Solid Waste Generation ENVE 521 WASTE GENERATION RATES

Solid &Waste Generation ENVE 521

WASTE GENERATION RATES Generation rates of MSW v. The reason for measuring generation rates is to obtain data that can be used to determine the total amount of wastes to be managed. v. Due to different methods of measurement, the solid waste generation rate has caused considerable confusion. 2

WASTE GENERATION RATES Measure of quantities *Quantities of volume Both volume and weight are used for the measurement of solid waste quantities, unfortunately the use of volume can be extremely misleading. õ A cubic meter of loose wastes, õ A cubic meter of Compacted in a packer truck, õ A cubic meter of further compacted in a landfill 3

WASTE GENERATION RATES *Quantities of weight To avoid confusion, solid waste quantities should be expressed in terms of weight. Weight can be measured directly regardless of compaction. The use of weight records is also important in the transport of solid waste because the quantity which can be hauled usually is restricted by highway weight limits rather than by volume. 4

WASTE GENERATION RATES Statistical analysis of generation rates õ In developing solid waste management system, it is necessary to determine the statistical characteristics of solid waste generation õ For many large industrial activities, the container capacity to be provided must be based on a statistical analysis of the generation rates and characteristics of the collection system. 5

WASTE GENERATION RATES õ The statistical measures should consider the mean, mode, median, standard deviation and coefficient of variation. Expression unit for generation rates *Residential kg/c/d ----kilogram per capita per day Typical per capita solid waste generation rates in. 6

WASTE GENERATION RATES *Includes residential and commercial *Commercial kg/c/d ------ kg per automobile for assembly plant or per case for a packaging plant 7

WASTE GENERATION RATES Repeatable measure of production Typical commercial and industrial unit waste generation rates 8

WASTE GENERATION RATES MSW predicting Methods In case of predicting residential waste generation rates, the measured rates seldom reflect the true rate because there are so many confounding factors such as: õon-site storage õthe use of alternative disposal locations 9

WASTE GENERATION RATES Therefore, the true rate is difficult to assess. Most solid waste generation rates reported in the literature actually collection rates and not generation rates. Direct measurement * Load-count analysis The number of individual loads and the corresponding vehicle characteristics are noted over a specified time period. 10

WASTE GENERATION RATES Example: Estimation of Unit Solid Waste Generation Rates for a Residential Area From the following date estimate the unit waste generation rate for a residential area consisting of approximately 1, 000 homes. The observation location is a local transfer station, and the observation period is 1 week. 11

WASTE GENERATION RATES (1) Number of compactor truck loads = 10 (2) Average size of compactor truck = 15. 3 m 3 (3) Number of flatbed loads = 10 (4) Average flatbed volume = 1. 15 m 3 (5) Number of loads from individual residents private cars & truck = 20 (6) Estimated volume per domestic vehicle = 0. 23 m 3 12

WASTE GENERATION RATES Solution 1. Set up the computation table 13

WASTE GENERATION RATES 2. Estimate the unit waste generation rate based on the assumption that each household is comprised of 3. 5 people. 33116 kg/wk Unit rate = ----------- = 1. 35 kg/capita/day (1000 x 3. 5)(7 days/wk) 14

WASTE GENERATION RATES Materials Mass Balance Analysis: d. M/dt = ∑Min - ∑MOut + rw Rate of accumulation of material within the system boundary Rate of flow of material = into the system boundary Rate of - material out of the system boundary Rate of generation of waste material + within the system boundary 15

WASTE GENERATION RATES Material Mass Balance Analysis Out. Flow (combustion gases and ashes) Inflow Outflow (materials) Stored materials (raw materials, products solid waste) Out flow (Solid wastes, solids in wastewater) Outflow (Products) System boundary 16

WASTE GENERATION RATES Question A cannery receives on a given day 12 tons of raw produce, 5 ton of cans, 0. 5 tons of cartons and 0. 3 tons of miscellaneous materials. Of the 12 tons of raw produce, 10 ton become products, 1. 2 tons end up as product waste, which is fed to cattle, and the remainder is discharged with the wastewater from plant. Four tons of the cans are stored internally for future use, and the remainder is used to package the product. About 3 percent 17

WASTE GENERATION RATES Cont Question of the cans used are damaged. Stored separately, the damaged cans are recycled. The cartons are used for packaging the canned product, expect for 5 percent that are damaged and subsequently separated for recycling. Of the miscellaneous materials, 25 percent is stored internally for future use; 50 percent becomes waste paper, of which 35 percent is separated for recycling with the remainder being discharged as mixed waste; and 25 percent becomes a mixture of solid waste materials. 18

WASTE GENERATION RATES Cont Question Assume the materials separated for recycling and disposal are collected daily. Prepare a material balance for the cannery on this day and a material flow diagram accounting for all of the materials. Also determine the amount of waste per ton of product. 19

WASTE GENERATION RATES Solutions 1. On the given day, the cannery receives the following: 12 tons of raw produce 5 tons of cans 0. 5 tons of cartons 0. 3 tons of miscellaneous materials. 20

Solutions Cont WASTE GENERATION RATES 2. As a result of internal activity a) 10 tons of products is produced, 1. 2 tons of produce waste is generated, and the remainder of products is discharged with the waste water b) 4 tons of cans are stored and the remainder is used, of which 3 percent are damaged c) 0. 5 tons of cartons are used of which 3 % are damaged d) 25% of miscellaneous material is stored; 50% become paper waste, of which 35 percent is separated and recycled, with the remainder disposed of as mixed solid waste; the remaining 25 percent of the miscellaneous materials are disposed of as mixed waste. 21

WASTE GENERATION RATES 3. Determine the required quantities a) Waste generated from raw produce i) Solid waste fed to cattle = 1. 2 ton (1089 kg) ii) Waste produce discharge with wastewater=(12 -10 -1. 2)tons=0. 8 T(726 kg) b) Cans i) Damaged and recycled = (0. 03)(5 -4) ton = 0. 03 ton(27 kg) ii) Used for production of product = (1 -0. 03)ton -0. 97 ton(880 kg) c) Miscellaneous materials i) Amount stored =(0. 25)(0. 3 ton) = 0. 075 ton (68 kg) ii) Paper separated and recycled = (0. 50)(0. 35)(0. 3 ton) = 0. 053 ton (48 kg) iii) Mixed waste =[(0. 3 -0. 075)-0. 053] ton = 0. 172 ton ( 156 kg) 22

WASTE GENERATION RATES Solutions Cont 3. Determine the required quantities e) Total Weight of product = (10 + 0. 97 + 0. 485) ton = 11. 455 ton (10, 392 kg) f) Total Material stored = ( 4 + 0. 0075) ton = 4. 075 ton ( 3696 kg) 4. Prepare a material balance and flow diagram for the cannery for the day a) Amount of material stored= inflow-outflow –waste generation 23

WASTE GENERATION RATES Solutions Cont 4. b) The material balance quantities i) Material stored = (4. 0 +0. 075)ton = 4. 075 ii) Material Input = (12. 0 +5. 0 +0. 5 +0. 3)ton =17. 8 iii) Material Output =(10. 0 + 0. 97+0. 485+1. 2+0. 03+0. 015+0. 053) =12. 753 ton iv) Waste Generation=(0. 8 + 0. 172)ton v) The final material balance is 4. 075 = 17. 8 – 12. 753 -0. 972 (verified) 24

WASTE GENERATION RATES Solutions Cont c) Material balance flow diagram 12 T raw Produce 5 T Cans 0. 5 T Cartons 11. 455 T Product 1. 2 T Waste Fed to Cattle 4. 075 T Stored Internally 0. 3 Miscellaneous 0. 8 T waste produce discharge with wastewater 0. 03 T Can Recycled 0. 015 T Carton Recycled 0. 053 T paper Recycled 0. 172 T mixed waste 25

WASTE GENERATION RATES Material Mass Balance Analysis 5. Determine the amount of waste per ton of product: a) Recyclable material = (1. 2 +0. 03 + 0. 015 + 0. 053)ton/11. 4. 55 ton= = 0. 11 tonrecycle material/ton product b) Mixed waste = (0. 8 + 0. 172)ton/11. 455 ton = 0. 085 ton mixed waste/ton product 26

WASTE GENERATION RATES Factors that affect generation rates 1) Lack of recycling & source minimization 2) Social background & legislation 3) Geographic & physical factors . 27

WASTE GENERATION RATES 1. Lack of recycling & source minimization Minimization in industries by: +Product design +recycling + product manufacturing, +Product packing, +minimal volume. MSW minimization in household by: +avoid disposal items, +excess packaging +usage of durable product, +recycle, 28

WASTE GENERATION RATES 2. Social background õUse of kitchen waste grinders While the use of kitchen grinders definitely reduce the quantity of food waste collected but it is not clear whether they affect quantities of wastes generated. õEducation bacground & awareness Think before disposal of types of Waste & cleaniness 29

WASTE GENERATION RATES 3. Geographic location & Physical Factor The influence of geographic location is primarily to the different climates that can influence both the amount of certain types of solid waste generated and the collection operation. Substantial variations in the amount of yard and garden wastes generated in various parts of the country are also related to climates 30

WASTE GENERATION RATES Example In the warmer southern areas where the growing season is considerable longer than in the northern areas, yard wastes are collected not only in considerably greater amounts but also over a longer period of time. Season of the year The quantities of certain types of solid wastes are also affected by the season of the year. 31

WASTE GENERATION RATES Example The quantities of food wastes are affected by the growing season for vegetables and fruits. Physical factor Collection frequency (affects amount collected) In general, where unlimited collection service is provided, more wastes are collected. However, it should not be referred that more wastes are generated. 32

WASTE GENERATION RATES Example if waste collection is limited to one or two times per week, he or she may, because of less frequent collection, will store those useless items like newspapers or other materials in their houses. With unlimited service, the house owner would tend to remove those useless items right away. 33

WASTE GENERATION RATES In this situation, the quantity of wastes generated may actually be the same, but the quantity collected is considerably different. So, the fundamental question of the effect of collection frequency on waste generation remains unanswered. 34