Kemija u Industriji (Jul 2012)
Procedures for Removal of Pesticides from the Environment
Abstract
Pesticides are widely used in food production, and it is believed that more than 1000 types of pesticides are in use. Organochlorines and organophosphorous pesticides are used in large quantities due to their efficacy and low cost. These persistent organic pollutants remain in the soil, silt, and sediment long after application, and enter into watercourses, finding their way directly into the food chain. Today, the following procedures are used to remove pesticides from polluted localities: low temperature thermal desorption, incineration, bioremediation and phytoremediation. Each of these technologies has its advantages and disadvantages. Ultimately, the ideal remediation process would be to completely destroy the pollutant without the production of byproducts. Some of these processes are only capable of moving and stabilizing the contaminant, but do not clean or fully eliminate the pollutant. Low temperature thermal desorption is an ex situ cleaning technology most often used to remove pesticides. The advantage of incineration is the complete elimination of the pollutant; however, this process is very expensive, as it requires transport of the media to the incinerator. The processes of bioremediation are stimulated by natural processes of microbiological degradation of contaminants through the interaction of microorganisms and nutrients from waste. Ex situ procedures include the use of bioreactors. Another procedure is land spreading, in which the contaminated medium is mixed with the soil, in which the native microorganisms degrade the pollutants. Efficacy in the biodegradation of toxic pollutants has been established for white root fungi, particularly those from the genus Phanerochaete. Phytoremediation is a green technology that uses plants, in which plants are not directly included in the process but serve as a catalyser for increasing the growth and activity of root microorga- nisms. In phytoremediation of pesticides, plants of the genus Kochia are often used, as it has been established that the interaction between the plants and microorganisms in the rhizosphere leads to the degradation of pesticides. Bioremediation and phytoremediation are two new methods that are still under assessment. Numerous laboratory studies and pilot studies are attempting to increase the applicable uses of bioremediation and phytoremediation, and overcome the limitations currently presented by these methods.
