Effluent energy recovery system

Abstract

A septic system thermal recovery mechanism includes a septic tank. The tank has a top, a bottom, and at least one upstanding side wall joining the top to the bottom. The top, bottom, and at least one sidewall define an interior of the tank, and the at least one sidewall is devoid of angular corners. A septic inlet is adapted and constructed to conduct septic waste material into the interior of the tank, and a septic outlet is adapted and constructed to conduct septic waste material out of the interior of the tank. A thermal exchange fluid conduit is embedded in the at least one wall of the tank The thermal exchange fluid conduit is connected to a source of thermal exchange fluid. The mechanism is configured such that thermal exchange fluid can be circulated through the thermal exchange fluid conduit without traversing an angular corner and without contacting the interior of the tank The sidewall can be provided as a cast concrete wall, with the thermal exchange fluid conduit being PVC tubing embedded in sidewall in a spiral configuration at the time the sidewall is cast. The sidewall itself can be configured in any suitable form, such as a substantially contiguous cylindrical wall, or four walls in two substantially parallel pairs of sidewalls, the contiguous sidewalls being connected together with rounded connecting portions. The thermal recovery mechanism can also include a second thermal exchange fluid conduit embedded in the top of the tank. In an embodiment, the mechanism can include first and second tanks constructed as described, with septic waste flowing from the first tank to the second tank. A thermal exchange fluid pump can be connected to circulate thermal exchange fluid sequentially through a return conduit, into a thermal exchange fluid conduit in the second tank, then through a first thermal exchange fluid conduit in the first tank, through a supply conduit and a thermal exchanger, through a thermal output zone, then back through the return conduit.

What is claimed is:  
     
         1 . A septic system thermal recovery mechanism comprising the following: 
 a septic tank having a top, a bottom, and at least one upstanding side wall joining the to the bottom, the top, bottom, and at least one sidewall defining an interior of the tank, the at least one sidewall being devoid of angular corners;    a septic inlet adapted and constructed to conduct septic waste material into the interior of the tank;    a septic outlet adapted and constructed to conduct septic waste material out of the interior of the tank; and    a thermal exchange fluid conduit embedded in the at least one wall of the tank, the thermal exchange fluid conduit being connected to a source of thermal exchange fluid;    whereby thermal exchange fluid can be circulated through the thermal exchange fluid conduit without traversing an angular corner and without contacting the interior of the tank.    
     
     
         2 . A septic system thermal recovery mechanism in accordance with  claim 1 , wherein the sidewall comprises a cast concrete wall, and the thermal exchange fluid conduit comprises PVC tubing embedded in the at least one sidewall in a spiral configuration at the time the sidewall is cast.  
     
     
         3 . A septic system thermal recovery mechanism in accordance with  claim 2 , wherein the at least one sidewall comprises a substantially contiguous cylindrical wall.  
     
     
         4 . A septic system thermal recovery mechanism in accordance with  claim 2 , wherein the at least one sidewall comprises four walls in two substantially parallel pairs of sidewalls, the contiguous sidewalls being connected together with rounded connecting portions.  
     
     
         5 . A septic system thermal recovery mechanism in accordance with  claim 1 , further comprising a second thermal exchange fluid conduit embedded in the top of the tank.  
     
     
         6 . A septic system thermal recovery mechanism comprising the following: 
 a first septic tank having a top, a bottom, and at least one upstanding side wail joining the to the bottom, the top, bottom, and at least one sidewall defining an interior of the tank, the at least one sidewall being devoid of angular corners;    a first septic inlet adapted and constructed to conduct septic waste material into the interior of the first tank;    a first septic outlet adapted and constructed to conduct septic waste material out of the interior of the first tank;    a second septic tank having a top, a bottom, and at least one upstanding side wall joining the to the bottom, the top, bottom, and at least one sidewall defining an interior of the tank, the at least one sidewall being devoid of angular corners;    a second septic inlet adapted and constructed to conduct septic waste material from the first septic outlet of the first tank into the interior of the second tank;    a second septic outlet adapted and constructed to conduct septic waste material out of the interior of the second tank;    a first thermal exchange fluid conduit embedded in the at least one wall of the first tank;    a second thermal exchange fluid conduit embedded in the at least one wall of the second tank;    a thermal exchange fluid circulation assembly including a supply conduit, a thermal exchanger, a thermal output zone, and a return conduit; and    a thermal exchange fluid pump connected to circulate thermal exchange fluid sequentially through the return conduit, through the second thermal exchange fluid conduit in the second tank, then through the first thermal exchange fluid conduit in the first tank, through the supply conduit and the thermal exchanger, and through the thermal output zone.    
     
     
         7 . A septic system thermal recovery mechanism in accordance with  claim 6 , wherein the first tank is adapted and constructed to contain sludge, and the second tank is adapted and constructed to contain gray water.  
     
     
         8 . A septic system thermal recovery mechanism in accordance with  claim 1 , wherein the respective sidewalls of the first and second tanks comprise cast concrete walls, and the thermal exchange fluid conduits comprise PVC tubing embedded in the at least one sidewalls in a spiral configuration at the time the sidewalls are cast.  
     
     
         9 . A septic system thermal recovery mechanism in accordance with  claim 8 , wherein the sidewalls of the first and second tanks comprise substantially contiguous cylindrical walls.  
     
     
         10 . A septic system thermal recovery mechanism in accordance with  claim 8 , wherein the sidewalls of the first and second tanks each comprise four walls in two substantially parallel pairs of sidewalls, the contiguous sidewalls being connected together with rounded connecting portions.  
     
     
         11 . A septic system thermal recovery mechanism in accordance with  claim 6 , further comprising a second thermal exchange fluid conduit embedded in the top of the tank.  
     
     
         12 . A method of constructing a septic system thermal recovery mechanism comprising the following: 
 forming a septic tank having a top, a bottom, and at least one upstanding side wall joining the to the bottom, the top, bottom, and at least one sidewall defining an interior of the tank, the at least one sidewall being devoid of angular corners;    securing a septic inlet to the tank at a position to conduct septic waste material into the interior of the tank;    securing a septic outlet to the tank at a position to conduct septic waste material out of the interior of the tank; and    embedding a thermal exchange fluid conduit in the at least one wall of the tank, the thermal exchange fluid conduit being adapted and constructed to be connected to a source of thermal exchange fluid;    whereby thermal exchange fluid can be circulated through the thermal exchange fluid conduit without traversing an angular corner and without contacting the interior of the tank.    
     
     
         13 . A septic system thermal recovery mechanism in accordance with  claim 12 , wherein the step of forming the at least one sidewall comprises casting a concrete wall, and the step of embedding a thermal exchange fluid conduit comprises embedding PVC tubing in the at least one sidewall in a spiral configuration at the time the sidewall is cast.  
     
     
         14 . A septic system thermal recovery mechanism in accordance with  claim 13 , wherein the step of forming the at least one sidewall comprises forming a substantially contiguous cylindrical wall.  
     
     
         15 . A septic system thermal recovery mechanism in accordance with  claim 13 , wherein the step of forming the at least one sidewall comprises forming four walls in two substantially parallel pairs of sidewalls, the contiguous sidewalls being connected together with rounded connecting portions.