Faculty of Engineering

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Subject: search.filters.subject.Effluent quality index

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Now showing 1 - 2 of 2
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    PublicationOpen Access
    Integrated Optimal Control of Urban wastewater Systems
    (2012) Rathnayake, U. S; Tanyimboh, T. T
    Sewer networks are designed to collect and transport wastewater to treatment plants. However, during wet weather periods stormwater runoff flows into these sewers and combined sewer overflows (CSOs) occur. Damage to the nearby natural waters from these CSOs is noticeable. This is because of the high pollution concentrations in CSOs. Controlling urban wastewater systems is one possible way of addressing the environmental issues from CSOs. Therefore, this research explores the development of a holistic framework that is intended to be used for the multi-objective optimization of urban wastewater systems, considering water quality in both sewers and receiving waters and the economics of wastewater treatment. Dry weather flows (DWFs) and stormwater runoff water quality compositions were considered. Temporal and spatial variations of the stormwater runoff were incorporated using pollutographs for different land-uses.
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    PublicationOpen Access
    Evolutionary Multi-Objective Optimal Control of Combined Sewer Overflows
    (Springer Netherlands, 2015-03-18) Rathnayake, U.S; Tanyimboh, T. T
    This paper presents a novel multi-objective evolutionary optimization approach for the active control of intermittent unsatisfactory discharges from combined sewer systems. The procedure proposed considers the unsteady flows and water quality in the sewers together with the wastewater treatment costs. The distinction between the portion of wastewater that receives full secondary treatment and the overall capacity of the wastewater treatment works (including storm overflow tanks) is addressed. Temporal and spatial variations in the concentrations of the primary contaminants are incorporated also. The formulation is different from previous approaches in the literature in that in addition to the wastewater treatment cost we consider at once the relative polluting effects of the various primary contaminants in wastewater. This is achieved by incorporating a measure of the overall pollution called the effluent quality index. The differences between two diametrically opposed control objectives are illustrated, i.e. the minimization of the pollution of the receiving water or, alternatively, the minimization of the wastewater treatment cost. Results are included for a realistic interceptor sewer system that show that the combination of a multi-objective genetic algorithm and a stormwater management model is effective. The genetic algorithm achieved consistently the frontier optimal control settings that, in turn, revealed the trade-offs between the wastewater treatment cost and pollution of the receiving water.