Introducing centralised wastewater treatment in Bangkok: a study of factors determining its acceptability

Abstract

Water pollution is a problem all over the world and also in Thailand and particularly in Bangkok. The Government of Thailand and the Bangkok Metropolitan Administration have realised the seriousness of the problem and have started the construction of centralised wastewater treatment systems. The idea of centralised wastewater treatment is new for Bangkok where wastewater is normally treated on-site in septic tanks. The start-up and operational costs of a wastewater treatment system are high. The success and the sustainability of the system require the support of the Bangkok population. In order to gain this support, a better knowledge and understanding of the environmental concerns of the Bangkok population, their willingness to pay for environmental improvements and the acceptability of a wastewater treatment project is needed. The study applied the theory of diffusion and adoption to examine the acceptance of the project by the residents of Bangkok, the contingent valuation method to analyse the willingness to pay of Bangkok residents and the theory of environmental psychology to investigate the factors influencing acceptance of the wastewater treatment project by Bangkok residents. Personal questionnaire interview surveys and the willingness-to-pay were used to provide information on these issues. The Bangkok residents were found to prefer a centralised system, but they had no clear preference for a cost recovery system. The majority preferred the convenience and easy comprehension of a volumetric flat rate system. Two-thirds of the respondents preferred a separate collection system and expressed a preference for the Bangkok Metropolitan Administration as the fee-collecting agency. Most were willing to pay Baht 86.87 per month or Baht 3.28 per m 3 (Baht 25=US$1), while the rate proposed by the BMA is Baht 3.50 per m 3. Distance to a klong (canal) and the direct experience of polluted surface water did not have any influence on the preferences. Monthly household income, level of education and environmental awareness were the principal factors that influenced acceptability of various aspects of the wastewater treatment system. However, acceptability declined when direct costs and changes in life style were involved. The conclusions of the study support the claim that the process of acceptance of wastewater treatment in Bangkok is closely related to the concept of adoption. The study found that complex stimuli, such as cost-effectiveness and the convenience of the technology, tend to influence the acceptability of the wastewater treatment project by Bangkok residents. In order to be able to introduce measures that require sacrifices from the population, the BMA should undertake campaigns of public hearings, public education and public surveys to know public opinion and the public's willingness to pay.