Mobile first for Scotgrass
One of the most innovative new products on show at Scotgrass 2010 is a mobile slurry separator. Specifically designed to fill a gap in contractors work loads created by the tightening of Nitrate Vulnerable Zone regulations, it makes slurry separation an economic prospect for smaller livestock farms.
The separator has been developed together with SAC Crichton Royal, Dumfries, in conjunction with Weld-Tech of Omagh Co Tyrone and CE Projects of Market Drayton Shropshire. It can be moved from farm to farm and left to run 24/7 on a plant hire basis or included in a full nutrient management contract involving slurry agitation, separation and carting and stacking of dry manure, followed by the spreading of solids and umbilical injection of the liquid in the early spring.
Hugh McClymont, farms manager, SAC Crichton Royal, explains: Slurry and muckspreading is forbidden during the four month closed period from November through to February on NVZ designated land. Consequently farms within areas may be forced to invest heavily in increased slurry storage while contractors, who have traditionally harvested silage during the summer and spread muck in the winter, may be shut down for almost a third of the year.
It is permitted to store dry manure in field heaps sited well away from water courses which is fine for loose housed cattle on straw, but no solution for the slurry-based housing systems found on most farms in the wetter, livestock producing areas, unless they are operating a slurry separator. Unfortunately with the economic threshold for separators at 400 cows, very few farms have been able to consider this option.
Realising that he needed a mobile separator for the two units at Crichton Royal, Hugh got in touch with Andrew Baxter of Weld-Tech and Simon Johnston of CE Projects and they designed a separator specifically for dealing with the SACs two farms, and as a template for a contracting approach that would bring slurry separation within reach of the average sized dairy farm.
The base of the unit is a specially fabricated 6m trailer, 2.47m wide with two in-built tanks, one to maintain continuous flow and the other for wash-down water. On this is mounted a single Sperrin Separator, although with room to add a second unit at a later date, an 11kw three-phase electric motor to power the slurry feed and agitation pump, a 5.5kw motor pumping surplus liquid away, a 1.5kw motor to run the separator, a muck conveyor driven by a 2kw motor and a push button electronic control system with emergency stop and automatic wash-down. They can also be adapted to be driven by a PTO.
At the heart is a 1m long by 900mm diameter stainless steel cylinder, which turns at just 22rpm, with the two compression rollers above, each 1m by 315mm with a 30mm rubber coating and 40mm of movement. Two hard rollers are sandwiched either side of the perforated screen and solids are removed by a nylon scraper while liquid drops through the screen via a stainless steel tank and overflow hopper, back to the store.
While costs vary greatly depending on the specification, a single unit, including fabricated trailer, will come in at 37-38,000 and a twin unit at around 50,000. For a triple unit with a potential top whack output approaching 150m3/hr, prices jump to 65-70,000 as a heavier, 2.5m longer trailer is needed, bringing trailer length to 8.5m in all.
Andrew Baxter of Weld-Tech says: As a static system the single unit is designed to separate slurry from a 500 cow herd. Allowing for travel, set-up time and the wide variation in slurry systems and thicknesses, taking an average size of 100 cows, a contractor should be able to handle 15 to 20 farms on a regular basis.