Effects of discharged water from the sewage plant and dynamic behavior of pollutants in Hori-River

堀江是流经名古屋市的受潮汐影响的河流。污水处理厂位于河的上游.河水和沉积物在沿着的许多地点取样。为了研究污水处理厂排放水对堀江水质的影响及污染物的动态变化，对堀江的水质和沉积物进行了多项监测。并对污水和河水中镍的去除进行了研究。结果表明：（1）堀江水体中Ni和NH 4-N的高浓度来源于污水处理厂的排放水。可以看出，这些污染是由污水厂的排放造成的。(2)从名古屋港侵入的海水是堀江中Se和Cr浓度高的原因。可以看出，这些污染是由位于名古屋港海滨的几家工厂的排放造成的。(3)疏浚作业导致了几种重金属的高浓度。(4)位于污水处理厂下游数百米处的樱桥附近经常观测到高浓度的Ni和NH 4-N。并对造成这一结果的原因进行了分析。最后指出，胶体污染物（Ni和NH_4-N）从淡水层向海水层迁移的抑制作用是造成堀江污染物浓度分布的主要原因。(5)堀江中Ni的最有效吸附剂是活性炭。(6)从吸附实验的结果来看，Ni在堀江中以胶体粒子的形式存在。对三年的研究进行了总结，并以书式报告的形式出版。

Hori-River is a tide affected river running in Nagoya City. A sewage plant locates at the upper stream of the river. River water and sediment were sampled at many points along the river. Several items of water and sediment quality were measured to investigate the effects of discharged water from sewage plant and dynamic behavior of pollutants in Hori-river. And the investigations about removal of Ni from sewage or river water were carried out. The results can be summarized as follows :(1) Discharged water from the sewage plant contributes the high concentrations of Ni and NH4-N observed in Hori-River. It can be seen that these pollution were caused by the discharge from sewage plant.(2) Seawater intruded from Nagoya harbor contributes the high concentrations of Se and Cr observed in Hori-river. It can be seen that these pollution were caused by the discharge from several factory located seaside of Nagoya harbor.(3) Dredging operation contributes the high concentrations of several heavy metals.(4) The high concentrations of Ni and NH4-N were often observed around Sakurabashi that is located in the several hundreds of downstream from sewage plant. The reasons of this results were investigated. Finally, it was pointed out that the restraint of colloidal pollutants (Ni and NH4-N) movement from the layer of fresh water to the layer of seawater would contribute such a concentration profile in Hori-River.(5) The most effective adsorbent for Ni in the Hori-River was activated charcoal.(6) From the results of adsorption experiment, it was suggested that Ni existed as colloidal particle in the Hori-River. The study for three years was summarized and published as the book-style report.