1. Consider the following data on a MSW sample. Component Percentage by weight (%) Jas-received] Food wastes 15 Moisture content (%) Jas-received] 70 Energy (Btu/lb) Jas-received] 2,000 Paper 40 6 7,200 Cardboard 4 5 7,000 Plastics 3. 2 14,000 Textiles 2 10 7,500 Rubber 0.5 2 10,000 Leather 0.5 10 7,500 Garden trimmings 12 60 2,800 Wood 2 20 8,000 Glass 8 2 60 Tin cans 6 3 300 Nonferrous metals 1 0 Ferrous metals 300 Dirt, ashes, brick, etc. 3,000 a) Estimate the overall moisture content of a sample of solid wastes with the composition given above. b) Determine the energy value (in kJ/kg) of the above MSW sample. Note: 1 Btu/lb -2.326 kJ/kg. c) Using the above data, estimate the number of British thermal units per pound (Btu/lb) of the remaining MSW if 90% of the cardboard and 60% of the paper were recovered by the homeowner. 2. A small community produces 1,850 kg of solid waste every day. The composition of their solid waste is given below. The waste is to be transported to a nearby disposal site at $50 per m². Calculate the annual total cost of this waste management service if the tipping fee of the nearby disposal site is $6.5/100 kg. Component Paper products Plastic Glass Food wastes 4.3 1.7 Percentage by weight (%) 30 Unit Weight (kN/m) 25 25 20 3. The energy contained in a kg of "as received" discarded MSW in the City of Saskville is 12,900 kJ/kg. The MSW has a moisture content of around 20%, and roughly 6% of the dry mass of MSW is hydrogen. Estimate the lower heat value (LHV) in kJ/kg. 4. One way to estimate the energy content of wastes is based on an empirical equation, which utilizes an ultimate analysis of the material in question. Consider the following empirical equation: =339 C+1440 H-1390+105 S Where C, H, O, and S are the mass percentages of carbon, hydrogen, oxygen, and sulphur in dry material. Using the following data, calculate the HHV of the dry waste and the HHV of "as received" waste accounting for the moisture content for each of the following three cases (a, b and c). a. Junk mail b. Mixed garbage c. Tires Moisture (% as received) Dry weight percentages C H 0 S 4.56 37.87 5.41 42.74 0.09 72.0 44.99 6.43 28.76 0.52 1.02 79.1 6.8 5.9 1.5 5. Determine the annualized cost of a large-size collection vehicle ($211,000) amortized over a seven-year period using a 9 percent discount factor. Calculate the total cost of interest. 6. Consider the following residential waste collection system: a) Suppose it takes 20 min to drive from the garage to the beginning of the route, 24 min to drive between the route and disposal site, and 16 min to return from the disposal site to the garage. It takes 12 min to offload a truck at the disposal site. The crew is given two 15-min breaks per day, and another 30 minutes is allowed for unexpected delays. If two runs are made to the disposal site each day, how much time is left in a 8-hour shift for actual refuse collection? b) Suppose the average distance between stops along the route is 80 m, and there are on average 1.8 containers at each stop. Each stop is for an individual household that puts 0.28 m' of refuse at the curb cach week, with density 120 kg/m². How many stops would be made per truckload, and how large should the truck be if it has a compaction ratio of 4.2? c) Estimate the required truck volume if only one run is made to the disposal site each day. 7. How long would it take (in hours) to fill a 25-yd' packer truck that compresses waste to 620 Ib'yd' if it travels 85 ft between stops at an average of 6 mph and it takes I min to load 155 lb of waste at each stop? If each stop services 4 homes and 2 collection runs are made per day, how many household could be provided with bi-weekly service (once for every 2 weeks) by this single truck (assuming a five-day week)? 8. Suppose each household puts out 0.2 m' of waste each week. Packer trucks with a compaction ratio of 3.5 take 24 seconds per household to collect the waste. Two trucks are being considered: a larger truck that makes two trips per day to the disposal site. and a smaller truck that makes three. Trips per day to disposal site Truck volume (m) Annualized truck cost (year) Total time driving, unloading, breaks (min/day) (i.e. Total time excluding t Larger track Smaller truck 15 88,000 215 130,000 160 a. Operating five days per week, with once-per-week pick-up, how many household would each truck service? b. How many hours per day would each truck and crew have to operate to fill the trucks each day? c. With the cost of crew being $42.5 per hour, what is the total annual cost of trucks and crew for each system? Also estimate the annual cost per household. d. As the municipal engineer, which system would you recommend if cost is a key factor?