Method and apparatus for in Situ water purification including sludge reduction within water bodies by biofiltration and for hypolimnetic aeration of lakes

摘要

A method and an apparatus for in situ purification by aeration and biofiltration of water from a water body. According to this method, polluted and/or oxygen deficient water is drawn through a conduit into a submerged chamber held adjacent to the surface of the water body. Water is oxygenated from three sources: air injected into the conduit to draw the water into the submerged chamber, air diffusing from the surface of the water body; and air injected in a lower portion of the chamber. The oxygenated water flows downwardly from the chamber through a submerged biofilter having a filter bed made of filtering media which may be preinoculated with beneficial microorganisms and essential nutrients. Rafted or floating vascular plants can be inserted into the chamber to enhance purification by fixing metals. If desired, organic sludge can also be drawn into the chamber for biodigestion by continuous or intermittent supply of microbial cultures specifically grown to optimize production of enzymes which solubilize the organic sludge. The biochemical oxygen demand (BOD) for the sludge solubilization is satisfied by the aeration and biological filtration capacity of the apparatus. Such method and apparatus are designed to provide a stable working environment in open water bodies. They can also be used achieve hypolimnetic aeration within a lake.