Measures to reduce the energy consumption for the sewerage plants - Essay Example

MEASURES TO REDUCE THE ENERGY CONSUMPTION FOR THE SEWERAGE PLANTS Sewage plants consume a lot power although they also generate a lot of heat and power. They generate heat through biogas production, which is purified and used to power locomotive machines like gas motors. The process of biogas production requires power especially in the fermentation and decomposition process because of temperature regulation. This is to say that production of energy from sewerage plants includes both aspects of increasing energy efficiency and reducing energy consumption. Biogas is produced through a process of anaerobic digestion (Jarvela & Juhola 2011, p. 183). Biogas production is environmental friendly. The purpose of this research paper is to give details on first the amount of energy consumed in sewerage plants. Second, the parts of the sewerage plants that require more energy than others do and lastly, measures to implement in order to reduce consumption of energy in sewerage plants. Biogas is a gas produced through the breakdown of organic matter in the absence of oxygen Sewage plants produce biogas, which is a good source of energy. During the sewage treatment process in the sewage plant, a lot of energy is consumed approximately 50 Kwh per person. That means that a substantial amount of energy is required to treat sewage from the population. Research shows that, sewage treatment is one of the sectors, which requires a lot of electricity. Biogas is a renewable source like wind and solar energy. For the production of biogas to occur, the sewage undergoes through a process known as anaerobic digestion. In this process anaerobic bacteria is used to breakdown the waste materials (Guczi & Erdohelyi 2012, p 60). The biogas produced is mainly carbon dioxide, methane, and small amounts hydrogen sulphide. Gases produced hydrogen; methane and carbon monoxide oxygen oxidizes them to allow release of biogas used as fuel. In the sewage plant, the sewage undergoes a certain process for the production of biogas. For instance, conventional sewage plants remove organic content by reacting the fats, proteins and carbohydrates with oxygen. In this process, aerobic respiration occurs that is in the presence of oxygen where most of the organic materials are converted to water and carbon dioxide (Mudhoo 2012, p. 174). Because of aerobic process in the sewage plant, there is production of bacteria cells, sewage sludge also known as bios lids and anoxidized organic matter. The sewage sledge is reduced from the sewage plant through anaerobic respiration in absence of oxygen thus producing biogas. As stated above biogas is mainly methane and carbon oxide and small amounts of hydrogen sulphide. The biogas produced is burned in a turbine to generate electricity. Anaerobic respiration produces 40 per cent of the energy used in sewage plant treatment. In the conventional sewage plant treatment, only one third of the energy is partially available. This is to say that, in the sewage plant biogas production cannot be fully relied. There is need for a backup power system or energy required in the sewerage treatment plant (Jarvela & Juhola 2011, p.121). In the sewerage plant, the plant consists of two digesters known as fermentation tanks (Deublein & Steinhauser 2011, p. 194). They are crucial in the sewerage plants because they provide a good environment in which anaerobic bacteria generate biogas. A lot of energy is required in the production of biogas because the digesters need to be constantly stirred and heated to ensure that a substantial amount of biogas is released. An airproof steel container holds the gas by floating on the fermentation digesters. The digesters have a gas outlet and a pump, which leads the sledge out into the drainage pit. In the sewerage plants, organic materials are feed in to the plants because they are highly biodegradable. The bacteria used to break down the materials feed into the plant are highly sensitive to temperature and pH (Fuchs et al 2012, p. 74). This means that temperature and pH should be kept constant at all times. As earlier stated, production of energy from sewerage plants includes both aspects of increasing energy efficiency and reducing energy consumption. In sewerage treatment plants, pumping and aeration process requires large amount of energy. Energy is required in the sewage plant for solid processing and liquid treatment. Aerobic respiration demands more energy than any other process in the sewerage plant. This is because energy is required to create air bubbles in the biological process of biogas production. There are different types of sewerage plants and they consume energy differently. Depending on the type of sewerage, the amount of energy consumed is between 20 to 45 kWh per person. Energy consumption depends on the size of the sewerage plant. The lower figure of the energy consumption the larger the plants while the higher the figure the smaller the plants. This is to say that, the larger the plant, the lower its specific rate of energy consumption. In addition, power consumption depends on the design of the sewerage plant. For instance, plants with aerobic digesters consume more energy. The design of the pumps also affects the rate of energy consumption. Saving energy consumption should not jeopardize sewage treatment quality but improve energy efficiency and quantity. This is to say that energy production in a sewerage plant depends on the design of the plant and its size. This is to say that anaerobic digesters are preferred over aerobic (Nayono 2009, p. 71). Several measures should be applied to reduce energy consumption in conventional water plants. As stated above aerobic respiration and the pumping system in most sewerage plants consume more energy than any other process. Because of this, one method that can be used to reduce energy consumption is operating the system manually this is to reduce the energy consumed in the pumping process. In addition, as stated above in aerobic respiration the energy required is to create air bubbles, which are used, in the biological process. Many aeration systems operate manually to produce air bubbles required in the biological process (Guczi & Erdohelyi 2012, p. 507). To maximize efficiency, in the creation of bubbles, the aeration system should be operated automatically by so doing the energy required in this process will reduce greatly. In addition, air should flow in the sewerage plant at the right time to reduce the amount of energy consumed. Research has shown that, changing the operation of aeration system from manual to automatic the energy demand will reduce from 20 per cent to 50 per cent (Villacampay, Brebbia & Mammoli 2011, p. 11). Other implementations to make in order reduce the amount of energy consumed in the sewerage plants include; the blower system in the plant should be replaced to provide an efficient energy system. Improvement of the blowers is another implementation to be set in place in order to reduce the amount of energy consumed in the sewerage plants for instance, lubrication of the blowers (Fuchs, et al 2012, p. 93). Replacement of blower motors with high efficient motors to reduce the energy required in aeration systems. Lastly, replacement of existing blowers with turbo blowers reduces the amount of energy consumption. Many sewerage treatment plants have fine bubbles, which diffuse into their mixed liquor aeration systems thus consuming more energy. Because of the diffusion of these fine bubbles in the aeration system, for biological process the amount of energy consumption in the plant reduces. However, if the fine bubbles are not well maintained they can foul leading to high requirement of energy. In the sewerage treatment plant, thickening is a process, which requires a lot of energy. In this process, the primary sludge is mixes with waste activated sludge. This is to reduce the cost of downstream treatment of solid materials. There are different methods used by different sewerage treatment plants to thicken their solids they include a centrifuge thickening, gravity belt thickening, and rotary drum thickening and dissolved air floating (Mudhoo 2012, p. 80). The processes requires different amounts of energy for instance many sewerage treatment plants use the dissolved air flotation, which requires aeration thus using a lot of energy because of the creation of bubbles, which are used in this biological process. Rotary drum thickeners and gravity belt thickeners do not undergo the process of aeration this means that, less energy consumption. Research has shown that, the energy consumed in rotary drum thickeners and gravity belt thickeners is 80 percent less than energy consumed in the air floating process because of the absence of the aeration process. This is to say that, to reduce energy consumption in sewerage plants they rotary drum thickeners and gravity belt thickeners should be used to avoid aeration process, which consumes a lot of energy (Deublein & Steinhauser 2011, p. 77). As stated above pumping system consumes a lot of energy. Several methods can be used to reduce energy consumption in the pumping station and the pumping systems in the sewerage treatment plants (Fuchs, et al 2012, p. 73). One of the methods is installing a variable frequency drive that is for plants that do not require constant operation in full spend. Replacing lower efficiency motors with higher efficiency pumps and motors is another strategy to reduce energy consumption in a sewerage plant. Another method to reduce the amount of energy required in a pump station is to plan staged construction. This is because pump station inflow increases as time goes on. Thus, it is important to ensure that pump station will support future flows. However, if the pumps are not constructed in a way to support future flows, the pumps will require more energy to support future flows (Nayono 2009, p. 73). In the sewerage plants, there are different processes, which require less energy. Because of this, there is a need to fully maximize them to ensure that the downstream processes are efficient. These processes are primary and secondary clarification, screening, chlorination, and gravity thickening (Villacampay, Brebbia & Mammoli 2011, p. 329). Optimizing the following processes will have little effect on energy consumption in the sewerage plant. However, some of these processes if poorly done may require a lot of energy. For instance, poor screening this result in accumulation of solid materials in anaerobic digesters. This affects the rate of biogas production, which is used in the sewerage plant thus leading to increases in energy consumption. In addition, primary treatment requires less energy but improper primary treatment can lead to high-energy demands, this is because it leads to lower production of biogas in the anaerobic digesters. This means that, although these processes require less energy it is important to carry them out in the right manner to avoid high consumption of energy (Mudhoo 2012, p.124). The other method to reduce energy consumption is using anaerobic digesters instead of aerobic digesters, which do not require aerobic respiration in the production of biogas (Guczi & Erdohelyi 2012, p. 17). Recent research has shown that, aerobic digesters are popular because they are easier to operate, require less capital and maintenance cost than anaerobic digesters. On the other hand, aerobic digesters consume a lot of energy because of the aeration process. This is because in this process, there is a need to form air bubbles, which are used in the biological process, and this requires a lot of energy. Although, anaerobic digesters consume less energy they require more capital and high maintenance cost research as shown that, anaerobic digesters use 33 percent less energy than aerobic digesters. This is to say that to reduce energy consumption in sewerage plant there is need to use the anaerobic digesters regardless of their high capital and maintenance cost (Nayono 2009, p. 71). In conclusion, as discussed above sewerage plants consume a lot of energy in processes such as aeration and the pumping systems. Because of this, there is, need to replace the aeration processes with anaerobic processes because it consumes less energy. Anaerobic respiration offers more energy with less consumption of energy this is because it does not require formation of bubbles, which consume a lot of energy. When setting up a sewerage plant one will require looking at the set up to ensure that the pumping system does not consume a lot of energy because pumping system greatly affects the level of energy consumption in a sewerage plant. In addition, there is need to replace pumping systems that have aged before there useful life. This is because such pumping systems increase the level of energy consumption. Lastly, biogas produced from the sewerage plants has various uses first, it is recycled and used in the sewerage plants that are in the digesters for heating and also to drive pumps and blowers in the sewerage plant and lastly generate electric power used in home appliances. Bibliography Deublein, D, & Steinhauser, A 2011 ,Biogas from waste and renewable resources an introduction. Weinheim, Wiley-VCH. http://lib.myilibrary.com/?id=337047. Fuchs M, et al 2012, Energy Manual Sustainable Architecture. Basel, De Gruyter. http://public.eblib.com/EBLPublic/PublicView.do?ptiID=1075583. Guczi L , & Erdőhelyi, A. 2012, Catalysis for alternative energy generation. New York, Springer. http://dx.doi.org/10.1007/978-1-4614-0344-9. Järvelä, M, & Juhola, S. 2011,Energy, Policy, and the Environment Modeling Sustainable Development for the North. New York, NY, Springer Science+Business Media, LLC. Mudhoo, A 2012, Biogas production: pretreatment methods in anaerobic digestion. Hoboken, N.J., John Wiley. Nayono S, 2009 Anaerobic digestion of organic solid waste for energy production. Karlsruhe, KIT Scientific Publ Villacampay, Brebbia C, & Mammoli, A. 2011, Energy and Sustainability III. Southampton, UK, Witt Press. Read More