A concept for planning and management of on-site and
centralised municipal wastewater treatment systems,
a case study in Bangkok, Thailand. II: Scenario-based
pollutant load analysis
Yoshiaki Tsuzuki, Thammarat Koottatep, Thitiphon Sinsupan,
Supattra Jiawkok, Chira Wongburana, Suraphong Wattanachira
and Yuttachai Sarathai
ABSTRACT
Scenario-based pollutant load analysis was conducted to develop a part of a concept for planning
and management of wastewater treatment systems (WWTSs) under the mixture conditions of
centralised and on-site WWTSs. Pollutant discharge indicators and pollutant removal efficiency
functions were applied from another paper in the series, which were developed based on the
existing conditions in urban and peri-urban areas of Bangkok, Thailand. Two scenarios were
developed to describe development directions of the mixture conditions. Scenario 1 involves keeping
the on-site wastewater treatment plants (WWTPs) within the areas of centralised WWTSs. Scenario 2
is dividing the centralised and on-site WWTS areas. Comparison of the smallest values of total
pollutant discharge per capita (PDC
total
) between Scenarios 1 and 2 showed that the smallest PDC
total
in Scenario 1 was smaller than that in Scenario 2 for biological oxygen demand, chemical oxygen
demand and total phosphorus whereas the smallest PDC
total
in Scenario 2 was smaller than that in
Scenario 1 for total nitrogen, total coliforms and faecal coliforms. The results suggest that the
mixture conditions could be a possible reason for smaller pollutant concentrations at centralised
WWTPs. Quantitative scenario-based estimation of PDC
total
is useful and a prerequisite in planning
and management of WWTSs.
Yoshiaki Tsuzuki (corresponding author)
School of Civil Engineering,
The University of Queensland,
QLD 4072, Australia
E-mail: tsuzuki.yoshiaki@gmail.com
Thammarat Koottatep
Thitiphon Sinsupan
Environment Engineering and Management,
Asian Institute of Technology,
PO Box 4, Klong Luang, Pathumthani 12120,
Thailand
Supattra Jiawkok
Department of Environmental Systems
Engineering,
Ritsumeikan University, Nojihigashi,
Kusatsu, Shiga 525-8577,
Japan
and
School of Health Science,
Mae Fah Luang University,
Chiang Rai 57100, Thailand
Chira Wongburana
Wastewater Management Authority,
Vibhavadi-Rangsit Rd,
Ladyao, Chatujak, Bangkok 10900,
Thailand
Suraphong Wattanachira
Department of Environmental Engineering,
Faculty of Engineering / National Center of
Excellence for Environmental and Hazardous
Waste Management (NCE-EHWM),
Chiang Mai University, Chiang Mai 50200,
Thailand
Yuttachai Sarathai
Water Quality Management Bureau,
Pollution Control Department,
Phahon Yothin Rd, Phayathai, Bangkok 10400,
Thailand
Key words | canal (klong) wastewater collection system, pollutant discharge per capita (PDC),
pollutant load per capita (PLC), scenario-based pollutant load analysis, seepage and
septage from on-site treatment systems and leachate from composting (SSL)
INTRODUCTION
Septage desludging intervals of typical on-site municipal
wastewater treatment plants (WWTPs) in Thailand were
reported as 5–10 years because of their open bottom struc-
tures (AECOM & SANDEC/EAWAG ). A Japanese
professional group for domestic wastewater collection and
treatment systems defined a stepwise improvement scheme
as a concept for a chronological approach to wastewater
treatment system (WWTS) development, especially in the
areas with existing canals ( Japan Sewage Association
). In the planning scheme, canal-type wastewater collec-
tion systems were developed along the existing canals for
wastewater collection. A double-layer double-system
1934 © IWA Publishing 2013 Water Science & Technology | 67.9 | 2013
doi: 10.2166/wst.2013.024