Patent ID: 6194275
Filing Date: 2001-02-27
Classification: H01L

Abstract:
Procedure for attenuating dissolved phosphorus from water passing through a septic tank, wherein:the septic tank is configured with an inlet conduit and an outlet conduit, and the procedure includes conveying the water therebetween;the water flowing through the outlet conduit has, dissolved in it, an ammonium content;the water flowing through the inlet conduit is contaminated by having, dissolved in it, a phosphorus content;the septic tank is so arranged and operated, as to its configuration and as to the manner and rate at which the water passes therethrough, that water in the septic tank is under such strictly anaerobic reducing conditions that the Eh voltage of the water is less than 0.3 volts;the procedure includes providing, in the septic tank, a body of treatment material;the treatment material in the body includes solid grains of Reductive Iron Dissolution material, being RID-material, being material that consists of either ferric hydroxide or ferric oxy-hydroxide or both;the conditions in the septic tank, as to the pH and the Eh of the water, are such that the ferric hydroxide or oxyhydroxide dissolves at a slow rate, and thereby releases ferrous ions into solution in the water, and the ferrous ions react with the phosphorus dissolved in the water, to produce solid ferrous-phosphate minerals, which precipitate;the procedure includes so configuring the body of treatment material in the septic tank, that the water, in flowing towards the outlet conduit, has sufficient residence time that a major proportion of the dissolved phosphorus precipitates out as solid ferrous-phosphate minerals;providing means for collecting the solid precipitate;and conveying the water, having now given up the major proportion of its dissolved phosphorus, out of the outlet conduit of the septic tank.