Optimal expansion of a coastal wastewater treatment and ocean outfall system under uncertainty (II): Optimisation analysis

Ni Bin Chang, Hsin-Cheng Yeh, Chin Hsien Chang

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

This paper presents an integrated simulation-optimisation assessment of the various physical, chemical, and microbiological processes that determine the transport and fate of key constitutes associated with coastal wastewater treatment and disposal effluents in coastal environments. The well-calibrated and validated ocean mixing simulation model - Cornell mixing zone expert system (CORMIX) - was employed in the first stage as an indispensable tool to simulate the initial dilution factor with respect to two major water quality indicators, biochemical oxygen demand (BOD) and Escherichia coli. The CORMIX outputs, which were obtained in a companion study, were used as the inputs in both deterministic and chanceconstraint based stochastic programming models to evaluate a few alternatives for system planning and design. Such integration allowed the identification of the optimal expansion strategies for a large-scale coastal wastewater treatment and ocean outfall system in the city of Kaohsiung, South Taiwan. Research findings clearly indicate that the original alternative proposed by the city government, which had planned on upgrading the wastewater treatment process directly from the primary to the secondary level, is economically undesirable. Given the technology options of primary or enhanced primary treatment, in the most cost-effective expansion strategy, the optimal length of a newly constructed second ocean outfall pipe is no less than 1260m in order to gain sufficient assimilative capacity in the ocean environment.With this strategy, the BOD standards in the ocean environment are met for both Classes B and A types of ocean waters. The reliability of this system design may be assessed by taking the stochastic characteristics of sewerage inflow and diffusion and dispersion processes into consideration. Such an optimisation analysis could eventually lead to considerable cost savings of up to 75% when compared to the original, officially favoured alternative.

Original languageEnglish
Pages (from-to)39-59
Number of pages21
JournalCivil Engineering and Environmental Systems
Volume28
Issue number1
DOIs
Publication statusPublished - 2011 Mar 1

Fingerprint

Outfalls
Wastewater treatment
Biochemical oxygen demand
Wastewater disposal
Stochastic programming
Expert systems
Escherichia coli
Dilution
Water quality
Costs
Effluents
Systems analysis
Pipe
Planning
Uncertainty
Water

Keywords

  • CORMIX
  • Chance-constrained programming
  • Coastal wastewater treatment
  • Ocean outfall
  • Optimisation
  • Systems analysis

ASJC Scopus subject areas

  • Civil and Structural Engineering

Cite this

Optimal expansion of a coastal wastewater treatment and ocean outfall system under uncertainty (II) : Optimisation analysis. / Chang, Ni Bin; Yeh, Hsin-Cheng; Chang, Chin Hsien.

In: Civil Engineering and Environmental Systems, Vol. 28, No. 1, 01.03.2011, p. 39-59.

Research output: Contribution to journalArticle

@article{798a553b54d3490c9afad22125dd18e3,
title = "Optimal expansion of a coastal wastewater treatment and ocean outfall system under uncertainty (II): Optimisation analysis",
abstract = "This paper presents an integrated simulation-optimisation assessment of the various physical, chemical, and microbiological processes that determine the transport and fate of key constitutes associated with coastal wastewater treatment and disposal effluents in coastal environments. The well-calibrated and validated ocean mixing simulation model - Cornell mixing zone expert system (CORMIX) - was employed in the first stage as an indispensable tool to simulate the initial dilution factor with respect to two major water quality indicators, biochemical oxygen demand (BOD) and Escherichia coli. The CORMIX outputs, which were obtained in a companion study, were used as the inputs in both deterministic and chanceconstraint based stochastic programming models to evaluate a few alternatives for system planning and design. Such integration allowed the identification of the optimal expansion strategies for a large-scale coastal wastewater treatment and ocean outfall system in the city of Kaohsiung, South Taiwan. Research findings clearly indicate that the original alternative proposed by the city government, which had planned on upgrading the wastewater treatment process directly from the primary to the secondary level, is economically undesirable. Given the technology options of primary or enhanced primary treatment, in the most cost-effective expansion strategy, the optimal length of a newly constructed second ocean outfall pipe is no less than 1260m in order to gain sufficient assimilative capacity in the ocean environment.With this strategy, the BOD standards in the ocean environment are met for both Classes B and A types of ocean waters. The reliability of this system design may be assessed by taking the stochastic characteristics of sewerage inflow and diffusion and dispersion processes into consideration. Such an optimisation analysis could eventually lead to considerable cost savings of up to 75{\%} when compared to the original, officially favoured alternative.",
keywords = "CORMIX, Chance-constrained programming, Coastal wastewater treatment, Ocean outfall, Optimisation, Systems analysis",
author = "Chang, {Ni Bin} and Hsin-Cheng Yeh and Chang, {Chin Hsien}",
year = "2011",
month = "3",
day = "1",
doi = "10.1080/10286600903243138",
language = "English",
volume = "28",
pages = "39--59",
journal = "Civil Engineering and Environmental Systems",
issn = "1028-6608",
publisher = "Taylor and Francis Ltd.",
number = "1",

}

TY - JOUR

T1 - Optimal expansion of a coastal wastewater treatment and ocean outfall system under uncertainty (II)

T2 - Optimisation analysis

AU - Chang, Ni Bin

AU - Yeh, Hsin-Cheng

AU - Chang, Chin Hsien

PY - 2011/3/1

Y1 - 2011/3/1

N2 - This paper presents an integrated simulation-optimisation assessment of the various physical, chemical, and microbiological processes that determine the transport and fate of key constitutes associated with coastal wastewater treatment and disposal effluents in coastal environments. The well-calibrated and validated ocean mixing simulation model - Cornell mixing zone expert system (CORMIX) - was employed in the first stage as an indispensable tool to simulate the initial dilution factor with respect to two major water quality indicators, biochemical oxygen demand (BOD) and Escherichia coli. The CORMIX outputs, which were obtained in a companion study, were used as the inputs in both deterministic and chanceconstraint based stochastic programming models to evaluate a few alternatives for system planning and design. Such integration allowed the identification of the optimal expansion strategies for a large-scale coastal wastewater treatment and ocean outfall system in the city of Kaohsiung, South Taiwan. Research findings clearly indicate that the original alternative proposed by the city government, which had planned on upgrading the wastewater treatment process directly from the primary to the secondary level, is economically undesirable. Given the technology options of primary or enhanced primary treatment, in the most cost-effective expansion strategy, the optimal length of a newly constructed second ocean outfall pipe is no less than 1260m in order to gain sufficient assimilative capacity in the ocean environment.With this strategy, the BOD standards in the ocean environment are met for both Classes B and A types of ocean waters. The reliability of this system design may be assessed by taking the stochastic characteristics of sewerage inflow and diffusion and dispersion processes into consideration. Such an optimisation analysis could eventually lead to considerable cost savings of up to 75% when compared to the original, officially favoured alternative.

AB - This paper presents an integrated simulation-optimisation assessment of the various physical, chemical, and microbiological processes that determine the transport and fate of key constitutes associated with coastal wastewater treatment and disposal effluents in coastal environments. The well-calibrated and validated ocean mixing simulation model - Cornell mixing zone expert system (CORMIX) - was employed in the first stage as an indispensable tool to simulate the initial dilution factor with respect to two major water quality indicators, biochemical oxygen demand (BOD) and Escherichia coli. The CORMIX outputs, which were obtained in a companion study, were used as the inputs in both deterministic and chanceconstraint based stochastic programming models to evaluate a few alternatives for system planning and design. Such integration allowed the identification of the optimal expansion strategies for a large-scale coastal wastewater treatment and ocean outfall system in the city of Kaohsiung, South Taiwan. Research findings clearly indicate that the original alternative proposed by the city government, which had planned on upgrading the wastewater treatment process directly from the primary to the secondary level, is economically undesirable. Given the technology options of primary or enhanced primary treatment, in the most cost-effective expansion strategy, the optimal length of a newly constructed second ocean outfall pipe is no less than 1260m in order to gain sufficient assimilative capacity in the ocean environment.With this strategy, the BOD standards in the ocean environment are met for both Classes B and A types of ocean waters. The reliability of this system design may be assessed by taking the stochastic characteristics of sewerage inflow and diffusion and dispersion processes into consideration. Such an optimisation analysis could eventually lead to considerable cost savings of up to 75% when compared to the original, officially favoured alternative.

KW - CORMIX

KW - Chance-constrained programming

KW - Coastal wastewater treatment

KW - Ocean outfall

KW - Optimisation

KW - Systems analysis

UR - http://www.scopus.com/inward/record.url?scp=78650269038&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78650269038&partnerID=8YFLogxK

U2 - 10.1080/10286600903243138

DO - 10.1080/10286600903243138

M3 - Article

AN - SCOPUS:78650269038

VL - 28

SP - 39

EP - 59

JO - Civil Engineering and Environmental Systems

JF - Civil Engineering and Environmental Systems

SN - 1028-6608

IS - 1

ER -