Dairy upgrade presents water recycling opportunity
Dairy farmers Brenda and Alex Spencer are midway through a dairy upgrade for the 200-cow farm they lease from Alex's parents, Russell and Joan Spencer, in Leongatha North.
'We are half-way through extending the cow yard and plan to also re-locate the laneways to improve cow flow and comfort,' Alex explains.
'As part of this plan we also hope to recycle effluent for yard washing', Alex said.
Installing hydrant washers
So far Alex and Brenda have installed hydrants in the cow yard, which Alex hopes will reduce the amount of time it takes for yard washing.
'We are spending 30 minutes a day cleaning the yard, so these hydrants will free up a bit more time', Alex says.
The hydrant washers will also be using effluent from the effluent system to wash the yard. This will save 5000 litres of fresh water each day — that's 1.8 megalitres, or 1,800,000 litres over the course of a year. The water saved will help to reduce the farm's dependence on the spring-fed dam supplying the property.
Capturing rainwater for plant and vat washing
The property is set up to capture as much rainfall from shed roofs as possible.
The dairy shed has well maintained guttering on all roof areas that flow into a plastic water tank. This water is then used to clean the plant and for vat washing.
The dairy shed roof which has an area of approximately 490 m² can capture 443,156 litres per year (annual rainfall of 952mm — this assumes 95 per cent of the rainfall enters the tank). Some of this water may overflow once the tank is full.
Benefits of using rain water
Using rainwater for plant and vat washing has many benefits such as:
- rainwater is typically better quality than bore water or river water
- river water used in the dairy may require filtration to remove sediments which can build up in the hot water service
- river water can also contain organic matter that can bind up chemicals and detergents
- bore water may be high in mineral salts such as iron oxide and may be hard
- detergents do not perform well in water that contains high levels of minerals or salts which are common in bore water
- poor quality bore water can also corrode metal work in the dairy.
Using plate coolers in dairy sheds
The plate cooler in the Spencers' dairy shed recycles rainwater. The water comes from an in-ground well, through the cooler and back into the well.
Plate-coolers are often the biggest user of water in the dairy.
When considering water use efficiency on farm, it's important to consider where the plate-cooler water goes. If plate-cooler water leaves the shed to a storage tank, check to see that the tank doesn't overflow when the plate-cooler is running for longer periods of time. If it is overflowing, there is a potential opportunity to either capture this water or divert it away for environmental flows such as to a wetland or dam.
The hot water rinse from the plant wash is recycled and used for the following milking's first flush. This saves around 300 litres per day, or 109,500 litres per year.
Upgrading the effluent system
In order to recycle effluent effectively, Alex and Brenda are planning to upgrade the effluent system. This will involve cleaning out and enlarging the existing single pond, and may include some form of solids removal such as a trafficable solids trap into the future.
Planting trees to reduce water consumption
Brenda and Alex also plan to plant more trees on the property to create shade for their cows. This can have the added benefit of reducing the stock drinking water consumption.
A lactating dairy cow can drink as much as 200 litres per day in the peak of summer.
The volume of water consumed will depend upon many factors including:
- the condition of the animal
- animal's diet
- animal level of activity
- quality of the water
- environmental conditions such as humidity and temperature.
- Good quality rainwater for vat and plant washing saves on cleaning chemicals and corrosion.
- Pressure on effluent storage ponds is relieved by recycling effluent for yard washing.