IN SITU BIOREMEDIATION OF A SOIL CONTAMINATED WITH HEAVY METALS AND ARSENIC

摘要

An experimental plot of about 800 m~2 consisting of a soil contaminated with heavy metals (copper, zinc, cadmium, lead) and arsenic was treated by a flushing system using acidified water leach solutions. The initial soil pH was in the range of about 5.4 - 6.0. The soil contained a rich indigenous microflora. The solubilization of contaminants was mainly a result of the activity of this microflora. This activity was enchanced by suitable changes in the levels of some essential environmental factors, such as water, oxygen and nutrient content of the soil. The removal of contaminants was efficient and within 18 months their residual concentrations in the soil, with the exception of that of the lead, were decreased below the relevant permissible levels for soils of such type. The pregnant soil effluents were treated by a natural wetland located near the experimental plot.