The launch of a new dairy effluent treatment technology that dramatically reduces methane emissions from farm dairy effluent ponds by more than 90 per cent has generated significant interest from New Zealand dairy farmers.
The technology, called EcoPond, has generated multiple inquiries and two pilot plants are installed, with plans to roll out another four or five early adoption units by early 2023, Ravensdown's EcoPond development manager Carl Ahlfeld said.
New research by Professor Hong Di, Professor Keith Cameron and PhD student Che Xueying of Lincoln University has also been published showing that, at the same time as reducing methane emissions from effluent ponds, EcoPond technology can also reduce the risk of phosphate and E. coli leaching from effluent application areas into water.
Reductions in the amount of dissolved reactive phosphate (DRP) are particularly important to help reduce nutrient pollution of rivers and lakes. Detailed scientific studies have now shown that EcoPond technology can reduce the risk of DRP leaching from effluent application areas by more than 90pc.
Professor Cameron said: "This finding is important because phosphate is often a limiting factor for the growth of aquatic algae associated with the eutrophication of streams and rivers. If we can reduce the phosphate going into rivers and lakes it will help to improve the health of those rivers and lakes."
Professor Di said the reduction in phosphate leaching occurred because the treatment additive used in the EcoPond system (iron sulphate) reacts with the DRP, converting it into a slow-release form of phosphate. This could be stored in the soil for plants to use, rather than being leached into rivers and lakes.
Iron sulphate is used worldwide to treat drinking water and is also approved as a food additive to boost the iron content of food, so the EcoPond treatment technology is safe and simple to use.
The Lincoln University research team have also found that treating farm dairy effluent with iron sulphate could reduce the risk of E. coli leaching into groundwater, rivers and lakes by more than 90pc. This reduces the risk to drinking water supplies from bugs leaching out of effluent application areas.
The results also show that land application of PFS-treated effluent on pasture soils can produce these significant environmental benefits without adversely impacting plant growth.
Mr Ahlfeld said EcoPond could be retrofitted into existing effluent systems. "EcoPond is designed to treat the fresh dairy effluent from the shed before it enters the effluent pond," he said.
Professor Cameron said was still early days for planning units in Australia - this would depends on progress in NZ and the level of interest from farmers.
Scientific paper references
Cameron, K.C., Di, H.J. (2021) Discovery of a new method to reduce methane emissions from farm dairy effluent. J Soils & Sediments. https://doi.org/10.1007/s11368-021-03014-w.
Che, X., Di, HJ, Cameron KC and Dodd, R. (2022) Treating farm dairy effluent with poly-ferric sulphate dramatically reduces phosphorus and E coli leaching through subsurface drains - A physical drainage model study. J. Soils & Sediments. https://doi.org/10.1111/sum.12809.
