Evaluation of a Developmental Heavy Metals Waste Treatment System.

摘要

The Heavy Metals Waste Treatment System, consisting of a precipitation reactor, a precision control and monitor system and an experimental parallel plate clarifier, has been used to evaluate hydroxide and sulfide precipitation processes for removal of heavy metals from industrial wastes containing 0 and 50% seawater. Removal of metals from simulated mixed-metal wastes by hydroxide precipitation was shown to be superior to theoretical projections apparently due to co-precipitation of minor components. However, the studies showed that discharge criteria cannot be met by this process alone for all metals of interest in industrial wastes, particularly if seawater is present. Also, optimum pH's vary for the different metals, and co-precipitation will not be quantitatively reliable. Hydroxide precipitation tests also showed that process demand for hydroxide reagent is roughly comparable to projections in the case of 0% seawater. However, treatment of 50% seawater can require as much as an order of magnitude higher reagent demand at high pH. The hydroxide process will therefore be uneconomical for testing or pretreating wastewaters containing high proportions of seawater, except at low pH's (e.g., 8 to 9).