Complete treatment of olive pomace leachate by coagulation, activated-carbon adsorption and electrochemical oxidation.
A battery scheme comprising sequential alum coagulation, activated-carbon adsorption and electrochemical oxidation over boron-doped diamond electrodes to mineralize a leachate from olive pomace processing is demonstrated. The effect of coagulant and adsorbent concentration on treatment efficiency was assessed in the range 0.1-50 mM Al(3+) and 2.5-50 g/L activated-carbon and optimal conditions were established. Coagulation at 7.5mM Al(3+) resulted in substantial solids and color removal (i.e. 80% and 93%, respectively). This was accompanied by only 30% chemical oxygen demand (COD) reduction (initial COD was about 3,500 mg/L). The latter increased to 80% though when coagulation was coupled with adsorption at 25 g/L activated carbon. Electrochemical oxidation of the original effluent for 360 min led to 63% and 82% COD reduction at 10 and 20A current intensity, respectively. When this process was tested as a polishing stage following coagulation and adsorption, overall COD removal reached values of 92% and 97%, respectively. The final effluent was also colorless and solids free. However, the treated effluent still exhibited ecotoxicity possibly due to the formation of ecotoxic oxidation products.
Mavros
Michael
M
Department of Environmental Engineering, Technical University of Crete, GR-73100 Chania, Crete, Greece.
Xekoukoulotakis
Nikolaos P
NP
Mantzavinos
Dionissios
D
Diamadopoulos
Evan
E
D002244:Carbon / Q000737:chemistry*; D004563:Electrochemistry; D005525:Food-Processing Industry; D007220:Industrial Waste / Q000032:analysis*; D007700:Kinetics; D031658:Olea; D010084:Oxidation-Reduction; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods
D007220:Industrial Waste; D002244:Carbon