This paper attempts to make one further step in energy efficiency improvement of wastewater treatment plants connecting it with environmental considerations, namely the suppression of unpleasant aromas. Solution of the optimum heat integration when the off-gas from reactors is considered as heat source together with the effluent heat, is presented. Further, the thermal management is linked to absorption efficiency through the classical concept of simultaneous heat and mass transfer. The conceptual approach of heat integration applied through Pinch analysis is extended to consider the mass exchange through a combined operating composite and equilibrium curve plot allowing for adjustment of uncertain variables, such as streams target temperatures and stripping water flowrate. An case study from an autothermal anaerobic digesting plant (ATAD) in Ireland is presented and the future plans of this ongoing project are discussed. © 2009 Elsevier B.V. All rights reserved.