Bung Makkasan
The numbers of people living legally in Bangkok City of Thailand has been estimated at 10 million, with about the same amount of people living there illegally. Thus, the total population living in the huge city of Bangkok is estimated at about 20 million population. This accounts for the daily community garbage of about 10,000 tons and wastewater of 4 MCM draining through 117 canals to Chao Phraya River and finally to the sea at the Gulf of Thailand. Due to the urban location on flatland there is one m MSL with the coverage area of 1200 km 2 . Despite a drainage system of 117 canals, the wastewater moves with difficulty from canals to the public Chao Phraya River. Then after that, the wastewater quality worsens with some evidences of black color and unpleasant smell. A key issue is that the water-borne diseases were found in every canal in the same degree as the urban drainage system. At the present time, the wastewater has been analyzed by many government agencies and they have found the same results as class 5 water quality, which indicated it could not be utilized for any purposes, except for transportation. In fact, the findings revealed that the wastewater elements could be identified as having high organic contents of BOD, COD, VOCs, total solids, suspended solids, very low dissolved oxygen, high concentration of heavy metals, etc. Such results traced the point sources as being the dense households and numerous numbers of active industrial factories. It could be seen that all those pollutants would contaminate Chao Phraya River and the Gulf of Thailand one way or another. Unfortunately, the lifestyle of Thai people depends upon the river water, meaning that the problems cannot be avoided. The above situation has been realized among Bangkok dwellers, especially H.M. the King Bhumibol, who introduced a means to treat such wastewater to better quality before draining it into public water sources such as the Chao Phraya River.