Methods of Waste Disposal Landfills - Case Study Example

Contents Introduction 3 Organization 3 Discussion 4 Conventional Landfills VS Bioreactor Landfills 4 Landfill Gas Generation 5 Landfill Leachate 6 Leachate Recirculation 7 Leachate Evaporation 7 Conclusion 7 Introduction Over the last few decades the generation and the disposal of waste has become an increasingly significant global issue due to a number of factors like tremendous increase in world population and ultimately an increase in waste generation. With the increase in waste generation there arise several questions about the waste management systems adopted throughout the world and their effects on the environment. Since many years landfill disposal methods are widely used throughout the world and there have been continuous improvements made to this method of waste disposal. Landfills have been used commonly for waste management of industrial residues, municipal refuse, waste water slush and recycle junk. The following document sheds some light on the waste management methods particularly focusing on landfills and their effects on the environment. Organization The following document will briefly discuss landfills, the different types of landfills used these days and their advantages and disadvantages. A brief comparison will be presented between the conventional landfills and the bioreactor landfills followed by some issues that are associated with landfills which include gas generation process and leachate production. The overview of landfill gas generation process will give the readers an idea of how actually a landfill works. Moreover, leachate creation and its management will also be discussed in short as it might be a serious issue related to landfills if not properly managed. Discussion The following section will consist of the discussion of the research highlighting the different forms of landfills, their effects and their advantages and disadvantages followed by landfill gas generation to give a basic idea of how a landfill works and leachate management techniques adopted to get rid of leachate (output of the landfill) which is a threat to the environmental health. Conventional Landfills VS Bioreactor Landfills A conventional Landfill is the one where trash is deposited in the ground and buried. Though with the advancement in environmental awareness, measures have been taken to design these landfills in order to protect environments; both human and natural. On the other hand a bioreactor landfill makes use of advanced microbiological methods and procedures to convert the decomposable waste. Bioreactor landfills are widely used in most developed countries due to its numerous advantages which include increase in the extent of waste decomposition, overall effectiveness of the process and conversion rates. (Urban Land Institute, 1996) Conventional landfills also commonly known as dry landfills have a higher volume of decomposed waste as compared to bioreactor landfills even after years. In a conventional landfill, the wastes are spread out evenly, compressed and later covered with soil until a specific landfill depth is reached. The final layer of the cover consists of clay. However, important to note that conventional landfills take several years to decompose the waste completely which is definitely not the case with bioreactor landfills. Another potential disadvantage of a conventional landfill is that there is always a chance of liner failure which may cause underground water contamination. (Bagchi, A. 2004) The basic purpose of a bioreactor landfill is to make use of certain procedures and methods to speed up the decomposition of waste material by promoting high moisture content in order to make it easier for the microorganism to decompose the waste. There are following different types of bioreactor landfills used commonly these days: Aerobic-Anaerobic Anaerobic Aerobic Facultative Landfill Gas Generation In a bioreactor landfill the major inputs are solid waste material and water whereas in response landfill gases and leachate are produced as outputs. Usually the gases which are found in landfills are nitrogen, oxygen, methane, carbon dioxide and ammonia. These gases are mainly produced by the organic reactions of decomposition of waste material. Significantly, methane and carbon dioxide are considered to be the major components of a landfill gas which are both produced by the organic waste materials in the landfill. First of all the organic decomposable components in the waste undergo a microbiological decomposition as soon as the waste is placed in the landfill. Oxygen present in the waste is later consumed by the micro-organisms and the waste undergoes an aerobic reaction. As a result a large amount of heat is produced and the temperature rises to 10-20 degrees Celsius. (Bagchi, A. 2004) During the next phase nearly all the oxygen is consumed and Nitrate and Sulphate present in the waste are transformed into Nitrogen gas during the anaerobic conditions. During this phase, because of concentrated carbon dioxide and the presence of organic acids, the PH levels of the leachate starts to fall down. Next, there occur two main reactions namely hydrolysis and acid genesis. During hydrolysis, the higher molecular components in the waste are transformed into simpler compounds which are easily consumed by the micro-organisms for their source of energy. During the acid genesis reaction, the microbiological compounds formed during the hydrolysis phase are further converted into simpler molecular compounds. Later, the micro-organisms convert the simpler molecular compounds (formed in the last phase) together with hydrogen gas to produce carbon dioxide and methane. At this stage the concentration of heavy components in the leachate drops significantly. After this phase, major nutrients are separated in the form of leachate and the left over material is easily degradable hence, the generation of gases is reduced significantly. In this phase the main landfill gases are carbon dioxide and methane with small quantity of nitrogen which might be occasionally present. (Tammemagi, H. Y, 1999) Landfill Leachate Landfill Leachate is a substance that penetrates through the waste in the landfill and consists of dissolved and suspended materials that may be a serious threat to human health and the environment. The quality of the leachate is determined by the type of waste and the chemical and biological activities that have occurred in the waste as a result of which the leachate is formed. If not properly managed, leachate can cause severe problems like contamination of underground water and soil. Without adequate measures for leachate management, the entire purpose of a landfill is not achieved. For this purpose there have been numerous practices and methods adopted in order to manage the leachate that is produced some of such methods are discussed below: Leachate Recirculation An important adaptation of leachate management system is to gather the leachate and re-circulate it through the landfill in order to decompose it even more and will provide the favourable conditions for bacteria growth. The bacteria will assist in anaerobic degradation of waste material. This method has been found to increase the water content of the landfill which provides favourable conditions for microorganisms to grow. (Tammemagi, H. Y, 1999) Leachate Evaporation Leachate evaporation has been found to be one of the simplest techniques of effective leachate management. Lined leachate evaporation ponds are used for this method. The left over leachate that is not evaporated naturally is later sprayed on the concluded portions of the landfill. However, it is important to cover the leachate evaporation ponds in areas or seasons with heavy rainfall. Conclusion Up till the last decade or so, there were no proper measures taken for effective management of waste but this is not the case today. Fortunately human race have found ways to dump the waste effectively and for this purpose landfills are contributing a lot in saving the human and environmental health. Landfills have proved to be a smart solution for effective management though there are a few issues involved. It is however required that adequate management of landfill leachate is done in order to avoid the nuisance that it can create for the environment. As the world population is growing tremendously, there is a need to build more and more landfills to get rid of the waste effectively in order to preserve a healthy environment for our coming generations. References California Integrated Waste Management Board. (1997). Integrated Waste Management Act: Flexibility and enforcement. Sacramento, CA (8800 Cal Center Drive, Sacramento, 95826: California Environmental Protection Agency, Integrated Waste Management Board. Bagchi, A., & Bagchi, A. (2004). Design of landfills and integrated solid waste management. Hoboken, N.J: J. Wiley. Jessup, D. H. (1992). Waste management guide: Laws, issues & solutions. Washington, D.C: BNA Books. Tammemagi, H. Y. (1999). The waste crisis: Landfills, incinerators, and the search for a sustainable future. New York: Oxford University Press. Urban Land Institute. (1996). Landfills and solid waste management: Selected references. Washington, D.C: Urban Land Institute. Waste news: Reporting on solid-waste management from product design to disposal and recovery. (1995). Detroit, Mich: Crain Communications. Read More