Ability of Water Lilies to Purify Water Polluted by Soap and Their Application in Domestic Sewage Disposal Facilities

摘要

Aquatic plants have the capability to decrease water pollution level. This capability was examined using water lilies in pots. The pots were placed in 50-1 aquariums. Soap was adopted as the pollutant. It is a main water pollutant from households. Purification capability was evaluated by measuring chemical oxygen demand (COD) and dissolved oxygen (DO) concentration. An evaluation index was derived using the half-width (t_w) at half maximum of a characteristic COD peak. The influences of water temperature and soap concentration on the index were examined. t_w decreased as water temperature increased, and the purification capability improved; t_w therefore, is a measure of purification capability. It decreased as soap concentration increased and t_w became larger. An average person uses about 3 g of soap and 50-100 1 of w ater when he showers. This amount of soap (3 g) was added to the aquariums and a predictive curve for the purification of water at 25℃ was introduced. The main polluting element in a household is phosphorus. The application of water lilies to domestic sewage disposal facilities for decreasing water pollution level was considered.