Long-Term Activated Sludge Treatment of Winery Waste Waters

Winery waste water, consisting primarily of clean-up water containing grape and wine residues, is being successfully treated by a long-term activated sludge treatment system. Retention time in the activated sludge basins ranges from 10 to 20 days. The system includes a screen, two activated sludge basins, clarifier, chlorination system, reaeration basin, sludge recycle and sludge digestion basin. Nutrients (anhydrous ammonia and phosphoric acid) are added to the influent. A polymer flocculant is added to enhance settleability of suspended solids in the clarifier. Characteristics of the treatment system influent and effluent are given, for both pressing (two months) and processing (10 months) seasons. System has achieved an efficiency of 99% in reduction of BOD5. Nitrogen and phosphorus removal has exceeded 90%. Total suspended solids concentration in the effluent was less than 20 mg/l. Problems encountered in the operation of the system generally have been related to low temperature. Ice formation in the wintertime resulted in loss of biological activity in the activated sludge basins and equipment damage. Installation of a submerged turbine aeration system solved the wintertime aeration and mixing problems.