Apparatus for the anaerobic purification of waste water

Abstract

In apparatus for the anaerobic purification of waste water the invention aims at improving the structure and the operation. In known apparatus of this kind there is a reactor tank with one or more aftersettling compartments in the upper part thereof, with inlet and outlet openings for water and sludge into and from the aftersettling compartments from and into the reactor tank respectively. Such apparatus is improved according to the invention be interrupted inclined walls of the aftersettling compartments to form such inlet openings, the wall parts thus formed being staggered at the inlet openings to screen them from rising gas so that this cannot enter the aftersettling compartments, by one such inclined wall extending downwardly past the opposite one to form an outlet opening for the resettling compartments screened against the entry of gas into them, by simple gas collecting hoods, a sludge discharge pipe below the level of the water in such compartments and by removable aftersettling compartments easily replaceable and loosely supported on supporting edges of the reactor tank.

I claim: 
     
       1. In an apparatus for the anaerobic purification of waste water (sewage or industrial waste) with a reactor tank for methane fermentation and an aftersettling (clarification) compartment in the upper part of the reactor tank, said aftersettling compartment having a discharge opening in the lower part towards the reactor tank so that active anaerobic sludge separated in the aftersettling compartment is allowed to flow back to the reactor tank, and an entry opening in a higher zone, through which the mixture of said sludge and water is allowed to flow from the reactor tank into the aftersettling compartment, with means to separate the generated gas flowing upwards from the mixture of sludge and water before this mixture flows into the aftersettling compartment, the improvement comprising an interruption in the inclined wall of said after setting compartment forming said entry opening, the parts to both sides of the interruption being at a distance from each other as measured from the lower part of the wall part above the interruption in a direction perpendicular to the wall part below the interruption said distance being sufficient, so that the opening is screened from gas rising in the reactor tank while allowing the mixture of sludge and water to flow into the aftersettling compartment, the lower part of the said wall below the interruption being at a distance from an opposite wall part of the aftersettling compartment to form together therewith the said lower discharge opening.Iadd., means enabling the substantial separation of the gas from the mixture of sludge and water and means to keep the sludge, still containing gas, in the middle part of the after settling compartment, including the overlap of said wall parts, the lowest point of one wall part above the interruption is positioned lower than the highest point of the other wall part below the interruption and, a submerged baffle intersecting the liquid level in the afersettling compartment between a point right above the zone where the sludge-water-mixture enters the aftersettling compartment and the discharge for purified water therefrom.Iaddend.. 
     
     
       2. An apparatus according to claim 1, wherein said wall past below the interruption extends downwardly past the lower edge of said opposite wall part to screen the discharge opening in the lower part of the aftersettling compartment towards the reactor tank against the entry of gas from said tank into said compartment. 
     
     
       3. An apparatus according to claim 1 or claim 2, wherein at least in two opposite downwardly converging walls of the aftersettling compartment such an interruption is provided. 
     
     
       4. An apparatus according to claim 3, characterized in that a hood for collecting and discharging gas is provided below the said lower discharge opening, which hood also prevents the rising of gas from the reactor tank into the aftersettling compartment. 
     
     
       5. An apparatus according to claim 4, wherein a sludge discharge pipe leads from a point below the normal liquid level in the aftersettling compartment to the outside of the apparatus. 
     
     
       6. An apparatus according to claim 5, wherein said sludge discharge pipe has closing means connected to sensing or time switching means to open and close said closing means temporarily and/or periodically. .[. 
     
     
       7.  An apparatus according to claim 6, wherein a submerged baffle intersects the liquid level in the aftersettling compartment between a point right above the zone where the sludge-water-mixture enters the aftersettling compartment and the discharge for purified water therefrom..]. 
     
     
       8. An apparatus according to claim .[.7.]. .Iadd.1.Iaddend., in which the discharge of purified water is positioned at the top of the said inclined interrupted wall of the aftersettling compartment, the submerged baffle being positioned above the same wall, farther from the central zone of the aftersettling compartment than said entry opening for the sludge-water-mixture into this compartment. 
     
     
       9. An apparatus according to claim 8, which comprises one or more aftersettling compartments, each embodied as a structural unit being adapted to be separately introduced into the reactor tank downwardly and removed therefrom upwardly. 
     
     
       10. An apparatus according to claim 9, wherein an aftersettling compartment has protruding parts by which it can rest sealingly on an inwardly protruding edge of the reactor tank below the upper edge thereof, so that above this protruding edge there is a space between the walls of the aftersettling compartment and the reactor tank wall which may serve as a collecting and discharge trough for the purified effluent. 
     
     
       11. An apparatus according to claim 10, wherein the walls of the aftersettling compartment and of the reactor tank below said sealing support form a collecting space for gas between them in communication with one or more gas collecting spaced formed between walls of or supported by the aftersettling compartment. 
     
     
       12. An apparatus according to claim 11, with a rectangular horizontal section of the aftersettling compartment, wherein said gas collecting spaces formed by parts of the aftersettling compartments are rectangular in horizontal section and open freely at one or both ends into or below said gas collecting spaces formed between the walls of the aftersettling compartment and the reactor tank. 
     
     
       13. An aftersettling compartment as a separate structural unit for use in an apparatus according to claim 9.