Patent ID: 6521128
Filing Date: 2003-02-18
Classification: C02F,Y10S

Abstract:
A process for treating water which contains carbonaceous solids, which process includesfeeding water which contains carbonaceous solids which provide metabolizable organic carbon, into a biological hydrolysis reaction stage; if the water is deficient in sulphate ions, adding sulphate ions to the water ahead of the reaction stage and/or in the reaction stage as the water passes along the reaction stage in the presence of sulphate ions, subjecting it to biological sulphate reduction in which sulphates in the waste water are converted to sulphides and during which the metabolizable organic carbon is metabolized by organisms involved in the biological sulphate reduction, with hydrolysis of the solids component thereof into non-digestible or refractory COD material, hereinafter also referred to as â€˜RefCOD materialâ€™, slowly biodegradable COD material, hereinafter also referred to as â€˜SBCOD materialâ€™, and readily biodegradable COD material, hereinafter also referred to as â€˜RBCOD materialâ€™, taking place, with at least some of the RefCOD and SBCOD material having a larger particle size than the RBCOD material, so that at least some of the RefCOD and SBCOD material thus settles to the bottom of the reactor stage as the water passes along the reaction stage; withdrawing, from the reactor, the RefCOD and SBCOD material that has settled to the bottom of the reactor, as a slurry component; recycling the slurry component, with shearing thereof, to the reaction stage, so that, in addition to the hydrolysis, fractionation of the RefCOD and SBCOD material, into RBCOD material, occurs; withdrawing, from the reactor, the treated water together with at least some of the RBCOD material; and withdrawing the sulphides from the reactor or oxidizing the sulphides to elemental sulphur in a surface layer of water in the reactor, and withdrawing this surface layer of water from the reactor.