various chemolithotrophic bacteria such as thiobacillus ferrooxidans by direct or indirect mechanisms catalyze the oxidation of metal sulfides and produce acid , i . e . sulfuric acid and soluble metal salts at a much faster rate than chemical oxidation . elimination of such bacteria would inhibit the formation of the acid . the natural production of such acids is particularly troublesome in mines e . g . coal mines , since acid water is produced which is damaging to the environment . an effective method of abating or eliminating such acid water production is to apply a bactericide such as a biodegradable organic surfactant which at low ph values are bactericides and hence inhibit the bacteria from catalyzing the metal sulfides . the affected acid water site can thus be treated with the surfactant which provides a temporary or short term result usually for a few months . a long term solution , that is 1 year to several years , is provided through the use of a slow release composition of the present invention in which a heterogeneous matrix contains a thermoplastic domain and an organic surfactant domain . a suitable porosity is created when proper amounts of surfactant are utilized so that a long term slow release composition is formed . a method of making the heterogeneous matrix or slow release composition involves the dry blending of a thermoplastic compound and various processing aids , subsequently adding a bactericide thereto and mixing under shear and heat the resulting molten composition . a suitable slow release article can be formed such as pellets .