Pollution Remediation Technologies - Literature review Example

Running header: pollution remediation technologies literature review Client inserts his/her name Tutor’s name Name of institution Course title Date of submission Introduction Environmental pollution is a major global concern since the consequences and effects of pollution are undesirable, and they cause economic impacts as well as threaten the life of humans, flora and fauna in the environment. In the recent past, the society has been involved in the struggle for prosperity and well being by engaging in numerous environmental activities. The 20th century was a time characterized by environmental awareness operations through which, the society became aware of the lack of concern for protection of the environment as well as other natural resources existing within the ecosystem. At the beginning of the 20th century, the disposal of industrial wastes from many industries was not regarded by many environmentalists around the globe as a main pollutant to the environment such as water, air and soil. This perspective triggered insufficient government action and legislation. That is the reason why massive contamination of water and soil has been witnessed all around the world and environmental disasters have been on the increase. For instance, the people of the US experienced disasters such as massive pollution in Lake Erie and Lake Ontario as illustrated by Ward (1999). Nevertheless, toxic wastes were discovered under the Love Canal in New York while more than 4 000 people died in London among other smog connected deaths. (Wise, 1968). The impacts of environmental pollution have been felt worldwide for seasons on end. Such disastrous events have triggered considerable public concern which has led to numerous changes in many societies, in the world. The wider pollution issue is now being manned with the seriousness it deserves and monumental changes have been observed recently. Both chemical and physical means are used to carry out environmental cleanup exercise. It is inescapable to find metal pollutants in the soil, water or even the air. In many nations that practice agriculture, mining and industrialization, metals as well as other inorganic contaminants are prevalent. They are found deposited in most waste sites, and their removal from the soil is often a difficult task as described by Cunningham et al. (1997). Most sources of such pollutants result from activities such as smelting, electroplating, gas exhaust fumes, energy and fuel production, the application of fertilizers to land and industrial manufacturing. The area of environmental cleanup has become a major area of concern since heavy metal contamination of the biosphere has increased much in the recent past as argued by Nriagu (1979). Worse still, the condition poses many health problems to human beings and also creates a major environmental problems that mar the world. Key concepts and the research area Water pollution is the most prominent pollution area identified. It is a global concern since the rate of population increase is high, and facilities for proper hygienic conditions are limited. Moreover, sewerage pipelines especially in urban areas lack proper monitoring surveys by the parties concerned. Many organizations have been put up such as NEMA to manage and strategize on how to handle the environment safely without causing any harm to flora and fauna in it. However, my concern lies in all the possible pollution areas that occur due to improper waste disposal and lack of concern for treatment and cleaning of the contaminated areas. It is prudent to note that, unlike other organic pollutants that are deposited on the environment, most metals are not easy to do away with entirely through either chemical or biological transformation or means as argued out by Cunningham and Ow (1996). However, research indicates strategies have been identified that have the capacity to reduce the toxicity of certain metals by influencing their speciation. They never degrade and they continue existing in the environment while causing harm as indicated in NRC (1999). Although some conventional remediation methods have been put up to clean up the heavy metals in the environment, each method has numerous benefits, limitations and costs. It is clear that the need to practice proper waste disposal, and to clean contaminated areas has become a productive interest for many public institutions, and private sectors. They are aware of the penalties and punishments imposed by regulatory agencies, and they are bound to perform their operations in that light. Government agencies, and other institutions began searching for resourceful, and cost effective methodologies that could be used to obtain remedies for the already contaminated areas which were the basis for initiatives that exist in the environmental arena to date. Below are some of the procedures used, and their scope as well as their limitations in regards to treatment and disposal of waste products in order to curb environmental degradation. Literature review arguments Many positive strategies have been put in place during the 1960’s, and early 1970 to increase public responsiveness, and to reduce environmental pollution by imposing regulations that govern environment handling. A solid waste disposal act was established in 1965 to regulate waste disposal on an unrestricted scale. (Reed et al., 1992). Research indicates that a National Environmental Policy Act (NEPA) was passed by the congress in 1969 which was the first of its kind to offer a national policy for the environment. In 1970, the annual earth day was held to recognize and address issues and problems that affect environmental management and care. The consecutive years were characterized by numerous changes in reference to environmental protection act, clean air act, safe drinking water act and other regulations for hazardous wastes. The pressure to observe the environmental rules and regulations for a quality environment were propelled. Begonia et al. (1998) gave much insight on the excavation and land fill method of cleaning a contaminated area. In this method, Soil is excavated from one area, which is contaminated, and it is filled in another area. The method is commonly employed when cleaning sites that have been contaminated with metals over period of time. Research findings indicates that the method is not appropriate because the polluted load is merely moved to a clean area, thereby contaminating it. This is because no effort is made to destroy or stabilize them. The measures used should involve isolating he contaminated material from the rest of the environment or rather reduce its impact on soil, water or air as discussed by Wood (1997). Despite the shortcomings, the landfill method has been used widely, and it is efficient in curbing the amount of water infiltration and also reducing the downward movement of the contaminants. Solidification and stabilization is another waste disposal and cleaning strategy identified by NRC (1997). It involves the suppression of the movement of contaminants in soil and other liquids through the reduction of their solubility levels. It can also be done by changing the permeability of their matrix by turning the material into solids and then controlling their change of state by stabilizing them. The main aim is to bind the materials physically to a solid mass which resists the leaching process more than the original soil material. The method has been successfully applied, and it can be concluded that its efficiency relies on the ability to mix the original soil with the stabilizer (NRC, 1999). Some of the materials used as stabilizers include lime, silicates, pozzolanic materials, polymers and clays. Long term monitoring and care of the solidified material is very important to ensure that leaching does not occur completely. According to NRC (1999), In situ Redox manipulation is a method used to reduce the toxic value of metals that are not hazardous in the reduced form. The method is important in the treatment of soil or ground water that is not easily accessible since it is out of the ground surface. It is performed by injecting a chemical reducing agent into the material or site that requires treating with nutrients meant to create a reduction in the subsurface of the substance. Aluminum, sodium and zinc, are the commonly used metals as educing agents in this method as identified by Wood (1997). It is important to note the importance of long term monitoring of the material since it may undergo reoxidation and mobilization of the contaminants may occur. Research indicates that the use of impermeable barriers can be used to surround underground water contamination sources, and it is regarded as one of the cheapest methods of environmental cleaning as argued in the NRC (1999). It is an effective method used in controlling the spread of metal contaminants in ground water. Barriers are usually used at landfills to separate the contaminated area from the outside environment. Wood (1997) argues that covering the contaminated area prevents the exposure of the rest of the environment from the risk of contamination. Soil washing method complement the excavation and land fill method of cleaning contaminated areas. It is a remediation strategy that aims at reducing the contaminant’s concentration in the soil as outlined by Wood (1997). After excavation, the contaminated soil is taken to a washing site where all the chemicals and large objects are leeched with certain chemical agents. Contaminants are thus completely destroyed before land filling is done as discussed in NRC (1999). This method is known to be less expensive than the disposal of contaminants. Research on Permeable Reactive Barriers indicates that it is a passive kind of treatment which involves placing a reactive material on the path of the contaminant. Treatment and cleaning occur as the contaminated plume flows by reacting with the chemical on its path. The metal contaminants are immobilized by precipitation through the treatment zone created along the flow channel. This method is significant especially in areas where the exposure of contaminants to the environment may pose serious danger or cause grave damages. Unfortunately, permeable reactivity cannot be considered as a solution to the problem since it only retards the contaminant during its migration. Another method has to be employed to complete the process that is when the contaminant reaches its destination so as to curb the dangers it may cause to the environment. (NRC, 1999). In regards to the research done by MADEP (1993), electro kinetic technologies are efficient when handling soils or materials with low permeability. These soils are not suitable for soil flushing or soil washing because it may be difficult to obtain the extracting solution. It entails the use of electronic fields to collect and do away with contaminants within the soil. Wood (1997) describes the method as an in situ which entails passing an electric current through a number of electrodes buried within the contaminated material. The magnetic rule applies in this case where the contaminant moves through the pore spaces in the soil water towards the oppositely charged electrode. Through the porous units in the electrodes, the contaminants are pumped to the surface in purging solutions. The solution is then moved to a treatment plant for the removal of contaminants. Proper prior preparation is crucial since the method gives rise to large amounts of acids and bases. Enough space is required to contain the products which may be pollutants in themselves. Many nations do not apply the method since it calls for numerous field testing techniques, before regulatory agencies allow for any treatment operation using the method as a remediation strategy. Ward (1999) identified bioremediation as a treatment method which is concerned with using living organisms to treat or to alter a contaminated area’s chemical condition. It is done through the manipulation of microbial organisms in large numbers to modify metal contaminants. In regards to NRC (1999), the aim of the microbial activity is to reduce the toxicity of the pollutant in the soil with regards to the goals of the remediation strategy. Reducing environments are intensified and maintained through the addition of suitable agents such as oxygen. With this activity, the inorganic contaminants are made highly soluble and immobile hence controlled (Wood, 1997). Just like other treatment methods, the strategy used in the immobilization of contaminants should be considered a temporary solution and not the ultimate solution, to curb the effects of contaminants to the soil completely. Limitations of previous research and the need for the search for alternatives The remediation technologies discussed above portray various weaknesses although their significance is worth mentioning. Most of the methods are used to clean a large area of metal polluted sites. This is because they involve chemicals which act extremely fast and are sensitive to the heterogeneous area that is contaminated as discussed by Cunningham et al. (1997). Most of the methods have been criticized since they are expensive and they disrupt the surrounding environment during the treatment operation. According to Cunningham and Ow (1996), of all the disadvantages of the remediation strategies, the position of the cost challenge forces scientists and other involved parties to search for alternative ways of reducing or controlling the impact created by poor disposal of waste products especially from industries. According to the criticism put forward by Cunningham et al. (1997), bioremediation for instance have the capacity to detoxify. However, the method is less amenable to some extremes within the ecosystem. It is more applicable to areas which are contaminated with organic pollutants only and thus more research is required to focus on this aspect of the bioremediation method. It is also precise that the method has a limited scope to treat the metal polluted areas completely, which makes it more cost ineffective as compared to other traditional methods. Also, plants sequester certain metals into their tissues as illustrated by Marschner (1995) and may remove the metals from the soil in that manner. More research in this area may venture more into the significance of plant related remediation rather than chemical usage. Cunningham and Ow (1996) shows that the method has the capacity to be less exorbitant have low impact and of course maintain environmental security. The methods need continuous review since pollution is something that happens constantly, and new technology has intensified, and diversified that types, and nature of pollutants that affects the government in the present world. For a long time, the effort to clean the polluted areas has been delayed. Many countries do not consider such an exercise a priority as discussed by Berti and Cunningham (2000). The methods used usually cause environmental degradation since soil erosion occurs and the results pose a danger to both animal and human life. The environment is further exposed to other agents of soil erosion such as wind and water. More research is needed to find out ways of perfecting remediation technology through the use of plants. The main concern should be to obtain an ideal plant that may accumulate large deposits of metal pollutants by sucking them from the soil. Root uptake is the main method through which the metals may be eliminated from the soil. Moreover, the plant elimination method should also consider the toxicity of metals in question. Zinc is considered one of the metals that can be efficiently eliminated through this method since it is not harmful to human beings and animals. Additionally, it is one of the prevalent metals that are found in the contaminated sites. Although previous research indicates the need for development of specialized agricultural practice, the area needs further attention to find out whether phytoextraction can be done in large scale and also to find out whether it can positively influence agricultural technology hence high productivity. This is because minerals lead to the growth of plants and absorption of these minerals is of great concern. With extensive research, proper application of phytoremediation technology has the potential to offer the best results at a relatively low cost. The existing technologies need a lot of finances in order to be executed successfully in regards to environment cleaning and maintenance. This intensifies the need to find out new cleanup strategies that are environmental friendly and are low cost. Nevertheless, the methods outlined in the literature review do not offer a satisfactory in terms of the solutions they offer to the environmental challenges at hand. Most of them reduce or cut off the impacts caused by the pollutant although they do not eliminate it completely. This calls for constant monitoring and maintenance which is very expensive. Either, the methods used lack the capacity to cover large areas. Because chemicals are involved in the treatment process, environmental pollution is bound to occur during the cleaning process thus posing more danger to life in the ecosystem. Conclusively, the research outlined offers a remedy to clean up environmental agencies although the solutions are yet to be found. As researchers venture more into the field, better methods as suggested above will arise, and they will lead to a better and secure environment in the future. References Begonia, G., Davis, C., Begonia and Gray, C. (1998). Growth responses of Indian mustard [Brassica juncea (L.) Czern.] And its phytoextraction of lead from a contaminated soil. Bull. Environ. Contam. Toxicol. 61:38-43. Berti, W. and Cunningham, S. (2000). Phytostabilization of metals. p. 71-88. In I. Raskin and B.D. Ensley (ed.) Phytoremediation of toxic metals - using plants to clean-up the Environment. John Wiley & Sons, Inc., New York. Cook, J. (1977). Environmental pollution by heavy metals. International J. En v. Studies. 10(4):253-266. Cunningham, S., Berti, W. and Huang, J. (1995). Phytoremediation of contaminated soils. Trends Biotech. 13:393-397. Cunningham, S. and Ow, W. (1996). Promises and prospects of Phytoremediation. Plant Physiol. 110:715-719. Cunningham, S., Shann, J., Crowley, E. and Anderson, A. (1997). Phytoremediation of contaminated water and soil. p. 2-19. In E.L. Kruger, T.A. Anderson, and J.R. Coats (ed.) Phytoremediation of soil and water contaminants. ACS symposium series 664. American Chemical Society, Washington, DC. MADEP (Massachusetts Department of Environmental Protection Publication). (1993). 310 CMR 40.0000: Massachusetts Contingency Plan (MCP). Boston. Marschner, H. (1995). Mineral nutrition of higher plants. 2nd ed. Academic Press, New York. NRC. (1997). Challenges of groundwater and soil cleanup. p. 18-41. In Innovations in Groundwater and Soil Cleanup. National Academy Press, Washington, DC. NRC. (1999). Metals and radionuclides: technologies for characterization, remediation, and Containment. p. 72-128. In Groundwater & soil clean up: improving management of Persistent contaminants. National Academy Press, Washington, DC. Nriagu, J. (1979). Global inventory of natural and anthropogenic emissions of trace metals to the Atmosphere. Nature 279:409-411. Reed, D., Tasker, I., Cunnane, R. and Vandegrift, G. (1992). Environmental restoration and Separation science. p. 1-21. In G.F. Vandegrift et al. (ed.) Environmental Remediation: Removing organic and metal ion pollutants. ACS Symposium Series 509. American Chemical Society, Washington, DC. Ward, C. (1999). Preface. In Groundwater and soil cleanup: improving management of persistent Contaminants. National Academy Press, Washington, DC. Wise, W. (1968). Killer smog; the world’s worst air pollution disaster. Rand McNally & Co., Chicago. Wood, P. (1997). Remediation methods for contaminated sites. p. 47-72. In R.E. Hester and R.M. Harrison (ed.) Issues in environmental science and technology: contaminated land and its reclamation. The Royal Society of Chemistry, Letchworth, U.K. Read More