Hazardous Waste Management: In-Situ Bioremediation

One of the technology applied in hazardous waste management is via biological method. Under biological method, I will briefly explain on bioremediation which can be divided into in-situ bioremediation and ex-situ bioremediation. Biological treatment, which in the context of hazardous waste treatment is more commonly referred to as bioremediation, is a process whereby waste materials are biologically degraded under controlled conditions. Nonetheless, bioremediation provides a technique for cleaning up pollution by enhancing the same biodegradation processes that occur in nature. Depending on the site and its contaminants, bioremediation may be safer and less expensive than alternative solutions such as incineration or landfilling of the contaminated

This approach may be advantageous since the costs of materials handling and some environmental impacts may be reduced. However, in situ processes may be limited by the ability to control or manipulate the physical and chemical environment during bioremediation. As we all know, in-situ bioremediation consist of bioventing, biostimulation, bioaugmentation, biosparging, fixed biobarriers, phytoremediation, and artificial wetlands. Bioventing is an in-situ treatment which combines an increase of oxygen (O2) and nutrients with vapour extraction. Bioaugmentation refers to the addition of naturally occurring microbes to contaminated materials and sites in order to achieve bioremediation. The process insures that the correct microbes are added in sufficient quantities. Biostimulation refers to the modification of contaminated areas to enhance the growth of indigenous microbes already present. This process may include utilising fertilisers and other nutrients to stimulate the microbes. This method presumes that the correct microbes are present. Bio sparging ims to increase biological activity of the soil by increasing the O2 supply. Air is initially injected through wells, where after pure O2 is injected. Fixed bio barriers use solid or viscous amendments placed across the flow path of contaminated groundwater to form a permeable reactive barrier. Groundwater flows to,

For ex-situ bioremediation consist of landfarming, composting, biocells, bioreactors, bioleaching. Land farming refers to a ‘low tech’ biological treatment which involves the controlled application and spread-out of a more-or-less defined organic bioavailable waste on the soil surface, and the incorporation of the waste into the upper soil zone. It is typically used for biological removal of petroleum products from contaminated soil. (Overview of Hazardous Waste Treatment Methods and Processes , november 2009)/ Methods of composting include, mechanical mixing and aerating, ventilating the materials by dropping them through a vertical series of aerated chambers. Bio piles are essentially heaps of contaminated soil placed on lined areas to prevent leaching. They are typically covered with plastic and liquid nutrients are applied. Bioreactor system that supports a biologically active and controlled environment for bioremediation. In bioleaching, bioremediation of heavy metal contaminated soil is achieved using acidophilic bacteria that oxidize reduced sulfur compounds to sulfuric acid. The process makes use of either a slurry or a heap leaching system.

Land farming