solid waste management urban

7/29/2019 Solid Waste Management Urban

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2

SOLID WASTE MANAGEMENT URBAN

LANDFILL

2.1

general concepts

According to the Brazilian Standard ( NBR 10004 ) solids or semisolids are those that "result

from the activity of the community of origin

industrial , domestic , hospital , commercial, agricultural , service and sweeping .

It is also considered from the solid residue systems oslodos

water treatment , those generated in equipment and facilities

pollution control, as well as certain liquids whose particularities

make it impossible to launch the public sewage system or water bodies

or required to do so, technical solutions and economically unviable in the face

best available technology " ( ABNT 1987) .

The waste can be classified according to their origin ( Table 2.1 ) ,

as stated in the first chapter of the fourth article of the state policy management

integrated solid waste in the state of So Paulo , or considering

ecological, health and economic and physical characteristics of

residues ( Table 2.2 ) , according to the Brazilian standard NBR ( 10,004 ) .

As for Origin

Urban Waste

Residential , commercial activities , street sweeping ,

tree pruning and the like.

Special Waste

Of the processes of transformation : Industrial ,

Agricultural , Radioactive , from the Services

Health and Construction .

Table 2.1 - Classification of Solid Waste according to their origin .


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The urban waste are generated in urban areas , while

Specials are generated during processing . These because of

fact possess unique characteristics , require more care

specific to the collection , packaging , transportation , handling and

disposal .

Management of Municipal Solid Waste - Landfill 29

waste Description

class I

( hazardous materials )

Characteristics of toxicity , flammability ,

corrosivity , reactivity , radioactivity and

pathogenicity that may present risks to

public health or adverse effects to the

environment.

class II

( non-inert materials )

Materials that do not fit the classes I

and III . The residues of this class may have the

following properties : flammability ,

corrosivity , reactivity , or toxicity

pathogenicity .

class III

( inert )

Materials which do not solubilize or have not

have any component dissolved in

concentrations greater than the standards

established ( NBR 10,006 - Solubilization of


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residues)

Table 2.2 - Classification of Solid Waste according to their physical characteristics .

The characteristics of the waste may also vary according Zanta and

Ferreira (2003 ) , due to factors that distinguish communities together ,

as social, economic , cultural , geographic and climatic aspects beyond

Biological and chemical products. Knowledge of these features enables a

most appropriate choice in the selection of treatment processes and techniques

disposal to be used.

The gravimetric composition of waste is another fact of great

importance with regard to its management, and can include

several categories as shown in Table 2.3 . It is also important to clarify the content

This moisture due to the fact that the weight of the organic waste is

determined in humid conditions , ( Zanta and Ferreira , 2003) .

It is also necessary , in addition to the qualitative aspects of knowledge

amount produced per day ( tonnes / day ; m

3

/ day) and production per capita

( ton / inhab.day ) . Data to be used in the planning of

GIRSU . Used in this practice , the quantities concerning waste

collected, Zanta and Ferreira (2003 ) .


Category Examples

matter

organic

putrescible

Food debris , flowers , pruning trees .

plastic


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Bags , bags , packaging for soft drinks , water and milk ,

containers of cleaning products , beauty and food ,

sponges, Styrofoam , kitchen , latex , bags

raffia .

Paper and cardboard

Boxes , magazines , newspapers , cards , paper , plates , books ,

books , folders .

glass

Glasses , beverage bottles , dishes , mirrors , packaging

cleaning products , beauty and food .

ferrous metal

Steel wool , pins, needles , product packaging

food .

metal noferroso

Beverage cans , scraps of lead and copper wiring

electric .

Madeira

Boxes , boards , popsicle sticks and matches, caps ,

furniture, firewood.

Cloths , rags ,

leather and

rubber

Clothes, cleaning rags , pieces of fabric , bags ,

backpacks , shoes, carpets , gloves , belts , balloons .

contaminant

chemical

Batteries , medicines , lamps , insecticides , rodenticides ,


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adhesives in general, cosmetic , glass enamels , packaging

pressurized pens loaded carbon paper, film

photographic .

contaminant

biological

Toilet paper, cotton swabs , cotton , bandages , gauze and

blood cloths , diapers,

napkins, syringes , razors , hair , hair ,

packaging anesthetics , gloves .

Stone, earth and

ceramics

Flower pots , plates , construction debris , earth, bricks ,

gravel , decorative stones .

several

Candle wax, soap and soap, charcoal chalk,

cigarette butts , corks , credit cards , crayons ,

long-life packaging , packaging metallized bags

vacuumed dust , abrasives and other hard materials

identification.

Table 2.3 - Basic examples of each category of solid waste .

Source : Adapted from Pessin , et al . (2002 )

It is the responsibility of GIRSU gerenciadoras actions related to

stages of generation , storage, collection and transport , recycling ,

treatment and disposal of solid waste , as follows:

Waste Generation - which promotes the generation of waste and not

changing consumption pattern of the society . Encouraging the consumption of

products more environmentally appropriate , and segregation of waste


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based on their characteristics , avoiding as much as possible , the mixture of waste

that contaminate raw materials. Valuing waste and

enabling greater efficiency in other stages of the process .


Packaging Waste - which guides the coherent

packaging waste according to its characteristics , facilitating

identification and safe handling during the later stages .

Collection and Transportation - which guides the operations of removal and

the waste to the local storage , processing or

final destination . Can be performed selectively and collection of waste

mixed.

Reuse and treatment - which includes , at this stage , actions

corrective aiming waste recovery and reduction of impacts

environmental . Recycling, reuse , recovery or composting are forms

reuse or waste treatment .

Final destination - that forwards following the steps previously

described , waste unused spaces reserved for the deposition

final ( landfill ) with health guarantees , and properly prepared

to collect the liquid and gaseous effluents .

Public health problems and environmental problems arise from not

appropriate treatment of the waste generated . Transmit diseases , like

infected animals and insects , or the air or water polluted

contaminated with toxic chemicals , can proliferate when the trash is deposited

open in landfills . Respiratory , intestinal and others that are

caused by polluted environments or through contact with animals

contaminated can lead to death .

The fact is that more and more throughout the world , generates a higher


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amount of waste . Therefore , the need to develop technologies

committed to preserving the environment and the preservation of

quality of life increases in size proportionally .

The average daily generation of municipal solid waste , the countries of

first world corresponds , according to Rose et al . , to 1.77 kg per capita . this

Indeed, the aggregate cost of treatment and waste management

resulting from revisions to the health and environmental standards , was cause for

investments , since the 80s, the waste recycling and selective collection

waste generated .

In Brazil , in big cities , according to Rose et al . , Household waste

already produced is around 0.8 kg per capita . This indicates the growing

need , in the country , programs that address the waste generated in a

adequate , and that may , in addition to fighting pollution , generate wealth and

jobs . Figure 2.1 explains the situation that is Brazil, in


aspect of the final disposal of waste , and reveals a good chance that the country

have with respect to the recovery of waste generated .

Disposal of Waste in Brazil

21%

36%

37%

6%

dump

landfill

landfill

other

Figure 2.1 - Disposal of Waste in Brazil


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Source : IBGE , 2000

Figure 2.2 shows a flowchart of the allocation of routes

solid waste in view of its energy use .

Figure 2.2 - Flowchart of the routes of disposal of solid waste .

Source : Adapted from Oliveira (2000 ) .


The activities of reuse or treatment using waste

as input , consuming less energy when compared to the input

virgin . This reveals a conservation of energy that contributes to the growth

economical, because it can generate cost savings and increase in productivity

micro and macroeconomic frameworks .

The reuse of solid waste through these activities , as well

to improve the economic productivity of companies or countries , also

contributes to minimizing the environmental impacts associated with the generation and

energy use .

The use of waste energy can occur through the use

its calorific value through incineration , gasification , the

utilization of the calorific biogas produced from waste , or the production of

Solid fuel from food scraps .

Incineration takes the calorific value existing in the trash through its

direct combustion for the production of steam. The process according to Oliveira

(2000 ) , has the advantage of the possibility of direct use of thermal energy , the

need for a continuous supply , which requires large amount

waste , low noise and odor , considering a small area

installation. Its disadvantages the impossibility to waste down

calorific value, of the need to maintain the auxiliary equipment

combustion , ash , for example, may have concentrations of


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toxic metals , high investment costs and operation and maintenance also

the possibility of emission of carcinogenic pollutants .

Gasification is a process that consists in breaking the chains

The residue polymeric material through a heat supplied to the

gassing composition simpler as methane , which are

utilized in heating processes in internal combustion engines ,

or turbines.

The utilization of gas from the landfill will be discussed

in more detail in this section later in this chapter.

It is of fundamental importance to study the composition of

solid waste to a better decision in respect of its

recovery and prevention, as possible , sending all materials

to the landfill , because after his disposal the only advantage will be that of

biogas.

The average composition of municipal solid waste collected in Brazil

according to research conducted in 1997 by IPT , is presented in Figure 2.3 .


Average Composition of waste in Brazil

3% 4 %

25 %

3%

65% Glass

metals

paper

plastic

organic

Figure 2.3 - Percentage breakdown of average litter weight in Brazil .


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Source : IPT / CEMPRE 1997

In landfill , the waste is deposited on the ground isolated so

ordinate , and is then covered with soil from the site itself, so that

is isolated from the environment. Formed thereby species chambers in which

gas produced and released manure, liquid substance formed by the dark

partially biodegraded organic waste .

The slurry accumulates in the bottom of these chambers and tends to seep in

soil can get up to reach the water table , which makes evident the

need for a ground perfectly sealed prior to deposition of garbage. the

existing standards require collection and processing of gas (NBR 8419 and

NBR 8849 ) , and slurry ( NBR 8419 ) .

The cell of the landfill space for the disposal of waste should be

perfectly sealed and the leachate collection system already installed , and the

each layer , each chamber formed in the gas collection system should

also be installed.

The location of the landfill should be carefully chosen ,

should cover large and, because of their drawbacks

operational ( smelly , garbage truck traffic , poor appearance , etc. . )

located away from urban concentrations .

2.2

Gas Generation in Landfills

The mixture of waste in landfills , discharged continually provides

a variety chemistry under the influence of natural agents suffer


physical, chemical and biological . The set of phenomena originates

the vectors of pollution in landfills through biogas and leachate .

See Figure 2.4 .


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The waste gas is produced within the landfill due to changes

biochemical occur there . The anaerobic biodegradation is achieved after

depletion of oxygen in the chambers of landfills . Compacting Garbage

made by machinery at the moment of deposition contributes to

reduction of oxygen inside the chamber .

This process occurs in several stages because the presence of

bacteria that feed on organic matter turning it into compounds

simpler . There are three main groups of microorganisms active in

process , hydrolase - fermentative organisms , methanogens and acetgenos

which are responsible for breaking the bonds of polymers and production of

carbon dioxide, acetic acid production and methane

respectively.

Figure 2.4 Scheme of the main environmental impacts of the disposal of

waste in landfills

The generation of landfill gas is affected by several variables ,

among which can be mentioned: nature of the wastes , humidity present in

residues physical state of the waste ( particle size ), pH , temperature,

nutrients , buffering capacity and rate of oxygenation . These are factors that are

responsible for the development of anaerobic digestion of

organic substrates ( Castillos Jr. , 2003) .

Landfills can generate approximately up to 125 cubic meters of methane gas

per ton of garbage in a period of 10 to 40. According to the Company

Generation of leachate

Emission of Odors Gas Generation

Groundwater Level

atmosphere



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Environmental Sanitation Technology , Cetesb (1999 ) , this generation in Brazil is

677 Gg / year, which may account for some 945 million cubic meters

per year.

Are presented in Table 2.4 the amount of waste and the rate of

production of some landfills USA.

Quantity of Waste Landfill Gas Production Rate

Azusa 6.350 x 10

6

0.002 kg m

3

/ kg.ano

Mountain View 3628 x 10

6

0.008 kg m

3

/ kg.ano

Sheldon - Arletta 5.450 x 10

6

0.014 kg m

3

/ kg.ano

Palos Verdes 18,143 x 10

6

0001 kg m

3

/ kg.ano

Scholl Canyon 4500 x 10


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6

0.006 kg m

3

/ kg.ano

Table 2.4 Amount of waste and production rate of landfill gas

health

Source : Adapted from Castillos , Jr.2003

2.3

Composition and Utilization of Landfill Gas produced in

toilets

The produced gas consists primarily of methane ( CH4 ) and carbon

dioxide ( CO2 ) . Other chemical species present in the gas depend

directly from the composition of the waste deposited there and the stage of the process

decomposition, which indicates that it is necessary to know their concentrations

an assessment of environmental impacts resulting within the rules

environmental regulations. See Table 2.4 and Table 2.5 .

composition Concentration

Methane CH4 44.03 %

Carbon dioxide 34.2 %

Oxygen O2 % 0:52

Nitrogen N2 20.81 %

Ammonia NH3 1.7 to 3.9 ppm

Propane C3H8 7 ppm

Butane C4H10 4 ppm

50 to 90 ppm Toluene

80 to 110 ppm benzene

Table 2.5 Composition of gases from landfill Mountain View , California , USA .


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Source : Adapted from Castillos , Jr.2003

The natural methane according to the IPCC (1996) corresponds to only

20 % of emissions leaving the remaining 80% resulting from activities


human . And according to Cetesb (2001 ) among the world's emissions

methane, 8 % fall to landfills and dumps . See Figure 2.5 .

Studies by Keller (1988) indicate that the landfill gas

contain six classes of compounds: saturated and unsaturated hydrocarbons ,

alcohols, organic acids and hydrocarbons , aromatic hydrocarbons ,

halogenated compounds , sulfur compounds and inorgnios .

Other studies made by Allen et al. (1997) in landfills England,

140 identify volatile organic compounds ( VOCs) , of which 90 are

Composition detected in all samples . They are: alkanes ,

aromatic compounds , cycle -alkanes , terpenes , alcohols and ketones and compounds

halogenated .

Figure 2.5 Global distribution of methane sources

Source : Adapted from MCT 1997

Methane , as previously stated , is a flammable gas and contributes

very strongly for increasing the greenhouse effect. The hydrogen sulfide and other

trace components of biogas are toxic and have unpleasant odors .

In contrast, due to the percentage of methane in its composition,

biogas produced in landfills can be used as fuel,

Sources of Methane

7%

7%

8%

11%


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17 % 22%

28 %

Animal waste

Wastewater treatment

landfills

Biomass burning

paddies

enteric fermentation

Coal , natural gas and ind .

petrochemicals


the generation of thermal or electric power , or cogeneration systems . The

calorific value of the gas is between 14.9 and 20.5 MJ/m3 or 5,800 kcal/m3 .

The use of waste gas is held in various countries ( Europe, America ,

Asia) and can be considered as the simplest use of waste energy

Urban solid .

This use of garbage shows as advantages : the reduction of greenhouse

greenhouse due to methane consumption , low cost for the disposal of

waste and use as fuel for power generation or gas

produced. The disadvantages : poor gas recovery in

recovery of about 50 % impossibility of use of the gas in locations

remote high cost to "upgrade " of plants , longshots autoignition or explosion . Comparing the

advantages and disadvantages , the first

have much larger impacts ( Oliveira , 2000) .

Figure 2.6 is a schematic of how small the gas is captured in the region

the landfill and used to generate electricity .

The capture system involves a network of pipes drilled uniformly

which run through the biogas, which is conveyed to a collector


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page. According to Rose et al. (2003 ), two system configurations collection

are used : vertical wells and horizontal trenches . The capture system

should be designed to enable monitoring and adjustments flows

biogas , facilitating its operation .

Liquid wastes that are collected through gutters located in

base of the landfill , can be redirected into the landfill , allowing

Decomposition greater and greater gas production .

Figure 2.6 Schematic capture and electricity generation from waste gas .

Source : Adapted from CADDET 393 2000

biogas

waste

Capture of biogas

thermoelectric


Before use , the process of energy conversion , biogas

passes through a phase of treatment. In this phase particulates are removed ,

impurities present in the condensate and gas. This treatment depends on the

end use of biogas .

The treated gas is directed to systems for steam generation

( boilers , furnaces ) or electric energy generation systems ( engines

stationary ) and can also be harnessed to heat rejected

heating water.

Its use as fuel for electricity generation is

the most common. A cogeneration system can be an alternative , and

obtain high efficiencies can be used for various purposes to ensure

more revenue for the project .

In Brazil , in 2003 , there were initiatives to leverage


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biogas generated in landfills or dumps old . Examples of these initiatives

are, for example , found in the cities of So Paulo and Salvador .

2.3.1

Bandeirantes Landfill Municipal

The Bandeirantes Landfill , in So Paulo , is considered one of the largest

world , receives about 7,000 tons of waste per day , 50 % of total

produced in the city . Its use began almost 30 years ago and is being

completed in 2006 , it is expected that this year is storing more than 30

million tons of garbage . The gases produced were simply burned

in vertical drains , releasing pollutants into the atmosphere . (Site Logos

Engineering ) .

On January 23, 2004 , was inaugurated Thermoelectric Gas

Bandeirantes Landfill Municipal already uses the biogas produced in

landfill to generate electricity .


Bandeirantes Landfill Figure 2.7 - Aerial Photo

Source : Website ARCADIS Logos Engineering

The correct use of gas provides a significant reduction in gas

methane, obeying in practice , which is given in Protocol

Kyoto on reducing emissions of greenhouse gases .

The capture of biogas is through pipes connected to drains

vertical strategically placed in the landfill , along with equipment

suction drying and burning the gas surplus .

The collected gas is routed to motor- generators , located in the plant

the filling, with a minimum concentration of 50% by volume , at a flow rate of

to 12.000m3 / h . This amount can generate electricity to power

a city of about 300,000 people .


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Figure 2.8 Bandeirantes Landfill - Moto - generators

Source : Website ARCADIS Logos Energy

The plant is connected to four alimentadoresde energy Eletropaulo

that delivers to parts of the city .

2.3.2

Social Environmental Park Canabrava

In the period between 1974 and 1997 the former landfill received waste Canabrava

generated by the city of Salvador . It was the scene of a reality of degradation

significant social . About 1000 scavengers working in cooperatives and

survived by scavenging garbage .

In partnership with the Government of Canada , the city of Salvador

undertook the construction project of Social and Environmental Park of Canabrava .

This project involved studies and actions for sealing the territory of the landfill to

the planning for recycling and composting of waste , and the

produzidosno utilization of gases inside the old dump .


Figure 2.9 Socio Environmental Canabrava Park - Units Composting

Screening Recycled and Leisure Areas .

The Social Environmental Park is now an urbanized area and houses a

large space for leisure community in the region . also integrating

this space is Canabrava Child Project , which performs actions related to

education of children of former scavengers , Park officials today . the

Composting plants for the production of fertilizer and screening material

recyclable ( plastic, glass , cardboard ) and a thermal power plant for the pilot

electric power generation .

The gas produced is channeled through vertical drains . after studies


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made chose three such drains , according to the level of

concentration of methane to power the motor- generator. See Figure 2.9 .

The biogas captured is filtered and dehumidified before being directed to

the generator , providing a greater concentration of methane in the combustor . The

remaining gases follow for burning in a flare .

Today , there is only a pilot plant with a capacity of 75kWh , which

feeds all the equipment and part of the complex of residences

residents.

In the graph shown in Figure 2.1 , one can still identify a

high percentage of the presence of garbage dumps in Brazil . In this sense , means


that initiatives such as this , held in Salvador , may set in

excellent opportunities for other cities in Brazil .

Figure 2.10 - Social Environmental Park Canabrava - Ducted Gas Inlet ,

Valves and Input Generator .

The biogas composition , are known volume concentrations

methane , carbon dioxide and oxygen in each well of power generator .

The average composition of September 2003 and February 2004 are

presented in Table 2.6.

Biogas composition ( vol )

September 2003

Biogas composition ( vol )

February 2004

CH4 39.6 % 24.6 %

CO2 32.8 % 27%

O2 0.2 % 0.4 %

Blend 27.4 % 48 %


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Table 2.6 Composition of the gases generated in the Park Partner Environmental Canabrava

Salvador , Bahia , Brazil

2.3.3

Center of Waste Disposal - Montreal (1988 )

The Centre for Waste Disposal , in Montreal , in 1988 ,

received about 30,000 tons of solid waste since 1968 . From the


motivation to improve the quality of life of people living

near the landfill , the city hall , along with companies

particular , built a plant for generating electricity , and

as fuel gas produced in landfills . The project was also contained

treatment of this gas to prevent environmental problems . CADDET (Result 393

- 2000) .

The gas produced in landfills is channeled into a filter , which removes

and particles existing in the condensed gas. Condensate is , in turn ,

piped to a place of treatment. Umcompressor raises the gas pressure

35kpa to ( g).

The compressed gas is burnt in a combustor having the capability of

produce 100.000kg / h of steam . The temperature inside the combustor is between

1650 and 1700

the

C. The steam is in turn channeled to a turbine

coupled to a generator. In the design conditions have to supply

a plant for generating electricity with installed capacity of 25MW .

The gas produced after combustion is composed mainly of

carbon dioxide ( CO2 ) and water vapor with traces of nitrogen oxides

(NOx) , carbon monoxide (CO) , sulfur dioxide (SO2 ) , hydrocarbons, and


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unburnt compounds .

In Table 2.7 we can find the composition of the gas produced in

and landfill gas composition delivered after combustion .

compounds

concentration

( by vol)

emissions

concentration

( by vol)

CH435 CO266 % , 7%

N220 % H2O 15.6 %

N217 O2 5 % 7%

CO 40% CO2 24 ppmv

232 ppmv ppmv H2S NOX21

VOC 's 743 ppmv ppmv SO233

HC 2 ppmv Table 2.7 Composition of gas produced in the landfill in Montreal and its

emissions after combustion process.

The concentration values obtained in the landfill in question ,

comply with regulatory laws on air quality in force in Canada .

According to the mass balance conducted using air as the oxidant

with 78 % nitrogen, 21 % oxygen and 1 % argon , emissions

nitrogen and carbon dioxide would be reversed. We present in Table 2.8 ,

probable values for concentrations of emissions in landfill montreal .


emissions

concentration

( by vol)


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CO217 , 7%

H2O 15.6 %

N266 , 7%

24 ppmv CO

NOX21 ppmv

SO233 ppmv

HC 2 ppmv

Table 2.8 emissions after combustion process of the gas produced in the landfill

Montreal , according to a mass balance conducted in this study.

From the values presented for the landfill in Montreal

began a study of a model for the simulation of a process

Combustion in which it was possible to investigate the concentration of pollutants

formed from biogas produced in landfills .

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