Author(s): Vinicius P. F. De Andrade; Rayssa V.B. Jacob; Andre L.S. Salomao
Linked Author(s):
Keywords: No Keywords
Abstract: Decentralized wastewater treatment is essential for remote locations lacking reliable sanitation infrastructure. This study assessed the performance of the long-term Engineered Ecosystem of CEADS/UERJ, located in Ilha Grande (Brazil), with a focus on phosphorus removal mechanisms in constructed wetlands (CWs). Monitoring occurred between September 2024 and April 2025, including measurements of phosphate, chemical oxygen demand (COD), dissolved oxygen (DO), oxidation–reduction potential (ORP), and macrophyte biomass. Average COD removal reached 78% in the primary–secondary treatment units, and final effluent COD values were below 8% of influent levels. Phosphate concentrations averaged 27.5 mg/L (influent), 24.7 mg/L (post-secondary treatment), and 9.0 mg/L at the CW outlet, yielding overall phosphorus removal efficiencies of 25–91%, with peak performance during spring. Mass balance analysis indicated limited direct contributions from substrate adsorption, or microbial biomass, suggesting substrate saturation after more than 16 years of operation. Unquantified processes, including microalgal assimilation and inorganic retention and macrophyte uptake, represented the dominant removal pathways. Seasonal macrophyte development appeared to enhance oxygenation and ORP, supporting higher removal rates during periods of greater biological activity. The findings provide relevant insights into the hydraulic and biogeochemical behavior of long-term CWs in decentralized wastewater systems, contributing to optimized design and operation in isolated communities.
Year: 2026