Heavy Metal and Phosphorus Removal from Waters by Optimizing Use of Calcium Hydroxide and Risk Assessment

Abstract

The optimizing using calcium hydroxide to remove dissolved heavy metal, phosphorus pollutants and algae was investigated. It was found that the concentration of calcium ion was minimal at pH 10.5 when a large amount of generated calcium carbonate increased the particle size of the precipitates and improved sedimentation of sludge and the removal efficiency of heavy metal and phosphorus significantly. Regardless of the initial heavy metals concentrations contained in the wastewater, the final treated concentrations were all extremely low. Risk assessment in alkaline environment of pH 10.5 was tested by fancy carp, daphnia, seed, luminescent bacterium Q67. The results showed that pH 10.5 had a little influence on the four tested organisms. Thus it is suggested that calcium hydroxide at pH 10.5 may be a potential method for treating wastewater and eutrophication water.