The Phytobac system enables contaminants typically originating from the filling, cleaning and washing of spray equipment, to be retained and degraded by microbial means, i.e. bioremediation. Phytobac is a sealed container of waterproof concrete, metal or plastic walls. The container is filled with a biomix of 70% topsoil and 30% chopped straw. The topsoil should be from conventionally cropped fields as this encourages the growth of the necessary microbial strains. The straw gives the biomix the required degree of porosity and serves as an energy source for the microorganisms.