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researching in seperating biodegradeble materials
1 RESEARCHING IN SEPERATING BIODEGRADABLE MATERIALS FROM MUNICIPAL SOLID WASTE BY HYDRAULIC POWER. Dinh Trieu Vuong and Vo Dinh Long Dinh Trieu Vuong is with Engineer of Environmental engineering. Email: trieuvuong16488@gmail.com Vo Dinh Long is with the Director of the Center for Environmental Resources Research, Ho Chi Minh University of Industry Email: vodinhlong@hui.edu.vn. Abstract: Municipal Solid Waste (MSW) consists of a myriad of discards from households, businesses, and institutions managed in common. Thus MSW is extremely heterogeneous, seasonally variable, and differing in composition even among different collection routes within a given municipality. The organic and inorganic fractions consist in MSW very dissimilar problems, yet are received as a mixture in a single waste stream. It is not difficult to see that the most biodegradable materials’ density is higher than the water’s one and the most recyclable materials’ density is lower than the water’s one. So, we can use water to separate MSW. To use water in separating MSW, we need establish required data: flow rate, stuff rate, belt position, capacity and water volume per one ton MSW. The researching results show that when we put MSW into water, MSW is separated to 3 part: - The heavy components that sunk to the bottom and were subsequently separated from the organic stream include ferrous metals, non-ferrous metals, glass and other inert materials. - The biodegradable materials suspend in water. - The light waste such as nylon bags, plastic bottles float on water surface. Besides, calculating also shows that extra advantages of this method about economic value, efficiency and environmental value. Keywords: Seperating MSW by hydraulic power, biodegradable materials, Municipal Solid Waste. 2 1. Introduction Growing of scientific and technical help human’s quality life enhanced. Thus, population is increasingly incremental, leading to increase the amount of Municipal Solid Waste (MSW). Besides that is exhausting the reserve of natural resouces, especialy is non-renewable resources as petroleum, coal . If this continues to happen in the future, people will no longer use mineral and the earth will be filled with waste. Therefore, in a few decades ago, many parts of the world were intrested in re- ultilization of waste, especially is MSW with many component can utilize as plastic, metal, glass, organic matter . Recycling or reusing MSW help reduce production costs for manufacturing companies, increase income for waste treatment companies and reduce pressure on natural resources is getting exhausted. The most important stage in the full technology utilization of solid waste is the seperation. In the past, the seperation is mainly done by hand. Nowadays, many technology automatically are used, for example riddle, magnetic field, wind To be able to apply these technologies, MSW must be removed biodegradable materials to reduce the MSW’s moister. In many countris around the world, applying these technologies is quite easy because MSW is serperated at source by people. However, in the other countries, as Viet Nam, MSW isn’t seperated at source, so applying these technology is difficult. Although, some waste treatment companies use labor to seperate MSW, this doesn’t bring economic benefits, so many companies don’t apply . Therefore, researching to create a device which can seperate biodegrades materials from MSW will contribute solving that problem. Since then, many waste treatment companies at Viet Nam as well as other countries on the world can apply in the full technology utilization of MSW. This brings many benefits in economics, social and especially environment. 2. Theoritical basis The density of different MSWs is different. We determined some components of MSW. The biodegradable materials’ density is about 1050 kg/m 3 and the nylon bags’ density is about 160 kg/m 3 . This show that, we can separate MSW depend on their density difference. We used water as an agent to separate MSW. When we put MSW into the uninterrupted flow, MSW is separated to 3 parts: 3 - Part 1 – The part floats on the water surface: include mainly components may be recycled for example plastic bottle, nylon bags… - Part 2 – The part suspends in the water which include biodegradable materials for example surplus foods, papers, garden wastes… - Part 3 – The part sunk to the bottom which include heavy components for example sand, stone, metal pieces, glass… 3. Experiments and Results. We have conducted experiments as the diagram in Figure 1. Figure 1: The research propress. Invest components and properties of MSW Build Laboratory scale model Operate the model to discover parameters Flow rate Input speed Water cycle change Data processing by Excel, Stat Graphics software Belt placement Basic parameters to build the system 4 Structures of the model are shown in Figure 2. Figure 2: The structure of the seperating biodegradable materials from municipal solid waste by hydraulic power model. The structure of the modle has three mainly parts: - The water tank: to separate the biodegradable material: this tank made of glass, so we can see its inside. Its size include length x width x height is 2 x 0,9 x 0,3 m. Suppling ion to tank is carried out by a pump 1Hp. The water is distributed by eight ejector. Every ejector’s diameter is 21mm. The water is circulated reapeatly. - The belt: there are 3 belts built up in the tank: one belt is used to collect the part float on the water surface, one belt is used to collect the suspended part and the other one is used to collect the sunked part. - The input system: include a rotary drum to drown MSW and a loading bin. That drum is assembled on the water surface and the bin is assembled on the drum. - The bracket: to carry the tank and the other things assembled in that. Experimental determination of flow rate 5 Figure 3: Chart of effective separation depend on flow rate. Depending that chart, inferred flow rate is effective from 0,12 (m/s). We selected 0,2 (m/s) for follow experiments Through above experiment we also draw a conclusion: effective classification doesn’t depend on the flow rate, but depend on property flow, which have to be laminar flow. The flow rate affects only the yield separation. Experimental determination of input speed Input speed, which is the weight of MSW input per once, affect directly effective system separation. If we put a lot of MSW into the water, MSW’s components will mix, therefore effective separation of biodegradable materials will low because the first belt will collect them before they can arrive to the second belt. Effectiveness (%) Flow rate(m/s) 6 Figure 4: Chart of effective separation depend on input speed. The input speed is most effective ≤ 1 (kg/once). We selected 0,5 (kg/once) for follow experiments. Through experiment, we saw that the time from dropping 0,5 kg MSW into the tank to meet the first belt is about 3 seconds. So, if the input speed is 0,5 kg/once and the flow rate is 0,2 (m/s), the system capacity is 600 kg/h. Experimental determination of belt placement MSW’s component have different properties will be located at different layers in the system separation. Therefore, the belts’ placement also affects the effective separation of system. The position of belt should be located at the boundary of this layer so that the effective separation wills height. Through two above experiments, we determined the position of the belt: - The first belt is located 10 - 15 cm from the edge of the collected basket to the water surface and 20 – 30 cm to rotary drum. - The second belt is located 20 cm from the edge of the collected basket to the bottom tank and 50 cm to the edge of the front collected basket Experimental determination of water cycle change Water cycle change is determinated through determinating the parameters indicating the levels of water pollution in order to treat water easily. Table 1: Change water quality entering the amount of MSW Input speed (kg/once) Effectiveness (%) 7 MSW’s Weigh(kg) TSS(mg/L) COD(mgO 2 /L) P-PO 4 (mg/L) N-NH 3 (mg/L) 500 1963,69 1033,77 29,2871 848,887 1000 3701,13 1440,35 58,5734 120,035 1500 5404,57 1752,33 87,8599 147,006 2000 7090,4 2015,34 117,146 169,744 2500 8764,99 2247,06 146,433 189,778 MSW always includes sand or soil. When MSW inputted water, heavy sands will sunk, light sands will suspend. Besides, biodegradable materials, which are degrading, will dissolve. These factors make total suspended solid in the water higher , obstructing flow. The height total suspended solid also erode equipment, especially the tank. Besides, if the total suspended solid is too high, they will stick more to MSW. So, we have to build a washing building follow. Changing water depends on total suspended solid than factors of organic pollution or nutrient. The table 3 show that with 250 (Liter), we will change water when MSW’s weigh is about 1 ton or 4 ton MSW/1m 3 water. Because total suspended solid is not too high and flow rate is 0,2 m/s, a part of solid will settle. Figure 3: Summary of design parameters and operating model. Number Parameter Unit Value 1 Flow rate m/s 0,2 2 Input speed Kg/once 0,5 – 1 3 The position of first belt from water surface m 10 – 15 4 The position of second belt from bottom tank m 20 5 The position of first belt from rotary drum m 20 – 30 6 The position of second belt from first belt. m 50 7 MSW’s weigh/ water in use Ton MSW/ 1m 3 4 8 water 8 Capacity Tấn/h 0,6 4. Conclusion In the course of the experiment, only the biodegradable material begin biodegrading can suspended and the effective separation will high. If the biodegradable material is emitted newly, the effective separation will low. We should use MWS emitted after 24 hour to separate by this system. The effective separation isnot high for biodegradable material. However, low efficiency does not mean that this method is not feasible, but due to some reasons: - Designing model is not suitable in terms of hydraulic. - The belt unstable operation. The discovered parameters were acceptable because the factors causing low efficiency and separation may be considered as independent parameters need to find. If we apply this technology in practice will be very suitable for treatment of MSW toward zero emission. This helps resolve an important step in this method is separating MSW, which previously difficult to apply in Vietnam as well as many parts of the world, where MSW activities not classified at source. 9 REFERENCES 1. George Tchobanoglous, Hilary Theisen, Samuel A. Vigil, Intergrated Solid Waste Management, McGraw Hill International Editions, Civil Engineering Series, 2002. 2. Le Huy Ba, Scientific Methods, 2nd Edition, HCMC National University Publisher, 2006. 3. Lenore S.Clesceri,Arnold E.Greeberg, Andrew D. Eaton, Standard Methodsfor the Examination of water and wastewater, 20th Edition, American Public Health Association, American Water Works Association, Water Environment Federation, 1999.