Abstract: The invention relates to an apparatus for cleaning a slow sand filter for a body of liquid while the liquid is in situ, in which there is a carrier adapted to traverse the body of liquid, and a device carried by the carrier and adapted to skim successive layers of sand from the filter. The carrier is a floatable vessel and the skimmer device is an auger. The skimmer device is controlled by depth control means which are automatically adjusted in response to the contour of the filter.

Abstract: A method of lining an existing pipe by pulling through it a collapsible, flexible, lay-flat liner having an innermost layer of impervious, elastomeric material which is compatible with the fluid to be carried by the pipe, a textile reinforcing intermediate layer, and an external protective layer of elastomeric material. The liner has an external circumference slightly less than the internal circumference of the pipe and is such that flow of fluid through the liner after the installation thereof expands the liner into non-binding contact with the internal surface of the pipe. The peripheral extension (diametral swell) of the liner at the intended working pressure of the relined pipe should be less than 10% and preferably less than 5%.

Abstract: A device for automatically sampling liquids includes a reversible gas powered motor driving a reversible pump. There are included in lines supplying the driving gas to the motor control devices which cause the gas to drive the motor and the pump in one sense for a predetermined period of time to purge the pump and subsequently to drive the motor and the pump in the opposite sense to draw a sample of the liquid. The motor preferably has two inputs. During the initial period of time the driving gas is connected to the first input driving the pump in the first sense. Subsequently the control devices remove the supply from the first input and connect it to the second input driving the pump in the opposite sense for a predetermined period of time and then stopping the motor. The control device is then reset so that upon the following actuation of the motor it is driven again in the one sense.

Abstract: The invention relates to a process for thickening digested sludge, comprising the steps of providing digested sludge to be thickened, and then passing a gas, preferably air, through the digested sludge at an intensity in the range of above 0.1 to 5 gas to 1 sludge, on a volume basis, per hour. Sludge can be thickened to greater than 5% solids in ten days, an improvement of nearly 10 times that of traditional practice, as shown respectively by plots B and A.

Abstract: A sewer cleaning shoe for use in removing the detritus and sedimentary matter that accumulates in the invert of sewers comprises a partly-cylindrical framework (1, 11, 14, 19) which fits in the invert of a sewer, a transverse barrier (2, 5, 23) which is connected to the framework and which, in use, substantially fills the lower part of a sewer but stops short of the top of the sewer to form a dam extending across the sewer, and an orifice (6, 18) through the transverse barrier adjacent its base through which, in use, a part of the effluent carried by the sewer is jetted to scour the detritus and sedimentary matter from the invert of the sewer. The transverse barrier stops short of the top of the sewer and provides a weir over which the remainder of the effluent flow takes place.