Mankind's rapid trend towards urbanization is projected to require accommodation for an additional 2.5 billion people by 2050, according to the UN department of economic and social affairs. This rapid development can lead to environmental impacts, such as the release of industrial, medical, and construction waste into soils. In 2010, 92% of global cement end-of-life waste was improperly disposed of. Although cement is increasingly used and constitutes by far the largest anthropogenic solid waste type by mass and volume, little is known about its effects on soil and the transport and retention of other contaminants in urban environments.
This study characterizes soil, cement end-of-life waste, and their combination in cement end-of-life waste amended soil (CAS) physically and chemically. Selected substances recognized as potential pollutants including pharmaceuticals (oxaliplatin and cisplatin, both organometallic compounds, and 5-fluorouracil, a halogenated organic compound) and the halogenated organic pesticide atrazine, were introduced to natural soil and CAS (soil amended with 10% cement end-of-life waste by weight). Batch tests and water-saturated flow-through column experiments measured transport and retention behavior. Additionally, natural soil exposed to affluent from cement end-of-life waste was tested. Samples were analyzed using LC-MS and ICP-MS to determine concentrations of elements indicative of the contaminants and a tracer element for quality assurance.
Results showed that in CAS columns, some contaminants remained in solution at higher concentrations than in representative soil. In columns with cement end-of-life waste affluent, contaminants were more strongly retained, indicating decreased mobility. Soluble Cr concentrations in all CAS and cement end-of-life affluent columns exceeded those in representative soil. This study demonstrates that soil amendment with cement end-of-life waste can increase contaminant mobility, while cement end-of-life waste affluent promotes contaminant retention.