**3. Integrated waste management system**

**Components**

280 Advances in Internal Combustion Engines and Fuel Technologies

**Table 2.** RDF components characteristics

Slovenian RDF produced from municipal solid waste.

**Table 3.** The average composition of Slovenian RDF

technical problems may arise during thermal treatment of RDF.

**MATERIAL COMBUSTION PROPERTIES Moisture Ash Combustibles Heating value**

combustible fraction (%) (MJ/kg) textile 7,56 5,76 86,68 16,65 chart board 6,85 11,88 81,27 17,49 soft paper 23,99 12,43 63,58 10,1 plastic foil 0,51 13,24 86,25 40,14 hard foil 0,4 5,28 94,32 40,12 PET bottles 0,42 0,15 99,43 21,51 wood 12,52 2,31 85,17 16,32 styrofoam 1,07 9,98 88,95 27,95

The average fraction composition of RDF, based on our investigations, is quite versatile but can still be presented with data in the Table 3. The data in the table is based on the research of

The MBT plant prepares the RDF according to the waste input stream quality, their technical capabilities and operation permits. Sometimes, to lower the operational costs, operators leave out certain sorting and processing systems thus produce coarser, lower-grade fuel with higher moisture and ash content. Still the RDF should be produced in accordance with the limits, set by the RDF utilizer. Such limits are for instance presented in Table 4 and were determined by the tests on pilot gasification unit by authors. If limits are not followed environmental and/or

**Fraction Mass share [%]** textile 12 - 16 chard board 10 - 15 soft paper 30 - 40 plastic foil 10 - 15 hard plastic 9 - 11 PET bottles 4 - 6 wood 2 - 4 styrofoam 0,5 – 1,5

The completely integrated waste management concept should be developed, build and in operation at regional level or really big cities for processing municipal solid waste. Such system is in economic terms effective if developed for over 200.000 people producing at least about 100.000 t/year of municipal solid waste. If developed for special conditions like mountainous regions, less populated areas,… these figures can be half or third of above mentioned because logistics cost and its environmental influence would make it worse to generate high waste quantities.

The integrated system should be based on law enforced separated collection, composting, recycling, MBT of residual waste, W-t-E of combustible fraction and disposal of inert fraction from MBT. Into the process of thermal treatment also sewage sludge from regional waste water treatment plants can be induced. Generally no special drying is needed for sewage sludge only mechanical dewatering process is utilized to squeeze the water out to get the sewage with about 25 % of solids.

The operation of the integrated waste management system must realize multiple objectives related to environmental protection. The waste reuse is increased and its treatment is ensured. The amount of emissions into the ground and underground water and the amount of green‐ house gas emissions is radically reduced. The project protects surface and underground water and prevents water pollution.

The schematic presentation of the whole system is presented in Figure 1.

The scheme represents material flow for the whole system. The technological processes are followed in the direction of arrows as depicted in the Figure 1. **Author(s) Name(s): Filip Kokalj and Niko Samec Chapter Title: Combustion of Municipal Solid Waste for Power Production** 

**Proof Corrections Form** 

Regional concept of integrated waste management should include: **PROOF CORRECTIONS FORM** 


from the municipal waste water treatment plant

Local, regional and national integrated waste management concept must be composed of many closely related and connected technical and technological processes. With the aim to establish an environmentally and economically acceptable waste management it is essential for all the technological and logistical steps in the process of waste management to be interlinked and

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When building waste management strategy it is essential to regard cost and environmental impact. The priority list of waste management methods, based on European philosophy and

To reduce the waste amount on the landfill, in accordance with the concept mentioned, waste must first be collected separately and then re-used or treated. In such manner the amount of the waste residue to be deposited on the landfill is minimised. The article shows many technical compliance arguments of the regional concept with the requirements, based on structural and

The composting plant performs composting of separately collected biodegradable waste. The processes aerobic or anaerobic type of composting and run mostly in an enclosed hall, separately from the employees and the environment. The procedure is fully automated and controlled from the control room. The prepared composting mixture is handled only by appropriate technology. The composting process is designed to make the biodegradable waste decompose into compost in the shortest amount of time possible. For this purpose, the mass is constantly treated with air (aerobic process) which is an essential element for a quick and effective decomposition or just mixed in closed reactor (anaerobic process). Such conditions

chemical analysis of municipal waste and foreseen technology for waste treatment.

Separate collection ensures three collected waste stream of MSW and they are:

**2.** Recyclable sorted household waste (packaging waste);

**3.** Remains of the sorted household waste.

ensure the suitable quality of the end product.

The plant consists of three parts:

**•** the composting area (reactor),

**•** the refining area (reactor).

**•** the reception area,

**3.1. Treatment of biodegradable waste**

harmonised.

directive [9] is:

**•** reduction of waste at the source,

**•** re-use and recycling of waste,

**•** energy recovery of waste and

**1.** Biodegradable waste;

**•** land filling of the waste residue.

with approximately 25% of solids.

consider convenient)

**•** land filling of biologically stable inert fraction and residue of thermal treatment. **31** 1 Use space, dash or hyphen between abbreviations and explanations (whatever you

1

**Figure 1.** Schematic presentation of integrated waste management concept

Local, regional and national integrated waste management concept must be composed of many closely related and connected technical and technological processes. With the aim to establish an environmentally and economically acceptable waste management it is essential for all the technological and logistical steps in the process of waste management to be interlinked and harmonised.

When building waste management strategy it is essential to regard cost and environmental impact. The priority list of waste management methods, based on European philosophy and directive [9] is:


The scheme represents material flow for the whole system. The technological processes are

**PROOF CORRECTIONS FORM** 

Figure 1)

from the municipal waste water treatment plant

abbreviations and explanations (whatever you

with approximately 25% of solids.

consider convenient)

**No. Delete Replace with 6** 11 delete Figure 1 insert the figure bellow the form (corrected

**Proof Corrections Form** 

**•** thermal treatment of calorific fraction and waste residue from sorting plant together with

**•** land filling of biologically stable inert fraction and residue of thermal treatment.

**31** 1 Use space, dash or hyphen between

**25** 2 where*ν 'k* and*ν ''k* designate where *ν 'k* and *ν ''k* designate

followed in the direction of arrows as depicted in the Figure 1.

**•** composting of separately collected biodegradable fractions,

sewage sludge from waste water treatment plant and

**Figure 1.** Schematic presentation of integrated waste management concept

**•** MBT of rest of waste after separate collection

**18** 21 from the municipal waste treatment plant waste with approximately 25% of solids.

**Author(s) Name(s): Filip Kokalj and Niko Samec** 

282 Advances in Internal Combustion Engines and Fuel Technologies

**•** separate collection,

**Line** 

**Page No.** 

Regional concept of integrated waste management should include:

**•** sorting of separately collected fractions and recycling marketable part,

**Chapter Title: Combustion of Municipal Solid Waste for Power Production** 


To reduce the waste amount on the landfill, in accordance with the concept mentioned, waste must first be collected separately and then re-used or treated. In such manner the amount of the waste residue to be deposited on the landfill is minimised. The article shows many technical compliance arguments of the regional concept with the requirements, based on structural and chemical analysis of municipal waste and foreseen technology for waste treatment.

Separate collection ensures three collected waste stream of MSW and they are:


#### **3.1. Treatment of biodegradable waste**

The composting plant performs composting of separately collected biodegradable waste. The processes aerobic or anaerobic type of composting and run mostly in an enclosed hall, separately from the employees and the environment. The procedure is fully automated and controlled from the control room. The prepared composting mixture is handled only by appropriate technology. The composting process is designed to make the biodegradable waste decompose into compost in the shortest amount of time possible. For this purpose, the mass is constantly treated with air (aerobic process) which is an essential element for a quick and effective decomposition or just mixed in closed reactor (anaerobic process). Such conditions ensure the suitable quality of the end product.

The plant consists of three parts:

**•** the reception area,

1


In case of anaerobic treatment biogas is produced. The biogas consists of 40% to 60% from methane and can be utilized in power and heat production. In developed countries it is generally used to power engines of turbines to produce highly subsidized electrical power. Technologies are also available to upgrade this biogas into bio-methane, having the same properties as natural gas what gives a possibility to inject this renewable source gas into national natural gas grid.

conditions limit the possibility for electrical power production to around 25% of input waste energy. This can be roughly calculated with simplified Eq. 1 having in mind that complete cycle total isentropic efficiency is calculated by multiplying all isentropic efficiencies of the

Rankine c.≈1 -

Legislation in European Union [9] has set strict limits for the beneficial utilization of energy produced by waste thermal treatment. The thermal treatment can only be regarded as "recovery operations" and not "disposal" if plants reach the energy efficiency of at least 0.65

All energies in Eq. 2 are calculated in GJ/year. The term Energy produced in Eq. 2 means annual energy produced as heat or electrical power. It is calculated with the energy in the form of electrical power being multiplied by 2.6 and heat produced for commercial use multiplied by 1.1. The factor 0.97 is a factor accounting for energy losses due to bottom ash and radiation. To reach the set efficiency the most practical way is to maximize the electric power production.

New technologies are emerging on the market and by utilizing other thermodynamic cycles it is possible to achieve higher conversion efficiencies of the energy of waste into power. Those technologies are based on gasification or pyrolysis process and employ produced synthesis

To get a building permit for a waste thermal treatment in Europe today the new plant must in

Developed countries also largely support production of electrical power from renewable energy sources. Every country has developed its own scheme to support this production and they are called feed in tariffs. These tariffs add up to regular prices of electrical power, making

Energy and environmental aspect make the energy utilization of waste justified and this process is obligatory in Europe to fulfill European waste directive demands. [9] Thermal waste processing must meet all legal requirements that define the process of waste incineration which is rather called waste recovery operations. [9] Heat generated can be used to produce electrical

Main W-t-E process task is total thermal decomposition of hydro carbon materials in waste and the utilization of the energy, deposited in waste. Thermal conversion process products are inert materials. The quantity and toxicity of the remains and quantity of formed pollutants is

Energy efficiency= Energy produced - Energy from fuels - Other energy imported

( Temperature of steam condensation <sup>K</sup> Temperature of steam superheating K

0.97×(Energy of waste input <sup>+</sup> Energy from fuels) (2)

Cycle total isentropic efficiency

Combustion of Municipal Solid Waste for Power Production

)

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(1)

285

cycle. This value is generally for W-t-E plants technology applied around 0.7.

Electrical power production eff.

set by Eq. 2.

gas in gas engine or turbine.

most cases fulfill this recovery standard.

this electrical power production very lucrative business.

power, hot water for heating and cool media for cooling.

primarily dependent of the process quality in the reaction chamber.[2]

#### **3.2. Recycling sorted household waste**

The sorting plant allows separately collected raw materials, such as plastic, paper, cardboard and metals, to be additionally sorted, in line with the primary objective of the technological procedure – to produce the best quality fractions of plastic, e.g. polyethylene (PEHD, LDPE), polyethylene terephthalate (PET) and polystyrene (PS), and paper, cardboard and other secondary raw materials intended for further processing. Additional sorting is performed since the collection sites and centers collect various kinds of plastic, various kinds and qualities of waste paper and cardboard and various fractions of waste metal. In separate collection there are always impurities that have to be eliminated before handover of recyclable fractions.

## **3.3. Treatment of the remains of the household waste**

The remains of the household waste is residual mixed municipal waste and is taken into MBT with the intend for biological stabilization of waste following further mechanical treatment. The waste is at the end of the process separated into combustible fraction (material to be utilized in W-t-E plants) and into inert fraction that is deposited at the landfill. The process of the mechanical and biological treatment of the remains of household waste is foreseen in the following treatment phases:

