On-site treatment systems in the wastewater treatment plants (WWTPS) service areas in thailand: Scenario based pollutant loads estimation

Abstract

In the previous studies, discharge of "seepage and septage from septic tanks and leachate from composting" (SSL) were found to occupy a larger portion of pollutant load in the ambient water in the peri-urban area around Bangkok, Thailand. On-site treatment methods including septic tanks are traditionally applied even in wastewater treatment plants (WWTPs) service areas in Thailand. Therefore, evaluation of the existence of on-site treatment facilities in WWTPs service area is considered to be important. Three scenarios were developed to estimate pollutant discharges per capita (PDCs) from domestic wastewater treatment systems in Thailand. PDCs estimation results showed that pollutant discharges to the ambient water are still larger even in the WWTPs sevice areas. Some of the reasons for the larger pollutant discharges are smaller pollutant removal ratios defined based on the treatment efficiencies in the existing WWTPs. Further consideration should be necessary on the traditional domestic wastewater treatment systems which combine on-site treatment and centralized treatment in Thailand.