Abstract: A wastewater treatment system comprising one apparatus (1) for de-nitrification and effluent solids removal, another apparatus (2) for biological main treatment, and a further apparatus (3) for solids removal (5), each apparatus including a volume (40) in which each process is performed, a media-retaining sieve (6) at the volume (40) and arranged to retain buoyant media particles (4) in the volume (40), and a gas sparging device (8), (9) which is located in a lower end region of the volume (40) and which is controllable by way of valves (11) and (15). The three volumes (40) are substantially (10) identical to, or multiples of, each other, the three sieves (6) are substantially identical to each other, and the three sparging devices (8), (9) are substantially identical to each other. The gas is sparged into the main treatment bed at a lower flow rate for wastewater aeration but intermittently at a higher flow rate to disrupt and clean the bed.

Abstract: An activated sludge system for the purification of wastewater includes a membrane reactor comprising: (i) an array of pairs of vertical membranes (14) parallel to each other, (5) the membranes being spaced apart from each other and being permeate to liquid but substantially impermeable to solid particles, (ii) liquid flow channels between the membranes (14) of each pair, (iii) a liquid-collecting channels communicating with the liquid-flow channels for receiving liquid which has permeated through the membranes (14), and (iv) gaseous fluid sparging ducts (5) allocated to and co-planar with the respective pairs of membranes (14) and extending substantially horizontally for introducing gaseous fluid into a mixture of the liquid and the solid particles about the array, so that the gaseous fluid rises through the gaps (8) among the outer major surfaces of the membranes (14), each of the ducts 5 having therealong only one row of sparge holes (6), those holes (6) being downwardty directed for emitting the gaseous fl

Abstract: A method for reducing the aqueous dispersion present in the amalgam being fed to a mercury cell which comprises reducing the velocity of amalgam stream at one or more stations along the amalgam flow where the amalgam enters a substantially static pool of amalgam which is itself covered by a layer of an aqueous phase, e.g., at lutes located at the exit of the cell, the exit of the denuder, the entry to a pump tank or pump, and the entry to a wash box feeding to the cell. The invention is advantageous for reducing chloride entrainment in the amalgam fed to the denuder and for reducing the build-up of thick mercury deposits on the baseplate of a mercury cell.