PURPOSE: To reduce the collection/treatment labor of a large amt. of sludge by adsorbing and removing gas generated from sludge by scattering artificial zeolite over the sludge.

CONSTITUTION: Sludge generates sulfuide gas and ammonia gas by bacteria and these gases are adhsorbed and removed by scattering artificial zeolite. That is, artificial zeolite is scattered throughout the sludge. By this method, methane gas, sulfide gas and ammonia gas are adsorbed by artificial zeolite and the discharge of them to environment is suppressed. Further, the growth/ propagation of bacteria is accelerated and the decomposition/modification of sludge is accelerated. This artificial zeolite is produced by adding alkali such as caustic soda to fly ash discharged from a power plant using coal as an energy source and treating the resulting mixture with hot water. The crystal thereof is rich in philipstadite.