Combined treatment of highly contaminated winery wastewater

Abstract

In recent years, electrocoagulation (EC) has received increasing attention concerning its potential for destruction and removal of organic and non-organic pollutants in wastewater. The objective of the current study was to examine the potential of EC, to treat different winery wastewaters (WWW), which are characterized by heavy loads of organic pollutants. To this end EC of WWW was conducted at 2 A, and applied voltage up to 10 V. Laboratory tests of raw WWW treatment in different application periods (from 10 to 40 min) of EC were carried out, and the removal efficiency was studied. The potential of EC to improve the water quality of raw WWW, prior to further processing, was demonstrated. Enhanced removal of the WWW pollutants was found at longer treatment periods. A 10 min batch treatment of WWW produced 16.4–27.9% reduction of the biochemical oxygen demand (BOD), 28.2–41.9% of the chemical oxygen demand (COD), and 89.2% the total phosphorus. In view of the high organic load of the WWW, this involved removal of thousands mg L −1 COD. This facilitates further treatment by aquatic plants. At 1:1, W:F dilution, 97.5 and 95.6% of the BOD were removed, after 23 days of treatment, with the floating Hydrocotyle umbellate and Eichhornia crassipes plants and aeration, respectively, as compared to 28.5% in the control. Emergent plants (salt marshes with rushes) proved to be exceptionally effective in removing 99.2% of the BOD and 98.2% of the COD. These plants performed well at the high organic loads of the WWW. A scheme for a two-stage treatment of raw WWW is described. In the first stage WWW is treated by EC and its effluent with reduced organic load is then purified in the second stage, comprising aquatic plants. Finally economic aspects of the proposed system are outlined.