How to Reduce Carbon-Foot Print in Wastewater Treatment Plants - Research Paper Example

How to reduce carbon-foot print in wastewater treatment plants Student name: Supervisor: Degree: University: Date of Submission: Table of Contents Table of Contents 2 1.Introduction 3 1.1Anaerobic digestion process 4 1.2 Aims and Objectives 5 1.Methodology 5 2.1 System design 5 2.1.1 Water source 6 2.1.2 Intake 7 2.1.3 Chemical addition and mixing 7 2.1.4 PH adjustment 7 2.1.5 Coagulation and flocculation 8 2.1.6 Sedimentation 9 2.1.7 Storage and removal of sludge 9 2.1.8 Filtration 10 2.1.9 Disinfection 11 2.2Anaerobic digestion 12 2.Literature review 14 3.1 Wastewater collection and treatment 14 3.2 Carbon footprint reduction 14 3.3 Three Rs 15 3.4 Anaerobic digestion Importance 16 3.4.1 Anaerobic technology 17 3.5 Kyoto protocol on anaerobic digestion 18 3.Results and discussion 19 4.1 Anaerobic digestion in reduction of the carbon footprint 20 4.Conclusion 21 5.Recommendations 21 Works Cited 23 1. Introduction Wastewater treatment needs oxygen in the entire process. Therefore, anaerobic digestion process works in the absence of oxygen. Thus, anaerobic wastewater treatment involves digestion of biosolids by the bacteria in the absence of oxygen. In the anaerobic digestion, the entire process works with production of biogas. In addition, for the success of the anaerobic wastewater, treatment requires aerobic digestion for oxygen introduction in the process, and this makes the entire anaerobic wastewater treatment cost effective. Essentially, anaerobic digestion involves biodegradable materials by microorganisms in the absence of oxygen. This process helps in most domestic processes to manage wastewater. Further, anaerobic digestion in industrial process helps in the production of drinks and food products. This process begins with the bacterial hydrolysis to the input materials. Such insoluble materials include organic polymers, which are broken down to soluble products available to bacteria. The soluble products (amino acids and sugars) are further broken down to hydrogen, organic acids, carbon dioxide and ammonia. Further, the bacteria convert the resulting organic acids to acetic acid, hydrogen, ammonia, and carbon dioxide (Frank 297). Lastly, the methanogenic bacteria convert the resulting products to carbon dioxide and methane. Thus, the archea methagonic acts a vital role in the wastewater treatment plants in wastewater treatment. The anaerobic digestion process in the waste management process lowers emission of landfill gas into the atmosphere, which is part of treating biodegradable materials in wastewater. It is thus clear that anaerobic digestion process is also a source of renewable energy. This is evident from the system releasing carbon dioxide and methane gases. In CHPs (combined heat and pressure) engines, the methane gas works as fuel, while water from the system I usable in many applications such as irrigation and home usage. 1.1 Anaerobic digestion process Anaerobic process has four stages of development, which follow the order, hydrolysis as the first, then acidogenesis, acetogenesis, and lastly the methanogenesis process. Hydrolysis involves breakdown of carbohydrates, fats and proteins to soluble sugars, fatty acids and amino acids respectively (Satoto 46). Hydrolysis of the complex material further undergoes acidogenesis, which results to carbonic acids and alcohols and gases (hydrogen, ammonia, and carbon dioxide). Further, they undergo actogenesis to hydrogen, carbon dioxide and acetic acid. The by-products from the acetogenesis by acetic bacteria undergo methanogenesis by the methanogenic bacteria to form methane and carbon dioxide (fig 1). Fig 1: Anaerobic digestion process and stages From fig 1, proves how the anaerobic digestion process starts, methane, and carbon dioxide are produced in the process. Further, in the wastewater treatment plant methanogenic bacteria breaks down the acetic acids to methane gas that can be used in cooking. 1.2 Aims and Objectives Aim: to develop a wastewater treatment plant that uses anaerobic digestion process This report gives a clear picture of wastewater treatment plants using anaerobic digestion process as the main way to reduce carbon footprint in the process. In addition, the report shows the importance of anaerobic digestion in the wastewater treatment plants This report targets to prove the need to have wastewater treatment plants that employ anaerobic digestion process. To develop an energy efficient system that will focus on zero emission of the carbon dioxide GHGs and safe the environment and bring positive environmental wastewater treatment plants. 1. Methodology 2.1 System design Figure 2: Water treatment process (Elizabeth 168) Water treatment must follow a number of steps during the treatment process before it is fit for usage in the indented purposes. 2.1.1 Water source This the source from which the wastewater for treatment comes from. The entire source contains contaminated water. Most of the contaminants are mostly industrial wastes, solid wastes, and soil particles. These, contaminants must be eliminated from the water before it is used in the indented purpose. The water source from which the system must be checked and all the foreign materials removed at the intake. Such materials that must be removed include logs, glass, dry tree leaves, and stones and other visible materials that cannot pass through the sieve. 2.1.2 Intake At the water intake, all materials that cannot pass via the sieve are eliminated from water before it enters the chemical addition chamber. Further, at the intake, water is cleaned through a sieve process and all soil particles removed from the water. Water in this stage is raw and has large particles, which are removed at the intake stage. Further, the raw water received in the intake is stored in the raw-water reservoir. In this reservoir, raw water undergoes natural sedimentation where the heavier particles are settled and removed. Water is allowed to pass to the chemical treatment tanks. 2.1.3 Chemical addition and mixing In this stage, water from the reservoir undergoes chemical dosage, a process that separates the remaining particles from water. In addition, chlorination is done at this stage, which prevents growth of the fouling organisms. 2.1.4 PH adjustment Rao & Tyagi (47) describes water as a must have a PH of 7, which is neutral PH level, thus due to presence of the sediments in the raw water, the stored water is either slightly acidic or moderately alkaline. Thus during the purification process soda ash, lime, or sodium hydroxide is added into raw water reservoir in this process. This must be done to stabilize the PH level. To increase hardness in water lime, which raises the calcium level, must be added in the process. Further, if the water used in the process is acidic, force degasifiers help in raising the PH level of water. This strips the dissolved carbon dioxide from the water. Moreover, making water alkalinic makes the coagulation and flocculation process becomes more efficient, thereby lowering the risk of having lead dissolving from the pipes. Sometimes, water will need addition of the acids that will help to lower the PH level in water. Making water alkaline does not necessarily guarantee absence of lead and copper dissolving in the system. Further, this improves the calcium carbonate precipitating ability of water towards metal protection thus lowering the possibility of having dissolved metals in water. Therefore, at this stage chemical are mixed water where water hardening and PH adjustment is done. 2.1.5 Coagulation and flocculation Addition of chemicals in water helps in removal of particles by removal of major particle that are suspended in water. These particles might be silt and clay, which are organic or others that are organic particles such as algae and bacteria. Generally, these particles are the major causes of turbidity in water and water coloration. Thus in this stage organic coagulants must be used to bring about chemical simulations in water as well as change the state of the particles. These coagulants may include aluminium sulfate and/or iron III salts. When added to the water these natural coagulants cause formation of iron III and aluminium ions. Thus, through flocculation these particles form larger particles through combination of the particles in a Brownian motion. When aluminium hydroxides adsorb the particles are eliminated via the filtration and sedimentation processes. 2.1.6 Sedimentation As water leaves the flocculation tank it enters the sedimentation tank, where there is settling of water that has been mixed with the coagulating chemicals. In this tank, water is at low flow velocity, thus, floc settles at this tank’s bottom. Therefore, it is necessary to have the flocculation tank must be closer to the sedimentation tank. This is to ensure that there is break in floc settlement. Usually, the flocculation tanks are rectangular or circular, where water is allowed to exit at the top of the tank, which allows enough time to settle floc in the tank. At this level, coagulants can be removed from the bottom of the tank without destructing the sedimentation process in the tank. Further, the sedimentation tank should be deep enough to ensure that water current does not affect the sedimentation process. To improve sedimentation performance in the particle removal, it is important to use flat plates and tubes, which reduces the available surface area of the tank that is available for the sedimentation tank. 2.1.7 Storage and removal of sludge A layer of the coagulated particles settles at the bottom of the tank forming sludge, which needs removal and treatment. This process, counts as art of the operational cost in water treatment process, which comes from disposal and treatment costs incurred on the sludge. Most of the times, when removing the sludge it might affect the particle removal efficiency from water. As water settles in the sedimentation tank, a layer of floc suspends on the upper part of the sludge, which is because of water forced up by the flow waves. This has a disadvantage in that it can affect the rate at which particles are removed from the water. Accidentally, sedimentation might fail and particles cannot settle easily out of the solution, a dissolved air flotation method can be used. This can be applied to water that has algae, which basically has low turbidity, where water is allowed to flow to the DAF tank, which has air diffusers at the bottom to create air bubbles which creates a floating floc. In this process, floating floc can be removed from the top and cleaned water extracted from the bottom of the tank. 2.1.8 Filtration This is the final separation stage, where the suspended particles that are remaining in water and the unsettled floc are removed through water filtration. Sand filters Rapid sand filters have been the most common filtration type, which has filtration layers arranged vertically with anthracite coal placed on the top of the sand as the top layer in the filtration system. This layer helps in removing the organic compounds from the water changing its taste and odour. The adjacent layers are sand layers, which help in trapping the particles suspended in water after the sedimentation process. The more the number of sand layers the more efficient is the filtration system. Allowing the system filtration process to have several layers ensures that the top sand layer does not clog easily thus allowing the filtration to run for longer periods. For clean water filtration, backwashing process is used to remove the embedded particles from water. The backwashing process requires that the filtration system to be blown up using compressed air through an air sourcing process. Contaminated water from the filtration process is mixed with intake raw water. Although mixing the water might lead to re-introduction of bacteria concentration in raw water, the contaminated water re-used ensures continuous water intake supply for the plant. This process is more advantageous in that it ensures filtration of smaller particles in water. Slow sand filters These filters may be used in areas where there is sufficient space of land. This is because water needs to pass slowly over the filters, which basically depend on the biological treatment processes. When the filtration process is complete, ions are removed from water together with the dissolved minerals. This is done through a series of processes and addition chemical for treatment. Ion exchange: zeolite columns are used in the process on replacing; this is done to remove the calcium and magnesium ions to soften water, which are replaced by potassium or sodium ion. . Preciatative softening: soda ash is used to precipitate calcium carbonate thus hardening water Electrodeionization: this may be achieved through ion exchange through a membrane for ion exchange. 2.1.9 Disinfection Water disinfection is achieved through addition of disinfection chemical compounds such as chlorine or chlorine compounds. This process is necessary to ensure that pathogens are killed; this kills all the possible pathogens by injecting a disinfecting dosage that helps to kill the microorganisms in the distribution system. Such pathogens that might be in water and must be killed include bacteria and viruses, which may include salmonella, protozoa, shigella and cholera. For this process to succeed water must stay in a storage tank for temporary storage. This allows sufficient time for a complete disinfection process. Storage After the disinfection, stage water is stored in temporary tank waiting distribution. During this storage period, all the remaining pathogens die due to lack of oxygen since the storage tank must be airtight. This makes the system act like an anaerobic digestion system where there is no oxygen present in the system, which ensures death of the present pathogens. 2.1.10 Distribution From the storage tank, water is distributed to the users through the designated channels that have been set to the users. Water from the storage tank is clean and ready for safe usage by the designated final user. The entire process of water treatment starts from the water source where water is collected and stored in the intake tanks, water treatment through flocculation and coagulation, filtration storage and water distribution. Water treatment process is used in wastewater treatment plants that are used for cleaning water for usage in both commercial and domestic water treatment processes. 2.2 Anaerobic digestion Over decades, anaerobic digestion has been the major practice for treating wastewater from industries in several parts of the word. In the beginning of the use of the technology, anaerobic digestion was used in these industries to control odor from the industrial surrounding, which was also targeted to meet the waste management strategies set by the industry. With success of the anaerobic digestion use in the market industry having become more popular, most industries have with time ventured in capitalizing in the technology to attain zero carbon footprint initiative to the ambient. The use and application of anaerobic digestion process in wastewater treatment has considerable low energy requirements. Therefore, anaerobic digestion is a means by which wastewater treatment can achieve high-energy savings, which mean there would be savings in the total operational cost of the entire system. Energy costs have increased overtime; thus using anaerobic digestion as the source of energy in the wastewater treatment process will greatly lower energy cost requirements. In fact, anaerobic digestion is a source of green technology that not only uses less grid energy than other energy sources. In the anaerobic digestion process, organic waste is degraded in the digester releasing methane gas. Methane gas harvested in the anaerobic digestion process replaces the use of organic fossil fuel that is non-renewable for household usage. Anaerobic digestion occurs in natural circumstances with uncontrolled settings in the absence of oxygen. In the absence of oxygen, microorganisms releasing a relative amount of methane gas break down organic matter. This degrades the waste matter and reduces the chances of releasing the carbon dioxide to the atmosphere. Wastewater treatment plants have a specific means by which the waste streams are handled, which involves the sludge released from the treatment plant. Therefore, this makes this process cost friendly compared to other means of wastewater treatment in the industries. This is because, the system serve a two dimensional process to reduce and reuse the waste applying anaerobic digestion. 2. Literature review 3.1 Wastewater collection and treatment Traditionally wastewater treatment plants used the filtration process to acquire clean water for domestic usage. This process has been adopted in the commercial levels as it ensures that maximum application of the water cleaning process as fully utilized. Further, wastewater treatment requires proper attention as any errors made can be of great damage to the final stage in water treatment plants (Gabriel 28). Moreover, anaerobic digestion is the major process that is applied in water treatment plants as it ensures that carbon dioxide is used in the process, which lowers the amount of carbon footprint in the ambient. This becomes possible in the storage tank after wastewater treatment where the tank is airtight and no oxygen is allowed in the tank. This ensures that all pathogens are full destroyed at this stage lowering carbon dioxide release to the ambient. 3.2 Carbon footprint reduction In an anaerobic digestion process, a flammable gas is released a used in cooking and lighting as well as other domestic applications. Consequently, carbon dioxide is released in the process thus this can be controlled from atmospheric pollution through proper control procedures. Further, in the process to lower the amount of carbon footprint in the ambient, there is need to develop an energy or power generating system (Jørgensen 27). Thus, the amount of energy can be generated when a comparable amount of carbon footprint is withheld is large and therefore developing energy systems from the anaerobic system. 3.3 Three Rs Reduce The three Rs that can be used to reduce carbon footprint include reduce, reuse and recycle. Most of the times disposing waste materials to soil in landfills acts as the major source of carbon dioxide increase in the ambient. Therefore, reducing the burning activities that involve burning of the carbonic materials greatly lower the amount carbon dioxide that is released to the atmosphere. Thus, these materials should otherwise be used in wastewater treatment plants, which ensure proper utilization of the waste without carbon pollution (Lazarova et al 194). Further, in order to reduce carbon footprint, the use of electricity in the wastewater treatment plant should not be made an option but should be stopped (Vesilind 217). This further helps lower the amount of carbon dioxide that would have otherwise been released to the ambient in the treatment process. Therefore, this process should be natural with minimal usage of external sources might otherwise lead to release of carbon dioxide into the ambient. Reducing the energy usage in the water treatment plant and further using the anaerobic digestion helps greatly by reducing energy that would be needed in the entire process to heat. Reuse Moreover, the reuse of the waste materials in the wastewater treatment plants contributes in a greater percentage the release of carbon dioxide to the atmosphere. Reusing the waste materials in anaerobic digestion for methane generation can be of great help considering this process must be carried out in the absence of oxygen (Morris 242). This lower the amount of carbon dioxide that would otherwise been released in the atmosphere. Further, waste reuse in the wastewater treatment plants ensures low emissions to the account of lowering municipal solid waste disposal (Water Environment Federation 147). Recycle Recycling is making use of the waste that would other being disposed but used to serve other purpose (Aysel & Subhas 297). This process ensures that there is less waste burning in the landfills, therefore, using the household waste and recycling the waste in wastewater treatment plants ensures reduced waste which reduce the household carbon foot print by approximately 1 ton per year. 3.4 Anaerobic digestion Importance Anaerobic digestion helps in degrading the waste matter generating gases, which include methane gas. Methane generated can be reused on the treatment plant site to power boilers or supplied to the local power producing companies that need to expand their power production portfolio (Nagle 37). This acts as a source of alternative energy for these companies since use of methane guarantees utilization of renewable source of energy with less or no carbon dioxide emission to the ambient. Further, Bitton (147) states that depending on the waste quality, the byproduct of anaerobic digestion is used as fertilizer. Plants grow well in fertile soils and this ensures these plants can utilize the carbon dioxide in the ambient reducing the carbon footprint from the atmosphere. In addition, using the anaerobic digestion byproduct as a fertilizer further reduces the need to manufacture chemical fertilizers, which are another source of carbon dioxide emission during production and transportation. 3.4.1 Anaerobic technology Since 1970’s there have been good number of anaerobic digestion systems. The design of the system will largerly rely on climatic conditions of the area in which the design will be set up. Location will further determine the success of the anaerobic digestion system that must be considered when selecting the best design for the digester (Erin 38). Lastly, when planning to design the anaerobic digester, type waste involved in the wastewater treatment plant will greatly determine the digestion time required. Low rate systems Geomembrane covers are used in these systems to accomplish the rainwater and gas control to the system (Carlos 207). Typically, the low rate anaerobic systems have large waste volumes which require less sophisticated operation of the system. High rate systems This system uses roofs that are fixed and flexible. Higher rate of operation calls for the design to be tank based process. Typically, these systems are used in treatment of smaller volumes with more concentration waste streams. Since the aim of using anaerobic digestion in industries is generating sludge, municipal wastewater treatment plant generates more sludge than other industries. Thus, this reason guarantees the municipal to benefit most (Vesilind, Susan & Lauren, 389). Mostly, the wastewater treatment plants that use food wastes and industrial compounds that have organic contents have higher benefits. Therefore, wastewater treatment plants are essential components that need to be installed in the food processing industries. This ensures higher amounts of methane gas production are released during the treatment process. Thus, for the industries that reuse the biogas have tangible benefits that give the company cost savings at a long-term basis. Moreover, treating water using the anaerobic digestion process guarantees safe way of reducing the higher amounts of carbon footprint from the ambient. 3.5 Kyoto protocol on anaerobic digestion Most of the installed anaerobic digestion plants have been impacted by Kyoto protocol. This has been successful in sense that they have overtime resulted to creating a trading system. In 2005 the Kyoto protocol treaty came into action with an aim to lower emission of the GHGs (green house gases). This treaty involved the members to enter into compliance markets and trade the carbon credits. In some countries where the treaty has not been ratified, businesses have focused on voluntary carbon credit markets. Further, the United Nations as one of the decentralized energy source has recognized development of the carbon markets. Thus, this makes an easy go ahead for the anaerobic digestion developers for wastewater treatment (Pablo 212). Development of clean energy system systems has seen the higher rate of reduced carbon footprint to the ambient, which will see the change in reduced global warming. Therefore, taking full advantage of this technology will ensure positive benefits to both economic and environmental development. 3. Results and discussion Anaerobic digestion will occur naturally requiring no oxygen for the process to occur. In this process, bacteria produce biogas by breakdown of organic materials. In this process, organic material are reduced which results in production of biogas that is in turn used to generate energy. This process is usually used in the places where wastewater treatment is given priority (van Haandel, & van der Lubbe 102). The use of anaerobic digestion in wastewater treatment plants has more advantages in that it helps in greater part in mitigating climate change. Wastewater treatment facilities have connection to the waste food landfills that contain the necessary materials that are necessary for use in the process to capture methane (Awwa Staff 37). Methane is the main source of gas release from the anaerobic process, which ensures minimal carbon dioxide is released to the ambient through burning of the landfills, which releases large amounts of carbon dioxide in the atmosphere. Thus, the major aim for the report is to reduce the amount of carbon footprint that is release to the ambient from normal daily activities. Incorporating waste food in wastewater treatment facilities increases financial backup when the two are used concurrently. This process ensures reduced energy costs as this project ensures sufficient energy is supplied from the system. Moreover, investing in the project is more of waste diversion as more food waste is diverted to the wastewater treatment facilities. Thus, most municipalities will see the investing process in the wastewater treatment plant as a great opportunity as the landfills are being exhausted, therefore creating a large stream of waste to the wastewater treatment plants. The largest proportion of municipal solid waste principally comes from waste food. Thus, larger proper proportion of the wastewater treatment plants will be composed of greater amounts of waste food. Wastes used in the wastewater treatment plants are easily biodegradable. Thus, using these materials in anaerobic system lowers the chances that landfills would otherwise increase the release of the carbon in the ambient. Moreover, wastewater treatment plants will help greatly in the process to generate renewable energy. The major reason why the anaerobic digestion process is used in this system is that it assists in a greater part in energy capture. 4.1 Anaerobic digestion in reduction of the carbon footprint Burning fossil fuels emits large amounts of carbon dioxide to the ambient that causes global warming at a very high rate. Thus reducing the reliance on the use of fossil fuels can greatly reduce the carbon footprint to manager levels. Using anaerobic digestion in water treatment helps to cut down the tremendous need to use fans to blow air into the system to supply oxygen. These fans need to use energy when running to blow air into the system, thus concentrating on the use of anaerobic digestion system ensures zero need to use fans. This further ensures that the biogases have been reused thus creating an environmentally friendly energy source. 4. Conclusion Adoption of zero carbon emission to the ambient is of great concern to the wide globe as a major concern. Thus, treatment of the wastewater plants has overtime been a big issue that deserved a changing plan. Other, than plants that use carbon dioxide during photosynthesis, there are no other living organisms that use oxygen, thus during the water treatment processes more carbon dioxide was released to the atmosphere (Mohee & Mudhoo 124). Largely, there has been carbon dioxide that has overtime created a global concern, while there have been major challenges faced from global population increase (David 3). Therefore, in the verge to lower the amount of carbon dioxide released to the ambient that all the wastewater treatment plants must employ the use of anaerobic digester, which does encourage re-use of the waste materials to generate gas used for energy generation. Many organizations and companies will invest on renewable technologies in the near future. This is as projected by Erin (46), showing the current state at which emission of the carbon dioxide is very high. Therefore, there would be a need for most of the companies and institutions to invest in anaerobic digestion systems in wastewater treatment processes. 5. Recommendations The world must work towards development of a free emission atmosphere; therefore, focusing of the full use of anaerobic digestion systems in water treatment plants is actually the key to success. Therefore, most of the food processing industries must invest on anaerobic wastewater treatment plants (Bishop 27). These would guarantee a mutual benefit for the industry since there is harvesting of biogas from the system. Further, municipalities are the largest waste producers; therefore, if all the municipalities focus on the technology use, this would mean reduced carbon footprint to the atmosphere (Roza 38). In addition, there is a need to call for investors and other organizations to focus on the use of zero emission technologies in wastewater treatment plants. Edmund & Renato (201) suggests that for safe environment with minimal emissions and reduced carbon footprint, industries must focus on investing and developing anaerobic digestion systems that will be used in the wastewater treatment processes. Works Cited Mohee, Romeela & Mudhoo, Ackmez Bioremediation and Sustainability: Research and Applications, New York: John Wiley & Sons, 2012, 124 Bitton, Gabriel, Wastewater Microbiology, New York: John Wiley & Sons, 2005, 346-347 Lazarova, Valentina, et al, Water-energy Interactions in Water Reuse, London: IWA Publishing, 2012, 199-204. Vesilind, Aarne, Susan, Morgan, & Lauren, Heine, Introduction to Environmental Engineering, New York: Cengage Learning, 2010, 388-389 Bishop, Amanda, How to Reduce Your Carbon Footprint, New York: Crabtree Publishing Company, 2008, 27 Roza, Gret, Reducing Your Carbon Footprint on Vacation, New York: The Rosen Publishing Group, 2008, 38 Rao, Surampalli, & Tyagi, R. D. Advances In Water And Wastewater Treatment, London: ASCE Publications, 2004, 47-50 David, Sarah, Reducing Your Carbon Footprint at Home, New York: The Rosen Publishing Group, 2008, 2-3 Nagle, Jeanne, Reducing Your Carbon Footprint at School, New York: The Rosen Publishing Group, Sep 1, 2008, 37 Awwa Staff, Desalination of seawater, New York: American Water Works Association, 2011, 69 Erin, Linley, H., Reducing Your Carbon Footprint, New York: The Rosen Publishing Group, 2008, 38 Morris, Collin, Encyclopedia of Sustainability, New York: Greenwood publishing, 2009, 242. Frank, Akpadock, City in Transition, Canada: FriesenPress, 2012, 297. Pablo, La Roche, Carbon-neutral Architectural Design, New York: CRC Press, 2012, 212. Carlos, Brebbia, & Ēlias, Beriatos, Sustainable Development and Planning V, Southampton: WIT Press, 2011, 207. Edmund, Wagner, & Renato, Pinheiro, Upgrading water treatment plants, New York: Taylor & Francis, 2001, 201. Aysel, Atimtay, & Subhas, Sikdar, Security of Industrial Water Supply and Management, New York: Springer, 2011, 197. Vesilind, Aarne, P., Wastewater treatment plant design. [1]. Textbook, New Jersey: IWA Publishing, 2003, 217. Gabriel, Bitton, Wastewater Microbiology, New York: John Wiley & Sons, Jun 9, 2011, 28. Satoto, Nayono, Anaerobic digestion of organic solid waste for energy production, London: KIT Scientific Publishing, 2009, 46. Jørgensen, S., Principles of Pollution Abatement, New York: Elsevier, 2000, 27. Elizabeth, Maczulak, Environmental Engineering: Designing a Sustainable Future, Infobase Publishing, 2010, 168. Water Environment Federation, Operation of Municipal Wastewater Treatment Plants, New York: McGraw Hill Professional, 2008, 102. van Haandel, Adrianus & van der Lubbe,Jeroen, Handbook biological wastewater treatment: design and optimization of activated sludge systems, The Netherlands: Quist publishing, 2007, 102. Read More

1.2 Aims and Objectives Aim: to develop a wastewater treatment plant that uses anaerobic digestion process This report gives a clear picture of wastewater treatment plants using anaerobic digestion process as the main way to reduce carbon footprint in the process. In addition, the report shows the importance of anaerobic digestion in the wastewater treatment plants This report targets to prove the need to have wastewater treatment plants that employ anaerobic digestion process. To develop an energy efficient system that will focus on zero emission of the carbon dioxide GHGs and safe the environment and bring positive environmental wastewater treatment plants. 1. Methodology 2.

1 System design Figure 2: Water treatment process (Elizabeth 168) Water treatment must follow a number of steps during the treatment process before it is fit for usage in the indented purposes. 2.1.1 Water source This the source from which the wastewater for treatment comes from. The entire source contains contaminated water. Most of the contaminants are mostly industrial wastes, solid wastes, and soil particles. These, contaminants must be eliminated from the water before it is used in the indented purpose.

The water source from which the system must be checked and all the foreign materials removed at the intake. Such materials that must be removed include logs, glass, dry tree leaves, and stones and other visible materials that cannot pass through the sieve. 2.1.2 Intake At the water intake, all materials that cannot pass via the sieve are eliminated from water before it enters the chemical addition chamber. Further, at the intake, water is cleaned through a sieve process and all soil particles removed from the water.

Water in this stage is raw and has large particles, which are removed at the intake stage. Further, the raw water received in the intake is stored in the raw-water reservoir. In this reservoir, raw water undergoes natural sedimentation where the heavier particles are settled and removed. Water is allowed to pass to the chemical treatment tanks. 2.1.3 Chemical addition and mixing In this stage, water from the reservoir undergoes chemical dosage, a process that separates the remaining particles from water.

In addition, chlorination is done at this stage, which prevents growth of the fouling organisms. 2.1.4 PH adjustment Rao & Tyagi (47) describes water as a must have a PH of 7, which is neutral PH level, thus due to presence of the sediments in the raw water, the stored water is either slightly acidic or moderately alkaline. Thus during the purification process soda ash, lime, or sodium hydroxide is added into raw water reservoir in this process. This must be done to stabilize the PH level.

To increase hardness in water lime, which raises the calcium level, must be added in the process. Further, if the water used in the process is acidic, force degasifiers help in raising the PH level of water. This strips the dissolved carbon dioxide from the water. Moreover, making water alkalinic makes the coagulation and flocculation process becomes more efficient, thereby lowering the risk of having lead dissolving from the pipes. Sometimes, water will need addition of the acids that will help to lower the PH level in water.

Making water alkaline does not necessarily guarantee absence of lead and copper dissolving in the system. Further, this improves the calcium carbonate precipitating ability of water towards metal protection thus lowering the possibility of having dissolved metals in water. Therefore, at this stage chemical are mixed water where water hardening and PH adjustment is done. 2.1.5 Coagulation and flocculation Addition of chemicals in water helps in removal of particles by removal of major particle that are suspended in water.

These particles might be silt and clay, which are organic or others that are organic particles such as algae and bacteria. Generally, these particles are the major causes of turbidity in water and water coloration.

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