LESSON 2: CHARACTERISTICS AND QUANTITY OF MSW

Goals

Determine why quantification is important

Understand the methodology used to quantify MSW

Become aware of differences among global production rates

Understand factors affecting waste generation rates

Become familiar with per capita generation rates

Goals, Cont’d

Explain why it is important to characterize MSW.

Become familiar with MSW descriptors.Understand the methods used to

characterize MSWDescribe the physical, chemical, and

biological properties associated with MSW.

Perform calculations using waste composition and properties.

RCRA Subtitle D Wastes

MSWHousehold

hazardous wastesMunicipal sludgeNon-hazardous

industrial wastesCombustion ash

SQG hazardous waste

Construction and Demolition debris

Agricultural wastes

Oil and gas wastes Mining wastes

MSW - RCRA Definition

Durable goodsNon-durable goodsContainers/PackagingFood wastesYard wastes Miscellaneous inorganics

MSW - Textbook Definition

Mixed household waste recyclables household hazardous waste commercial waste yard waste litter bulky items construction & demolitions waste

What are the sources of RCRA Subtitle-D Wastes? Residential Commercial Institutional Industrial Agricultural Treatment Plants Open Areas (streets, parks, etc.)

What is the Nature of Municipal Solid Wastes?OrganicInorganicPutrescibleCombustibleRecyclableHazardousInfectious

Importance of Generation RatesCompliance with Federal/state

diversion requirementsEquipment selection,Collection and management

decisionsFacilities designMethodology

– Materials Flow– Load Count

Factors Affecting Generation Rates Source

reduction/recycling Geographic location Season Home food waste

grinders Collection

Frequency GNP trend, Per

capita income

Legislation Public attitudes Size of households Population density Pay-As-You Throw

Programs Population

increase

EU Waste Generation Study Studied correlation between waste generation

and:– Population– Population density– Age distribution– Employment– GDP– Infant mortality– Life expectancy– Average household size– Unemployment– Tourism

Waste generation has grown steadily in Europe for over 20 years

Strongest Correlation

Generation increases with: – Population– Age distribution (fraction in 15-39,

employment)– The rate of increase in GDP (for example

Poland, Spain and SlovakiaGeneration decreases with average

household size Low income areas had low amounts of

plastics, paper and cardboard, but not organics

Conclusions

Continued increase in MSW generation rate is expected– Because of economic grown– Improving health– Increasing urbanization– Offset by declining percent of 15-59

year olds

Composition Studies

Materials FlowManual Sorting

Manual Sorting Methodology Study PlanningSample PlanSampling ProcedureData Interpretation

Sample Plan

Load SelectionNumber of Samples

Sampling Procedure

Vehicle UnloadingSample Selection and RetrievalContainer PreparationSample PlacementSorting

Waste contents areunloaded for sorting

Appropriate mass of material is selected randomly

Each load is separated manually by component example - Wood, concrete, plastic, metal, etc.

Components are separated

Each component is weighed and weights recorded

Data Interpretation

Weighted Average based on Generator Source Composition/Distribution

Contamination Adjustment

US MSW Composition

Terminology

Generated Waste = Disposed (Collected) Waste + Diverted

Waste

Specific Weight

Values: 600-900 lb/yd3 as delivered

Function of location, season, storage time, equipment used, processing (compaction, shredding, etc.)

Soil Phase Diagram

Vsample=Vsolids+Vliquid+Vgas

Vvoids = Vliquid + Vgas

Wsample=Wsolids+Wliquid

(Wgas~0.00)

V=volume, W=weight or mass

Moisture content (MC)

Weight or volume basedWeight: wt. of water/sample wt.

• MCwet= Wwater/(Wwater+Wsolids)

• MCdry= Wwater/Wsolids

Volume: Vwater/Vsample

Chemical Composition

Used primarily for combustion and waste to energy (WTE) calculations but can also be used to estimate biological and chemical behaviors

Waste consists of combustible (i.e. paper) and non-combustible materials (i.e. glass)

Proximate Analysis

Loss of moisture (temp held at 105o C)

Volatile Combustible Matter (VCM) (temp increased to 950o C, closed crucible)

Fixed Carbon (residue from VCM)Ash (temp = 950o C, open crucible)

Ultimate Analysis

Molecular composition (C, H, N, O, P, etc.)

Table in notes

Typical Data on the Ultimate Analysis - ExampleFood Wastes

– Carbon: 48%– Hydrogen: 6.5%– Oxygen: 37.6%– Nitrogen: 2.6%– Sulfur: 0.4%– Ash: 5%

Energy Content

Models are derived from physical composition and from ultimate analysis

Determined through lab calculations using calorimeters

Individual waste component energy contents

Empirical Equations

Modified Dulong formula (wet basis):BTU/lb = 145C +610(H2-02/8)+40S +

10NModel based on proximate analysis

Kcal/kg = 45B - 6WB = Combustible volatile matter in MSW (%)

W = Water, percent weight on dry basis

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Last updated April 18, 2023 by Dr. Reinhart