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Proceedings of the International Conference on Sustainable Solid Waste Management,

5 - 7 September 2007, Chennai, India. pp.348-355

348

Co-incineration of Municipal Solid Waste in Cement Industry

Axel Seemann

Centre for Sustainable Development, Bangalore, India

ABSTRACT

The aim of the paper is to introduce the use of high calorific waste components as secondary

fuel in cement plants. For this purpose the basic ideas and requirements of co-incineration will

be explained. This includes physical properties of the secondary fuel to be produced from solid

waste as well as technical requirements of the required pre treatment of the waste. The highlywater containing organic part of municipal solid waste has to be separated from the high calo-

rific fraction, which can be used as secondary fuel. The remaining organic components can be

used for composting or for the generation of bio gas.

Based on experiences in Europe as well as on studies on waste generation in the City of Ban-

galore and Karnataka, possibilities for the use of municipal solid waste as secondary fuel in

India will be discussed in the paper.

Keywords: Municipal Solid Waste, Mechanical Biological Waste Treatment, Recycling, Reuse,

Anaerobic, Composting

1.0 INTRODUCTION

The Indian gross domestic product (GDP) increased 2.5 times over past 2 decades. As a consequenceof increasing industrial activity and a continuous rise of incomes, there has been as well a significant

increase in waste generation in India. The present system of solid waste management in India, like any

other fast growing countries has to be adapted to these changes. Illegal dumping is a major problemthat raises significant concerns with regard to safety, property values, and quality of life in our com-

munities.

The Centre for Sustainable Development (CSD) in Bangalore has carried out studies on waste genera-

tion and the composition wastes. Based on information generated, approaches for the recycling ofmunicipal solid waste have been developed and adapted to Indian conditions. Especially a combina-

tion of anaerobic composting of organic parts of waste combined with the use of high caloric waste as

secondary fuel in cement plants is a very promising recycling option.

2.0 COMPOSITION OF MUNICIPAL SOLID WASTE IN INDIA

The waste from residential, commercial and institutional activities in a municipality is commonlytermed as Municipal Solid Waste (MSW). As defined in the Municipal Solid Waste Rules, 2000 mu-

nicipal solid waste includes commercial and residential wastes generated in a municipal or notified

area in either solid or semi solid form, excluding industrial hazardous wastes but including treated

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bio-medical waste.

The quantity and the content of municipal solid waste (MSW) varies according to the socio-economic

status and cultural habits, prevailing climate, location, urban structure, density of population and ex-tent of non-residential activities. The Centre for Sustainable Development (CSD) in Bangalore has

carried out studies on generation and composition municipal and industrial wastes. To assure repre-

sentative results, the study covered main areas of urban waste generation. From focus areas wastesamples were taken and analysed. The segregated wastes were weighed to ascertain the percentage

composition of individual waste constituents. The waste composition is shown in Figure 1.

Percentage wise constituents of Municipal Solid Waste in Residential Area

Organic matter

81,00%

Plastics

10,75%Metals

0,50%

E - waste

0,25%

Glass

1,25%

Paper

6,00%Cloth0,25%

Plastics

Paper

Cloth

Metals

Glass

E - waste

Organicmatter

Percentage wise constituents of Municipal Solid Waste in Commercial Area Sample 1

Cloth

5,00%

Coir

1,00%

Plastics

12,00%

Coconut shell

5,00%

Paper

8,00%

Organic matter

69,00%

Plastics

Paper

Coir

Cloth

Coconut shell

Organic matter

Percentage wise constituents of Municipal Solid Waste in Slum area

Cloth

3,50%Paper

12,25%

Plastics9,25%

Organic matter

75,00%

Plastics

Paper

Cloth

Organicmatter

Figure 1 Composition of Municipal Solid Waste in India [Seemann 06]

3.0 MECHANICAL BIOLOGICAL TREATMENT (MBT)

In waste management there is a worldwide push towards implementing a 3R strategy: Reduce, Reuse

and Recycle. This policy puts an emphasis on energy recovery over the disposal of waste in landfills,

encouraging technologies such as mechanical biological treatment (MBT) providing a high calorificfraction which can be used as secondary fuel.

Mechanical-biological Waste Treatment (MBT) is a technique to pre treat solid waste prior to dis-

posal. The facilities required can be operated with relatively simple equipment, i.e. with a low degree

of automation and modest expenditures on process technology and structures. However, depending on

the anticipated results of treatment and on financial and other conditions it is also possible to imple-

ment highly sophisticated and enclosed facilities with optimised process technology.

The use of MBT in conjunction of using the high calorific fraction as secondary fuel could present a

number of environmental advantages. In the field of recycling, there would be a reduction of odoursand emissions arising from waste handling and treatment [Senkpiel/Ohgke 98], as well as an improvedrecycling of materials such as metals and finally the possibility of converting the organic fraction into

soil conditioners (or compost). The energy recovery through production and use of secondary fuel in

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cement kilns is a major advantage saving natural resources and reducing green house gas emissions.

MBT consist of the two main technical elements the den mechanical treatment ant the biologicaltreatment. The configuration of MBT plants as well as the chosen equipment can differ extremely.

MBT plants can incorporate a number of different processes in a variety of combinations. The "me-chanical" element is usually an automated mechanical sorting stage. This either removes recyclable

elements from a mixed waste stream, such as metals, plastics and glass or processes them. It typically

involves factory style conveyors, industrial magnets, eddy current separators, drum sieves, shredders

and other tailor made systems.

The "biological" element refers to either:

Anaerobic digestion,

Aerobic composting or to

a combination of both techniques

In general it can be said that processing biodegradable waste either by anaerobic digestion or by

composting, MBT technologies help to reduce the contribution of greenhouse gases to global warm-

ing. But in anaerobic digestion being the more efficient option.

Figure 2 shows flow sheeting diagrams for main MBT configurations. The simplified dry stabilisation

technique on the right hand side can be an option to introduce the MBT technique in emerging

Figure 2 Flow Sheeting Diagrams for Main MBT Configurations [Nelles Et Al 07], [SWMPP 06]

Municipal Solid Waste Municipal Solid Waste

Co-

Incineration

Mecanical Treatment

Biological Treatment

Biological

Treatment

MecanicalPost-

Treatment

Landfill

(Ash)Landfill Recycling/

Landfill

Secondary

Fuel

LowCalorificFraction

HighCalorificFraction

Mecanical PostTreatment

Mecanical Treatment



Municipal Solid Waste

Biological Treatment

Recycling/

Landfill

Secondary

Fuel

Mecanical PostTreatment



Secondary

Fuel

Dry Stabilisation TechniqueConventional MBA Technique Simplified Dry Stabilisation

Technique

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countries, having a high amount of organics in their municipal solid waste. This technique is currently

in a trial stage in Thailand by the Thai-German Solid Waste Management Project (TWMP), Bangkoka cooperation of the Ministry of Natural Resources and Environment (MoNRE) in Thailand and the

German Technical Cooperation (GTZ)

4.0 APPLICATION OF MBT UNDER INDIAN CONDITIONS

The waste composition as well as the climatic conditions in India differ very much from European

countries were MBT-Techniques are commonly applied. First experiences with the introduction of

MBA-techniques under Asian conditions have been made in Thailand by the Thai-German SolidWaste Management Project (TWMP) in Bangkok a cooperation of the Ministry of Natural Resources

and Environment (MoNRE) in Thailand and the German Technical Cooperation (GTZ).

To use the municipal solid waste maintained in the MBT for other applications the material was seg-regated into three fractions by sieving drums: diameter less than 10 mm, between 10 and 40 mm and

diameter more than 40 mm. The sieved products have been investigated for composition, physical-chemical characteristics as well as for its heating value.

The results of the analysis of the physical and chemical composition of the municipal solid waste afterMBT are shown in the figures below. Figure 3 compares the composition of the high calorific fraction

after MBT of 5 and 9 months. In respect of the main components the composition is very similar after

5 month and 9 month treatment. The content of plastic, which has a high calorific value is 72 % after 5months and 80 % after 9 months treatment.

Figure 3 Composition of the High Calorific Fraction after 5 Months (Left) and 9 Months (Right) MBT

[ERC/GTZ 07]

The physical and chemical characteristics of the solid waste treated by a 5 and 9 months MBT processis shown in Table 2. It is obvious that the characteristics of 5 months MBT are about the same as that

for a 9 months treatment. The fine fraction below 10 mm is mainly compost, while the fraction bigger

than 40mm contains the high calorific materials, which is indicated by the parameters density andvolatile solids. While the density is approx 132 to 143 kg/m3 compared to 590 to 816 kg/m3 for the

fraction less than 10mm, the content of volatile solids is much higher in the high calorific fraction(790 to 842 mg/g) to 215/175 mg/g in the fraction less than 10mm.

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For most of the parameters the concentration of heavy metals in the treated solid waste is lower than

the limiting values for secondary fuels in Europe (see Table 3). Arsenic is the only exception exceed-

ing the limits. The high concentration of aluminium and iron in the materials is even useful for cementproduction, which needs these metals as additives for the clinker. The most critical heavy metal, mer-

cury, is within the limits for secondary fuels. Therefore, the use of the high calorific fraction as fuel in

cement production seems to be feasible. The is fortified by the high calorific value of the material with

a diameter greater than 40 mm which is much higher than for the other fractions and approximately atthe same level as the heating value of diesel fuel.

Table 2. Physical and Chemical Characteristics After 5 and 9 Months MBT Process [ERC/GTZ 07]

5 months MBT 9 months MBT

Parameter< 10 mm

10 mm -

40 mm

> 120

mm< 10 mm

10 mm -

40 mm

> 120

mm

Phisical & chemicalDensity (kg/m3) 590 589 132 816 673 143

Moisture content (%) 29 37 16 27 25 13

Total solids (mg/g) 712 720 843 31 748 879

Volatile Solids (mg/g) 215 244 790 175 336 841

Ash Content (mg/g) 784 756 210 825 664 159

Organic Carbon (mg/g) 371 268 110 300 195 114

Hydrogen (mg/g) 14 16 53 12 22 56

Nitrogen (mg/g) 21 16 5 13 9 5

pH 7.9 7.6 8.1 8 8.3 7.7

Chloride (mg/g) 8 10 9 6 7 7

Sulfate (mg/g) 10 11 1 6 10 4

Heavy metals

As (mg/kg) 223 132 49 172 138 30

Cr (mg/kg) 24 35 1932 63 31 13

Fe (mg/kg) 2058 2140 1678 2127 1820 1615

Al (mg/kg) 15153 40479 4248 18268 50228 5092

Hg (mg/kg) 1.1 0.31 ND 0.56 0.37 0.46

Cu (mg/kg) 143 121 33 196 96 96

Mn (mg/kg) 221 136 109 310 202 68

Ni (mg/kg) ND ND ND ND ND ND

Cd (mg/kg) 1.7 0.9 ND ND ND ND

Pb (mg/kg) 90 141.4 13.3 130.7 64.9 36.1

Calorific valueAs collected (J/g) 6050 14603 33168 5132 18196 36867

Moisture free (J/g) 6122 15234 33801 5680 18810 38230

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Table 3. Maximal Content of Heavy Metals in Secondary Fuels in Europe [MUNLV 05]

Parameter Content of Heavy Metals

in mg/kg TS Average Maximal

Cadmium Cd 4 9

Thallium Tl 1 2

Mercury Hg 0,6 1,2

Antimony Sb 50 120

Arsenic As 5 13

Lead Pb 70 190 200 400

Chromium Cr 40 125 120 250

Cobalt Co 6 12

Copper Cu 120 350** 300 700**

Manganese Mn 50 250 100 500

Nickel Ni 50 100

Vanadium V 10 25

Tin Sn 30 70

5.0 CO-PROCESSING OF MUNICIPAL SOLID WASTE IN CEMENT KILNS

Cement production has very high energy requirements, which typically account for 30-40% of theproduction costs (excluding capital costs) [Coprocem 06]. Traditionally, the primary fuel has been

coal, but a wide range of other fuels is also used, including petroleum coke, natural gas and oil. In

addition to these fuels, various types of waste can be used as fuel. Co-processing refers to the use ofwaste materials in industrial processes, such as cement production. The co-processing of selected

waste materials in the cement industry is a proved alternative and possible solution for treatment of

high caloric wastes. Co-processing has the following characteristics during the production process: The alkaline conditions and the intensive mixing favour the absorption of volatile components

from the gas phase. This internal gas cleaning results in low emissions of components such as SO2,

HCl and, with the exception of mercury and thallium, this is also true for most of the heavy metals.

The clinker reactions at 1450C allow incorporation of ashes and in particular the chemical bind-ing of metals to the clinker.

Figure 4 shows the feeding points and the temperature profile of a rotary kiln for clinker production.

The Primary firing system can be used by macerated materials as lignite, treated fractions of waste,

scrap wood as well liquid waste as used oil, solvents and heavy fuel oil. The secondary firing can be

used for tyres, paper and sewage sludge. Beside the physical requirements on the fuel the temperaturesin the kiln limit the used of secondary fuels. While some plastics, tyres and some kind of sludges can

be fired at the secondary firing, Fuels containing hazardous substances have to be fired at the mainburner. Only the use in the main burner ensures that hazardous substances are destroyed due to the

high temperatures above 1450 C combined with a residence time of over 2 seconds.

A major restriction for the use of secondary fuels is the content of chlorine. High chlorine contents

lead to corrosion problems in the cement plant but also to problems at the connection of the pre-heater

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to the cement kiln. Chlorine containing plastics as PVC are melting at low temperatures. The melted

plastic can hamper or even block the material flow form the pre heater into the cement kiln. Due to

this problem cement industry in Europe is limiting the content of chlorine in secondary fuel to 0.3 to0.5 mass-%, depending on the company and cement kiln. These limits are even stricter than the limit-

ing values set by the authorities, which are allowing a chlorine content of 1 mass-%.

Figure 4 High Calorific Fraction after BMT

Figure 5 Feeding Points and Temperature Profile of a Rotary Kiln with Cyclone Preheater [Ebertsch 07]

6.0 CONCLUSIONS

The high calorific fraction of municipal solid waste can be used as secondary fuel in cement industryaccording to its physical composition. Concerning the chemical properties of the material there arestill some open points. The major concern is the content of chlorine arising from PVC in the waste. As

Exhaust gas to electro-

static precipitator

1

Mehl-aufgabe

1

2

3

4

43

2 1

VDK

Primary firing system

o Macerated material- lignite- treated fractions of

industrial waste- scrap woodo Liquids

- waste oil, used solvents- heavyfuel oil

2000C1000C

evaporation

cooler

350C

150C 850C

Main Burner

raw meal dosage

Monitoring

firing temperatur

Secondary firing system- old tyres- paper sludge- sewage sludge

Exhaust gas to electro-

static precipitator

1

Mehl-aufgabe

1

2

3

4

43

2 1

VDK









2000C1000C

evaporation

cooler

350C

150C 850C

evaporation

cooler

350C

150C 850C

Main Burner

raw meal dosage

Monitoring

firing temperatur

Monitoring

firing temperatur



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a next step towards the use of high calorific fraction of municipal solid waste in cement industry, the

PVC content has to be analysed. This analysis is carried out by CSD but till now the results are notavailable. PVC is a limiting material in secondary fuels due to its low melting point and especially

because chlorine can react to dioxin and furan, which are extremely poisonous substances.

In order to obtain the high calorific fraction of municipal solid waste a pre treatment of the waste isabsolutely required. Biological mechanical treatment BMT is a very good option combining aerobic oranaerobic composting with mechanical cutting and segregation. BMT generates a high calorific frac-tion that can be used as secondary fuel. The application of BMT with Asian waste composition andclimatic conditions in Thailand showed promising results. On the one hand BMT converts the organicfraction into a stable and non reactive material, which can be land filed without risk. In some cases theorganic can even have the quality to be used as manure. The use as mature requires a very strict moni-toring and management of the waste input stream into the BMT process.

A broad application of BMT combined with the use of the high calorific fraction as fuel in cement

kilns could solve more than one problem of infrastructure in India. There is the general problem ofproper management of municipal solid waste including avoidance of wild dumping and other negativeeffects for the environment like ground water contamination by leaking pump sides and landfills. Butthe concept is also a solution for another problem. Secondary fuel can be used by the high energydemanding Indian cement industry saving the natural coal resources in India.

REFERENCE

Centre for Sustainable Development, CSD 04, Study on the Composition of Industrial Waste in Ban-galore City, Bangalore, (2005).

Centre for Sustainable Development, CSD 05, Study on the Composition of Municipal Solid Waste inBangalore City, Bangalore, (2005).

Seemann, A, Seemann 06, Solid and Industrial Waste Management in India Cases of Karnataka -,in: proceedings of Sixth International Ecocity Conference (Ecocity6), 3

rdto 6

thDecember 2006,

Bangalore, India, (2006).

Seemann, A., Seemann 07, Co-Processing of high calorific Wastes - techno-economical evaluation ofPaint Sludge Recycling Techniques - in: South Indian Stakeholder Meeting, Bangalore, May(2007).

The GTZ-Holcim Public Private Partnership: Summary, Coprocem 06, Guidelines on Co-processingWaste Materials in Cement Production, (2006).

Senkpiel, K., Senkpiel/Ohgke 98, Ohgke H.: Abbau von Biomuell durch anaerobe Fermentation, in:Gesundheits-Ingenieur-Hausphysik-Bauphysik-Umwelttechnik, 119 (1998), Heft 6

Ebertsch, G., Ebertsch 07, Co-Processing of Hazardous Waste in Cement Kilns European Experience Legislation and Requirements, South Indian Stakeholder Meeting, Bangalore, (May 2007).

Environmental Research Centre (ERC) Naresuan University, Gesellschaft fuer Technische Zusam-menarbeit, ERC/GTZ 07, Solid Waste Management Programme for Phitsanulok, SummaryReport - Characteristics of Solid Waste after Mechanical Biological Treatment (MBT), Phitsa-nulok, (April 2007).

Nelle, M., Nelles et al 07, Morscheck, G.; Degener, P.: MBA-gute Technik mit Verbesserungsbedarf,in UmweltMagazin, Maerz (2007).

Environmental Research Centre (ERC) Naresuan University, SWMPP 06, Solid Waste ManagementProgramme for Phitsanulok, Phitsanulok, Thailand, (2006).

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