Wastewater Generation and Potential Reuse in Tomato Processing Industry: A Field-Scale Assessment in Tunisia

Water scarcity and increasing pressure on freshwater resources have intensified interest in the reuse of agro-industrial effluents in semi-arid Mediterranean regions. This study examines the volume, temporal variability, and physicochemical characteristics of wastewater generated by a tomato-processing plant in central Tunisia during the 2022 production campaign. Wastewater discharge was continuously monitored throughout the season, combined with physicochemical analyses to assess effluent quality and reuse potential. Results show strong variability in wastewater generation, closely related to production cycles and operational activities, particularly cleaning operations. Specific wastewater production ranged from 1.5 to 1.7 m3 per ton of processed tomatoes. The effluents were characterized by variable salinity conditions and dominant Na-Cl facies, with electrical conductivity values ranging from 2.09 to 8.01 dS/m and an average value of 4.06 dS/m. While pH and BOD5 remained within Tunisian standards, COD occasionally exceeded regulatory limits, indicating residual organic pollution. Over the 84-day campaign, approximately 490,000 m3 of wastewater was generated, representing a significant non-conventional water resource. This volume could potentially irrigate 98–163 ha depending on crop water requirements. However, salinity and temporal variability remain key constraints for large-scale reuse. Unlike previous studies based on short-term or laboratory-scale assessments, this work provides a field-scale, season-long evaluation under real operating conditions.