Abstract: A method for the remediation of contaminated soil directly and effectively removes the contaminants such as organic halides from the contaminated soil, using remediation agents for soil. In more detail, the agents include a slurry of fine iron particles in which the fine iron particles having average particle size less than 10 &mgr;m are dispersed in water; and an aqueous suspended liquid that contains fine iron particles having average particle size less of 1 to 200 &mgr;m and a hydrophilic binder; and these agents are employable for the method for the remediation of contaminated soil.

Abstract: A method for the remediation of contaminated soil comprising causing a carbonic acid aqueous solution to penetrate into the soil to liberate and remove contaminants contained in the soil.

Abstract: To provide a Thiobacillus thiooxidans growth inhibitor, a cement composition, and a cement structure which are capable of inhibiting effectively growth of Thiobacillus thiooxidans not only in the neutral pH range but also in the acidic pH range of 4 or below, of which active component metal ions are sufficiently prevented from being dissolved and released when contained in a cement structure, and of which effect can be maintained for a prolonged period of time. The inhibitor contains a first component selected from the group consisting of nickel phthalocyanine powders, powders of a nickel phthalocyanine derivative, and mixtures thereof, and a second component selected from the group consisting of tungsten powders, powders of a substantially water-insoluble tungsten compound, a water-soluble salt of tungstic acid turning to substantially water-insoluble when reacted with cement, and mixtures thereof.

Abstract: A Thiobacillus thiooxidans growth inhibitor containing as the active ingredient at least one substance selected from the group consisting of a tungsten powder and tungsten compounds. Under acidic conditions of pH value of 4 or less, this growth inhibitor sufficiently inhibits the growth of T. thiooxidans. When added in a very small amount to, for example, a structural material such as concrete in a sewage disposal plant, etc., it can therefore inhibit the growth of T. thiooxidans without substantially decreasing the strength, etc. of the structural material per se.

Abstract: A dephosphorizing material containing iron and/or an iron-containing compound, a cementitious material, water, and a mixing agent for accelerating bleeding as the starting material, and having fine pores therein formed by solidifying the starting materials while bleeding not less than 2.0% by weight of the water contained in the starting materials to render the percent water absorption of not less than 10%; and a dephosphorizing method which includes bringing the dephosphorizing material into contact with a phosphorus-containing aqueous solution. This dephosphorizing material can effectively reduce the phosphorus concentration in sewages, rivers, or the like by fixing the phosphorus component on its surface. The dephosphorizing method is so simple that it can be effected merely by bringing the dephosphorizing material into contact with a phosphorus-containing aqueous solution, thus being capable of removing the phosphorus component effectively without necessity for any special controls.

Abstract: A dephosphorizing material disposed so that a material containing iron as a main component and a calcium compound material contact a phosphorus-containing aqueous solution, and provided with a water-permeable material at least around the material containing iron as a main component. A phosphorus component of sewage and river water can be removed easily by simply bringing this dephosphorizing material into contact with such phosphorus-containing aqueous solutions, without employing any special solution control method. This dephosphorizing material is capable of reducing the outflow of iron rust occurring due to the oxidation of iron during a dephosphorization of a phosphorus-containing aqueous solution, and the iron effluent can be eliminated by the action of the calcium compound material. Accordingly, this dephosphorizing material can be applied practically to sewage and river water.

Abstract: A process for placing a cement composition having high strength is provided. The process comprises the steps of adding a viscosity increasing agent, vacuum de-bubbling under reduced pressure and allowing the de-bubbled cement composition to be hardened. At the vacuum de-bubbling step, relatively large foams present in the cement composition are removed and only fine bubbles are left in the composition. The strength of the cement composition is remarkably improved by the removal of large bubbles.