A new slurry treatment system using a unique seaweed-based prebiotic has been installed in an indoor pig breeding unit in Devon, resulting in water that will be clean enough to be returned directly to watercourses – subject to permit.

Ekogea UK’s Farm Slurry Management System turns raw pig or dairy slurry into a compact digestate, reducing the volume of slurry to store, while also producing an added value solid product that can be used either as a natural fertiliser with high plant-available nutrients or as a quality feedstock for anaerobic digestion (AD).

This process helps build a circular farm economy with the resulting water cleaned through an H2e waste water treatment plant that is clean enough to be released into water courses under permit. As a consequence, the energy-efficient system also drastically cuts on-farm ammonia emissions.

The process has three main stages:

  1. Raw slurry is pumped through a simple ‘on-farm’ screw press to get rid of larger material and solid matter, typically around 5% of the volume of the raw slurry and solids are then stored.
  2. The remaining slurry (95% by volume) is pumped to Ekogea’s Farm Slurry Concentrator. This further separates the liquid retaining around 99% of suspended solids as ‘concentrated slurry’, which is then combined with the screw press solid creating either a valuable ‘on farm’ biofertiliser or transported to an AD Plant as a feedstock.
  3. The processed water (around 85% by volume) flows to the gravity fed and organic H2e waste water treatment plant where it is dosed with Ekogea’s BioComplex additive. This reduces the level of ammonia and nitrous oxide in the water by stripping out suspended solids and toxic compounds.

The resulting concentrate (15% by volume) is an easily stored or transportable sludge, which can be further de-watered to produce a dry stackable solid. The process reduces the costs and risks of storage and spreading slurry to land whilst allowing a greater percentage of the nitrogen to be fixed in the solid.

The concentrated solid, high in plant-available NPK, can then be used ‘on-farm’ or sold as a high value bio-fertiliser. Alternatively, it can be sold as a quality feedstock for local anaerobic digestion plants under contract, which helps to resolve the phosphate issues faced by the farm and turns their slurry into a valuable asset, as well as an additional revenue stream.

The H2e process treats the grey water to meet Environmental Agency discharge standards and the polished water can then be re-used on the farm or released into water courses under permit. Alternatively, the process can be altered to allow more of the N to remain in the grey water for a nitrogen-rich fertiliser.

The whole investment, including separator, concentrator and H2e plant, came to just under £150,000, which is estimated to break even within 4-5 years – specifically based on savings on slurry handling and lagoon maintenance and the value of the concentrate as a biofertiliser or AD feedstock.

For more information, a downloadable brochure is available on Ekogea’s website at: https://www.ekogea.co.uk/concentrator-for-farm-slurry/