GB471277A - Method of and composition for the treatment of water - Google Patents

Abstract

Compounds of iron and manganese are removed from water by filtration through a bed of granules comprising a mixture of cement and particles of manganese dioxide or triferric tetroxide, the granules being of a size to pass through a 10 mesh screen and to be retained on a 60 mesh screen. The treatment also removes hydrogen sulphide from the water. The oxide may be formed into granules in admixture with cement or particles of the oxide may be held by cement in the pores or on the surfaces of a granular base material such as pumice, lava, earthenware, porcelain, sand, slag, coke or charcoal. The cement may be Portland cement, a hydraulic cement containing a large proportion of alumina, rubber latex, phenol condensation resins, pitch or asphalt. In filtering, the bed of granular material becomes clogged by precipitate and is cleansed by back-washing. The granules should be of such size and density that they are suspended in the back-wash stream. The base material may comprise a water-softening agent such as base-exchange compound. An example of the preparation of suitable material is described according to which a mixture of finely divided pumice, powdered pyrolusite, alumina cement and water is cast into small blocks which are crushed into granules when the cement has set. In another example finely divided zeolite and pyrolusite are cemented together by rubber latex or artificial resin. If the water under treatment is deficient in oxygen it may be aerated or treated with oxygen or ozone prior to its passage through the bed. If the water contains hydrogen sulphide the efficiency of the bed may be maintained by periodic treatment with a solution of potassium or sodium permanganate or by continuous addition of such permanganate to the water. The Specification as open to inspection under Sect. 91 states that the finely-divided active material may be cemented to larger surfaces, such as coarse rock, large sheets or boards, which are arranged in the water stream. This subject-matter does not appear in the Specification as accepted.