Wetland Discharge Water Filtration of a Mesotrophic Lake

Contaminated watershed discharge has been impairing surface water with excessive suspended solids, organic matter, and particulate nutrients. Those contaminated suspended particles are dated to settle in the water column and will be further on its sediment. Lake Johanne, a shallow mesotrophic lake located in the SainteAnne-des-Lacs municipality in Quebec has been receiving wetland discharge water through the years. In this paper, onsite remediation of this water employing nonwoven geotextiles as filter media is investigated. The method was based on a tank near the lakeshore with a floating geotextile filtration system operated continuously (either with a 1-day or 0.5-day retention time). Wetland water was pumped into the tank, filtered by a selected non-woven geotextile combination with distinct apparent opening sizes, and returned to the lake by gravity. This experiment ran during the summer and mid-fall of 2022. Samples from both the inlet and tank were acquired every 2-3 days and filter media were changed upon clogging. Therefore, the study objective was to improve the discharge water quality before entering the lake. Water quality parameters evaluated on the deployment (i.e., from both inlet and tank) were total phosphorus, total organic carbon, total suspended solids (TSS), particle size, and turbidity. The onsite experiment provided an average attenuation of suspended particles, water cloudiness and nutrients around 25, 42, and 76% for total phosphorus, turbidity, and TSS parameters, respectively. Furthermore, the proposed remediation improved the water quality of the evaluated wetland water discharge, consequently, proving the feasibility of this possible remediation.