Research Papers - Department of Civil Engineering

Permanent URI for this collectionhttps://rda.sliit.lk/handle/123456789/598

Browse

Filters

2012 - 20152

Advanced Search

Filter by

Settings

Author: search.filters.author.Tanyimboh, T. TSubject: search.filters.subject.Optimal control

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    PublicationOpen Access
    Optimal control of combined sewer systems using SWMM 5.0
    (Southampton: WIT Press, 2012-04) Rathnayake, U. S; Tanyimboh, T. T
    Combined sewer networks carry wastewater and stormwater together. Capacity limitation of these sewer networks results in combined sewer overflows (CSOs) during high-intensity storms. Untreated CSOs when directly discharged to the nearby natural water bodies cause many environmental problems. Controlling urban wastewater systems is one possible way of addressing the environmental issues from CSOs. However, controlling urban sewer systems optimally is still a challenge, when considering the receiving water quality effects. In this study, a multi-objective optimization approach was formulated considering the pollution load to the receiving water from CSOs and the cost of the wastewater treatment. The optimization model was tested using an interceptor sewer system. The results demonstrate the benefits of the multi-objective optimization approach and its potential to establish the key properties of a range of control strategies through an analysis of the various tradeoffs involved. Keywords: combined sewer overflows, effluent quality index, evolutionary computing, genetic algorithm, multi-objective optimization, combined sewer systems.
  • Thumbnail Image
    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.