A removable cover of a storage vessel, the storage vessel is selected from the group consisting of cesspool, septic tank, sump chamber and grease trap, the removable cover comprising:
- a heat exchanger integrated with the removable cover;
- a first inlet which receives a first heat transfer fluid which is transmitted to the heat exchanger;
- a first outlet which transmits the first heat transfer fluid away from the heat exchanger;
- a second inlet which receives a second heat transfer fluid from the storage vessel;
- and
- a second outlet which transmits the second heat transfer fluid back to the storage vessel, after the second heat transfer fluid exchanges heat with the heat exchanger.