Performance evaluation of single- and multi-effect evaporators for multi-pollutant removal and energy efficiency assessment in baker's yeast wastewater

Abstract

Wastewater from the baker's yeast industry contains high concentrations of organic and inorganic pollutants, necessitating effective treatment to minimize environmental impact. This study examines the falling film evaporator (FFE) and forced circulation evaporator (FCE) as single-effect units, as well as their combined performance in a multi-effect evaporator (MEE). To evaluate the performance of these systems, concentration reduction (C-RE), pollution load reduction (PL-RE), and grey water footprint reduction (GWF-RE) metrics are applied. Additionally, a new energy-based indicator is introduced to measure energy consumption per unit of pollutant reduction (ECI-PL) and grey water footprint reduction (ECI-GWF), providing a broader perspective on treatment sustainability. Based on C-RE, FFE removes 98.9 % of total phosphorus (TP), 94.4 % of biochemical oxygen demand (BOD5), and 93.5 % of chemical oxygen demand (COD), while FCE achieves the highest total nitrogen (TN) reduction at 32.8 %. GWF-RE for TP is observed at 99.4 % in FFE, 91.5 % in FCE, and 94.2 % in MEE. Energy consumption analysis reveals that the ECI-PL for TP removal ranges from 297 to 2560 kWh/kg. Despite its high energy demand, this process effectively reduces pressure on receiving water bodies, preserving between 617 (FFE) and 631 m3 (MEE) of freshwater for every kg of TP removed. These findings demonstrate that advanced evaporator systems effectively reduce the ecological footprint of baker's yeast wastewater, enhancing environmental sustainability. The results show that FFE is the most efficient in pollutant removal while maintaining lower energy consumption; however, TN reduction remains limited in this system. © 2025 The Authors.