Human excreta and domestic wastewater are predominantly treated by primary onsite treatment systems in Thailand. Technically, accumulated fecal sludge and effluent from those primary treatment systems must be properly further treated. In response to the King’s concern on the unhygienic practices on nightsoil management, Nonthaburi municipality established a plant of anaerobic digestion and became a model plant for managing nightsoil in other cities. Based on a recent survey, nearly all nightsoil treatment plants in the country utilize the anaerobic digestion system. In terms of wastewater management, decentralized treatment systems are increasingly needed in the country. Considering limited coverage of centralized treatment system, Korat municipality has supported communities along Lum Ta Kong canal to install anaerobic filter system at household level. This initiative can help improve quality of the canal over the past several years.
Given the good management of the low-cost and low-tech nightsoil treatment at Nonthaburi municipality as well as the onsite wastewater treatment system at Korat Municipality, this study was conducted aiming to promote low-cost and low-tech nightsoil and wastewater treatment systems by studying and analysing their success factors. Other low-cost and low-tech facilities which have been well recognized as good model(s) and replicated were also investigated, including Supanburi municipality and Suan Kaew Temple for nightsoil treatment systems and Bang-Pha-Rok community and Pang Kone municipality for decentralized wastewater treatment systems.
Findings from this study indicate that the anaerobic digestion system is a good option for nightsoil treatment in large to medium sized municipalities, while other technologies or management initiatives should be considered for small sized cities. For the anaerobic digestion system to be cost-effective, an integrated management including collection, transportation and treatment is required. Simple wastewater treatment facilities which are additionally installed to treat liquid fraction overflowed from pre-treatment system like septic tanks as well as grey water can substantially improve effluent quality particularly for canal communities in Korat and Bang-Pha-Rok community where effluent was directly discharged to water bodies. Converting drainage ditches located across the Pang-Kone municipality to constructed wetlands for treating wastewater is a unique initiative which its success resulted from an integrated approach through identifying local needs and applying the technologies appropriately to local characteristics.
It can be concluded from the treatment facilities mainly implemented at city level like nightsoil treatment plants or communal wastewater treatment plants that strong leadership, political support, qualified and adequate human resources and involvement of relevant authorities are their key success factors. Whereas individual facilities like onsite treatment systems, awareness and participation of local residents are crucial. Other common success factors found in this study include external partial funding support, adaptability to local situations, local networking, technical supports from academia and NGOs, sense of ownership, and motivation to be highly recognized. To successfully replicate the treatment systems identified as good models in this report, selection and management of the systems to suit different common conditions of each city/community such as size, human resources, geography, institution, and financial status is highly recommended.