IntroductionThe urban sewage and domestic/industrial used water heatpump (HP) technology has attracted interest in recent years [1]. Thisrecovery application aims to reduce energy consumption of build-ings, and provides a new energy source through a HP applicationusing wastewater (WW) because space heating and cooling, anddomestic hot water supply represent the biggest share in energyconsumed by residential buildings [2]. WW in urban sewage andbuildings retains a significant portion of its energy, and recyclingthe energy in these heat sinks is the essential phenomenon in devel-oping wastewater heat exchangers (WWHEX) [3]. Swiss researchesreported that more than 15% thermal energy supplied to buildingswas lost through the sewer system [4]. To recover this energy, var-ious types of heat exchangers (HEX) can be developed accordingto the area of use like domestic, sewage, filtered sewage, etc. Inrecent years, an increasing amount of research has been pursuedfor heat recovery using WWHEXs. In the present study, varioustypes of HEXs used in both large scale WWHEX facility and sci-entific studies are reviewed to provide a general understanding ofthe developments in this field.