Immobilization of Heavy Metals in Soil Using Natural and Waste Materials for Vegetation Establishment on Contaminated Sites

Contaminated land is increasingly becoming an important issue worldwide. Many contaminants are persistent in soil for a large number of years. With the increase in public awareness regarding the consequences of contaminated soil, many researchers are concentrating on developing cost-effective and socially acceptable soil remediation technologies. Soils of many sites, which have been left derelict after industrial decline, harbor a broad suite of metal and organic contaminants. Land where such contaminants are deemed to pose a significant risk to receptors is considered contaminated under modern guidance. Remediation to break identified pollutant linkages would precede reclamation and plant establishment. One approach to break the pollutant receptor linkage is to utilize materials that effectively create soil conditions that immobilize contaminants whilst providing essential plant growth properties in terms of nutrition and water holding capacity. Materials that may achieve this include: 1) composts derived from materials such as sewage sludges and other municipal sources; 2) natural or synthetic zeolites; or 3) industrial by-products such as red-mud or other iron-rich materials such as iron grit or iron oxyhydroxides. Remediation techniques that utilize such materials may be cost-effective compared to more traditional methods and may effectively divert materials from the waste stream and could thereby make a dual contribution to sustainable development.