Design of an integrated bioprocess for the treatment of tuna processing liquid effluents

• Published in: Process biochemistry (1991) 2000-05, Vol.35 (9), p.1013-1017
• Main Authors: Achour, M, Khelifi, O, Bouazizi, I, Hamdi, M
• Format: Article
• Language: English
• Subjects: Activated sludge; Anaerobic digestion; Biogas; Tuna processing; Wastewater
• ISSN: 1359-5113; 1873-3298
• DOI: 10.1016/S0032-9592(00)00133-3

A biodegradation system used to treat the discharged concentrated liquid effluents from a tuna-processing unit is described. The study includes a characterisation of the industrial effluents, the design of a bioprocess treatment and the testing of its performance. The liquid effluent to be treated contained 1570 mg/l suspended matter, 1450 mg/l fats, a chemical oxygen demand (COD) of 11 100 mg/l and a biochemical oxygen demand (BOD) of 6600 mg/l. The designed system included a physical pre-treatment unit used to remove the fats and the suspended solids through a decanter, an anaerobic digester and an activated sludge aerated bio-reactor. The pre-treatment unit allowed the elimination of 40% of the suspended matter and fats expressed in terms of COD. The anaerobic system transformed 45% of the dissolved COD into methane gas with a production of about 0.25 m 3 methane per kg of degraded COD. The aerated treatment unit achieved 85% reduction of COD. An integrated system, combining the three steps, permitted the processing of 1.2 kg COD/m 3 per day and the removal of up to 95% of the COD with minimal energy consumption and minimal sludge production.