The solution to store, save and supply water
Saving water in dairies (part 3)
Part 3
Washing Vat and Milking Machine
The volume of water required to clean the plant varies with the size of the dairy. Larger dairies (over 60 sets of clusters) use up to 5,000L while even smaller dairies use around 2,000L daily.
This is not a place to skimp on water because getting a hygienic clean is vitally important for our industry. However, many farmers use a range of strategies to make sure they are using water wisely in the plant washing process.
The links below show some options:
- Enhance vat cleaning
- Check plant wash regime
- Increase turbulence
- Re-use detergent wash
- Re-use final rinse water
1, Enhance Vat Cleaning
Description
Cleaning the vat is not a place to skimp on water but it may be worth checking that your current cleaning regime matches the manufacturer’s recommendations.
As a general guide, the amount of hot water required for effective cleaning is 1-3% of the milk vat’s storage capacity, although the design of the vat makes a big difference and there is a poor relationship between size and water use. The number of cycles per wash and the temperature of each cycle will also affect the total volume of water required.
The newer spray heads ($150-$400) and pumps ($1,000 - $2,000) increase kinetic energy and can sometimes reduce water use.
Systems that re-use the detergent wash fluids are available but the costs of maintaining their temperature can be high.
Tips on Getting the Best Result
Check and clean spray heads periodically. Use correct chemicals. Retro-fitting vats with new spray heads can be tricky – seek professional advice.
Pros and Cons
New spray head systems can usually be retrofitted to vats with sealed lids, older vat designs may leak.
Issues in Making it Happen
Labour
Nil unless requires manual cleaning. Significant OH&S risk with entering confined spaces.
Milk Quality
Nil unless inadequate cleaning.
2,Check Plant Wash Regime
Description
Reviewing your cleaning program can often lead to water savings. Excessive water volumes mean higher water heating and chemical costs.
Jetter systems are by far the most water efficient way to clean the milking machine. Typically 6-8 litres per cluster are needed for each wash cycle. An easy way to check that enough water is being used is by ensuring the wash drum does not empty during recirculation. If it does, more water is required.
Some automatic cleaning units can further reduce the amount of water required for effective cleaning.
Reverse flow systems use a lot more water than jetter systems and are expensive to run, so consider installing a jetter system.
Tips on Getting the Best Result
Use a warm pre-rinse to warm pipework and remove most of the residue. Fully drain out pipework between milkings.
Check manufacturer’s specifications and take advice from your technician / chemical re-seller.
Pros and Cons
Better cleaning protects milk quality, reduces power and chemical costs. Lower volumes can mean quicker drops in temperature so monitoring is needed.
Issues in Making it Happen
Labour
Nil unless requires manual cleaning.
Milk Quality
Protecting milk quality is the primary concern and must not be put at risk.
Environment
Using less water means less waste to effluent.
3, Increase Turbulence
Description
Air injectors (also called ‘flushing pulsators’) increase turbulence and improve cleaning – making it less likely that additional cleaning of the plant will be required.
Air injectors are usually located on the milk line. They periodically (2-3 cycles per minute) admit air, creating a large slug of wash fluids to increase mechanical scrubbing down the milk line. They are standard issue on newer installations but some older dairies with milk lines of 50mm or more may benefit from a retrofit if cleaning is less than ideal.
Tips on Getting the Best Result
Should be fitted professionally and filters checked periodically. Easy to see if working by watching action of wash fluids through face plate of receiver.
Pros and Cons
Permanent fix.
Reduce power and chemical costs and may improve milk quality.
Will reduce the temperature of the wash solutions more quickly.
Issues in Making it Happen
Milk Quality
Should improve effectiveness of clean.
4, Re-Use Detergent Wash
Description
Acid detergent solutions designed for use in cold water are well suited for re-use. Capturing and storing the solutions for re-use requires minor changes to the pipework and an extra sealed wash barrel.
Capturing and storing the alkali solution is more problematic as the solution needs to be hot when used (at least 65oC). This means that the storage barrel needs to have a heating element and good insulation.
Regular monitoring of pH and top-ups are required and the solutions need replacing every 2 - 6 weeks (although some farmers do it less frequently).
Tips on Getting the Best Result
Commercial re-use systems are available but most examples in Australia have been put together by farmers and chemical supply companies on a case-specific basis.
Pros and Cons
Permanent water and chemical savings (and power too). Can use the best quality of water available for plant wash.
Difficult to automate and / or integrate into existing automated systems. Heating costs for keeping alkali hot can be substantial.
Issues in Making it Happen
Labour
Manual labour required, OH&S issues with storage of wash chemicals.
Environment
Nil - may improve this.
5, Re-Use Final Rinse Water
Description
The last hot (sterilising) rinse from plant washing can be saved and re-used as the first pre-rinse at next milking – saving 200-800 litres per day.
It is important that the pre-rinse water is warm (around 38oC) so the wash barrel should be covered and well insulated.
Tips on Getting the Best Result
Insulation is important to prevent heat loss during storage. Ensure the milking machine drains well after the each cycle to minimise contamination with detergents and milk residue.
Pros and Cons
Relatively easy to do as equipment is already in place. At present it is difficult to automate this or configure automated systems to save hot sanitising rinse.
Issues in Making it Happen
Labour
Manual labour required to divert wash fluids. OH&S issues with storage of hot water.
To be continued
