GB867818A - Septic and antiseptic sewage disposal unit - Google Patents

Abstract

867,818. Sewage; gravity-separation apparatus. LIGHT, D. J. N., and BLAIR, B. J. Aug. 4, 1959, No. 26591/59. Classes 46 and 111. The rectangularly shaped primary anaerobic digestion tank 11, of a size to carry substantially more sewage than will be delivered to it at any one time by the system it serves, is a digestion chamber for the raw sewage influent which may enter the plurality of openings 16 in the top of the primary tank. In the initial digestion decomposition, gas produced is led off through a vent pipe 17 set in an opening 19, while the top of the tank 11 is also provided with a covered opening 18 to permit the periodic removal of accumulated sludge in the bottom of the tank by means of a pump. The flow of sludge-laden liquid through the first compartment of secondary anaerobic digestion tank 12 will be through the entrance opening 14 from tank 11, downwards and through the centre partition opening 38 and thence upwards and decanting through the lateral partition-opening 28 to the next compartment. This down-up-down pattern of flow is repeated through each of the compartments, materially aiding in the deposit of solid material in the bottom of each compartment and decreasing the possibility of a direct and rapid passage of the solid material across the top of the tank without proper sedimentation. It is desirable that the scum will not be decanted with the effluent from chamber to chamber and bafflles 32 are provided over the openings 14, 28, 29, 30 and 31 (illustrated in Fig. 4). A reseeding pump (not shown) draws through pipes 35 a portion of the contents, liquid and solid, of one of the compartments of tank 12. This is transported by means of a feeder pipe 20 back to the tank 11 where it is mixed with the incoming sewage to accelerate the initial septic digestion. Antiseptic contact chamber 13 is a simple rectangular tank, of size proportionate to the rest of the unit, into which the septic effluent from the previous operations is received. After the long series of sedimentations and decantings, the septic effluent will be comparatively free of solids, and as it enters the tank 13 it is subjected to the action of a predetermined amount of hypochlorite introduced into the chamber by a hypochlorite feeder 44 situated adjacent the gooseneck inlet. The hypochlorite required will vary in proportion to the volume of raw sewage delivered to the unit and the required dosage may be readily calculated by measuring the residual chlorine content of the ultimate effluent from tank 13, by an appropriate test, e.g. the orthotolidine colour-reaction method. The oxidized and sterile liquid may finally be discharged by automatically controlled means directly to a leaching pit or open waters without danger of pollution. In the figures an electric sewage pump 45 has been illustrated, but siphon or other transporting means may be used alternatively. Modifications of the tanks to make them suitable for use on board a ship are described. The direction of travel of the effluent through the secondary tank may be longitudinal along the length of the unit instead of from side to side.