Method and apparatus for filtering industrial and human waste

Claim 1

Apparatus for filtering a fluid containing extraneous solids comprising a confining tank, fine filter means defining a first perforate barrier at the top of the tank, means defining a second perforate barrier below the first perforate barrier, said first and second perforate barriers defining a space therebetween for receiving a filter bed and said second perforate barrier defining with the bottom of the tank, a repository for filtrate, a bed of buoyant, loosely-associated, discrete filter bodies of such volume as to partially fill the space between said first and second barriers, said second perforate barrier comprising a perforated plate having perforations too small to permit passage of the filter bodies, but large enough to permit extraneous solids to gravitate from said space to said repository, said bed being held against upward displacement at its upper side by said first perforate barrier, but unconstrained at its lower side by said second perforate barrier, a conductor vertically disposed in the tank and centrally positioned to introduce a fluid to be filtered into the midst of the bed below the upper barrier at a pressure of 10 to 100 psi to cause dense packing of the bodies above the region of entry of the fluid into the tank against the first barrier and dispersion of the bodies below the region of entry of the fluid into the bed accompanied by weltering of the dispersed bodies and detachment of the solids from the bodies by such weltering such that the detached solids gravitate downwardly from the dispersed bodies through the second perforate barrier into the repository at the bottom of the tank, means for withdrawing solids from said repository, and means for drawing filtered fluid from the tank upwardly through the densely-packed region of bodies above the region of entry of the fluid into the tank through the first perforate barrier.

Claim 3

The method of filtering a fluid containing extraneous solids comprising: confining a bed of buoyant, loosely-associated, discrete filter bodies within a tank between vertically-spaced upper and lower perforate barriers in such volume as to incompletely fill the space between said barriers and to provide a repository below said lower barrier, said upper barrier comprising a fine filter, and said lower barrier comprising a perforated plate having perforations too small to permit passage of the filter bodies, but large enough to permit extraneous solids to gravitate from said space to said repository, introducing said fluid through a vertically disposed conductor, centrally situated in said tank, into the midst of the bed in a region below the upper barrier at a pressure of 10 to 100 psi to cause dense packing of the filter bodies in the bed above the region of entry of the fluid into the bed against the upper one of the perforate barriers and dispersion of the filter bodies of the bed below the region of entry of the fluid into the bed accompanied by weltering of said dispersed filter bodies such as to rub the solids accumulated thereon from the filter bodies to cause gravitation of the solids downwardly through the dispersed filter bodies and through the lower one of the perforate barriers into said repository, collecting the downwardly-gravitating solids in said repository, withdrawing the collected solids from said repository, and drawing off the filtered fluid from the tank upwardly through the densely-packed region of the filter bodies above the place of entry of the fluid into the bed and through the upper one of the perforate barriers.

Claim 4

The method of filtering a fluid containing extraneous solids comprising: confining a bed of buoyant, loosely-associated, discrete filter bodies within a tank between vertically-spaced upper and lower perforate barriers in such volume as to incompletely fill the space between said barriers and to provide a repository below said lower barrier, said upper barrier comprising a fine filter, and said lower barrier comprising a perforated plate having perforations too small to permit passage of the filter bodies, but large enough to permit extraneous solids to gravitate from said space to said repository, introducing said fluid through a vertically disposed conductor, centrally situated in said tank, into the midst of the bed in a region below the upper barrier at a pressure of 10 to 100 psi to cause dense packing of the filter bodies in the bed above the region of entry of the fluid into the bed against the upper one of the perforate barriers and dispersion of the filter bodies of the bed below the region of entry of the fluid into the bed accompanied by weltering of said dispersed filter bodies such as to rub the solids accumulated thereon from the filter bodies to cause gravitation of the solids downwardly through the dispersed filter bodies and through the lower one of the perforate barriers into said repository, collecting the downwardly-gravitating solids in said repository, withdrawing the collected solids from said repository, and drawing off the filtered fluid from the tank upwardly through the densely-packed region of the filter bodies above the place of entry of the fluid into the bed and through the upper one of the perforate barriers.