-waste recovered||$10,000||99.5kg/d|
|Wash water recovery farm-waste recovered||$50,000||167kg/d|
|Reuse water recovery||60m3/d||700m3/d||$150,000|
* When the cheese factory plant operation was compared for October 1992 and 1993, wastewater had reduced by 130 m3 per day, yet milk production had increased by 400 m3 per day.
Table II : Product Recovery
|WPC Plant expansion||1,400m3/d||2,200m3/d||up to $5,000,000|
The projects have shown consistent performance in reduced wastewater volumes and increased product recovery when the results for the 1993/94 and 1994/95 years are compared to the results for the year prior to implementation
The capital costs of projects have been a hurdle in a number of cases. With the increase in the number of uses of the reverse osmosis technology, the capital costs are expected to fall.
This case study was submitted to UNEP IE by the New Zealand Ministry of the Environment (address above). It was edited for the ICPIC diskette in July 1997. Subsequently it has undergone a formal technical review in September 1998 by Dr. Prasad Modak, Environmental Management Centre, Mumbai, India.