It does not seem to be easy for citizens to consider quantitatively on the relation between domestic wastewater and water pollution problems including water pollution in a coastal zone. Only some citizens with good environmental intentions take measures to reduce pollutant load such as using paper filter or mesh net at kitchen sink, decreasing detergent for washing clothes and decreasing shampoo and soup at bath, and quitting to drain residual liquid including dressing, noodle soup and used edible oil. Basic concepts or important and necessary points for the preparation of EAH books for domestic wastewater are considered as the followings: (1) Tables are prepared for each domestic wastewater treatment method; (2) Basic parameters of water quality are COD (or BOD), T-N and T-P; (3) Citizens can easily fill the tables in regards to the effective actions to reduce pollutant loads; and (4) Pollutant loads reduction effects can be easily calculated; and (5) EAH books should be prepared for each drainage area, because pollutant loads per capita running into coastal zones or rivers by wastewater treatment methods are dependent on the drainage area.
In this paper, pollutant loads per capita flowing into public waterbodies was analyzed in the drainage areas in Chiba City, Chiba Prefecture, which faces Tokyo Bay, mainly to conduct comparative study on the index and to obtain basic data to prepare EAH books of domestic wastewater in Chiba City area.
It was found that pollutant loads per capita flowing into public waterbody were different between the drainage regions, and variation of COD loads per capita was found to be larger than thar of BOD. BOD loads per capita flowing into public waterbody were calculated as 0.83 g-BOD person-1 day-1 for WTP populations, 0.8-2.4 g-BOD person-1 day-1 for combined jokaso populations, 8.3-24 g-BOD person-1 day-1 for simple jokaso populations, and 7.8-21 g-BOD person-1 day-1 for night soil treatment populations. COD loads per capita flowing into public waterbody were calculated as 2.3 g-COD person-1 day-1 for WTP populations, 0.8-4.0 g-COD person-1 day-1 for combined jokaso populations, 3.2-13 g-COD person-1 day-1 for simple jokaso populations, and 3.4-12 g-COD person-1 day-1 for night soil treatment populations. The effect of riverside water purification facilities and agriculture village wastewater treatment facilities are not included the pollutant loads per capita for combined and simple jokaso populations and night soil treatment facilities.
A format of EAH books of domestic wastewater was prepared for simple jokaso populations in the drainage area of Chiba City with populations weighted average pollutant loads per capita flowing into public waterbody. The EAH books should be prepared for each drainage area and domestic wastewater treatment method.
Pollutant loads per capita by domestic wastewater treatment methods and drainage area, and EAH books of domestic wastewater have been proposed as essential indexes and effective tools in the field of water environment education and dissemination.