Persistant Organic Pollutants in Soil and Its Phytoremediation

Persistent organic pollutants (POPs) of soil mainly exhibit toxic characteristics that posses hazard to whole mankind. These toxic pollutants includes several group of compound viz., polychlorinated biphenyls, polybrominated biphenyls, polychlorinated dibenzofurans, polycyclic aromatic hydrocarbons, organophosphorus and carbamate insecticides, herbicides and organic fuels, especially gasoline and diesel. They can also be complex mixture of organic chemicals, heavy metals and microbes from septic systems, animal wastes and other sources of organic inputs. Phytoremediation is an emerging technology which can be used for remediation of soil from organic pollutants. In this chapter an attempt has been made to discuss about the sources of organic pollutants, factors that influenced the uptake of organic pollutants by plants, the different mechanism responsible for organic pollutants, phytoremediation of organic pollutants and their advantages and limitation.

DIFFERENT BIOLOGICALLY ACTIVATED SYSTEMS RESISTANCE TO INHIBITION

Biologically activated sorbent (BAS) are believed to be more efficient than separate conventional activated sludge and sorbents systems in removing phenols and others persistant organic pollutants from wastewater. These days, applications of biological activated systems treatment for various kinds of industrial wastewater are attracting greater attention as one of the efficient technologies. But the process is not very good understood, and there is not much parameter, which could describe stability and reliability of system and which could compare different BAS systems. The aim of this study was to investigate the resistance of different biologically activated sorbents to inhibition using respirometric measurements. To choose the most resistant to inhibition biologically activated system from five BAS: BAS-A, BAS-B, BAS-C, BAS-D and conventional activated sludge for comparing. Also to evaluate potential applicability of respirometric method for monitoring bioactivity in BAS systems. The pesticide 3,5-dichlorenol was chosen as inhibitor compound for experiment. The respiratory inhibition measurements were done with different biologically activated systems using different concentration of pesticide. The experiment was accomplished using respiratory inhibition method which described in Lithuanian normative document for environmental protection (Land 45-2001): activated sludge respiratory inhibition test. In parallel saprophyte bacterial counts were determined by spread plate technique and calculated as amount of saprophyte in one litter. The results from both tests showed that the most resistance system to respiratory inhibition was BAS-A. Respirometric method is applicable for monitoring bioactivity in BAS systems.

Interactions between ectomycorrhizal fungi and soil saprotrophs: implications for decomposition of organic matter in soils and degradation of organic pollutants in the rhizosphere

Ectomycorrhizal fungi and saprotrophic microorganisms coexist and interact in the mycorrhizosphere. We review what is known regarding these interactions and how they may influence processes such as ectomycorrhiza formation, mycelial growth, and the dynamics of carbon movement to and within the rhizosphere. Particular emphasis is placed on the potential importance of interactions in decomposition of soil organic matter and degradation of persistant organic pollutants in soil. While our knowledge is currently fairly limited, it seems likely that interactions have profound effects on mycorrhizosphere processes. More extensive research is warranted to provide novel insights into mycorrhizosphere ecology and to explore the potential for manipulating the ectomycorrhizosphere environment for biotechnological purposes.Key words: ectomycorrhizal fungi, ectomycorrhizosphere, rhizosphere, rhizosphere carbon flow, decomposition, rhizosphere remediation.