Geochemical Modeling Applied in Waste Disposal, and Its Relevance for Municipal Solid Waste Management

Solid waste management is a challenge for municipalities mainly due to the increasing generation of residues worldwide. Much waste still ends up in landfills, either as a final disposal sink, or as a temporary yet long-term storage prior to eventual landfill mining. Through degradation and infiltration processes, these materials threaten groundwater, soil and the environment, invariably causing expressive societal concern. Waste managers, environmentalists and regulators alike focus upon predicting how these complex geochemical systems will evolve over decades. Geochemical modeling and transport simulation are commonly used to support the design, operation or characterization of these dynamic systems. In this targeted critical review of the literature over the last two decades concerning geochemical modeling applications to waste disposal (including municipal, incineration residue, and industrial), we have attempted to provide an assessment of the current state of knowledge in this field, supported by a comprehensive list of modeling methodologies and data analyses, relevant for municipal solid waste (MSW) management systems. The information provided is meant to be useful for specialists when planning, implementing or adapting MSW systems.

Study on the evolution and transformation of chlorine during co-processing of hazardous waste incineration residue in a cement kiln

The co-processing of hazardous waste in a cement kiln can eliminate a large quantity of hazardous wastes, but the excessive existence of chlorine will affect not only the operation of a cement kiln but also the quality of cement products. In this study, the mixtures of hazardous waste incineration residue and raw meal were incinerated in a high temperature tubular furnace. The distribution ratio of chlorine in flue gas, clinker and fly ash under different experiment conditions was obtained and the influence of the co-processing conditions on chlorine evolution and transformation was studied. The results showed that chlorine mainly existed in flue gas and clinker, and only less than 1% of chlorine existed in fly ash. The incineration temperature had a significant influence on the distribution of chlorine. The higher the incinerating temperature, the greater the distribution ratio of chlorine in flue gas and fly ash. The proportion of chlorine in all parts remained basically unchanged while the temperature was higher than 1300°C. With the increase of the retention time, the proportion of chlorine released into the flue gas increased. The distribution ratio of chlorine in each part remained unchanged after about 30 minutes. There were four stages of the rate of chlorine release. In addition, the chlorine content of the sample had little effect on the partition of chlorine. Some suggestions on the co-processing of hazardous waste in a cement kiln are put forward based on these experimental results.