Process and Apparatus for Recovering Energy from Wastewater

Abstract

The invention provides a process and apparatus for the recovery of heat energy from wastewater. Wastewater, for example grey water from a domestic residence, is introduced to a detention chamber, which provides effective decoupling between the introduction of new wastewater and the demand for heat energy from its ultimate application. A heat exchange surface, in contact with the wastewater on one side and a working fluid on the other, extracts heat from the detention chamber through thermal conduction and the working fluid is transferred, via a heat pump, to a second heat exchange surface. The second heat exchange surface, in contact with the working fluid on one side and heat energy storage media on the other, transfers heat energy to the storage media through conduction. Heat energy can then be extracted from the storage media for applications including heating of potable water, or provision of building heating.

1 . A process for recovering heat energy from wastewater comprising
 a. Collection of wastewater in a reservoir;   b. Transfer of heat energy from the collected wastewater into a working fluid;   c. Transport of the working fluid;   d. Transfer of the heat energy from the working fluid to a heat energy reservoir; and   e. Transfer of the heat energy, on an as needed basis, from the heat energy reservoir to an incoming water supply.   
     
     
         2 . The process of  claim 1 , wherein the process further comprises one or more of the following steps:
 a. Passing influent water over a filter to remove particles larger than approximately 200 μm;   b. Delivery of the wastewater, with heat energy removed, to a wastewater treatment system for water recovery.   
     
     
         3 . The process of  claim 1 , wherein the incoming water supply is potable water suitable for human contact through washing or bathing. 
     
     
         4 . The process of  claim 1 , wherein the incoming water supply is potable water suitable for human consumption through drinking or food preparation. 
     
     
         5 . The process of  claim 1 , wherein the incoming water supply is for use in space heating. 
     
     
         6 . The process of  claim 1 , wherein transport of the working fluid is carried out by means of a heat pump. 
     
     
         7 . The process of  claim 2 , wherein the filter is periodically backwashed with purified wastewater. 
     
     
         8 . The process of  claim 1 , wherein the working fluid is a refrigerant gas. 
     
     
         9 . The process of  claim 2  wherein the wastewater treatment system uses mechanical separation of impurities. 
     
     
         10 . The process of  claim 2 , wherein the wastewater is grey water. 
     
     
         11 . An apparatus for the removal of heat energy from wastewater comprising the following:
 a. A device allowing seamless interconnection between the wastewater supply and the process described herein;   b. A heat exchange surface in contact with the wastewater;   c. A heat storage reservoir containing heat storage media;   d. Heat exchange surfaces in contact with the heat storage media; and   e. Plumbing to transfer working fluid between the heat exchange surfaces.   
     
     
         12 . The interconnection device of  claim 11 , wherein the interconnection device includes a detention chamber. 
     
     
         13 . The interconnection device of  claim 11 , wherein the interconnection device includes a wastewater backflow prevention device. 
     
     
         14 . The interconnection device of  claim 11 , wherein the interconnection device includes a level sensor to control a pump. 
     
     
         15 . The interconnection device of  claim 11 , wherein the interconnection device includes a pump for the transfer of cooled wastewater to a treatment system. 
     
     
         16 . The interconnection device of  claim 11 , wherein the interconnection device includes an integrated filter. 
     
     
         17 . The interconnection device of  claim 11 , wherein the interconnection device includes a sealed lid to prevent the ingress of water. 
     
     
         18 . The interconnection device of  claim 11 , wherein the interconnection device includes a vent to encourage reliable flow of wastewater. 
     
     
         19 . The interconnection device of  claim 16 , wherein the filter is capable of removing particles larger than approximately 200 μm. 
     
     
         20 . The apparatus of  claim 11 , further comprising one or more of the following:
 a. A compressor to move the working fluid between the heat exchange surfaces;   b. A device promoting phase change in the working fluid;   c. Temperature measuring devices;   d. A thermostatic control system;   e. A supplemental, backup heating device;   f. Phase change media in the heat storage reservoir; and   g. Plumbing connecting the potable water supply to the heat storage device;   
     
     
         21 . The apparatus of  claim 20 , wherein the device promoting a phase change in the working fluid is a thermostatic expansion valve. 
     
     
         22 . The apparatus of  claim 20 , wherein the device promoting a phase change in the working fluid is a capillary tube. 
     
     
         23 . The apparatus of  claim 20 , wherein the incoming water supply is potable water suitable for human contact through washing or bathing. 
     
     
         24 . The apparatus of  claim 20 , wherein the incoming water supply is potable water suitable for human consumption through drinking or food preparation. 
     
     
         25 . The apparatus of  claim 20 , wherein the incoming water supply is for use in space heating.