Water savings planned with new dairy
A new dairy for Binginwarri dairy farmers Bernie and Bettine Dijs has thrown up new opportunities to implement water-saving measures. The result is likely to be a healthier bottom line and a healthier environment.
Binginwarri dairy farmers Bernie and Bettine Dijs are facing the challenges and excitement of planning and building a new dairy.
They are mid-way through building a 60-unit rotary which includes many innovative features to help improve water, energy and labour efficiencies.
Milking to date has occurred in a 32-unit herringbone shed which can take up to three-and-a-half hours per milking, at peak, for 500 cows.
Bernie plans to expand the herd to 650 cows in the near future.
It is anticipated that the new shed will halve the milking time and provide the infrastructure, including larger vats, needed for the growing herd.
"Halving the milking time to two hours means that we will be reducing the time in the shed and also water needed for the plate cooler to cool the milk," Bernie reasons.
Water use in the plate cooler should be related to the amount of milk and its flow rate.
A rotary will have more milk flow, so more water will be needed per unit of time than a smaller dairy.
However, newer dairies use an industrial plate cooler that has a lower ratio of water-to-milk than the smaller plate coolers often seen in older dairies.
The new dairy will also have a two-staged plate cooler.
The first stage uses bore water and the second stage uses a chilled water-glycol mix.
Two-stage pre-cooling allows the milk to be chilled to six degrees by the time it enters the vat.
This process helps with chilling, so the vat will only need a smaller compressor.
"We also hope to install new plant cleaning equipment that will recycle detergent and also has a cold water rinse," Bernie said.
"This will help to save on detergent and energy costs for heating the water."
The dairy has also been designed to maximise cow flow.
This includes a cow underpass to allow milked cows to go under cows coming up the lane into the dairy. This feature has allowed Bernie to have a yard that holds 200 cows, even though he intends to milk 650 cows.
Whilst saving space and costs in terms of concrete, the underpass also helps to save the amount of water used to wash down the yard.
This is because the cows are spending less time on the yard and are therefore manuring less.
The new yards will be washed with two hydrants.
These save time and water, targeting dirty areas of the yard rather than having a more 'broad brush' approach.
The effluent is gravity-fed from the yard into a two-pond effluent system. The effluent from the second pond can also be recycled for yard washing.
Capturing shed run-off for plant wash
Bernie's shed is supplied with bore water – not always an ideal option. "Bore water can be hard on equipment, and can contribute to a ferric build up on the plant," Bernie explains.
Consequently, rainwater is needed to clean the vat and plant. For this purpose, a 270,000-litre rainwater tank has been installed to harvest water that falls onto the 672m² shed roof.
So how much water can the roof supply?
If Binginwarri receives 850mm per year then rainfall falling onto the roof for one year is equivalent to:
- 672m² x 0.85m x 0.95 (runoff factor to account for evaporation and gutters overflowing) = 542.64m³ To convert metres cubed to litres, multiply by 1000. Therefore, rainfall harvested is equal to 542.640 litres or 0.543 megalitres per year.
- This roof area can supply 1486 litres of rainwater per day.
The plant rinse requires 900 litres (minimum) to 1800 litres (maximum) of water to run.
If the plant is rinsed twice daily then 2000 litres of water will be required.
As a result, recycling the water that is used for plant rinsing may need to be considered for this operation to make up the shortfall.