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Chemical precipitation is a useful conventional process to remove heavy metals from aqueous solutions. In this work, a waste sludge from the Solway process was used as a precipitation agent for the precipitation of Cu (II), Ni (II), Pb (II) and Zn (II) ions with an initial concentration of 50 mg/L. The results of the research showed that the waste sludge from the Solway process completely removed Pb (II) ions from the solution in the pH range of 8.39 -11.74, also good efficiency was shown in other cations. The maximum precipitation efficiency for Cu (II) is 99.890% at pH 10.98, Ni (II) 99.940% at pH 11.81, Zn (II) 99.616% at 10.1. Waste sludge is proved to be a good precipitate for cation separation.

The quality of mineral water is conditioned by a number of factors, primarily the quality of water in the water source. The aim of this study was to determinate content of Ni2+ and Mn2+ ions in the mineral water, after treatment by selective ion-exchange column. The primary objective of investigated technological process was optimal performance of the column, during the processing of water, so that the content of Ni2+ and Mn2+ ions in the mineral water, after treatment reduce to allowable concentration, and the concentration of Mg2+ ions in the mineral water decreases insignificantly, and thereby the cost of water treatment are not increased. Also, during the study, was determined the effect of application of ion - exchange columns in the physico-chemical water parameters, such as turbidity of the water, the water hardness and pH value.

Chemical precipitation is the most widely used method for heavy metal removal from water, and its effectiveness depends on several factors such as the type and initial concentration of heavy metals present in water, the precipitating agent used and the pH of the solution. In this paper an experiment of chemical precipitation and removal of Pb(II) and Zn(II) from their monocomponent and two-component aqueous solutions was carried out in a laboratory by batch process, using sodium carbonate as precipitating agent. The influence of initial concentrations of Pb(II) and Zn(II) and pH values of their aqueous solutions on the efficiency of precipitation and removal of lead and zinc ions was examined. By increasing the pH of the aqueous solutions, a higher efficiencies of chemical precipitation and removal of Pb(II) and Zn(II) were obtained, with higher removal efficiencies being achieved for the lead. The efficiency of removal of heavy metals was higher in solutions that had higher initial concentrations of heavy metal ions.