Phytoremediation as a Sustainable Alternative for Organic Matter Removal From Slaughterhouse Wastewater Pretreated by Immediate One-Step Lime Precipitation

Abstract

In this study, slaughterhouse wastewater previously treated by immediate one-step lime precipitation was treated using a vertical flow constructed wetland (VFCW). A VFCW pilot scale planted with Vetiveria zizanioides in light expanded clay aggregates was used to study the influence of the organic load applied (3 to 212 g m−2 d−1) and the bed depth of the VFCW (0.35 and 0.70 m) on the organic matter removal (COD). Two VFCWs operated in parallel under continuous flow, and a hydraulic load of around 80 L m−2 d−1 was used. The results indicated that an increase in the organic load decreased COD removal efficiency. The bed depth of the VFCW had a significant influence on the removal of organic matter, with greater removal at high bed depths. For organic loads applied up to 9.5 g m−2 d−1, COD removal efficiencies of 71.4 ± 4.0% and 85.2 ± 3.4% were observed for lower and higher VFCW bed depth, respectively, which met the requirements for water reuse for irrigation. Throughout the tests, Vetiveria zizanioides did not show signs of toxicity, and its growth was substantial. Keywords: slaughterhouse wastewater, vertical flow constructed wetlands, Vetiveria zizanioides, organic matter removal, immediate one-step lime precipitation