Winery wastewater treatment in a hybrid constructed wetland

Abstract

A full-scale hybrid constructed wetland (CW) was built to treat mixed effluent derived from a winery and tourist establishment. The treatment system consisted of a hydrolytic upflow sludge bed (HUSB) digester for suspended-solids removal, a vertical-flow (VF) constructed wetland and three parallel subsurface horizontal-flow (HF) constructed wetlands. The HUSB reduced TSS loads to 72–172 mg L −1, helping to prevent clogging, while organic loads for the wastewater entering the VF ranged from 422 to 2178 mg COD L −1 and from 216 to 1379 mg BOD 5 L −1. At an average hydraulic loading rate (HLR) of 19.5 mm d −1 and average surface loading rates (SLR) of 30.4 g COD m −2 d −1 and 18.4 g BOD 5 m −2 d −1, the overall VF + HF CW system reached average removal efficiencies of 86.8% of TSS, 73.3% of COD, and 74.2% of BOD 5. The system also removed 52.4% of total Kjeldhal nitrogen (TKN), 55.4% of NH 3-N and 17.4% of phosphates. While the VF unit showed high removal rates, the HF unit operated at lower removal rates than those previously reported. The CW units showed rapid adaptation to low pH values. A linear-regression analysis indicated that the independent variables SLR and temperature determined more than 95% of the variation in performance and efficiency of the CW system and offered simple mathematical models for design and system-description purposes.