he main environmental problems of fish canning industries are high water consumption and high organic matter, oil and grease and salt content in their wastewaters. This work aims to analyze the situation (water consumption, wastewater production, wastewater characterization, etc.) of different plants located north of Douro river, in Portugal, in order to propose various solutions to their problems. Thus, initially it was made an identification and implementation of prevent and control pollution measures within the industrial units in order to reduce water consumption, minimize the wastewater production and reduce the pollutant load to treat. Then, the evaluation of wastewater treatability was started through a sedimentation and coagulation-flocculation process, with two organic coagulants (RIPOL 070 and RIFLOC 1815), commonly used in wastewater treatment. Sedimentation experiments showed that the flotation of 54% of oils and greases occurred, and 36% of total suspended solids were removed. The coagulation-flocculation process gave good results, especially in terms of oil and grease and total suspended solids removal. The best suspended solids removal efficiencies were 53% and 79%, using 400 mg/L of RIPOL 070 and 150 mg/L of RIFLOC 1815, respectively. At these dosages, both coagulants demonstrated excellent oil and grease removals, about 99% for RIFLOC 1815 and 88% for RIPOL 070.
