Title: Evaluation of mesoscale physical habitats in sediment and water quality improvement - a mesocosm study for urban canals

Authors: Sanjana De Zoysa; Kurugama A.T. Chandeep; Pathirathne H.D.R. Pathirathne; Pattiyage I.A. Gomes

Addresses: Department of Civil Engineering, Sri Lanka Institute of Information Technology, New Kandy Road, Malabe 10115, Sri Lanka ' Department of Civil Engineering, Sri Lanka Institute of Information Technology, New Kandy Road, Malabe 10115, Sri Lanka ' Department of Civil Engineering, Sri Lanka Institute of Information Technology, New Kandy Road, Malabe 10115, Sri Lanka ' Department of Civil Engineering, Sri Lanka Institute of Information Technology, New Kandy Road, Malabe 10115, Sri Lanka

Abstract: This study investigated the applicability of different types of attenuation processes (i.e., aeration and stirring) with and without dilution in nutrients (nitrogen and phosphorous) and sulphide-polluted sediment cleanup via laboratory mesocosms. Attenuation refers to the decline in contaminant concentration, a phenomenon driven by processes like dilution, mixing, and dispersion. Dilution, a remedial method involving the blending of contaminated water with uncontaminated often happens with uncontaminated runoff or a tributary. Regardless of the seasons, aeration, stirring, combined aeration and stirring, and dilution generally resulted in better removal efficiency of pollutants. Aeration combined with stirring showed notable improvements across multiple water quality parameters, and parameters seemed to be treatment type dependent, but without any significant differences. Dilution reduced electrical conductivity and increased dissolved oxygen but did not influence ammoniacal nitrogen and phosphate. The energy consumption for a unit percentage improvement via aeration and stirring was 0.04-0.25 USD and 0.03-0.15 USD, respectively. Therefore, relying solely on attenuation processes without dilution is deemed economically infeasible in real or prototype applications. This research sheds light on potential applications including pros and cons, emphasising the need for a balanced approach, and setting the stage for future studies.

Keywords: aeration; dilution; energy; mesocosms; mesoscale physical habitats; sediment; stirring; water quality.

DOI: 10.1504/IJHST.2025.143110

International Journal of Hydrology Science and Technology, 2025 Vol.19 No.1, pp.93 - 115

Received: 20 Jun 2023
Accepted: 24 Dec 2023
Published online: 03 Dec 2024 *

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