Adsorptive properties of sewage sludge for cations of ammonia, alkali and alkaline earth metals

Анотація

Disposal of sludge waste water as an agricultural fertilizer is well known. Such use prevents the presence of a large number of dwellings heavy metals that may affect directly toxic to vegetation or accumulate in food chains of ecosystems.
For qualitative and quantitative understanding of the behavior of toxic metals in soils treated is essential information on the adsorption capacity and specificity of the solid phase sewage sludge. Currently, few such studies.
         Purpose - to explore the adjacent adsorption alkali ions (Na, K) and alkaline earth (Mg, Ca) metals and ammonium ion to the solid phase sewage sludge. For this studied: the total content of metals in sediments and in their separate liquid phase; distribution of metals and ammonium ion when mixed solids sludge with a solution of sodium and ammonium; cation exchange capacity of the solid phase precipitates.

It was found, that the liquid phase of a sewage sludge surmounts to less than 80 % of a total sludge volume. Moreover, 28 % of the sludge volume is due to water bound with the solid phase, which contains among other non-specifically adsorbed ions. Based on the metal distribution coefficients between the solid and the liquid phases of a sludge, affinity sequence for alkali and alkaline earth metals was found, which, in order of rise of their affinity, is: Na⁺<K⁺<Mg²⁺<Ca²⁺. Using competitive adsorption of cationexchange ions, the sequense was complemented to include ammonia ions, and was found to be: Na⁺<K⁺<ΝΗ₄⁺<Mg²⁺<Ca²⁺.