| abstract |
A method of processing sewage in which non-biodegradable solids are first removed from the sewage for separate disposal and the sewage is then introduced to the bottom of a fermentation cell (113) designed to optimize sedimentation and methane fermentation of settleable organic solids, most of which settle in the fermentation cell (113). The fermentation cell (113) contains sulfate-reducing microorganisms which release sulfides that combine with multi-valent metal particles in the sewage to form insoluble particles, a portion of which settles in the fermentation cell (113). The remaining metal sulfides, other suspended solids, microorganisms, nutrients, and pathogens in the sewage are then removed by natural means followed by dissolved air flotation (118), slow sand filtration (122) and disinfection (124). Finally, reverse osmosis (126) is carried out to produce purified water and a high-salinity concentrate. |