Thursday, December 12, 2019
Chiefly Disposed From Individual Households-Myassignmenthelp.Com
Question: Discuss About The Chiefly Disposed From Individual Households? Answer: Introducation The following is a concept design of a waste water system designed for Miri, Indonesia. The system is significant to that area because it is specific to the locations altitude which is 5m above the sea level. Being a coastal area, the land is gently sloping. The nearest river is 500m away from the treatment site while the ocean is 5km from the treatment site. In this concept design, a system is needed that can enable the treatment of water gathered from the local area community, treating it into a harmless waste product and further disposing it accounting river as effluent. With a population of 20000 people, the per capita water usage is estimated at 130l per day. This means that large volumes are collected from individuals and as no industrial activity is noted in that area, it is assumed that the disposal water is chiefly disposed from individual households. This means that the waste itself is not toxic but rather domestic, organic waste matter. As such, no complicated mechanism of waste water treatment is necessary and therefore it is recommendable to use large open space purification methods (Hoekstra, 2005). In this design, an analysis is done comparing 3 main types of water treatment in order to obtain the best disposal alternative. These 3 methods of disposal are aerated tank disposal, oxidation and the use of a biofilm filter (Vesilind, 2003). With the population at 20000 people and per capita usage at 130l/c/day, we have an overall water disposal rate of 2600m3 of water per day. However, as there is a conversion of sewage water to water supply of 85% - 95%, 90% will be considered for this case therefore leaving the treatable discharge at 2340m3 per day. Alternatives: Waste water is usually an effluent of a variety of processes ranging from industrial to domestic which have varying degrees of toxicity and pathogen accumulation. It is therefore imperative to identify a model or process which cleans out the specific contaminant targeted to such a level of cleanliness that would be acceptable for direct human consumption. As it stands, a variety of state of the art methods of achieving this exist with varying working principles. This report seeks to single out and carefully analyze three main processes of treatment which utilize aeration, oxidation and biofilms in the relative purification of the waste water (Campbell, 2011). The use of an aeration tank is a purification method that combines both the bacterial decomposition activities and reactions to break down wastes in the waste water into less harmful substances. When the right amount of oxygen is allowed into the water or imposed on it, this provides an optimal environment for aerobic digestion of the pollutants. It is mainly used in municipal and industrial processes where large quantities need to be purified over a short time to the cleanest possible degree. It is a secondary process and is proceeded by purification, disinfection and other water sanitation processes (Oxymem, 2014). This method works by supplying oxygen needed by pre-introduced bacteria in the water so as to provide them with the optimum conditions for the aerobic decomposition of waste water pollutants. The end product of this degradation is usually carbon dioxide and water formed by decaying the organic hydrocarbon compounds. The lack of oxygen in waste water treatment results in slow and incomplete reactions which make the water even harder to treat and in some cases even produce odours. This makes the aeration tank relatively safer than other technologies that limit the amount of getting into the waste water to aid in the breakdown of pollutants. Aeration happens in aeration tanks where nothing, other than air is introduced into the water and is the most effective method for breaking down activated sludge (Pure Water Gazette, n.d.). The main advantages of this method are the relatively cheaper capital and maintenance costs and the less equipment required. It is therefore preferred as a secondary process when treating large volumes of water as this process can happen on an open aeration water basin or in a tank with the air being imposed onto the water. The products of this organic reaction are also relatively safe and do not need to be filtered metals and other chemicals are involved. This also significantly reduces the cost of further treatment practices that the waste water would pass through. Another method of state of art treatment that could be considered is the oxidation ditch. This is a process of molecular breakdown that happens when a compound is introduces to a reducing or oxidizing material. In most cases, the end product of this is usually a precipitate and can be filtered out in subsequent water treatment steps. Oxidation ditches are also used by financial and industrial authorities but are best suited for treating waste water whose state of pollution is chemical in nature. They can therefore be set up in a variety of regions with the best possible regions being those closest to industries (Mohajerani, 2009). This method, while similar in description to the aeration tank method works in a significantly different way. While aeration tank method uses the oxygen pumped into it or regulated into it from the air to provide an optimum environment for bacteria, this method uses the oxygen in the air to directly break down chemical components by reduction and oxidation. The precipitates are relatively clean and further reactions into more toxic compounds are prevented in the tank. It usually works for wastewater with a mixed liquor suspended solid mass falling in between the range of 3000ppm to 4500ppm. This method of treatment can handle flows of up to 3500m3 of water per day with a BOD content of 100ppm to 250ppm (Waste Water System, 2017). This method is advantageous as it produces the cleanest effluent without requiring extensive infrastructural investments. It utilizes rotors that provide for circulation at a slow rate in order to allow for maximum oxygen uptake by the water allowing enough time for precipitates to settle. This provides for a reliable and safe method of particle separation without needing further investment in filtration systems. As such, it would be suitable for any urban center provided the population did not exceed the amount that can be produced within a given time period. It is however slow leading to low treatment rates which means it cannot be applicable to areas with a great demand of clean water (Evoqua, 2017). Another state of art treatment method is the use of a biofilm filtration unit. This is where waste water having been discharged from industries or rivers is channeled into a filtration layer that consists of an organic lining and a filter. This seepage occurs slowly with pollutant substances in the water being trapped by the film leaving the water to flow on in a cleaner state. This method of water purification works well in low demand areas where the number of people using the water does not exceed 8000. It is therefore best suited for either domestic usage or usage in town areas where the number of people to be serviced by the clean water is relatively low (Jiang, 2013). This method works by attaching a layer of organic microorganisms onto the lining of a variety of materials that are applied in the purification stages. This allows the microorganisms to attack the pathogens that would otherwise have been too small to combat using a regular filter therefore leaving relatively clean water to flow out. This method does require part replacement as the filters need to be cleaned then replaced on a regular basis. These are usually replaced after regular intervals as letting a filter run too long without changing it would lead to either blockages or further contamination of the water. The filtration layer could be any permeable membrane or material and can even include granular solids like sand (Jiang, 2013). This method of water filtration is mostly used in rural areas due to its easy assembly and the relatively lower demand population. It is significantly cheaper than most other models of waste water treatment but however, it is very effective for treating the said water. Installation of this biofilm does not require great professional expertise as the other methods and it can be used by individuals for residential water cleaning purposes depending on both the amount of contaminant and the level of cleanliness required. The effluent from this method is fairly clean but in most cases, that may change depending on the level of toxicity or contamination (Jiang, 2013). Reccommendation: The method of breakdown used will be the aeration tanks. This tanks are especially beneficial in such a small community as they are adequate enough to cater for the needs of the residents. It is also cost effective with the development of this waste water treatment system necessitating only to provide and open surface wide enough to allow for aeration with the best possible surface area to volume ratio. Aerated tanks are also fairly easy to operate and need minimal skilled operatives operating the equipment in comparison to the other methods. Aerated tanks would be easier to service and clean for silted material over time in comparison to the other methods. Owing to the fact that it is going to be draining into a river, the necessary steps will have to be put in place to ensure the best possible quality that will not be toxic to anything or anyone using the river. These steps are outlined below. Water from a dirty source will come in as influent and head over to storage at the storage pool. Here, it will be retained briefly so that it can enter the screening zone gradually. This is done intentionally to prevent blockage of the chambers. Screening will then take place with the filtration of waste water taking place to remove the huge particles. From here, water is then redirected to the grit chamber so as to begin the process of settling down the insoluble solids. They are usually separated from the rest and cleared later during chamber cleaning. After the dropping of some particles in the grit chamber, the waste water moves on to the silt chamber where siltation then occurs in order to separate the finer, insoluble particles that were not removed in the earlier. From this point onwards, the process of purification can begin at the primary purifier. From here, it proceeds to the aeration tank for further decomposition through aerobic activity and then to the necessary disinfection using chemical action (Norweco, 2006). Other necessary tertiary treatment such as Phosphate removal, nitrogen removal etc. will be included in the treatment. All this is included to ensure that the water has achieved the desired output of 0.25 the solid concentration. From here, the water is now released as effluent. The sludge on the other hand will be disposed of systematically in a process beginning from the sludge storage pool. Here is where it is stored after extraction from the influent during the primary waste water treatment processes. It is then stored in a sludge thickening tank where its density is significantly increased by reducing the amount of water contained. Owing to the amount of sludge expected, the sludge dewater facility to be used can be rotating discs which will be provided in accordance with the quantity of sludge. After that, anaerobic or aerobic digestion can take place before drying and final disposal in landfill. Equipment, Cost Project Time: There are 4 main aerated tank systems which include package plants, oxidation ditches, surface aerated basins and deep shaft vertical treatment. In this case study, it is recommendable to use the package plant due to the economic aspect of it considering that 20000 people is too minute a figure to develop a large-scale system. The package plant condenses more activities into one allowing there to be little retention time versus the amount of water processed. The equipment used in this water treatment include a pump for pumping the waste water across the course of purification. While a majority of the processes will operate under gravity, a pump is needed to raise the water and even dispose it as effluent. This process also uses a wide variety of tanks, each of which is specialized to its specific purpose. These include the storage pool/tank, the silt chamber, the aeration tank, the disinfecting tank, sludge thickening tank and digestion tanks. A grit chamber will also be constructed between these processes whose main purpose is to slow water down long enough to provide for deposition of solids. Filtration membranes are important too and are available in a variety of sized and shapes to suit various treatment plant dimensions. Other aerating equipment e.g. a blower is necessary to ensure proper aeration. Finally, rotating disks will need to be availed to cater for the dewatering of the sludge in its near solid state. The chemicals needed for disinfection could be either ozone, chlorine dioxide or chlorine. The treatment plant could cost between $250 million to $400 million depending on the preliminary site reports, site conditions and complexity of the design. The running costs would cover replacement of the filters, removal of silt and deposited solids, periodic cleaning of the channels and pipes, power requirements and cost of skilled and unskilled labour. References Centi, G. and Perathoner, S., 2014. Advanced Oxidation Processes in Water Treatment. In Handbook of Advanced Methods and business Processes in Oxidation Catalysis: From Laboratory to Industry (pp. 251-290). Comninellis, C., Kapalka, A., Malato, S., Parsons, S.A., Poulios, I. and Mantzavinos, D., 2008. Advanced oxidation processes for water treatment: advances and trends for RD. Journal of Chemical Technology and Biotechnology, 83(6), pp.769-776. Hoekstra, A.Y. and Hung, P.Q., 2005. Globalisation of water resources: international virtual water flows in relation to crop trade. Global environmental change, 15(1), pp.45-56. Ikehata, K. et al., 2008. Ozonation and Advanced Oxidation Treatment of Emerging Organic Pollutants in Water and Wastewater. Ozone: Science and Engineering 2006 (30): 21-26. Jiang, G. and Yuan, Z., 2013. Synergistic Management of anaerobic wastewater biofilm by free nitrous acid and hydrogen peroxide. Journal of hazardous materials, 250, pp.91-98. Hoekstra, A.Y. and Hung, P.Q., 2005. Globalisation of water resources: international virtual water flows in relation to crop trade. Global environmental change, 15(1), pp.45-56. https://www.worldometers.info/world-population/indonesia-population/ Mohajerani, M., Mehrvar, M. and Ein-Mozaffari, F., 2009. An overview of the integration of advanced oxidation technologies and other processes for water and wastewater treatment. Int J Eng, 3(2), pp.120-46. Poyatos, J.M., Muio, M.M., Almecija, M.C., Torres, J.C., Hontoria, E. and Osorio, F., 2010. Advanced oxidation processes for wastewater treatment: state of the art. Water, Air, and Soil Pollution, 205(1-4), p.187. Radjenovi? et al., 2008. Membrane Bioreactor (MBR) as an Advanced Wastewater Treatment Technology. Handbook Env. Chem. Vol. 5 Part S/2: 37-101. Sheng, G.P., Yu, H.Q. and Li, X.Y., 2010. Extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems: a review. Biotechnology advances, 28(6), pp.882-894. Sheng, Z. and Liu, Y., 2011. Effects of silver nanoparticles on wastewater biofilms. Water research, 45(18), pp.6039-6050. Wang, L.K., Hung, Y.T. and Shammas, N.K. eds., 2005.psychology treatment processes (Vol. 3). Humana Press. Wang, L.K., Ivanov, V., Tay, J.H. and Hung, Y.T. eds., 2010. Environmental biotechnology (Vol. 10). Springer Science Business Media. Wang, L.K. and Pereira, N.C. eds., 1979. Handbook of environmental engineering (Vol. 4). Humana Press. Wang, L.K., Shammas, N.K. and Hung, Y.T. eds., 2010. Advanced biological treatment processes (Vol. 9). Springer Science Business Media. Wang, L.K., Shammas, N.K. and Hung, Y.T., 2007. Biosolids treatment processes. Humana Pr Inc. Wang, L.K., Shammas, N.K., Selke, W.A. and Aulenbach, D.B., 2007. Flotation thickening. Biosolids Treatment Processes, pp.71-100. Vesilind, P. ed., 2003. Wastewater treatment plant design (Vol. 2). IWA publishing.