Abstract: The invention relates to a method for the thermal hydrolysis of sludge characterized in that it is carried out in at least two reactors operating in parallel, in each of which the sludge undergoes a complete thermal hydrolysis cycle. Said cycle comprises different stages consisting in supplying the reactor with the sludge, injecting live stream in order to bring said sludge to a pressure P and a temperature T at which hydrolysis can occur, maintaining the sludge at said pressure P and said temperature T for a certain amount of time, suddenly bringing said sludge to the atmospheric pressure by releasing the flash steam and emptying said reactor of the hydrolysed sludge. Furthermore, the inventive method consists in time shifting the cycle of one reactor to the other in order to use the flash steam produced from one reactor to inject it into the other reactor.

Abstract: The invention relates to a method for the thermal hydrolysis of sludge characterized in that it is carried out in at least two reactors operating in parallel, in each of which the sludge undergoes a complete thermal hydrolysis cycle. Said cycle comprises different stages consisting in supplying the reactor with the sludge, injecting live stream in order to bring said sludge to a pressure P and a temperature T at which hydrolysis can occur, maintaining the sludge at said pressure P and said temperature T for a certain amount of time, suddenly bringing said sludge to the atmospheric pressure by releasing the flash steam and emptying said reactor of the hydrolysed sludge. Furthermore, the inventive method consists in time shifting the cycle of one reactor to the other in order to use the flash steam produced from one reactor to inject it into the other reactor.

Abstract: The invention concerns a flocculation-decantation method by ballasted flocs using a granular material and a step which consists in treating the sludge derived from flocculation-decantation in a circular grit trap wherein the auxiliary liquids tangentially injected into the sludge substantially in the same direction as the latter. The invention also concerns a circular grit trap with a cylindrical part of diameter D tangentially supplied with the suspension to be treated and a conical part and provided with a cylindrical chamber injecting wash-water provided at the conical part outlet and having a diameter D′ ranging between 0.35 D and 0.65 D, said cylindrical chamber having at least a tangential supply of auxiliary liquid along the same feeding direction as said tangential supply of the suspension to be treated.

Abstract: The invention relates to a process for obtaining senarmontite and obtained senarmontite.The invention process consists in a direct hydrolysis of antimony trichloride by means of a basic solution, the hydrolysis being carried out in the presence of an oxidizing agent.Use: Obtention of senarmontite.

Abstract: The invention relates to a process for obtaining photostable valentinite and to valentinite obtained by said process.The process consists in carrying out a basic hydrolysis of antimony trichloride at a temperature comprised between about 80.degree. and 100.degree. C. with a weight ratio of H.sub.2 O/Sb.sub.2 O.sub.3 equal to or greater than about 10.Obtention of photostable valentinite.