An improved service model for fecal sludge management toward citywide inclusive sanitation: a case study in Bangkok City, Thailand

ABSTRACT Bangkok City is served mainly by non-sewered systems (NSSS), which rely on vacuum trucks to collect fecal sludge (FS) from various sources, including cesspools, septic tanks, and pre-fabricated treatment units. However, safely-managed sanitation in Bangkok City could not be achieved because only 13% of the collected FS is properly treated at two fecal sludge treatment plants (FSTPs). This study aimed to develop an effective FS collection model for fecal sludge management (FSM) by examining key factors, such as the volume of vacuum trucks per area (TA), acceptable collection cost (ACC), % annual accessibility service (AS), and % illegal vacuum truck services (ITS), utilizing multiple linear regression (MLR). The findings indicated that the improved % FS collection efficiencies to be ‘moderate’ and ‘high’ could be achieved by increasing the TA, ACC, and AS values to be 0.74–1.34 and 1.35–1.40 m3/km2, 4.30–4.60 and 4.61–4.80, and 10.01–15.00 and 15.01–20.00%, respectively, while the ITS values decrease to be 10.01–12.00 and 0.00–10.00%, respectively. To ensure equitable, safe, and sustainable FSM practices for all in Bangkok City toward the year 2030, there are still other challenges to be overcome, such as obtaining budget for improvement actions and cooperation from the concerned stakeholders.