Exploring granular filter media in sustainable drainage systems (SuDS) for stormwater pollutant adsorption: A pilot study

• Published in: Chemical engineering research & design 2024-10, Vol.210, p.437-444
• Main Authors: Tota-Maharaj, Kiran, Karunanayake, Chamaka, Cheddie, Denver, Azamathulla, Hazi Md, Rathnayake, Upaka
• Format: Article
• Language: English
• Subjects: Geotextile membranes; Granular filter media; Pollutant removal; Stormwater management; Stormwater quality model; Stormwater treatment systems; Water pollutant adsorption
• ISSN: 0263-8762
• DOI: 10.1016/j.cherd.2024.08.035

Granular filter media are integral to sustainable drainage systems (SuDS) for their efficiency in removing pollutants from urban runoff. This study focuses on understanding the filtration processes within these media by combining a pilot experimental study with a modeling approach. The experimental study involved characterizing the physical and hydraulic properties of various granular filter media materials, including sand, pea-gravel, gravel, and geotextile membranes. Three laboratory-scale stormwater filtration rigs were tested to evaluate the filter media's pollutant removal capacity and hydraulic performance. This work presents a phenomenological model that predicts the spatial variation in the concentrations of stormwater and urban runoff substances, specifically nitrate ions (NO3-), phosphate ions (PO43-), chemical oxygen demand (COD), and suspended solids, by studying their concentration profiles. The stormwater quality model was used to predict the concentration profiles for stormwater with an average inflow consisting of 2.9 mg/L nitrates, 3.4 mg/L phosphate ions, 225 mg/L COD, and 3.3 mg/L of suspended solids. The predicted outlet concentrations matched well with measured experimental data. The results showed that adding geotextile membranes to a granular filter significantly improves its ability to adsorb dissolved species for stormwater applications. This research highlights the importance of understanding the physical and hydraulic properties of granular filter media and their impact on stormwater pollutant removal efficiency. The developed model can assist in the design and optimization of stormwater treatment systems by predicting the performance of different filter media materials, allowing for informed decision-making and improved system functionality. •The study uses experiments and modelling to analyze filtration in granular media.•Filter media properties, including sand, gravel and geotextiles, were characterized,•Laboratory rigs were tested to evaluate the pollutant removal capacity.•Geotextile membranes boost granular filters' ability to adsorb dissolved species.•The model aids stormwater system design by predicting filter media performance.