- Sustainable Effluent Management
An effluent pump is a key part of that system, moving effluent from storage to where it can be put to good use across the farm. Choosing the right pump and setting up your pond and application equipment correctly can help you make the most of the nutrients in your effluent while keeping the system working effectively.
Local council regulations must comply with the Resource Management Act, making it more important than ever for farmers to have a robust effluent management system in place. The good news is that once you implement best-practice techniques, you’ll turn your waste into a valuable resource that delivers good returns. You can feed your farm with nutrients and reduce your dependence on artificial fertilisers.
Here, we discuss what an effluent pump is, what it is used for, and factors to consider when choosing a pump and managing the wider effluent system on your property.
An effluent pump moves liquid waste from storage ponds to application areas across your farm. Unlike standard water pumps, effluent pumps are built to handle the abrasive nature of farm waste, including the bits and bobs swept up from the cowshed and yard that would quickly destroy conventional pumping equipment.
They must be robust and typically feature hardened impellers, wear-resistant casings, and powerful motors that maintain consistent flow rates even when handling thick, contaminated liquids.
Effluent pumps power your irrigation systems, whether you’re using a drag hose or a travelling irrigator setup. They provide the muscle, meaning the pressure and flow, needed to distribute effluent evenly across your paddocks.
They also allow you to transfer effluent between ponds for cleaning, remove accumulated solids, and manage water levels during heavy rainfall events.
Your pump is only one part of the wider effluent system, so your pond design, capacity, placement and management all influence how effectively you can store and move effluent around the farm.
Effluent ponds are storage systems designed to collect and store the liquid waste produced in your cowsheds, feedpads, and other farm facilities. These ponds serve as the central hub of your nutrient management system, temporarily holding effluent until you can spread it on your paddocks.
Effluent management regulations in New Zealand are comprehensive, with regional councils setting specific rules on storage capacity, application rates, and setback distances from cowsheds and waterways. Understanding these requirements when setting up and managing your pond will save you a nightmare later on.
Years ago, it was common to have three ponds to collect and filter effluent from the cowshed. That’s no longer possible. Best practice for an effluent pond today is very different.
Council regulations often mandate lined storage to prevent leaching and use drop testing to check for leaching and leakages. Many existing ponds are unlined or lined with clay, so that’s the first thing to check. Is your pond compliant with your local authority rules?
Careful pond design is your crucial first step for effective effluent management. Your ponds must be sized to handle daily effluent production, cope with sudden downpours, and provide adequate storage during bad weather when you can’t get out to apply the effluent to your paddocks.
They can range in size from 500,000 litres to 6,000,000 litres, although the average size in New Zealand is two to three million litres. The required size depends on your herd size and your farm’s topography.
On average, one cow produces 50 litres of effluent per day, so for instance, a 200-cow herd will produce 10,000 litres of effluent per day. However, the larger the pond, the larger its footprint and rain catchment area. It is often good practice to go deeper and have a smaller footprint.
Ideally, place it lower than your cowshed so gravity can move the effluent to the pond; otherwise, you will need a pump.
Milk supply companies also have specific setback requirements from the cowshed, along with regulations on distances from waterways and neighbouring properties. Consider prevailing wind directions to minimise odour impacts on neighbours and your own facilities. Working with an accredited designer like Nevada will help you make all those decisions.
High-density polyethene plastic (HDPE) pond liners offer the widest and most secure range of options. This tough, high-strength material comes in a wide range of sizes, depths, and shapes, and complies with environmental and regional regulations.
HDPE liners are preferred over rubber because the seams are welded together, ensuring longevity. Rubber-lined ponds are more likely to use adhesives to join seams. HDPE liners can be customised to your terrain and circumstances. You can choose from several factors, including geomembrane density, tensile strength, UV durability, and chemical resistance, to find the perfect liner for your topography.
Managing your pond level is important. If you leave it too long and the level rises too high, it can lead to expensive problems if you are caught off guard by a sudden downpour or a pump malfunction.
Getting contractors in to empty your pond is also expensive. You will get better value out of your pond by spreading fresh a little, and often. Before busy periods on the farm, like calving time or before winter, you want the level as low as possible.
In winter, there are fewer opportunities to spread because of the wet weather. A low level at this time will give you some wiggle room.
You have several options, and this is where your effluent pump comes into its own. With a pumping system at the pond, you can pump through a pipeline to an irrigator. Once set up, this is simple to use and can be automated, allowing it to spread at night as well.
The drawback of a travelling irrigator is that it requires a lot of manual handling, takes hours to set up, and blockages are not uncommon. Irrigators are also less precise. They throw the effluent higher, which increases volatilisation and makes it harder to get close to waterways and boundaries..
A drag hose system can move the most effluent. A drag hose system can manage 100 to 200 cubic metres an hour. For comparison, a travelling irrigator can only handle 20 cubic metres an hour.
You can use it across multiple farms or irregularly shaped paddocks, helping you get the job done quickly and efficiently. The only drawback is that you have a smaller window of opportunity to use a drag hose system. You have to pick your days; the weather conditions have to be right, and if you use it continually in one place, you will oversaturate the paddock.
A slurry tanker is your best option if you want to spread your effluent efficiently. Slurry tankers can hold from 6,000 litres to 37,000 litres of effluent. A 12,000-litre tanker takes about three minutes to fill and lets you reach every corner of your farm, getting closer to waterways and boundaries. This can save you thousands in fertiliser costs.
Effluent quality will quickly diminish. By spreading often, you use your effluent when it is most nutrient-rich, and your paddocks receive the greatest benefit.
Three key factors matter when selecting a pump.
First, your irrigator specifications vary, and each has different flow and pressure requirements. Then there’s the elevation. Do you need to pump uphill or downhill to your paddocks? Then there is the distance.
Together, these factors determine the pressure and flow your effluent pump needs. Choosing a pump without considering the wider system can leave you with too little pressure at the application point or more pumping capacity than you actually need.
Check out our article on pressure and flow requirements for your effluent pump, with links to handy pressure calculators.
We recommend a progressive cavity (PC) pump for most setups; they are shore-mounted, safer, and easier to service, and can be automated with an intelligent pump controller. You can find a whole discussion about the merits of progressive cavity pumps versus centrifugal pumps here.
Then you have to decide what to choose: an electric pump or a PTO-powered pump. Electric pumps offer convenience and automation, but running power to your pond can be prohibitively expensive.
A PTO-powered pump isn’t an issue, and it’s also more powerful; you can run it across multiple farms if you need to. We can help you weigh up the pros and cons of each system.
Pond capacity problems often develop gradually as solids accumulate, compromising your effective pond volume. To negate that, it is good practice to stir your pond before you spread. You might think you can save a step and go straight to spreading, but you are doing yourself a disservice.
If you leave the effluent to its own devices, the solids and liquids will separate. Over time, the solids will generally sink to the bottom of the pond, reducing the volume. The top layer of liquid will also have a lower nutrient value.
Hiring a contractor to empty the pond and remove the solid buildup will be expensive, a significant portion of the cost of a stirrer. Nevada stirrers are shore-based and use centrifugal force to mix the whole pond. Submersible stirrers only move a fraction of the pond material.
If you discharge effluent onto the nearest paddocks to the cowshed, you can saturate the ground and cause metabolic problems in your cows. By spreading it across the whole farm, you can rotate paddocks as the cows move. This gives the paddock the maximum time to regenerate.
Success in effluent management comes from treating it as an integrated system, not isolated components. Your effluent pump, pond design, application equipment, and management practices can all work together.
This will transform a simple waste product into a valuable resource for your farm. Effluent is a rich nutrient resource that can improve your soil, help you grow grass, and ultimately increase milk production.
If you need help with any of these, please reach out to our sales team. They know their stuff and will be more than happy to help you find the best solution for your farm.
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