Milk cooling efficiency
- The primary milk cooling system should use about two to three times as much water for the volume of milk cooled. If there is a continuous flow of water when milk is coming through the cooler intermittently, more water is being used than necessary. To cut this water use, a solenoid valve can be installed at the inlet to the cooler and linked to the milk pump, or a variable flow drive so water and milk flow match.
- Use correct flow rates through the plate cooler – two to three litres to every one litre of milk. Increasing water volume does not decrease water temperature. To check the ratio click here.
- Ensure the plate cooler is serviced regularly and has adequate pumps and water storage to function efficiently. Cleaning and improving the efficiency of plate cooling will require the services of a technician who can align the plate’s spacings correctly.
- Pre-cooling water before it enters the shed can improve water use efficiency as less water is needed to cool milk. Click here for more information on milk cooling systems.
Reducing plant and vat wash water
- Ensure all refill tanks and cylinders have an automatic shut-off to avoid overflows. Toilet cisterns or trough floats have been used as proven refill and shut off options.
- Consider heat exchange or pre-heating to improve energy efficiency.
- Seek advice from your detergent rep on litres required for hot/cold wash options.
- Hot water used for plant clean-up can be reused for any cleaning around the dairy shed (e.g. washing out buckets) saving electricity as well as water.
Improving yard washing efficiency
- On warm, sunny days, pre-wet the yard with a hose or sprinkler to help prevent dung from sticking.
- Use a scraper or a chain (inside an old yard hose) on the backing gate to break up dung before hosing.
- Wash the yard after each milking.
- Work the hose water actively and close to the effluent.
- Hose the yard with high water volume under low pressure so you are pushing effluent not spraying it around.
- Include a timer setting on the yard wash down pump. Set a time standard for wash down and train staff to achieve it.
- Consider capturing excess cooler water (that would otherwise go to waste) in another tank or tipper drums for yard wash.
- Flood wash with greenwater recycled from the effluent pond. There are strict compliance requirements for this practice under the New Zealand Food Safety Authority’s Code of Practice for the Design and Operation of Farm Dairies (NZCP1). If you are recycling green water, get advice from your dairy company representative to ensure you are compliant with terms and conditions of supply.
Water saving tips
Liquid ring vacuum pumps
Half of the water from liquid ring vacuum pumps can be recycled (as long as the temperature is less than 40°C) and half captured for yard wash. Check the manufacturer’s specifications for your pump as the temperature of the water needs to remain below specific values.
Rotaries
Minimise the number of nozzles in the milking shed and consider using water blaster nozzles to reduce flows. Have smooth easy to clean surfaces in the dairy and use scrapers to wipe effluent off the rotary to speed up wash down. Consider air blasts or other methods such as floating plastic toys instead of water to get cows to back off.
Choosing the right system
Get water-use specifications from the manufacturer if installing a new system. Commercial yard washers and clean flood water washing are time efficient but can use a lot of water. Weigh up staff time, power costs and water use when choosing an efficient system for the milking shed.
Calculating effluent volumes
Reducing the volume of water used for yard wash down can significantly reduce effluent storage requirements. The Dairy Effluent Storage Calculator is a tool to determine the dairy effluent storage requirements for a dairy farm.
Capture and use rainwater
Rainwater from the dairy shed roof that drains onto the yard enters the effluent system. Capturing this rainwater by diverting the gutters into a tank reduces the volume of effluent you have to manage and store. It also provides water for yard wash-down which reduces the amount of fresh water required from your main supply.
Look out for overflows
Be vigilant to tanks or cylinders losing water and get everyone on farm into the habit of watching for problems. Installing an auto shut-off wherever possible will eliminate this risk of water loss.
Daily check on pressure of water at the taps and hoses
Low water pressure at taps and hoses can alert you to water loss in the system. On some farms, water pressure in the house may be affected by water use out on the farm. This can be a helpful sign any time day or night.
Tank floats
Floats in tanks should be set far enough down from the top that overflows are avoided. Check your tanks and make adjustments where necessary.
Recycle cooler water
If you have once-through cooler water in excess of what’s needed for yard wash-down, consider installing a tank close to the shed to store the excess. This water can be used later for yard wash-down or reticulated down the farm as stock water.
