SEWAGE TREATMENT METHOD Russian patent published in 1997 - IPC

FIELD: sewage purification practice at small- and large-scale purification and after-purification plants for treating effluents of domestic and industrial origin. SUBSTANCE: proposed method uses conventional procedure of treating effluents with activated sludge in aerotanks and secondary settling tanks, followed by tertiary treatment (after-purification) by contacting water with immersed higher aquatic plant in flow-through channel. Inventive novelty of proposed method resides in using aquatic plant Najas microdon. Sewage flow rate in flow-through channel is set in such manner that 1 kg of plant weight would be present per about 2.4 g of nitrogen-containing substances and per 0.5 g of phosphates daily. Water temperature in channel is maintained over range +12 - +20 C, 15% by weight of Najas microdon biomass being removed from reaction pool every 20 days. EFFECT: reduced inflow of biogenic elements together with treated sewage into water pool, thereby diminishing water florescence and improving its chemical composition. 2 tbl