Company ProfileCase Study: Intensive Pig Unit—Rocas do Vouga, Portugal
The Problem
Portugal has a large number of independent pig farms and the effluent the pigs produce is currently being poured into rivers after minimal treatment, or transported at cost for disposal. While the effluent is not of a highly complex nature, the difficulties with treatment of it are compounded by the dispersed nature of the industry.
The EversTech Solution
EversTech developed a biological system that involved a minimal capital outlay and that could be self-financing over the medium term through resource recovery. A full-scale pilot plant was built at a 200-pig farm in Rocas do Vouga, which is now fully commissioned and operational.
Bio-augmentation in this context produces a biogas of 80% methane and zero levels of hydrogen sulphide, making it ideally suited to generate electricity. Furthermore, the biomass produced makes an excellent fortified compost or organic fertilizer when left to dry, but an even more acceptable liquid fertilizer when applied directly from the digester overflow storage tank to the land. The resource recovery package gives each plant a payback period of less than two years.
The considerable levels of resource recovery have generated a good deal of interest in the pig farming community and related industries. Large scale plants based on the successful pilot trial are now being considered throughout the Industry.
Results
Average gas produced per day = 30 m3, of which 70–80% is methane (CH4).
Total potential electricity generation = 10 kws/hr or 240 kws/day, with full heat recovery.
Actual generation is about 3.5 kws/hr as there is no heat recovery on this size of plant because it would make the installation unnecessarily complicated.
Package treatment units were completed and have been operational since 1997.