Combination of long term aerated storage and chemical coagulation/flocculation to winery wastewater treatment

Winery wastewaters from white and red wine production were studied, in the first stage of this work, by a coagulation/flocculation process using four different coagulants (FeSO4, Al-2(SO4)(3), FeCl3 and Ca(OH)(2)). The optimal pH and volume of coagulant added were studied. From the results achieved it was possible to verify that coagulation/flocculation allows, within optimal conditions of pH and coagulant dosage, an efficient removal of turbidity (aluminium sulphate, 92.6%) and total suspended solids - TSS (calcium hydroxide, 95.4%). However, it revealed small capacity to remove the COD load of winery wastewaters even from white or red wine production. As an alternative a previous and economical aerobic biological process was evaluated in articulation with the coagulation/flocculation process. The long term aerated storage (LTAS) was studied with two different aeration periods (2.4 h/day and 4.0 h/day) trying to reach a better significant COD removal with reduced operational costs. Long term aerated storage possibilities obtained a COD degradation of 75% in 11 weeks for an aeration period of 4 h/day. A way of optimizing the LTAS process and removing the remaining organic load was the combination with the chemical coagulant/flocculant studied in the first stage of this work. Therefore, to the LTAS effluent were applied the four coagulants within optimal conditions. Calcium hydroxide was selected as the best coagulant to apply to the LTAS effluent. Through the combination of the LTAS process followed by the calcium hydroxide coagulant an overall removal efficiency of 84.5% was obtained for COD, 96.6% for turbidity, 98.7% for volatile suspended solids (VSS) and 99.1% for TSS. (C) 2010 Elsevier B.V. All rights reserved.