Chapter 8 solved problems

Transcription

1 Chapter 8 solved problems Given: You are a community activist and believe in recycling. It has been decided to make two categories: the first for paper and cardboard and the second for everything else. You think that you can get 50% of the 458 homes to participate. You have actually counted the residents and there are 1338 of them. You have made a mini-survey of the paper wastes such as wrappers, packaging and determined that newspapers are about 1/3 of the total paper; the rest you hope will be separated to the tune of 75%. Find: The big meeting is Tuesday night and the neighbors want some hard numbers on how you are going to accomplish the recycling. 1. Computation table to calculate volumes. Component Total Solid Wastes, lb (T3-7,p.52) Waste Materials Separated, lb (col. 2x75%) Specific Weight, lb/yd 3 (T4-1, p.70) Volume, yd 3 (col. 3/4) Organic Food wastes 8.0 not-recycled 490 Paper 35.8x1/ Cardboard Plastics Textiles 1.8 not-recycled 110 Rubber 0.4 not-recycled 220 Leather 0.4 not-recycled 270 Garden 17.3 not-recycled 170 Wood 1.8 not-recycled 400 Inorganic Glass Tin cans Aluminum Other metal 3.0 not-recycled 540 Dirt Ashes, etc. 2.7 not-recycled 810 Total Determine the relative volumes newspaper + cardboard = newspaper + cardboard =.1158yd3 others, plastics, glass, tin cans, aluminum = others, plastics, glass, tin cans, aluminum =.1161 Note: =.2319,OK The relative volume is useful for calculating the relative size of the bins..1158/.2319= /.2319=.50 In this case, the split is 50/50 which is ideal. The meaning is the collection containers would be of equal size.

2 3. Determine a pickup scenario Assume: 3.82 lb/cap.day, T6-3,p residents x 3.82 lb/cap.day x.50(participation rate) = 2556lbs/day vol. of news and cb = 2556lbs/day x.1158yd 3 /100lbs vol. of news and cb = 2.96yd 3 /day vol. of others = 2556lbs/day x.1161yd3/100lbs vol. of others = 2.97yd 3 /day Possibilities: You are getting about 3x7days/week=21 yards/week yard trucks that each operate the route: one trip for each truck, once/week 2. 2-bifurcated trucks that collect both materials at one time, the route is traveled once/week. 4. The next step should be of primary interest: Cost Analysis What are the revenues earned: - Earnings from recycled materials - Costs avoided by not paying for the materials being landfilled vs. Costs - Equipment - Labor Ancillary issues - Meeting AB939 - Do the right thing because you believe it. Given: A new sub-division with a single, central park serves about 500 homes. The average occupancy is 2.8 cap/residence. Find: The director of public works wants to know if he can service the park, once per week collection with a single hoist truck. T6-3, p.138: "Parks and recreational areas".12lbs/cap.day T4-1, p.70: assume rubbish, 220 lbs/yd 3 T8-3, p.205: 6-12yd 3 capacity for a hoist truck 1. weight of park material weight = 500 residences x 2.8 cap /residence x.12lbs/cap.day x 7 days/week weight = 1176 lbs/week 2. Volume of park material volume = 1176 lbs/week / 220 lbs/yd 3 volume = 5.3 lbs/yd 3 vs yd 3 capacity Therefore, a hoist system can be used.

3 example Given: A stationary container system (mechanically loaded), 3.5 collection trips/wk, 8hrs/day, 3.22 h/trip (pick up time), at site time.1h/trip, round trip = 10miles, a=.018 h/trip. b=.020h/trip, productive time = 85% Note: Even though a partial trip (3.5 collection trips), a full trip (4) will have to be made to the disposal area. Find: Time required per week But we Know ; He need the >>> days/week =? Nw = [ H ( 1 w ) / Tscs ] * Tw Tw; is Conversion factor to day / week T w = 1.84 days/week Given: A stationary container system costs $.037/ton.minute. A transfer station costs $.023/ton.minute + $2.03/ton. Find: The round trip haul trip at which a transfer station becomes economical. 1. Analytical.037X =.023X X = 145 minutes, time must be 145 minutes 2. Graphical SC Cost ($/ton) TS 145 minutes Time (minutes)

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5 Islamic University of Gaza Solid Waste Management EENV4312 First Semester ( ) Quiz 1 Instructors: Dr. Ahmed Abu Foul Eng. Taher Abu Nama Allowable Time 15 Min. Closed Book Student Name: Student No.: The amount of solid waste generated per day in a resedential area ia a bout 300 yd 3. There are 8 yd 3 containers size at the rear of every house. The collection vehicle capacity is 30 yd 3 /trip. Determine the time required per trip; number of trips required per day and the length of workday. Assume that the disposal site is located 15 mi away; haul-time constants a and b are h/trip and h/min, respectively; container utilization factor is 0.625; compaction ratio is 2; container unlaoding time is 0.05 hr/cont.; at site time is 0.10 h/trip; avg. time spent driving between cont. locations is 0.01 h/location; avg. time to drive from the garage to the first container location and from the last container location to the garage each day are 15 and 20 min, respectively; offroute factor is equal to 0.15; number of containers pickup locations per trip is 12. Useful formulas table: Thcs= Phcs + s + (a + bx) Phcs= pc + uc + dbc Tscs= Pscs + s + (a + bx) Pscs= (ct)*(uc) + (np - 1)*(dbc)