Multi-criteria Decision Making Models in assessment of heavy metals leaching from waste

The paper presents a specific model used for the assessment and selection of the method of heavy metals leaching from waste materials. A recommendation for the rational selection of leachability method was made, taking into account the crucial parameters affecting the leaching process derived from the authors' research experience. The assessment models were supplemented with characteristics relating to the cost and time required to perform the tests. An approach was developed that makes the weights of the assessment criteria dependent on the degree of environmental risk from particular heavy metals and waste types. Using multiple-criteria decision analysis four models were developed for the assessment and selection of a test method for the leaching of heavy metals from waste, differing in the way in which the weights of the assessment criteria depend on the potential threat the waste poses to the environment. A key element of the proposed approach is assigning the weights of the criterion to the toxicity of the heavy metal and the kind of wastes and their management scenario. The results obtained indicate that the current practice of only imposing a batch leaching test is inappropriate. The choice of method should be justified in terms of environmental safety and reasonable in terms of time and costs. The results of the paper indicate the possibility of using the proposed model in practice as a recommendation for the method for heavy metals leaching from waste materials and their further treatment in accordance with the principles of sustainable waste management.