Abstract: A method of cleaning filtration modules for the treatment of raw water, or wastewater, or activated sludge, is provided by circulating particles in untreated water. The deposits located on the filter membrane outer surfaces are removed by the mechanical action of the particles, without significantly damaging the membrane. Initially, untreated water, wastewater, or activated sludge is chemically-mechanically pretreated. Then the untreated water or wastewater polluted with biologically active material is discharged into a membrane bioreactor system having a filtration unit including at least one filtration tank. At least one submerged filtration membrane module is present in the filtration tank. The untreated water or wastewater in this filtration tank is filled with particles and circulates inside the filtration tank. The particles are non-porous, biologically resistant polymer particles.

Abstract: The invention describes a method to prevent the formation of struvite in wastewater treatment plants. For that purpose, calcium silicate hydrate (CSH) is metered out into the excess sludge.

Abstract: A method of cleaning filtration modules for the treatment of raw water, or wastewater, or activated sludge, is provided by circulating particles in untreated water. The deposits located on the filter membrane outer surfaces are removed by the mechanical action of the particles, without significantly damaging the membrane. Initially, untreated water, wastewater, or activated sludge is chemically-mechanically pretreated. Then the untreated water or wastewater polluted with biologically active material is discharged into a membrane bioreactor system having a filtration unit including at least one filtration tank. At least one submerged filtration membrane module is present in the filtration tank. The untreated water or wastewater in this filtration tank is filled with particles and circulates inside the filtration tank. The particles are non-porous, biologically resistant polymer particles.

Abstract: To a gas which contains H.sub.2 S and water vapor and which is to be desulfurized oxygen is added at such a rate that the gas contains 1 to 20 moles O.sub.2 per mole of H.sub.2 S. At a temperature in the range of 50.degree. to 180.degree. C. the gas is contacted with activated carbon, which is thus laden with elemental sulfur and with at least 3% by weight sulfuric acid. In a suitable processing, the gas which is to be desulfurized and contains at least 1000 ppm H.sub.2 S+SO.sub.2 is initially passed at a temperature from 100.degree. to 180.degree. C. through a catalytic prepurifier, in which elemental sulfur is adsorbed on a high-metal-oxide catalyst, oxygen is admixed to the gas coming from the prepurifier and the gas at a temperature of 50.degree. to 180.degree. is contacted with the activated carbon for a final desulfurization.