The unique benefits of a bladder tank for effluent storage make them the ideal solution for some specific farming situations. However, there are some common situations where a bladder tank is an option but may not be the best option when considering investment costs, system efficiency and futureproofing of the farm.
When A Bladder Tank Is Best
One of the main features of a bladder tank is that it provides a closed effluent storage solution. The benefits of closed storage is that there’s no risk of oxidation, external contamination, evaporation, or people falling in! They are also transportable and earthquake resistant. This makes bladder tanks the ideal solution for:
- Swampy & high-water table sites where it’s not possible to dig an effluent pond.
- Temporary sites, such as leased land, or where a farm is being restructured, and you do not want to install infrastructure.
- Extremely high rainfall areas, where a pond would be prone to overflow. These are areas that experience rainfall of 3 metres or more, as evaporation must always be considered.
- Sites close to residential properties where safety, odour and council compliance are an issue.
Other Common Considerations
Bladder tanks are a common consideration for dairy farmers who need storage for deferred irrigation from their sump, or when the main storage pond is not big enugh. If you are considering buying a bladder tank for these reasons, you may want to weigh it up against the cost and benefits of a HDPE lined pond.
HPDE lined ponds are the most popular choice of effluent storage in New Zealand, and there is a good reason for it. When looking at the wastewater industry across New Zealand, over 60% of containment is in HDPE lined ponds. This means just 40% is spread across bladder tanks, above ground tanks, rubber lined ponds, unlined ponds and any other form of wastewater storage.
At a cost of $20-50K for a bladder tank it is often more cost efficient to install a HDPE lined pond or upgrade your existing effluent storage. While a bladder tank may still be the right choice for your farm, here’s why we’d recommend considering a HDPE lined pond where possible:
- Cost effectiveness – HDPE lined ponds are the most cost effective storage solution in terms of installation, management and maintenance.
- Energy efficient & council compliant – wherever possible, effluent should drain to your main storage through gravity. Not only does this save on energy requirements in terms of pumping, but there’s peace of mind knowing if there’s a power outage your effluent is still running to the right place.
- Futureproofing – A HDPE lined pond will last a lot longer than other effluent storage options and is easy to integrate with other effluent management equipment.
- Solids management & nutrient use – Managing solids is much easier with a pond. Using a shore mounted electric slurry stirrer or PTO stirrer the effluent can be thoroughly mixed, meaning nutrients are evenly distributed. Although a submersible stirrer can be used for a bladder tank, this will not be able to achieve the same efficiency or effectiveness.