Waste Management

Published on November 2016 | Categories: Documents | Downloads: 57 | Comments: 0 | Views: 519
of 53
Download PDF   Embed   Report

Research and development of a waste management plan for handling plastic material.

Comments

Content

Department Of Mechanical Engineering

M.Eng. Mechanical Engineering Waste Management

Syafawati Hasbi May 2009

Supervisor: Miss Elena Rodriguez-Falcon Dr Roger Lewis

Thesis submitted to the University of Sheffield in partial fulfilment of the requirements for the degree of Master of Engineering

Summary Currently, the waste in Pabal is sorted, scavenged and some of them is burnt. Due to the wet climate, waste like paper decomposes quickly, however the plastic waste such as crisp, cookies and snacks packets still remains. In this context, a waste review and research has been carried out to find a practical solution to reduce, reuse and recycle the plastic waste. A test had been conducted to identify the types and properties of these packaging. There are three stages involves in this project which are the collection, recycle and reuse stage. For the collection process, the community and the public official cleaning will be provided with a 35 litre blue bag for the plastics waste. The plastics waste will be deposited in the blue bin and will be send to the separation unit while other waste will be deposited in the green bin and will be send to the designated area. In addition, two separation devices had been developed to ease the waste collection and separation process. At the separation unit, the polypropylene waste will be send to the manufacturing unit while other plastic waste will be send to the recycling unit in Pune. Several ideas of reusing the polypropylene waste were generated. In order to manufacture the reusable product, a test to determine the best method of joining was carried out. The waste management plan proposed will helps to keep the village clean, educate the community and generates incomes to develop the village.

Nomenclature
PP: Polypropylene HDPE: High density polyethylene LDPE: Low density polyethylene PVC: Polyvinylchloride PVDC: Poly vinylidene dichloride SPI: American Society of Plastic Industry UWEP: Urban waste expertise programme

 tensile : Tensile stress
F: Force A: Area
ii

Contents
Summary.................................................................................................................................ii Nomenclature..........................................................................................................................ii Contents.................................................................................................................................iii Acknowledgements................................................................................................................iv 1. Introduction.....................................................................................................................1 1.1 Problem description..................................................................................................1 2. Waste generation.............................................................................................................2 2.1 Plastic........................................................................................................................2 2.2 Plastic waste generation............................................................................................4 2.2.1 Background...................................................................................................4 2.2.2 Plastic waste generation in Pabal..................................................................4 2.3 Polymer Identification test........................................................................................5 2.3.1 Methodology.................................................................................................5 2.3.2 Results..........................................................................................................6 2.3.3 Conclusion....................................................................................................7 2.4 Polypropylene...........................................................................................................7 2.4.1 Introduction..................................................................................................7 2.4.2 Properties of polypropylene.........................................................................8 3. Plastic waste management method.................................................................................9 3.1 Background..............................................................................................................9 3.2 Selection process.....................................................................................................11 4. Waste collection and separation....................................................................................12 4.1 Background.............................................................................................................12 4.2 Plastic waste collection and separation process in Pabal........................................12 4.2.1 Economics of collection and separation process in Pabal...........................14 4.3 Design for separation device..................................................................................15 4.3.1 Concept development..................................................................................15 4.3.2 Design ideas................................................................................................17 4.3.2.1 Design 1................................................................................................17 4.3.2.2 Design 2................................................................................................17 4.3.2.3 Design 3................................................................................................20 5. Recycle..........................................................................................................................22 5.1 Background.............................................................................................................22 5.2 Recycling in Pabal..................................................................................................25
iii

6. Reuse.............................................................................................................................27 6.1 Background.............................................................................................................27 6.2 Reuse in Pabal.........................................................................................................27 7. Manufacturing process of reusable product.................................................................28 7.1 Method of joining plastic........................................................................................30 7.1.1 Methodology...............................................................................................30 7.1.2 Results and discussion................................................................................32 7.1.3 Conclusion..................................................................................................37 7.2 Manufacturing process of the reusable product......................................................37 7.2.1 Manufacturing the reusable product in Pabal.............................................37 7.2.2 Manufacturing process...............................................................................39 7.2.2.1 Product 1: Envelopes............................................................................41 7.2.2.2 Product 2: CD pouch.............................................................................42 7.2.2.3 Product 3: Pencil case...........................................................................43 7.2.2.4 Product 4: Decorative and gift shred....................................................44 7.2.2.5 Product 5: Coursework binder or book cover.......................................44 7.2.2.6 Product 6: Raincoat.............................................................................44 8. Conclusion....................................................................................................................45 9. Reference......................................................................................................................45

10. Appendices..................................................................................................................47

Acknowledgements
Miss Elena Rodriguez-Falcon and Dr Roger Lewis for their supervision, help, expertise amd advice throughout the project Mr Richard Key for his help in setting up the houndsfield tensometer to test the method of joining two plastic sheet.

iv

v

1. Introduction
1.1 Problem description
Pabal is a rural village in Pune District, India located 80 miles east of Mumbai. The total population of Pabal is approximately 9000 with the core (which has radius of about 2 km). Primarily, those outside the core village live in hamlets and are farmers.

Figure 1.1 Pabal (Source: MapOfIndia) In Pabal, families produce about a kilogram of garbage a day. Some of the waste is sorted and scavenged; but the remaining waste is piled in designated areas throughout the village or on the road side. Usually, the waste deposited in the designated area is burnt. At the moment, there is no organised disposal system in place. Most of the waste found in these areas or by the roadside consists of plastic packaging, paper and cardboard waste. Other waste such as metals are sold as scrap and food waste is eaten by pigs that owned by the community member. Generally, paper and cardboard decompose quickly due to the wet climate, but plastic waste still remains. The most common plastic waste found is plastic packaging from snacks, cookies or biscuits.

Figure 1.2: Plastic waste at Pabal (Source: engIndia)

The purpose of this project was to find a practical solution to reduce, reuse or recycle the waste. As the main problem comes from plastic waste, this project will be focusing on developing a waste management mechanism to handle, reduce, reuse or recycle plastic waste.

2. Waste generation
2.1 Plastic
Basically, there are about 50 different groups of plastics, with hundreds of different properties. Not all plastics are recyclable. The two main types of plastic are thermoplastics, which soften when heated and harden again when cooled, and thermosets, which harden by curing and cannot be re-moulded [10]. Typical types of plastics are shown in table 2.1 Plastic group 1.Thermoplastics Plastic type High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), Polypropylene(PP), Polystyrene (PS), Polyvinyl Chloride (PVC) 2. Thermosets Epoxy resins, Phenolics, Polyurethane, Polyamide, Polymethylmethacrylate, Styrene copolymer Table 2.1 Typical types of plastics [10]

2

The most common types of plastics used are thermoplastics as they comprise 80% of the plastics used in the world [8].The majority of the plastics are used in the production of packaging, household and domestics products, electrical and electronic goods. In order to make sorting and recycling easier, the American Society of Plastic Industry (SPI) has developed a standard marking code to help consumers identify and sort the main types of plastics [11]. The code is a 3-sided triangle arrow with a number in the centre and letters underneath. The 3-sided arrow was selected to isolate and distinguish the number code from other markings. The number indicates the types of plastics from which the container is made. The standard marking codes used and theirs application is shown in table 2.2 Standard marking code Types of plastic Polyethylene terephthalate (PET) Application Fizzy drink bottles and ovenready meal trays High density polyethylene (HDPE) Bottles for milk and washing up Polyvinyl chloride (PVC) Food tray, cling film, bottles for squash, mineral water and shampoo. Low density polyethylene (LDPE) Carrier bags and bin liners

Polypropylene (PP)

Margarine tubes, microwaveable meal trays, snacks packaging

Polystyrene (PS)

Yoghurt pots foam meat or fish trays, hamburger boxes and egg cartons, vending cups, plastic cutlery, protective packaging for electronic goods and toys

Any other plastics that do not fall into any of the above categories

An example is melamine, which is often used in plastic plates and cups

Table 2.2 Standard marking code of plastics and theirs application (Source: SPI)
3

Plastic are used widely in numerous application in life due to the beneficial properties of plastics. Generally, plastic have extreme versatility and ability to tailored to meet very specific needs, lighter weight than competing materials, extreme durability, resistance to chemical, water and impact, good safety and hygiene properties for food packaging, excellent thermal and electrical insulation properties and relatively cheap to produce [11]. The increase in volume of plastic waste has creates a cause of concern to the society. The main problems of plastic waste are it is not biodegradable, it cannot be mixed with one another as the chemical reactions that ensue will cause processing difficulties, and it is hard to recycle without separation from food or other waste.

2.2 Plastic wastes generation
2.2.1 Background Socio-economic development, degree of industrialisation and climatic condition often affects the waste generation rates. In India, the amount of plastic wastes generated is increasing due to the rapid rate of urbanisation in India. The rise in plastic consumption is due to the rising affluence and public embracement of western consumerism [5]. Plastic has been used by the public to replace the traditional method of packaging due as it is cheaper. Moreover, plastics usage has grind down the traditional industries in India and have slowly propagated the throwaway culture in India society. The consumption of bottled water, fast food and can drinks has also contributes to the rise of plastic waste generation in India. The widespread use of plastics as a packaging medium has resulted in increase of plastic waste generation, thus creates environmental and health problems. 2.2.2 Plastic waste generation in Pabal In Pabal, the plastic wastes are mainly from crisp, cookies and biscuit packages. According to National Solid Waste Association in India (NSWAI), the total municipal solid waste generation in Pune district is 1000 MT per day while the municipal solid waste generation is 390 gms per capita per day. Of the total municipal solid waste generated, 400 MT per day comes from domestic municipal solid waste [18]. The municipal solid waste composition is illustrated in figure 2.6 below.

4

There is no exact data about the waste generation in Pabal. However based on the information given, each family produce about a kilogram of waste per day, including organic waste, dust and dirt which accumulate on the floor at home. The total population of Pabal and its surrounding areas in 2005 was about 9000 with an average number of people per household is somewhere between 2 and 6 [21]. Assumption has been made that each family consists of 5 members. Based on this assumption, there are about1800 families live in Pabal. Hence, the total estimation of volume of waste generated in Pabal is approximately 54000 kg per month. According to figure 2.1, plastic waste comprises about 0.7% of the total volume of the municipal solid waste composition. Thus, the volume of plastic waste generated in Pabal is about 378 kg per month.

Figure 2.1: Pune District Municipal Waste composition (Source: NSWAI)

2.3 Polymer Identification test
In Pabal, the main plastic waste comes from packages for biscuits, crisp and cookies and it will not decompose like cardboards and papers. A simple test has been done to identify the types of plastics of these packages. 2.3.1 Methodology The test was conducted using two samples from biscuits and crisp packages, one with a metallised surface and one without a metallised surface. The objective of the test was to define the types of plastics of which the packages were made. Before the test was carried out,
5

the samples were cut down to manageable size. Several tests were then conducted to investigate the flexibility of the samples. For the first test, the samples were cut into small sliver. The condition of the chips of the sample was observed and then recorded. The second test was a float test. This test is to investigate the flexibility of the plastics and can be carried out using water or corn oil. The first test was carried out using water while the second one used corn oil. For the float test using water, a small bowl was filled with water and a little washing-up liquid is added to avoid the surface tension of the water prevent the sample from behaving as it should. The sample was placed in the bowl and pushed down. After a couple of minutes, the sample was released and the floating condition of the sample was observed and recorded. The same procedures applied to the float test using the corn oil. Next, the copper wire test was carried out. One end of a 5cm copper wire was held with a pair of pliers. A candle was lit and the free end of the wire was placed into the flame until it was hot and no longer had a green colour. Then, the wire was removed from the flame and touched onto the plastic sample. A small amount of the plastic was expected to melt onto the wire and stick to it. The end of the wire with a small amount of plastic on it was then placed into the flame. The colour of the flame was observed and recorded. The last test conducted was to define whether the sample is flexible, semi-rigid or rigid. The sample was bent repeatedly and the surface of the sample was felt by hand. The observations were then recorded. 2.3.2 Results The results of the test were illustrated in table 2.3 below.

6

Types of test Sample Sliver test Metallised surface The sample has smooth sliver and no powdery chips Float test (water) Float test (corn oil) Copper test Both of the samples floated Both of the samples floated

Result Non-metallised surface The sample has smooth line and no powdery chips

The colour of the flame for both samples is blue. The sample burn slowly and cleanly, drips and has a distinct sweet wood odour.

Flexibility test Surface test

Both of the sample bend repeatedly without breaking The sample has shiny and smooth surface Table 2.3: Results for polymer identification test The sample has smooth surface

2.3.3 Conclusion Having done the test, it can be concluded that the crisp packet is made from polypropylene, one of thermoplastics. The sample with metallised surface is made from an aluminium film attached to a flexible polypropylene film and is sandwiched together. On the other hand, the sample with non-metallised surface is made from polypropylene coated with PVDC coating or acryclic.

2.4 Polypropylene
2.4.1 Introduction Polypropylene (PP) is a thermoplastic polymer commonly used in food packaging such as crisp packets, ketchup bottles, yogurt containers, medicine bottles, medical syringes, beakers, automobile battery casings and carpeting markets. Structurally polypropylene is a vinyl
7

polymer which is quite similar to polyethylene but with a methyl group attached to every alternate carbon atom in the backbone. It is made of polymerisation of propylene by ZieglerNatta polymerisation or currently by metallocene catalysis polymerisation [4]. The repeat unit of polypropylene is -CH2 -CH(CH3 )-

Figure 2.2: Polypropylene monomer unit (Source: Recoup) Polypropylene has an intermediate level of crystallinity between low density polyethylene (LDPE) and high density polyethylene (HDPE), its Young modulus also intermediate. This material is less tough than HDPE and less flexible than LDPE. It also has excellent moisture barrier characteristics, good clarity, high gloss and good tensile stress. As PP has only average gas barrier properties, it is often used in combination with metallised film, PVDC coating or acrylic which provides additional barrier properties. The general properties of polypropylene are illustrated in table 2.4 below. Properties Maximum temperature Minimum temperature Melting point Tensile strength Hardness Specific gravity 135 °C 0 °C 170 °C 4500 psi /31 MPa R95 0.9 Value

Table 2.4 : General properties of Polypropylene ( Source: DynaLab)
8

2.4.1 Properties of Polypropylene The crisp packet is made from polypropylene laminated onto a metal foil. This material comprises polypropylene film which has been metallised on one surface by vacuum deposition of high purity aluminium. The appearance is of aluminium foil, but the film has the flexibility, strength and thickness of the base film which is the polypropylene. The general properties of this metallised film are the same of slightly better than the base film. Metallised polypropylene plastics are made from various metals including aluminium, chromium or a combination of nickel and chromium. Aluminium film has consistent optical density and act as a barrier to moisture and light, with superior heat sealing properties. It is highly craze and crack resistant. Metallised polypropylene plastic exhibits superior tensile properties resulting in superior formed barrier whereby gas and moisture barrier properties are maintained despite high tensions and stresses.

3. Plastic waste management method
3.1 Background
Generally, there are several methods that can be used for waste disposal. These methods are shown in figure 3.1 below.

Figure 3.1: Methods of waste disposal [8]

Landfill is the quickest and cheapest way to get rid of the waste. Landfill is the oldest form of waste treatment and is low cost compared to other disposal options. In India, landfill or open dumping is the most commonly accepted way of disposing waste. Waste is collected,
9

transported and deposited at the low lying areas. Most of the waste is suitable for landfill. In addition, other disposal options will also require landfill as the final disposal route for the residue. This method however threatens the quality of life of the community by the nuisances from the odours, smokes, dust, litter, and pests. During monsoons, the rain will dissolves the toxins present in the waste and permeates the soil and pollutes groundwater. Moreover, this method is not a preferable solution as the waste dump produces other environment and health problem. Nevertheless, this is the method used by the local community in Pabal at the moment.

The other method of waste disposal is the incineration. This method is very convenient and safe mean of waste disposal. The combustible material in the waste is converted to gaseous oxides. The incombustible residue is then disposed of via landfill. There are four main waste incinerator technologies which are mass burn, fluidised bed combustion (FBC), pyrolysis and gasification [9]. However, this method encourages more waste, wastes energy and causes pollution from the smoke, gases and ash from the incinerators that contain harmful dioxins which causes cancer. As Pabal is a small village, the smokes, gases and ash might affect the villager’s health that live near the incinerator.

Another method considered is deep well injection. This method disposes the waste by storing the waste permanently in underground strata. Deep well injection method is far cheaper than incinerations but the safety of this method cannot be clearly demonstrated. However, this method is not suitable to be implemented due to the limited suitable place in Pabal.

Last but not least are the recycle and reuse methods. Both of these methods promote energy savings, resource conservation and a cleaner environment. In term of cost, this method is cost effective compared to others mean of waste disposal. By definition, waste reuse involves using the product or package more than once or reusing it in another application, not necessary the original application. The example of reusing includes reusing the carrier bag, glass and milk bottles. The advantages of reusing waste are that it can reduce the amount of waste produce, extends the lifetime of the material used and helps to save raw materials and energy used to produce a new product. Recycling in the other hand is the collection, separation, clean-up, and processing of waste materials to produce a marketable material or
10

product. Due to market demand for recycled content material and the price of oil, the demand of recycled material is expanding. Recycling reduced consumption of energy and reduced the amount of solid waste going to waste dump in the village. In addition, this method would generate income for the local community in Pabal by reusing the waste to manufacture a new product. This method however requires high degrees of local community participation.

3.2 Selection process
All the methods are assessed using the following morphological chart in table 3 to find the best method of waste disposal in Pabal. Each method of waste disposal is ranked between 1 to 5; where 1 indicates poor and 5 indicates excellent. The best method chosen is the method with the highest mark.

Waste disposal method/ Criteria Waste dump Landfill

Effectiveness Impact to

Health

Economic

Suitability to implement in Pabal

Total

environment issues

3

1

1

2

4

11

3

2 1 1

1 1 1

2 3 2

3 2 3

11 10 9

Incineration 3 Deep well injection Reuse and recycle 4 2

5

4

4

5

22

Table 3: Morphological chart of the selection process

Having considered the pros and cons of each method of waste disposal, the best options for Pabal community are to recycle and reuse waste.

11

4 Waste Collection and separation
4.1 Background
There are three methods of waste collection. There are curbside collection, drop off or buy backs centers and material recovery facilities [10] The curbside collection requires the residents to use one or more containers to separate and recyclable materials that are diverted from the normal waste stream. The type of and number containers can vary dependent on the variety of materials collected and the degree of separation desired. The design, capacity, and construction of the containers can also vary. For example, the green bin is used for refuse stream and blue bin for recyclable stream. The second one is the drop off or the buyback centres. The voluntary participation in recycling programs is often related to the ease with which an individual can participate. The drop-off centres make the recyclable materials collection easier and less expensive to implement than curbside programs. They are especially effective in areas where regular waste collection is not required or available. Buy back centres offer all of the benefits of drop-off centers and the increased incentives of monetary benefits to participants. They are however more expensive to operate because they must be staffed, secured, and handled cash. The last one are the material recovery facilities (MRF). MRF is a facility that receives, sorts, and prepares commingled recyclables materials for marketing to end-user manufacturers [8]. Most commingled processing systems separate the containers made from plastic, glass and aluminium and do not attempt to separate the fibers. Mechanical separation techniques are used to separate the commingled recyclable. This method has high processing efficiency, however the efficiency of this method rely on the mechanical equipment used.

4.2 Plastic waste collection and separation process in Pabal
Having considered the local situation in Pabal and the population density of the area, the best collection method to be used is the curbside collection. However, other factors such as degree of source separation that the community will be willing to tolerate and still participate, the desired capture levels, the amount of money available to pay for the programme, and the source of the fund should be taken into consideration before this method can be implemented.
12

A separation centre will be built at the designated area where the waste is deposited. This programme requires the community to use one or more containers to separate the recyclable materials. Each household in Pabal will be supplied with a 35-litre blue reusable bag to store the plastic waste. Based on the information given, people in Pabal sold metals and plastics as scrap. Apparently, waste separation had already been implemented in the community. By giving them a reusable bag to separate their waste, the separation process will be more systematic and consistent. In addition, two wheel bins will be placed around the village. The blue bin is used for plastic waste while the green bin is for other waste. Both of these bins will be used by the villagers to deposit their waste. By this way, the waste will be separated mainly by hand prior to collection. As Pabal is a small village that has constraint on technologies available, fund and transportation, the collection service will be made by the public official cleaning. The collection service will be made twice a month. The waste deposited in both of these bins will be collected and transported to the separation centre. Plastic waste collected from the blue bin will be separated once again at the separation centre while the other waste will be deposited at the designated area. At the separation centre, the plastic waste is sorted according to its types. Even the separation of the plastic waste is made at home, separation at the separation centre is also necessary as the community cannot be relied on to make perfect sort every time. The workers at the separation centre will sort the plastic into two categories which are the polypropylene and other types of plastics. The polypropylene waste will be send to the manufacturing centre while the other plastic waste will be send to the recycling centre at Pune. On the other hand, waste that is scattered throughout the village and by the road side will be collected by the public cleaning official. The public cleaning official will discard the item from the trash and separate them according to their type before depositing them to the designated area. This macrosorting process can be either manual or automated operation.

13

Figure 4.1: Waste flow in the collection and separation process 4. 2.1 Economics of collection process The cost of collection and separation process will involves cost of labour which includes the public official cleaning and the workers at the separation centre wages, labour overhead which includes the clothing, insurance and supervision, publicity which includes advertising, leaflet printing and distribution and the cost of building the separation centre. The publicity of this programme is essential to create awareness among the community and increase their participation. 4.2.2 Problems expected in the collection and separation process Problems might arise due to lack of participation from the community, economic and human resource. High participation from the community are needed in order to ensure the collection and separation process successful. As this programme is still new for the community, they
14

need to be continuously informed about the programme. Continuous information campaign is vital to achieve higher participation. Door-to-door visits, leaflet distributions of informative materials, school visits and posters can be made to increase awareness of the community [3]. In addition, the efficiency of the separation process might be low due to lack of hand-sorting PP experience. Continuous supervision and additional training might reduce this problem. In addition, this programme will also creates job opportunities for the community as workers are needed at the separation and manufacturing centre. Incomes for these workers can be generated from the plastics waste sold to the recycling centre.

4.3 Design for separation device
4.3.1 Concept development The existing method of separating different types of plastic is to separate by hand. However, this method is costly and prone to error as it is difficult to distinguish different types of plastic. Nowadays, technologies such as x-ray fluorescence, infrared and near infrared spectroscopy, electrostatics and floatation had being introduced to separate plastics automatically [7]. The first techniques being considered for the design of separation device is electrostatic separation technique. This technique involves the application of electrostatic charge. When two different types of plastic rub together, a positive charge will be develops on one surface and a negative charge on the other. The charged plastic is then supplied to the rotating drum electrode into an electrostatic field formed between the drum electrode and the flat plate electrode. The positively charged plastic is attracted to the negatively charged drum electrode and vice versa

Figure 4.2 Electrostatic Separation Techniques (Source: Hitachi Zosen)
15

The next technique to separate mixed plastic is by density separation. Different densities of materials are used to carry out the sorting physically. Generally, this technique is only effective in separating plastics materials with densities less than 1 g/cc, usually polyethylene and polypropylene [7]. Density separation is a practical method for the sorting of certain types of plastics at relatively low cost. Froth floatation is the cheapest and most extensively used process for the separation of chemically similar minerals and to concentrate ores for economical smelting. This method originates from Japanese researcher back in 1970s [1]. Plastic floatation is a combination of froth floatation and gravity separation. Accordingly, the idea of particle control was applied for separation of mixed plastics. Compared to other separation techniques, froth floatation has a reduced cost. The process involves are selectively attaching air bubbles to specific plastic, lifting these particles to the surface and then mechanically removing the particles held in the surface froth. Next is the air table method. Air table method is a dry gravity separation. Dry gravity separation has the attraction of low capital input and operating cost and is environmentally friendly due to the absence of water, chemical and drying requirements. Air table does not require separating the low-density fraction from the air stream and is capable of effectively treating plastic with different densities [2].

Figure 4.3 Schematic design of air table (Source: Dodbiba et al, 2004)

16

Last but not least are the near infra red technique. Infra red energy is used to heat and dry a washed stream of mixed thermoplastics. To separate polypropylene, the mixed stream is irradiated to a point in which the polypropylene is softened but not melted. Following the heating stage, the mixed plastic stream is fed through a set of rollers. The softened polypropylene sticks to the roller and is removed from the stream. The remaining mix continues through the process, which progressively heats and separates the next desired plastic, until all the components in the mix are separated from each other. 4.3.2 Design ideas Based on several techniques discussed, design ideas were generated during brainstorming session. 4.3.2.1 Design 1 Design 1 is a magnetic separation device. This design will apply the principle of magnet to collect the metallised crisp packet. As mentioned earlier, the crisp packets are made from metallised polypropylene which is sandwiched together. The metal used in the film is aluminium. However, aluminium is not magnetic [16]; thus the metallised plastic cannot be separated using magnetic properties. Therefore, the idea of having a magnetic separation device is not viable. 4.3.2.2 Design 2 Design 2 involves the combination of the electrostatic separation and the vacuum litter collector. This design can be used for quick response clean-ups as well as cleaning confined and awkward areas where the mechanical sweepers cannot access. In Pabal, this design can be used to collect and sort the plastic waste on the roadside. Design brief and specification Design 2 is made up from several components which are the intake port, the exhaust port, an electric motor, a voltage supply, the fan, an electrostatic pre-charge hopper, two charged pole, a splitter, suction hose (diameter: 125mm) two collector bins, wheels and housing (88.9cm x 48.3 cm)

17

Figure 4.4: Design 2

Mechanism of design 2

Figure 4.5(a): The mechanisms of the Design 2
18

Figure 4.5 (b): Mechanism of design 2 The voltage supply makes the motor works. The fan which has an angled blade is attached to the motor. The fan blades force the air forward as it turned. The air is forced towards the exhaust port. The density of particles increases in front of the fan and decreases behind the fan as the air particles are driven forward. The drop in pressure behind the fan creates suction, a partial vacuum inside the device. As the air pressure inside the device is lower than the pressure outside, the air will be pushed into the device through the intake port. The rotating fan creates a constant flowing stream of air moving through the intake port and out the exhaust port. The moving air particles will rubs against the waste such as crisp packets or cookies packages as they move. When the suction is strong enough, the friction carries the waste through inside the device. When the waste is already inside the device, it will be placed in the pre-charging hopper where they will received an induced electrostatic charge causing the polypropylene which is the crisp packet to become negatively charge and the other plastic waste to become positively in charge. The induced charge must be applied for an adequate duration about 30-60 seconds and at sufficient strength to create opposite charges on the surface of the plastics waste. If the
19

strength applied exceeds the amount needed, the waste will attract to one another, thus prevent the separation. The negative terminal of the voltage supply is attached to one plate and the positive terminal of the voltage supply is attached to the other one as well as the electrostatic pre-charging chamber by means of leads. The vertical plates are made from a conductive material such as aluminium foil. The plates define two oppositely charged electrostatic fields beneath the precharger hopper. The mixed wastes which have been charged will then be released from the pre-charging hopper by free fall due to gravity influence, passing through the opening gate to migrate down between the two oppositely charged plates. As the stream of mixed wastes passing through the two oppositely charged plates, the negatively charged polypropylene waste are drawn towards the positive poles and the positively charged other plastic waste are drawn towards the negative poles producing two divergent stream. The splitter is used to increase the separation efficiency. The falling position of the waste varies depends on the charging factor such as the mixture of waste ratio, charger material, drag force, and electrostatic force. By having the central splitter, the polypropylene waste stream can be strongly deflected to the positive poles while others waste which might have a neutral charge and fall freely will be deflected to the negative poles. The polypropylene waste can then be collected from the collector bin 2 while the other stream of plastic waste can be collector from the collector bin 1. Design 2 constraints However, the device might not be feasible to be developed in Pabal due to the limited resource of materials and skilled labour. Further investigation is needed to build the prototype of the device as this idea is only conceptual at the moment. However, in the near future, the local community in Pabal may build this device when they have the capability to do so. 4.3.2.3 Design 3 Due to the limited resource of materials and skilled labour in Pabal, the design of the separation device should be within the resource available. In this case, design 3 will apply the
20

idea of having a handheld mechanical device to collect and separate waste on the roadside of Pabal. Design brief and specification Design 3 consists of a two brush rollers that act as sweeper, 133.4 cm x 78.7 cm x 83.8 cm bin, 25.4 cm diameter semi-pneumatic wheels and tube handles.

Tube handle s Bin

Wheels

Brush roller

Figure 4.6: Side view of design 3

Pneumatic wheels

Brush rollers

Figure 4.7: Top view of design 3

21

83.8 cm 133.4 cm

78.7 cm 25.4 cm 12.5 cm

Figure 4.8: Dimensions of design 3

Mechanism of design 3 Design 3 will collect the waste in a circular motion. When it is pushed forward, the roller with brushes will move in opposite direction and collect waste that it comes in contact with. It will collect everything in its path and accumulates waste such as crisp packet, papers, tissues, dirt and other waste inside the hopper. The waste from the hopper can then be collected and separated manually by hand. The hopper and the tube handle can be built using woods or plastics.

22

Direction of moving

Figure 4.9: Mechanism of design 3 Design 3 constraints Design 3 can be build within the resource available in Pabal. However the drawback of this design is it is not practical to be used at uneven road surface. In addition, it cannot collect waste from hard-to-reach or inaccessible area. Nevertheless, the waste can be collected manually by the workers.

5. Recycle
5.1 Background
Recycling involves several stages which are the waste generation, collection, separation, processing and final disposal stage. Recycling plastic packaging divides into two categories; the first one is the mechanical recycling while the second one is the chemical or feedstock recycling [8]. Mechanical recycling of plastics refers to processes which involve the melting, shredding or granulation of waste plastics. Plastics must be sorted prior to mechanical recycling. On the other hand, the chemical or feedstock recycling is describes as a range of plastic recovery techniques to make plastics which will break down the polymers into their constituent monomers which in turn can be used again in refineries or petrochemical and chemical production. The advantage of feedstock recycling is it has a greater flexibility over composition and is more tolerant to impurities than mechanical recycling.

23

There are several benefits of recycling plastic waste. Firstly, the plastic production requires significant quantity of resources, primarily fossil fuels, both as a raw material and to deliver energy for the manufacturing process [9]. It is estimated that 4% of the world's annual oil production is used as a feedstock for plastics production and an additional 3-4% during manufacture [2]. In addition, plastics manufacture requires other resources such as land and water and produces waste and emissions. The impact on environment depends on the types of plastics and the production method used. Plastic production also involves the use of potentially harmful chemicals, which are added as stabilisers or colorants. On the other hand, recycling plastic waste are also cost-effective disposal, promotes energy savings, resource conservation, cleaner environment. However the disadvantage is it requires high degrees of consumer participation The main problems of recycling plastic waste are various type of plastic waste cannot be mixed with one another, the chemical reactions that ensue cause too much processing difficulties. Furthermore, not all plastics are recyclable. Polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC) are the types of plastic which are commonly recycled. In India, the material recycling of plastics is estimated to be 60% [14]. Recycling is an economically driven activity in India. The recycling unit is divided between the formal (municipal) and informal sector. The informal plastic recycling unit involves of waste pickers, kabariwala (itinerant waste buyer), scrap dealer, bulk buyers and recyclers [5]. However, this unit has outdated technology and unskilled labour

Figure 5.1: The hiercachy of the informal sector (Source: Priya Narayan, 2001)
24

Even though India has a high rate of recycling, the recycling process does not employ current technology but is done by experience [5]. The colour, transparent, hardness, density and opacity are taken into account when separating the plastic waste. The plastic waste is then sent to the granulators. The traditional grinding and extrusion to obtain granules is the only technology employed in recycling plastic waste. The granulators make granules from the plastic while the converters make plastic products out of granules. Basically, the plastic product made from the recycled plastic is not necessary has the same usage of its origin. There is a wide range of products that have been manufactured from recycled plastics [6]. Figure 5.2 shows the application of recycled plastics. Type HDPE/LDPE Method Applications

Injection moulding, blow moulding or Bottles, toys, flower pots, traffic calendaring cones, buckets, tumblers, household items, sacks, agriculture drainage pipes, bags, sheets

PP

Injection moulding or blow moulding after controlled degradation

Buckets, household items, suitcases

PVC

Injection moulding, calendaring

Drainage pipes, bottles, footwear, cables, medicine covers, rigid pipes

Table 5.1: Application of recycled plastics (Source: UWEP)

5.1 Recycling in Pabal
Polypropylene recycling is environmentally and economically viable. Recycled polypropylene can be manufactured buckets, household items and suitcases (refer to table 5.1). As mentioned earlier, most of the plastic waste in Pabal comes from crisps, biscuits and cookies packaging. Previous test (refer to 2.3) identified that they are made from polypropylene laminated onto metal foil (metallised crisp packet) and polypropylene coated with PVDC coating or acryclic (non-metallised crisp packet). As separating the plastics from the metal or the PVDC coating are virtually impossible and not economic viable, these kinds of plastics are very hard to recycle. In addition, recycling of PP is not well established due to high levels of food contamination, degradation of PP during processing and variability of batch composition [13]. Thus, this option is a dead end to the community in Pabal. However,
25

for other types of plastics, the community can collect and sell them to the nearest recycling centre which is situated at Pune. A recycling centre cannot be developed in Pabal due to the technology and resource constraints.

Figure 5.2: Recycling centre in India (Source:UWEP)

By selling the collected plastic waste, the community can generate incomes for their village. Below is the purchase price for a kilogram of plastic waste. Material type Plastics Road waste Window planks, vegetable cutting planks, radio case, cassette covers Hard plastics, bucket, baskets, canes, tooth paste covers, disposable cups, cosmetics, detergent bottles and milk covers Figure 5.3: Selling price for material collected (Source: UWEP) 9.00 2.00 6.00 Price (Pound sterling/kg)

26

6 Reuse
6.1 Background
Waste reuse involves using a product or package more than once or reusing it for another application [2]. Reusing is preferable to recycling as it uses less energy and fewer resources. Reusing a product or packaging extends the lifetime of material used and therefore reduces the waste quantity requiring treatment and disposal. In addition, reuse of materials can also take the new form of new use of applications in a different environment that that of the original function.

6.2 Reuse in Pabal
As the plastic waste generated in Pabal cannot be recycled, the other option that available is to reuse them. Crisp packets and other plastic food packaging only have a single use before being disposed off to landfill. By reusing the crisp packet, less energy is wasted on producing new products. For example, it takes 500 140g crisp packet in order to make one fleece garment. Moreover, reusing the crisp packet will also encourage the community to be environmentally conscious. Several ideas of reusing the crisp packet had been generated during brainstorming session. The ideas of reusing the crisp packet are illustrated in figure 6.1

27

Figure 6.1: Ideas of reusing crisp packet

7Manufacturing the reusable product
7.1 Method of joining the plastic
In order to reuse the crisp packet, an experiment has been carried out to investigate its strength and methods to join the crisp packets before they can be reused.

28

7.1.1 Methodology Two types of crisp packet were used in this experiment, the metallised crisp packet and the non-metallised crisp packet. Firstly, the sample was joined together using different types of joining method such as glue, staples, thread, tape (clear pressure sensitive tape) and heat treatment as shown below (figure 7.1 and 7.2)

(a)

(b)

(c)

(d)

(e)

Figure 7.1 Method of joining non metallised plastics: (a) heat treatment (b) superglue (b) staples (d) tapes (e) thread

29

(a)

(b)

(c)

(d)

(e)

Figure 7.2 Method of joining metallised plastics: (a) heat treatment (b) superglue (c) staples (d) tapes (e) thread

Then, the crisp packets were cut into 14.5 x 3.5 cm size sample as illustrated in figure 7.3

14.5 cm

3.5 cm

Figure 7.3: Test sample Next, the sample was attached to the Hounsfield tensometer as shown in figure 7.4

30

Figure 7.4: Tensile test using Hounsfield tensometer: Metallised plastic

Each sample from the metallised crisp packet was tested two times with different directions of load. The first test was conducted with the joint perpendicular to the load while the second test was carried out with the joint parallel to the load. These procedures were illustrated in figure 7.5

Joint direction

Load direction

Load direction

Joint direction Figure 7.5 (a) Test 1

31

Load and joint direction

Load and join direction

Figure 7.5 (b) Test 2 After that, load was applied to the sample and the reading of its maximum load was taken. The experiment was then repeated using the sample from non-metallised crisp packet. 7.1.2 Results and discussion The results of the tensile test of each joining method are illustrated below (refer to table 7.1 and 7.2)

32

Metallised plastic

Method of joining No joint Heat treatment Glue Staples Tape Thread

Load (N) 28 45 15 5 17 10

Non metallised plastic

No joint Heat treatment Glue Staples Tape Thread Table 7.1: Results of test 1

20 10 30 5 40 5

Metallised plastic

Method of joining Heat treatment Glue Staples Tape Thread

Load (N) 60 30 35 110 10

Non metallised plastic

Heat treatment Glue Staples Tape Thread Table 7.2: Results of test 2

20 35 10 30 5

33

Having done test 1 and 2, it appeared that the sample tends to tear at the edge, thus reduced the accuracy of the test itself (shown in figure 7.6)

(a)

(b) Figure 7.6: Tear at the edge

In order to overcome this problem, both edges of the sample were taped to increase their strength. This is shown in figure 7.7

34

Joint direction

Load direction

Load direction

Joint direction Figure 7.7: Test 3 Test 3 was carried out using these samples. From the results of test 1 and 2, it can be seen that the direction of joining contributes significantly to the strength of the joint. The best direction to join the sample is perpendicular to the load direction, thus test 3 was conducted with the best three methods of joining in perpendicular direction. Below is the result of test 3: 7.1.2.2.3 Test 3 Metallised plastic Method of joining Heat treatment Tapes Staple Load (N) 75 45 7

Non metallised plastic

Heat treatment Tapes Staple Table 7.3: Results of test 3

30 35 7

35

Figure 7.8: Comparison between methods of joining of metallised plastics

Figure 7.9: Comparison between methods of joining of non-metallised plastics Tensile stress of each sample was calculated using below equation

 tensile 

F A

where  = stress, F= load, A= area

6.1

Area of sample = 14.5 cm x 3.5 cm = 50.75 cm² = 0.0051 m²

36

Test 1 Load (N) Tensile Stress (kN/m²) Metallised plastic Heat treatment Glue Staples 45 15 5 8.867 2.956 0.9852

Test 2 Load (N) Tensile Stress (kN/m²)

Test 3 Load (N) Tensile Stress (kN/m²)

60 30 35

11.82 5.911 6.897

75 45 7

14.78 8.867 1.379

Non metallised Heat treatment Tapes Staples 10 40 5 1.970 7.882 0.9852 20 30 10 3.941 5.911 1.970 30 35 7 5.911 6.897 1.379

Table 7.4: Tensile stress of sample 7.1.3 Conclusion In conclusion the joining direction should be perpendicular to the direction of load in order to increase its strength. For the metallised plastic, the best method of joining is by using heat treatment while for the non-metallised plastic; the best method is using tape (clear pressure sensitive tape). However, the values of load might not be accurate as the test was conducted only once due to time constraint and the difficulties in joining the plastic. In future, the test should be repeated few times and several readings should be taken in order to increase the accuracy of the result.

7.2 Manufacturing process of the reusable product
7.2.1 Manufacturing the reusable product in Pabal The common occupations in Pabal are barber, potter, blacksmith, farmer and laundere [21]. People in Pabal change jobs during different seasons. During summer, these people travel to Mumbai to find jobs. Normally, the careers of the community are inherited from their parents to children.

37

In order to increase their standard of living, the community can manufacture the reusable product themselves. This activity will create job opportunities for a portion of the community such as housewife and school leavers. Jobs would include collecting the crisp packet, manufacturing and selling the reusable product. This would help to stabilise the local economy and make money in the area. The reusable product does not have to be a product that can be used by the community. Reusable product like CD pouch, purse and envelope can be exported to large city area like Mumbai. In the long run, this activity will generate steady income for the local community in Pabal. 7.2.2 Manufacturing process The manufacturing process of the reusable product includes the collecting, cleaning, drying, polishing and the final makeover process. Below are the initial manufacturing processes of the reusable products: Step 1: Collecting the crisp packet The crisp packets are collected using the separation device or from the landfill manually. Step 2: Cleaning the crisp packet The crisp packets are sorted and broken packets are removed. Most of the crisp packets are washed manually in buckets as shown in figure 7.8. These packets are left soaked with dish washing liquid. The water in the bucket can be used for the next load as the water supply in Pabal is limited. The packets are then turned inside as illustrated in figure 7.9 and the few packets which are ripped are removed. Next, the packets are rinsed in the bucket as shown in figure 7.10.

38

Figure 7.10: The crisp packets are soaked with dish washing liquid

Figure 7.11: The crisp packets are turned inside out

Figure 7.12: The crisp packets are rinsed
39

Step 3: Drying the crisp packet The crisp packets are left on the drying line during windy days to let them dried before they can be reuse.

Figure 7.13: Drying the crisp packet Step 4: Polishing the crisp packet Using a cloth, the crisp packets are polished to wipe out any stubborn grease on the crisp packet.

Figure 7.14: Polishing the crisp packet Step 5: Final make over

40

The crisp packets are then ready to be reused. They can be joined together using the heat treatment for metallised plastic and tape for the non-metallised plastic before they can be manufactured to the reusable product.

In order to manufacture the reusable product, research had been made to determine the amount of stress a product can withstand. Table 7.3 shows the estimation of load required for certain products. Product Tent Tensile strength Warp 85 daN (minimum) Other information Weight: 85kg Volume: 0.29 m³ Raincoat Airship envelopes 50 MPa 1000N/cm Weight: 230 g/m Material: Zylon/Vectran Paper envelope (15 mm²) Handbag 15mm/N 6000 pounds Material: Basket-weave pattern made from the seatbelt used by Ford CO Flower pot 1250MPa Material: Moplen EP 340S Polypropylene, Impact polymer Table 7.3: Estimation of load required for a product Having considered the amount of load these products can withstand; the envelope, CD pouch, pencil case, decorative or gift shred, and coursework binder are chosen to be the manufactured reusable product as crisp packet can only withstand small amount of load due to the nature of its material. 7.2.2.1 Product 1: Envelope After the joining process, the crisp packet is then cut into the desired shape to make the envelope (refer to figure7.15). These envelopes can be used to post letters, cards, or CDs.

41

Figure 7.15: The crisp packet envelopes manufacturing process 7.2.2.2 Product 2: CD Pouch The crisp packets are light, strong and water impermeable. As they are rectangular in size, they are the perfect shape for CD pouch. Manufacturing the CD pouch only takes two steps. First, the crisp packet is turned inside out with a sleeve of cardboard inside. Next, the CD is inserted and the label is glued to the CD pouch. The CD pouch is then ready to be used.

Figure 7.16: The CD pouch manufacturing process
42

7.2.2.3 Product 3: Pencil case The crisp packet also can be used to make a pencil case. Materials needed to manufacture a pencil case using crisp packets are crisp packets, sticky back plastic, needle and thread, glue, a zipper, and a pair of scissors. Firstly, the crisp packets are cut into random shapes. After that, the back of the plastic is peeled off. The random shapes crisp packets are then glued onto the whole sheet as shown in figure 7.17 below. Next, the plastic foil is glued on each side to make a pouch. Finally, the zipper is sewn into the top of the pouch.

Figure 7.17: Manufacturing process of pencil case using crisp packet (Source: Instructable Robot)

43

7.2.2.4 Product 4: Decorative and gift shred The crisp packet can be shredded and use in gift bag as illustrated below

Figure 7.18: Decorative and gift shred 7.2.2.5 Product 5: Coursework binder or book cover The crisp packet can also be used as coursework binder or book cover.

Figure 7.19: Coursework binder 7.2.2.6 Product 6: Raincoat Nearly half of the people in Pabal made their clothes themselves as they are cheaper from buying ready-made clothes [21]. Generally, cotton canvas is used by the tailor to makes shirts. Apart from using cotton canvas, the crisp packets can also be used to makes shirts. As Pabal experiences two seasons in a year which is the dry and monsoon season, it might not be feasible to make a shirt using crisp packet. However, as crisp packet is strong and water
44

impermeable, it can be used to make a raincoat instead of shirt. In Pabal, it is estimated that there are approximately 25-45 rainy days each year [21]. A raincoat made from crisp packet can be used during this season. As people in Pabal are capable of making shirt themselves, it would not be a big problem for them to manufacture the raincoat. Rather than making the raincoat for their use, they can manufacture the raincoat themselves and sell them to other cities in India.

8. Conclusion
Based on the test conducted, it can be concluded that most plastic waste such as crisp, cookies and snacks packets are made from polypropylene. Recycling these plastics is a dead end to the community in Pabal as it is impossible to separate the PVDC coating or metal film from the plastics. Nevertheless, these plastics can be reuse to manufacture a new product such as CD pouch, envelope, decorative and gift shred, pencil case or raincoat. Manufacturing unit can be developed in Pabal to manufacture these products. By manufacturing these products themselves, the community can generates incomes as it offers job opportunities to housewife and school leavers.

9. Reference
Reference
A Paper 1. H. Shen, E. Forssberg and R.J Pugh, Selective floatation separation of plastics by particle control, Resources, Conservation and Recycling, 2001 pg 37-50 2. G Dodbiba and T Fujita, Progress in separating plastic materials for recycling, taylor & Francis Group, 2004 pg 176-177 3. T. D Lenkas, Y Razis and E Fillis, First results of a pilot project for packaging waste recycling in Maroussi and Vrislissia, Greece, 1996 4. Andrew Simons, The recycling of polypropylene containers: An assessment of the viability of the recycling of polypropylene container, Recoup, 2005

45

5.

Priya Narayan, Analysing plastic waste management in India: Case studies of polybags and PET bottles, 2001

6.

Esha Shah and Rajaram, Plastic Recycling in Bangalore, India, Urban Waste Expertise Programme (UWEP), 1997

7.

Gjergj Dodbiba, Jun Sadaki, Atshushi Shibayana, Toyohisa Fujita, Sorting techniques for plastics recycling, The Chinese Journal Process Engineering, 2006

B Book 8. Herebert F. Lund – The McGraw-Hill Recycling Handbook, McGraw-Hill, United States, 1993 9. 10. 1974 11. Sunggyu Lee, James G. Speight, Sudarshan K Loyalka, Handbook of alternative fuel technologies, CRC Press, 2007 pg 403 12. 2002 Francesco Paolo La Mantia, Handbook of plastic recycling, iSmithers Rapra, Paul T Williams – Waste treatment and disposal, John Wiley & Sons, 2005 R.M. Ogorkiewicz- Thermoplastics: Properties and design, John Wiley &Sons,

C Chapter or Article from Edited Proceedings or Series 13. Inoue Tetsuya, Daiku Hiroyuki, Hamada Shogo, Tamakoshi Daisuke, Tsukahara Masanori, Maehata Hedihiko, Niwa Tsutomu, Yamada Koichi, Kakeda Kenji – The application of the electrostatic separator for covering materials of waste electric cable, Hitashi Zosen technical review, 2001 14. Government of India (GOI), National plastic waste management task force report, MOEF, New Delhi, 1997 15. Headley Prat Consulting, Understanding plastic film: Its uses, benefits and waste management option, American Plastics Council,1996,pg 6

46

16.

Piyush Gupta, Future of metallised films in flexible packaging, Multilayer Packaging film, Flex Industries Ltd, 2007

[D] Website

17. Maps of India http://www.mapsofindia.com/maps/maharashtra/districts/pune.htm 18. Pune District Municipal Waste composition www.nswai.com/ 19. Propylene quick facts http://www.dynalabcorp.com/technical_info_polypropylene.asp 20. Plastic recycling information sheet http://www.wasteonline.org.uk/resources/InformationSheets/Plastics.htm 21. Pabal information http://www.engindia.net/

9. Appendices

47

Exhaust port Electric motor Fan Voltage supply + + Suction hose (diameter: 125mm)

Positive charged plate

Negative charged plate

Splitter

Collection bins

Inlet port

48

Sponsor Documents

Or use your account on DocShare.tips

Hide

Forgot your password?

Or register your new account on DocShare.tips

Hide

Lost your password? Please enter your email address. You will receive a link to create a new password.

Back to log-in

Close