Abstract
Relationships between domestic wastewater pollutant discharge per capita (PDC) and economic development indicators were discussed in this paper. The chronological relationships in Lakes Shinji and Nakaumi area as a case study of chronological relationships showed inverted U-shaped curve, namely environmental Kuznetz curve (EKC), for COD, TN and TP. PDC-COD of forty-seven prefectures in Japan in 2004 spatially had one-order relationship with gross prefecture incomes per capita. However, significant relationships were not observed for PDC-TN and PDC-TP. The regional relationship in the coastal area in developing countries in 1998-2002 showed that there was typical regional relationships between PDC-BOD and PPP-GNI per capita. The relationship between PDC-BOD and PPP-GNI per capita of developing countries in Southeast Asia, Pacific and African Regions with similar climate, water resources and economic condisions showed that PDC-BOD were in wider range when PPP-GNI per capita was smaller and in narrower range when PPP-GNI per capita was larger. The relationship between PDC-BOD and newly introduced water, sanitation and economic parameter (WSEI) in this study showed the same tendency. These relationships were similar to the original Kuznets relationship of income and equity. The transition levels were US$ 3,000-4,000 for PPP-GNI and 1.0 for WSEI, respectively.
