Abstract: Subterranean service pipes, eg. water mains, are tapped by minimal excavation to expose the upper half of the main and then locating (with respect to the main) a conventional pipe-tapping device but without employing means encircling the pipe. Thus, a clamp can be used, or a saddle adhesively secured to the pipe. The clamp or saddle preferably provide means for proper orientation of the drilling and tapping tool with respect to the main.

Abstract: A supply of water is continuously monitored to ensure purtiy by dividing the supply into a number of parallel streams and flowing each through a fish tank containing a fish (or other aquatic animal), the health of each fish being monitored by electrodes in each respective tank. The fish tanks are located together in a main tank and the water supply is drawn from a header tank via pipework, the tank being fed from supply. The apparatus includes an electronic system to monitor the activity of the fish.

Abstract: Solids suspensions are dewatered by filter plate pressing by adding a flocculant downstream of the filter press pump(s), the pump(s) being of the positive displacement type whereby the amount of flocculant required can be determined from the speed of the pump(s). Apparatus is provided which includes a filter plate press, one or more filter press pumps of the positive displacement type, and means for sensing the speed of the pump(s) and for controlling the dose of flocculant in dependence thereon. A mixer is constructed as a cylindrical chamber with radial inlets and axial outlets, and includes plate-like impellers.

Abstract: Apparatus for use in the laying and/or replacement of pipes under ground comprises a casing (1), a frusto-conical impact member (2) secured to one end of the casing and adapted to form an underground passage for the casing when the apparatus is being driven through the ground, a piston (7) reciprocally mounted in the casing and arranged to be driven by a source of compressed air or other fluid to engage the impact member (2) with a series of impacts to drive said member and the casing through the ground and a control valve member (11) adapted to be connected to a source of compressed air or other fluid and arranged to reciprocate the piston in the casing by means of said compressed air or other fluid. A pipe fitting (31) is connected to a tubular spacer member (23) which is mounted on the other end of the casing (1), said pipe fitting being adapted to be clamped to the leading end of a pipeline (29 and/or 30) which is to be laid in the underground passage formed by the impact member (2).

Abstract: Apparatus for use in the laying and/or replacement of pipes underground comprises a sleeve having a front end and a rear end, a percussive drive means in the form of a pneumatically-operated impact mole mounted in the sleeve and arranged to drive the front end of said sleeve through the ground, means for securing the leading end of a pipe to the rear end of the sleeve and means for pushing the pipe through a bore formed in the ground as the sleeve is advanced through the ground by the mole. The means for securing the end of the pipe to the sleeve includes an annular spigot which allows relative axial movement to take place between the pipe and the sleeve in order to prevent impact stresses on the sleeve from the mole from being transmitted to the pipe. The pipe pushing means desirably comprise hydraulic rams arranged to bear on a plate located at the rear end of the pipe.

Abstract: In a water treatment apparatus, the jets in the distributor arms of a percolating filter are kept clear from jamming by automatic actuation of plungers which enter the jets to dislodge any obstructions therein, each plunger being individually mounted on the arm adjacent its respective jet.

Abstract: In the aerobic digestion of sludges, particularly but not exclusively primary sedimentation sewage sludges, a layer of sludge foam is deliberately maintained over the sludge surface to improve the efficiency of the process. The layer of foam may have a volume of at least 50% of that of the sludge. The digestion process is effected in a digester, in which the amount of foam may be reduced (as necessary) by injecting sludge directly into the foam to cause local collapse thereof. A digester vessel especially suited for use in the process is described.

Abstract: High pressure liquid jets including finely divided abrasive particles suspended therein, are produced a substantial distance (e.g. from 20 m up to 100 m or more) from the liquid and particle sources by separately pumping the liquid and the particles over the distance, and then combining the two in a venturi and delivering the mixture to a nozzle. The abrasive particles are conveyed over the distance in a carrier fluid (e.g. air) which is then separated off immediately before the particles arrive at the venturi.

Abstract: Gases are dissolved in aqueous liquids and sludges by employing the preliminary step of subjecting the liquids to a reduced pressure to remove incidental gases dissolved or contained therein, and then dissolving the required gases therein. The invention is of particular utility in the oxidative treatment of surface waters, waste waters or sewage, in which the latter are first de-gassed before being oxygenated. The degassing can be effected by, for example, using a siphon.