Evolutionary multi-objective optimal control of combined sewer overflows

Upaka S. Rathnayake, Tiku T. Tanyimboh

Research output: Contribution to journalArticle

29 Citations (Scopus)
117 Downloads (Pure)


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.
Original languageEnglish
Pages (from-to)2715–2731
Number of pages17
JournalWater Resources Management
Issue number8
Early online date18 Mar 2015
Publication statusPublished - 1 Jun 2015


  • optimal control
  • effluent quality index
  • integrated wastewater management
  • combined sewer system
  • wastewater treatment cost
  • water pollution control
  • combined sewer overflow

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  • Research Output

    • 29 Citations
    • 2 Proceeding
    • 1 Conference contribution book

    Integrated optimal control of urban wastewater systems

    Rathnayake, U. S. & Tanyimboh, T., 16 May 2012. 8 p.

    Research output: Contribution to conferenceProceeding

    Multi-objective optimization of urban wastewater systems

    Rathnayake, U. S. & Tanyimboh, T., Jul 2012. 8 p.

    Research output: Contribution to conferenceProceeding

  • Optimal control of combined sewer systems using SWMM 5.0

    Rathnayake, U. S. & Tanyimboh, T., Apr 2012, Urban Water 2012 conference proceedings. Mambretti, S. & Brebbia, C. A. (eds.). Southampton: WIT Press, p. 87-96 10 p.

    Research output: Chapter in Book/Report/Conference proceedingConference contribution book

  • 8 Citations (Scopus)

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