Plant selection to be used in vertical flow wetland for leachate treatment

ITURRIA, M.; SANCHEZ, G.C.; MAINE, M.A.; HADAD, H.R.

Aarhus

Simposio; 8th International Symposium on Wetland Pollutant Dynamics and Control-WETPOL 2019; 2019

Aarhus University

Sanitary landfilling is the most preferred solid waste management strategy all over the world, being the generation of landfill leachate one of the main environmental problems arising from this practice. Leachates are result of undergoing physicochemical and biological changes in landfill body, percolation of rainwater through the wastes and their inherent moisture content. Landfill leachate is a complex wastewater that requires treatment prior to its release into a receiving water body in order to avoid and mitigate environmental pollution. Villa Dominico municipal landfill is located near Buenos Aires (Argentina). This landfill was in operation until 2004, and then it was closed. A wetland system is proposed to treat the leachate. The main objective of this work was to select plants to be used in vertical subsurface flow wetlands (VFWs) for the leachate treatment. The tolerance to leachate of the following wetland plants: Typha domingensis, Scirpus americanus, Sagittaria montevidensis, Cortaderia selloana, Iris pseudacorus Echinodorus grandiflorus, Ruellia brittoniana, Bambusa vulgaris, Bambusa tuldoides, Zantedeschia aethiopica and Hibiscus striatus, was studied. Some of them are used as ornamental plants. Removal efficiencies were determined in the VFWs planted with the most tolerant of the studied species. Twenty-liter lab-scale VFWs were filled with sand and crash stone 30-60 and planted with the studied macrophytes. The experiment lasted 16 months. The leachate used in this study was collected from the Villa Dominico municipal landfill. At the beginning of the experiment, 1:10 diluted leachate was used. Then, dilutions of 1.5:10, 2:10, 2.5:10, and 3:10 were used. Electrical conductivity (EC), pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total dissolved solids (TDS), ammonium (NH4+), and dissolved oxygen (DO) were measured in leachate before and after treatments. The chemical composition of the studied raw leachate was: pH= 8.2-8.6, EC= 18,900-23,800 􀁐mhos cm-1, Total phosphorus (TP)= 22.3-27.7 mg l-1, Nitrate (NO3-)= 39.9- 60.9 mg l-1, NH4+= 948.9-3097.6 mg l-1, BOD=636.5-837.9 mg O2 l-1, COD= 2411.4-3022.8 mg O2 l-1. All plant species showed high tolerance to studied diluted landfill leachate, except for Hibiscus striatus that only tolerated 1:10 diluted leachate. Sagittaria montevidensis, Cortaderia selloana and Echinodorus grandiflorus presented injury symptoms and decreased their growth at 3:10 diluted leachate. In consequence, these species were discarded. For VFWs planted with the other species, using 3:10 diluted leachate, the removal efficiencies ranged between: 40-67% for NH4+, 20-35% for BOD5 and 60-70% for COD. Electrical conductivity decreased 24-30%. DO increased in leachate after all treatments, presenting the highest increase in the treatment planted with Scirpus americanus. No significant differences in TDS was verified.Typha domingensis, Scirpus americanus, and Iris pseudacorus presented the highest tolerance, and VFWs planted with these species presented the best removal efficiencies in the leachate treatment.