Determination of properties and elemental composition of municipal solid waste in order to proposal of waste-To-energy project in Binh Duong province - Phung Chi Sy

Journal of Science and Technology 54 (2A) (2016) 56-63 DETERMINATION OF PROPERTIES AND ELEMENTAL COMPOSITION OF MUNICIPAL SOLID WASTE IN ORDER TO PROPOSAL OF WASTE-TO-ENERGY PROJECT IN BINH DUONG PROVINCE Phung Chi Sy 1, * , Nguyen Thanh Tuyen 2 , Nguyen Thi Lien 2 1 Environmental Technology Center (ENTEC), 463 Phan Van Tri Street, Go Vap District, Hochiminh city, Vietnam 2 Thu Dau Mot University, No 6 Tran Van On street, Phu Hoa ward, Thu Dau Mot city, Binh Duong province, Vietnam * Email: entecvn@yahoo.com Received: 1 April 2016; Accepted for publication: 15 June 2016 ABSTRACT Domestic solid wastes are classified into 10 samples of 04 groups with different sizes: 2 samples with sizes under and over 120 mm (M1-1, M1-2); 2 samples with sizes under and over 80 mm (M2-1, M2-2); 2 samples with sizes under and over 40 mm (M3-1, M3-2); 4 samples with sizes under 40 mm, 40 to 80 mm, 80 to 120 mm and over 120 mm (M4-1, M4-2, M4-3, M4-4). Results of sorting 10 solid waste samples into food, cloth, wood, plastic, paper, rubber/leather, metal, glass, other organic and inorganic components shown that recycled combustible, non-recycled combustible portions are ranged from 15,46 to 93,90 %, from 5,34 to 80,17 %, respectively. The density of 10 compressed garbage samples is ranged from 525,9 to 2016,7 kg/m 3 ; moisture contents are ranged from 18.03 to 20.92 %. Ash content is ranged from 1.12 to 9.49 % dry weight; Calorific value is ranged from 3164,9 to 5757,0 kcal/kg of garbage. The volume of leached water from 10 kg wet garbage pressed by 250 kg load in 2 days is 300 ml (equivalent to 327,1 g). Results of elemental composition analysis shown that the contents of C, H, N, Cl, S are ranged from 35,00 to 51,96, from 6,01 to 6,23, from 0,41 to 0,88, from 0,44 to 0,56, from 0,14 to 0,84 %, respectively. On this basis, the author have proposed a waste-to- energy plant with capacity of 250 tons of waste/day to generate the electricity with capacity of 17,0 MW/day. Keywords: Solid wastes, classification, elemental composition, waste to energy 1. INTRODUCTION Every day, about 1,000 tons of municipal and industrial solid waste, non-hazardous waste are dumped in Binh Duong province. Currently, the management of solid waste in urban and industrial areas of Binh Dương is still weak. According to [1], in 2015, the average rate of solid waste collection and treatment is 90 % and mainly concentrated in urban areas. The collection and transportation of solid waste in Binh Duong province are realized by 65 organizations and Determination of properties and elemental composition 57 individuals. Currently, majority of non-hazardous solid waste originated from Thu Dau Mot, Di An, Thuan An towns etc. are collected, transported and treated in the Binh Duong South Waste Treatment Complex with volume about 620 ton/day [2]. The project on solid waste sampling and analysis was implemented in the Binh Duong South Waste Treatment Complex from December 2013 to January 2014 in framework of contract between Environmental Technology Centre (ENTEC) and JFE Engineering Corporation (Japan) in order to propose a waste-to-energy plant in Binh Duong province [3]. 2. MATERIAL AND METHODS 2.1. Sorting and sampling methods 2.1.1. Sampling steps Step 1: Approximate 110 kg of fresh municipal waste was collected from 3 random positions at the offloading point of the garbage truck, which is mixed to create a uniform sample. Step 2: After mixing, the sample was deviced into 5 smaller portions, including 4 portions (samples M1, M2, M3, M4) with weight of about 25 kg per each and about 10 kg for the portion (sample M5), which were stored and preserved in the assigned foam storage boxes for experimental analysis and measurement of the leachate volume. 2.1.2. Wastes sorting Domestic solid wastes are classified into 10 samples of 04 groups with different sizes: 2 samples with sizes under and over 120 mm (M1-1, M1-2); 2 samples with sizes under and over 80 mm (M2-1, M2-2); 2 samples with sizes under and over 40 mm (M3-1, M3-2); 4 samples with sizes under 40 mm, 40 to under 80 mm, 80 to 120 mm and over 120 mm (M4-1, M4-2, M4-3, M4-4). The samples from M1-1 to M4-4 and M5 were stored in sealed plastic bags, labelled and placed in foam box for storage. 2.2. Laboratory analysis methods 2.2.1. Method of determination of bulk density and physical components of fresh garbage Bulk density of the solid waste was determined for 10 samples from M1-1 to M4-4 by compressing in the cylindrical tube with the radius (R) of 0,08 m under a pressure of 0,4 kg/cm 2 . Density was calculated by the ratio of the weight and volume of the garbage after compression. The volume of the compressed garbage is V= Sxh, where h is the height of the compressed garbage in the cylindrical tube (m), S is the base area of the cylindrical tube. Which is calculated as follows: S = πR2 = 3.14 × (0.08)2 = 0,02 (m2) Physical components of fresh garbage were determined for 10 samples from M1-1 to M4-4, including food, paper, plastic, fabric, wood, rubber/leather, metal, glass, other (shredded organic material and other inorganic debris such as rocks, clay brick etc.). After manual sorting the components of the fresh garbage were weighted individually on electronic scales (± 0.01 g). 2.2.2. Method of determination of moisture contents Moisture contents of fresh garbage were determined for 10 samples from M1-1 to M4-4 by the difference of weight before and after drying at a temperature of 105 o C in about 4-5 days to Phung Chi Sy et al. 58 constant weight. For samples M1-1. M1-2, the moisture contents were determined for each physical component, while for samples from M2-1 to M4-4, the moisture contents were determined for the mixed samples. 2.2.3. Preparation of samples for determination of the ash content, calorific value, element components The ash contents and calorific value were determined for 6 samples from M1-1 to M3-2, while the element components were analysed only for samples M1-1 and M1-2. For the purpose, all components of 6 samples were mixed each with others to get the composite samples, which were sorted to remove the non-combustible components. The remained combustible components were cut into size of 2 cm × 2 cm, then crashed to the size of 2 - 3 mm by using grinder with 28.000 rounds per minute, dried at 105 0 C for 2- 3 hours, then put into Desiccator to absorb the moisture. Procedure for determination of ash contents is as follows: (1). Weighting 5 g of each sample from M1-1 to M3-2 and putting in the heat-resistant ceramic cups with lids. Both cups with and without solid waste were numbered, weighed and volumes recorded, (2). Putting the samples into the furnace and incinerate at temperature of 800 o C for 3 hours, (3). Cooling the ash in furnace, drying it at a temperature of 105 o C for about 2-3 hours, (4).Weighting immediately the ash sample after cooling and drying. For determination of calorific value, six samples of 1 g from M1-1 to M3-2 were weighted, then sent to Petroleum Technology Laboratory, Ho Chi Minh University of Technology for determination of the calorific value by the Bomb colorimeter. For analysis of element components, 2 samples M1-1, M1-2 of 10 g were weighted, then sent to Environmental Quality Laboratory, Institute of Environmental Technology belong Vietnam Academy of Science and Technology (VAST) and Center of Standards Measurement and Quality Technology of Binh Thuan Province for analysis of the element components, including carbon, hydrogen, nitrogen, chlorine, sulphur and oxygen by the Automatic Element Analyser. 2.2.4. Method of determination of the leachate volume Procedure for determination of the leachate volume is as follows : (1). Putting the vessel to collect the leachate drain in a flat and steady surface, (2). Putting the solid waste sieve with diameter of d = 40 mm over bearings, (3). Putting the existing stainless steel mesh in the bottom of garbage sieve, (4). Spreading 10 kg of sample M5 on the net, (5). Spreading a plastic layer onto garbage surface, (6). Spreading a large plastic sheet of 2 m x 2 m on top, (7). Putting a hard surface to spread the load equally over the whole garbage surface, (8). Putting a load of 0.06 kg/cm 2 (with heavy water cans with total weight of 250 kg), (9). Pull-down the plastic cover leachate tray and skills required, (10). Keeping the compact force over the sample for 2 days (48 hours), (11). Measuring the volume of leachate (ml). 3. RESULTS AND DISCUSSION 3.1. Results of solid waste sorting, determination of bulk density and ash content Results of solid wastes sorting, determination of bulk density and ash content are presented in Table 1. Determination of properties and elemental composition 59 Table 1. Results of solid wastes sorting, determination of bulk density and ash content. Item Symbol of samples M1-1 M1-2 M2-1 M2-2 M3-1 M3-2 M4-1 M4-2 M4-3 M4-4 Weight (kg) 6.1 19.2 12.1 13.1 16.9 7.0 7.5 5.1 5.3 6.9 Volume (m 3 ) 0.0116 0.0180 0.0060 0.0134 0.0216 0.0054 0.0140 0.0062 0.0056 0.0064 Density (kg/m 3 ) 525.9 1,066.7 2,016.7 977.6 782.4 1296.3 535.7 822.6 946.4 1078.1 Ash content (% of dry weight) 7.66 5.80 3.70 1.34 9.11 1.12 9.49 3.98 7.66 5.80 The bulk density and ash content of 10 garbage samples are ranged from 525,9 to 2016,7 kg/m 3 and 1.12 to 9.49 % dry weight, respectively. The average ash content of 5 samples is 5.87%. The results of determination of bulk density and ash content will be used for technological calculation and design of the waste-to-energy plant. 3.2. Results of determination of the sample's physical components Results of determination of the sample's components are presented in Table 2. Table 2. Results of determination of the sample's components. Item Symbol of samples M1-1 M1-2 M2-1 M2-2 M3-1 M3-2 M4-1 M4-2 M4-3 M4-4 Food 5.18 4.83 6.67 3.90 0.00 2.33 0.00 0.00 0.00 1.46 Textile 31.43 4.71 15.01 0.47 13.46 0.00 0.85 4.25 3.23 0.00 Wood 21.82 19.42 20.85 15.06 19.83 7.29 21.47 10.85 14.11 13.40 Plastic 27.36 18.96 31.86 14.04 26.44 2.92 62.15 46.79 20.16 2.91 Paper 8.14 11.26 11.26 13.65 18.63 2.92 9.89 16.59 14.11 1.46 Rubber/ Leather 0.00 0.00 1.84 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Metal 0.00 1.15 0.50 0.62 0.00 0.00 0.00 0.00 0.00 1.17 Glass 0.00 0.46 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Other organic component 5.34 37.82 10.00 45.25 20.44 80.17 5.65 21.52 36.29 75.96 Other inorganic component 0.74 1.38 2.00 7.01 1.20 4.37 0.00 0.00 12.11 3.64 Phung Chi Sy et al. 60 Results of sorting 10 solid waste samples into food, cloth, wood, plastic, paper, rubber/leather, metal, glass, other organic and inorganic components shown that recycled combustible, non-recycled combustible portions are ranged from 15.46 to 93.9%, from 5.34 to 80,17 %, respectively. The results of determination of recycled combustible portions will be used for heat balance calculation and estimation of electricity generation capacity of the waste- to-energy plant. 3.3. Results of determination of moisture contents Results of determination of moisture contents of 8 samples are presented in Tables 3. Table 3. Results of determination of moisture contents of samples from M2-1 to M4-4. Item Symbol of samples M2-1 M2-2 M3-1 M3-2 M4-1 M4-2 M4-3 M4-4 Original weight (g) 12.1 13.1 16.9 7.0 7.5 5.1 5.3 6.9 Dry weight (g) 10.1 10.5 14.3 4.6 5.2 4.8 4.5 5.5 Moisture contents (%) 16.45 19.85 15.38 34.29 30.67 5.88 15.09 20.29 Average moisture of each sample (%) 18.21 20.92 20.63 18.03 Average moisture of 03 samples (%) 19.45 Analysis results shown that moisture contents were ranged from 18.03 to 20.92 %. The results of determination of moisture will be used for calculation of air emissions volume and concentrations generated from the waste-to-energy plant. 3.4. Results of determination of element components Table 4. Results of element components analysis of samples M1-1, M1-2. Element M1-1 (%) M1-2 (%) First Time Second time Third Time Fourth time Average rate First time Second time Third time Fourth time Fifth time Average rate Analyzed by Center of Standards Measurement and Quality Technology of Binh Thuan Province C 52.40 53.40 51.30 47.40 51.13 47.10 54.70 50.70 56.10 51.20 51.96 H 6.51 6.04 5.83 6.54 6.23 5.96 6.60 5.93 6.40 5.14 6.01 N 0.29 0.41 0.45 0.77 0.48 0.60 0.34 0.46 0.17 0.46 0.41 S 0.17 0.13 0.15 0.12 0.14 0.20 0.14 0.17 0.15 0.14 0.16 Analyzed by Environmental Quality Laboratory C 36.10 35.80 - - 35.95 34.00 36.00 - - - 35.00 N 0.78 0.67 - - 0.72 0.76 0.10 - - - 0.88 Cl 0.67 0.45 - - 0.56 0.47 0.41 - - - 0.44 S 1.16 0.51 - - 0.84 0.48 0.72 - - - 0.60 Determination of properties and elemental composition 61 Results of determination of element components of samples M1-1, M1-2 analyzed by Center of Standards Measurement and Quality Technology of Binh Thuan Province and Environmental Quality Laboratory belong VAST and are presented in Table 4. Results of elemental composition analysis in Table 6 shown that the contents of C, H, N, Cl, S are ranged from 35,00 to 51,96, from 6,01 to 6,23, from 0,41 to 0,88, from 0,44 to 0,56, from 0,14 to 0,84 %, respectively. The average elemental composition of solid waste is presented in Table 5. Table 5. The average elemental composition of solid waste. Elemental components Carbon (C) (%) Hydrogen (H) (%) Oxygen (O) (%) Nitrogen (N) (%) Sulfur (S) (%) Ash (A) (%) Moisture (W) (%) Solid waste 47.7 6.12 20.04 0.53 0.29 5.87 19.45 The content of oxygen component can estimated based on the equation (C + H + N + O + S + A + W = 100 %) analyzed results of C, H, N, S, A, W presented in tables 1-5. The results of determination of element components will be used for calculation of air emissions volume and concentrations generated from the waste-to-energy plant. 3.5. Results of determination of the leachate volume Before executing cutwater test, the 40 mm screen, the net and solid waste were weighted. The results were obtained as follows: (1). Weight of the screen 40 mm and the net without solid waste sample (M5) is 18,6 kg, (2). Weight of the screen 40 mm and the net with humid solid waste sample (M5) is 28,8 kg. After putting a load of 0,06 kg/cm 2 (with heavy water cans with total weight of 250 kg) on the 10,2 kg humid garbage sample, the leachate collected for 2 days is 300 ml, equivalent to 327,1 g. It means that the leachate from one ton of fresh garbage is about 30 litters (or 32,71 kg). The results of determination of the leachate volume will be used for calculation of waste water volume and concentrations generated from the waste-to-energy plant. 3.6. Results of determination of calorific value The results of determination of average calorific values are presented in Table 6. Table 6. The results of determination of average calorific values. Item Symbol of samples M1 M2 M3 M1-1 M1-2 M2-1 M2-2 M3-1 M3-2 Calorific value of classified sample (KCal/kg) 4455.6 4743.2 5757.0 3940.9 4677.0 3164.9 Weight of classified sample (kg) 6.1 19.2 12.1 13.1 16.9 7.0 Weight of each sample (kg) 25.3 25.2 23.9 Calorific value of each sample (KCal/kg) 4,673.8 4,812.9 4,234.1 Average calorific value of 3 samples (KCal/kg) 4,573.6 Phung Chi Sy et al. 62 The average calorific value of 3 samples is 4,573.6 kcal/kg of garbage. The heat obtained from solid waste combustion can be estimated also based on the Mendeleev empirical formula: Qsw = 81C +300H - 26(O - S) - 6W (kcal/kg) where C, H, O, S, A, W are weight percentage of carbon, hydrogen, oxygen, sulfur, ash and moisture contents in the solid waste sample. The calculated result is as follows : Qsw = 81x47.7 +300x6.12 - 26x(20.04-0.29) - 6x19.45 = 3,863.7 + 1,836.0 -513.5-116,7= 5,069.5 kcal/kg. The results of determination of calorific value will be used for heat balance calculation and estimation of electricity generation capacity of the waste-to-energy plant. 3.7. Proposal of waste-to-energy project The obtained results are suitable for heat recovery, therefore, a waste-to-energy plant has been proposed for Binh Duong province [4]. The proposed capacity of solid waste combustion is about 250 tons/day, which is mixture of domestic, industrial and hazardous solid wastes with the weight ratio of 15: 10: 12, respectively. The average calorific value of the solid waste mixture is 4573,6 kcal/kg, which is equivalent to 19,144.4 kJ/kg. The energy obtained from solid waste combustion is 250,000 kg/day × 19,144.4 kJ/kg = 4,786,100,000 kJ/day =4.79 MJ/day. The power generation potential is 4.79 MJ/day: 84,600 s/day ≈ 56,6MW. If the efficiency of the power generation is about 30 %, the capacity will be 17,0 MW. 4. CONCLUSIONS Domestic solid wastes were classified by screening through suitable diameters sieves into 10 samples of 04 groups with different sizes: 2 samples with sizes under and over 120 mm (M1- 1, M1-2); 2 samples with sizes under and over 80 mm (M2-1, M2-2); 2 samples with sizes under and over 40 mm (M3-1, M3-2); 4 samples with sizes under 40 mm, 40 to 80 mm, 80 to 120 mm and over 120 mm (M4-1, M4-2, M4-3, M4-4). Results of sorting 10 solid waste samples into food, cloth, wood, plastic, paper, rubber/leather, metal, glass, other organic and inorganic components shown that recycled combustible, non-recycled combustible portions are ranged from 15,46 to 93,9 %, from 5,34 to 80,17 %, respectively. The bulk density of 10 garbage samples was determined by compressing in the cylindrical tube, which was ranged from 525,9 to 2016,7 kg/m 3 . Analysis results shown that moisture contents were ranged from 18.03 to 20.92 %.; Ash content was ranged from 1.12 to 9.49 % dry weight; Calorific value is ranged from 3164,9 to 5757,0 kcal/kg of garbage. The volume of leached water from 10 kg wet garbage pressed by 250 kg load in 2 days is 300 ml (equivalent to 327,1 g). Results of elemental composition analysis shown that the contents of C, H, N, Cl, S are ranged from 35,00 to 51,96, from 6,01 to 6,23, from 0,41 to 0,88, from 0,44 to 0,56, from 0,14 to 0,84 %, respectively. The obtained results are suitable for heat recovery, therefore, the author have proposed a waste-to-energy plant with capacity of 250 tons of waste to generate the electricity with capacity of 17,0 MW/day. Determination of properties and elemental composition 63 Acknowledgements. The research was thanked to the helps and support from JFE Engineering Corporation (Japan) and Binh Duong Water Supply and Environment One-member Limited Company. REFERENCES 1. 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