An approach to optimize chemical partial stabilization of hazardous wastes

The issues of the treatment of hazardous wastes cannot be solved easily and must be properly faced to avoid management and legal problems. In this work the stabilization process of different hazardous wastes containing metals was investigated at lab and full scale to understand if a "common approach" can be defined, at least for some categories of wastes, in order to provide useful information to the managers of waste treatment plants on the wastes that can be more efficiently and safely treated together within the same "mix". Results indicated that, for the investigated metals, most of the wastes shows a similar predictable pH-dependent behavior, with the exception of the molybdenum. For waste containing this metal a different approach is proposed in order to achieve the partial stabilization goal. Specifically, the efficiency of using of zero valent iron and the sodium sulphate was confirmed by experimental results indicating that this approach can be used successfully. However, the narrow border of economic convenience in applying this treatment to such specific typologies of wastes strictly depends on the current market scenario.