Combined installations and works (CW; patents 1020379, 1533239, 1761688,1761690, 2114792 and international application PCT/RU 096/00202) are designed for biochemical purification of the sewage produced by settlements, towns and enterprises and characterized by impurity concentration BOD max. 1,000 mg/L, suspended matters amount max. 400 mg/L.
After being mechanically processed, the sewage is discharged to mixing chamber 1 where it is mixed with the sludge mixture coming from settling aerotank 2. From chamber 1 the sewage and sludge mixture is driven by pump 3 to biofilter irrigation system 4 consisting of spouting chutes 5 with outlet pipes 6 and reflecting disks 7. The falling liquid jets are broken upon the disks thus irrigating the biofilter feed. The biofilter with the immobilized microflora is designed for sorption and oxidation of 50-70% organic impurities.
The existing CW use as their biofilter feed, corrugated asbestos boards which are hard and rough enough to hold microflora on their surface. Further on we plan to use flat feed from glass-reinforced plastic of high specific surface. To exclude feed siltation, the boards' roughness is altering according to the height, it also has waved partitions and slots.
Oxidization of the remaining impurities of up to 98% purification level is achieved with the help of the active sludge in settling tank 2. To saturate the sludge with additional oxygen and to stir the aerotank contents, water jet operation is applied. After the biofilter the liquid is driven by collecting tray 9 to air-spripping towers 10 into which air is sucked (0.6-0.9 m3 per 1 m3 of liquid) as a result of vortexes. The air-spripping towers distribute the air mixture over the aeration tank inside. Meanwhile 30-35% of the required oxygen get into the aerotank due to the air oxygen solution in the silt mixture, and 70-65% of oxygen due to the air bubbles lifting during the process of mass-transmission in the columns. Efficient stirring is provided in the aeration tank by the jets hitting on the aerotank bottom and gas-liquid flow movement. The sludge mixture displaced from the aeration zone is discharged through a slot to the settling zone where some part of it is compacted and driven back to the aeration zone, while the rest is making a suspended sludge layer.
Photos of the objects, film about work of existing sewage treatment plants, and existing CW performance quality for 1985-2000 period.
