The society of developing countries with rising population and rapid economic growth depends on the development of the infrastructure, such as roads, railways, gas, electric power, etc. However, the environmental issue, for instance waste water treatment, has not been stressed as one of the most important problems to be solved. For past several decades, the construction of drainage, sewage, and waste water treatment as environmental requirements has lagged far behind the economic development. A lot of waste water improvement project should be introduced by government to improve the water conditions. On the other hand, it is reported that more than 447.000 km long sewer pipeline has been used at the end of 2011 fiscal year in Japan.
Figure 1 shows the yearly accumulating length of sewer pipelines installed in Japan. Microtunneling technology is needed because we expect very long sewage pipeline should be installed by trench-less works in big cities. The effective trench-less technology of pipe works should be involved for placing of pipelines when the situation of future developing countries is considered.
Figure 2 shows the circumstantial view of dirty and contaminated Sumida River in Tokyo about 50 years ago. It also shows that men and women were walking beside the river with with their noses picked up for bad smell.
Figure 3 shows the improved view of beautiful and clean Sumida River in Tokyo now and the beautiful and entertained night scene of the Sumida Fireworks and the Tokyo Sky Tree Tower which in 634 m tall behind the Sumida River. Men and women can enjoy the various leisure facilities in and by the River.
[to be continued]