METHOD OF PROCESSING WASTE WATER SEDIMENTS (VERSIONS) Russian patent published in 1998 - IPC

FIELD: waste water treatment. SUBSTANCE: primary sediment and activated sludge are subjected to anaerobic fermentation, aerated for 0.1 to 3 days, compacted, and, after adding reagents, mechanically dehydrated. Prior to compaction, sediment is washed with water, a part of compacted sediment is aerobically stabilized and aerated, whereas cationic flocculant is used as reagent before mechanical dehydration. Aerobically stabilized is 5 to 40% of compacted sediment and washing is carried out in presence of anionic flocculant. In another embodiment of process, aeration of aerobically digested sediment is carried out in two steps: before and after compaction. Part of compacted sediment is subjected to aerobic stabilization and then transferred into the first aeration step. Sediment after the second aeration step is subjected to second-step aerobic stabilization and a part of aerobically stabilized second-step sediment is recycled. EFFECT: accelerated process and reduced power and reagents consumption. 6 cl, 2 ex