Control of Soil Pollution at Dumping Site by Polytar Mix Formation

within Erbil Province –Iraq

Jwan J. Abdullah1 and Jwan J. Shekh Mohammed

2

1 Environmental Sciences, Environmental Department, Science College, Erbil, Iraq. University of

Salahaddin/ Kurdistan Region 2 Transportation Engineering, Civil Department, Engineering College, Erbil, Iraq. University of Salahaddin/

Kurdistan Region

Abstract. Over the past few years, the Erbil -Iraq city has produced 100 tons of solid waste daily yet there

is no sanitary land fill for ultimate disposal of solid waste. For a long time, it has been a common practice to

dispose of soil waste in open low-lying areas. Recently, the government commissioned a new process to

separate solid wastes in to organic and inorganic fractions. In the present study, particular interest are plastics,

because plastics are not eco-friendly as they are non-biodegradable or degrade very slowly, and could secrete

pollutants including heavy metals into the soil. The binding property of plastics in its molten state has helped

in discovering a method of safe disposal of plastic waste, which is their use in road laying. This study

determines some common heavy metals in soil at depths of 0-15 cm the concentration of heavy metals

including Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined, and Fe recorded highest value comparing with

other metals. While, the main aim is to use the plastic waste to mix with bitumen. This mix has high Marshall

Value, low penetration value and resistance to water penetration.

Keywords: Soil heavy metals, softening point, penetration value, flash and fire point, ductility test

1. Introduction

Concern over the possible ecological effects of the increasing accumulation of metallic contaminants in

the environment is growing. Consequently, the investigation of heavy metals in soil is essential because even

slight changes in their concentration above the acceptable levels, whether due to natural or anthropogenic

factors, can result in serious environmental and subsequent health problems [1], [2]. Many works report that

indiscriminate municipal waste dumps could pollute soil, surface water and groundwater, and this has

attracted considerable attention from scholars and governmental agencies in the past 20 years[3]-[5]. Dump

sites soil contain a variety of heavy metals in different concentrations, depending on the age, contents and

location of the area[6], [7]

Plastics are ubiquitous and deeply integrated into today’s lifestyle. They are used for packaging,

protecting, serving, and even the disposal of all kinds of consumer goods. As a result of the industrial

revolution, mass production of goods started, and plastic seemed to be a cheap and effective packaging

material. Use of this non-biodegradable (according to recent studies, plastics can stay as long as 4500 years

on earth) products are growing rapidly and the problem is what to do with plastic-waste Studies have linked

the improper disposal of plastic to problems as distant as breast cancer, reproductive problems in humans and

animals, genital abnormalities, and much more [8].

The waste polymer-bitumen blend can be prepared, and a study of the properties can throw more light on

their use for road laying. Plastics are organic in nature and bitumen is also a mixture of organic compounds,

hence a mixture of the two is possible. Potential benefits of the use of this mixture as suggested include: safe

disposal of these waste plastics, improved solid waste management, better environmental hygiene, decreased

bitumen consumption by 10%, source of supplementary income to self-help groups, no toxic emissions,

2015 5th International Conference on Environment Science and Engineering

Volume 83 of IPCBEE (2015)

DOI: 10.7763/IPCBEE. 2015. V83. 1

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decreased penetration point and increased load-bearing capacity of the road, reduced wear and tear and

increased longevity of the road, no melting of bitumen during summer, and improved water resistance [9].

Roads lay out with shredded plastic display much higher durability than those asphalted with the ordinary

mix. The binding property of plastic makes roads last longer besides giving added strength to withstand more

loads. While a normal “highway quality” road lasts four to five years, it is claimed that plastic-bitumen roads

can last up to 10 years. Furthermore, rainwater will not seep through because of the plastic in the tar,

resulting in fewer road repairs. Additionally, as each kilometer of an average road requires over two tonnes

of poly blend, using plastic will help to considerably reduce non-biodegradable waste [8].

Contamination of the environment by heavy metals is viewed as a global problem because of their

effects on the ecosystem in several countries. A similar situation prevails in Erbil, as a result of industrial

activity and poor domestic waste disposal and management practices, which have led to high levels of

environmental pollution. The main purpose of this study therefore is to investigate the concentration of

heavy metals in the soil at dumping site, at the same time; this research can potentially decrease the amounts

of plastic wastes by mixing it with bitumen, which will be of considerable advantage to the country’s

environment and economy.

2. Material and Methods

The study is divided into two sections; the first section investigates the extent of soil pollution by

municipal waste dumps, the second part is to investigate effect of plastic waste on tar quality.

Soil samples from 8 sampling sites were collected in a circular pattern at a distance of 100 m apart. The

soil samples were collected according to standard methods (State Environmental Protection Administration

of China, HJ/T166-2004 2004)[10]. Dry samples of soil were packed within polyethylene mixed well, and

directly transferred to the laboratory. Heavy metals determined from the samples were measured by atomic

absorption spectrophotometer (PYE UNICAM SP9). Atomic absorption spectrophotometer samples were

prepared using the method described by [11]

The second section of this study involves the plastic-bitumen mix. The plastic waste is melted and

mixed with bitumen in a particular ratio. Normally, blending takes place when temperature reaches 45.5°C;

but when plastic is mixed, it remains stable even at 55°C. The vigorous tests at the laboratory level proved

that the bituminous concrete mixes prepared using treated bitumen binder fulfilled all the specified Marshall

mix design criteria for surface course of road pavement. There was a substantial increase in Marshall

Stability value of the BC mix, in the order of two to three times higher value in comparison with the

untreated or ordinary bitumen. Another important observation was that the bituminous mixes prepared using

the treated binder could withstand adverse soaking conditions under water for longer duration [8].

In this study, mixing plastic with bitumen is the basic process. The aggregate is heated to around 170°C.

To that, waste plastics at different rates (for this study, 2%, 5% and 10%) are added. They get melted and

coated over the aggregate. Next, bitumen (160°C) at different rates (4%, 5% and 6%) was added, and

Marshall Stability and other tests of bitumen are determined for various percentages of aggregate –polymer-

bitumen mix. Then, the best combination was chosen and used for road laying. Parameters to be studied on

waste plastics for road construction include softening point, penetration value, flash and fire point, and

ductility test as described by [11]

3. Results and Discussion

3.1. Soil pollution by solid waste dump

Soil pollution by municipal solid waste at dumpsites were assessed. Results showed that a number of

metal pollutants from the Kani Qurzallah waste dump site (Table 1).

The heavy metal concentrations observed in the soil showed that Co has the least concentration with

10.92 - 22.76 mg/kg, while Fe had the highest concentration with 2330.02-3671.1 mg/kg. The level of heavy

metals in the dump site soil and controls were above the background level range recommended for farming

[12]

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Some heavy metals like As, Cd and Pb, have been reported to have no known bio-importance in human

biochemistry, physiology and consumption, but can be toxic at very low concentrations [12,13]

Comparing this study’s result with those from other countries showed that the high value of Cr conforms

to similar findings (Table 2) in US, China, Poland and India’s soils. India recorded higher value than the

other countries because chromium functions in mammalian glucose metabolism and appears to be essential

to man and animals. Cu and Zn are essential plant micro nutrients. They can also bind to soil organic matter

and become unavailable to plants. In this study, the high levels of Cu concentration in the soil of a dumpsite

are similar to metals analysis in soil reported in US, China and India; it differs only with that of Poland

(Table 2). For Zn, the high values are similar to findings in US, China and Poland as shown in Table 2.While,

higher levels of Ni and Pb are in agreement with the high concentrations obtained in other countries, Mn

levels are higher than reported from other countries that were compared with the present work. In most soil,

Fe is present in large quantities; on average, between 3-5% of soil consist of Fe, which makes it the fourth

most abundant element in the earth crust. Fe levels obtained from this study are lower than those reported by

[12] in India.

Table 1: Average levels of heavy metals at dump site in Erbil (mg/kg).

Sampling site Co Cr Cu Fe Mn Ni Pb Zn

S1 20.62 87.12 62.11 2360.1 511.07 99.06 28.11 79.62

S2 12.76 51.16 311.6 561.03 86.17 86.17 20.17 71.30

S3 10.92 68 51.90 2990.1 273.20 78.71 16.39 89.10

S4 21 77.3 57.70 2690.20 436.11 90.21 25.90 64.29

S5 18.66 80 69.20 3530.7 252.03 70.69 16.20 80.11

S6 16.12 82.23 61.77 3671.1 279.56 49.36 21.01 78.52

S7 11.92 49 49.12 2911.1 249.72 33.50 17.35 50.91

S8 22.76 88.46 73.8 2330.02 368.98 57.49 23.70 88.69

Total 134.76 583.27 737.2 21044.35 2456.84 565.19 168.83 602.54

Table 2: Comparison of Heavy metal levels at Erbil with other countries.

Metals This study Study in USA(a)

Study in china(b)

Study in Poland(c)

Study in India (d)

Co 10.92-22.76 ND NA NA NA

Cr 49.00-88.46 6.59-208 19.3-150 3.7-75.3 ND-145.45

Cu 49.12-73.80 2.896-101 7.26-55.1 2.0-18.0 5.34-198.23

Fe 3671.1-2330.02 NA NA NA 576-16234

Mn 249.72- 561.03 43-2532 134-1740 83-1122 NA

Ni 33.50- 99.06 2.44-69.4 77.3-70.9 2.0-27.0 343-1409

Pb 16.20- 28.11 4.62-55.4 9.95-56.0 7.1-50.1 ND-623.95

Zn 50.91-89.10 12.6-183 28.5-161 10.5-1547 ND

(a) [12];

(b) [13]

;

(C) [2];

(D) [14]

ND = Not Detected; NA = Not Available.

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4. Mixing of plastic with bitumen

Plastic use in road construction is new. It is already in use as PVC or HDPE pipe mat crossings built by

cabling together PVC (polyvinyl chloride) or HDPE (high-density polyethylene) pipes to form plastic mats.

The plastic roads include transition mats to ease the passage of tyres up to and down from the crossing. Both

options help protect wetland haul roads from rutting by distributing the load across the surface. An initial

study was conducted in 1997 to test for strength and durability. Plastic roads mainly use plastic carry-bags,

disposable cups and PET bottles that are collected from garbage dumps as an important ingredient of the

construction material. When mixed with hot bitumen, plastics melt to form an oily coat over the aggregate

and the mixture is laid on the road surface like a normal tar road [8]

Table 3: Result of each test for different rates of plastic.

Amount of Plastic

in Bitumen (%)

Penetration

Value (mm)

Flash

Point (°C)

Fire Point

(°C)

Ductility Value

(cm)

Softening Point

(°C)

0% 61 220 270 108 52

2% 57 250 280 117 56

5% 43 260 280 125 61

10% 32 260 280 138 63

Table 4: Marshall Test result.

Amount of Bitumen (%) % of Waste Plastic Marshal Stability (kg)

4

0

880

5 970

6 1050

4

2

1250

5 1170

6 1210

4

5

1470

5 1330

6 1350

4

10

1760

5 2000

6 2500

The result of each test for different levels of plastic inclusion is shown in Table 3. From the observed

results, it can be concluded that an increase in the plastic inclusion rate decreases the penetration value. This

confirms that the addition of polymer increases the hardness of bitumen. The study of the flash point and fire

point of the polymer–bitumen blend was conducted in order to understand the inflammability nature of the

blend. The ductility is increased by the addition of polymer to bitumen. The increase in the ductility value

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may be explained as follows: the long polymer molecules when mixed hot, physically interlock the material

and this may help to reduce cracking at the surface. It is observed that the softening point increases by the

addition of polymer to bitumen. The influence over the softening point depends on the chemical nature of the

polymer added; this result agrees with that of [15].

Regarding the flexibility of plastic-bitumen-aggregate mix for, study the effect of both variation of waste

plastics content and bitumen content in the plastics-bitumen-aggregate mixture was carried out, and Marshall

Stability values are given in Table 4. It is observed that the addition of waste plastic increases the Marshall

Stability value to a fairly high value. It is also observed that the addition of 10% waste plastics results in a

higher value at the optimum percentage of bitumen (6%). Higher percentage of waste plastics required

increased percentage of bitumen even though this resulted in a higher Marshall Stability Value.

In general, it may be concluded that this method is the best suited process for the use of high percentage

of plastic waste and for higher performance of the flexible pavement. Hence, it may be inferred on the basis

of Marshall Stability Value that the 10% blend of waste plastics is an optimum percentage for road

construction, considering the cost factor and the consumption of bitumen; these findings are in agreement

with those of[15]

5. Conclusion

Based on the results of the present investigation, the following conclusions can be drawn. Levels of Co,

Cr, Cu, Fe, Mn, Ni, Pb and Zn were high in Kani Qurzallah dumping site soil. The results indicated that the

concentration of some heavy metals were above the literature levels of a typical soil. This warrants

remediation action as it can affect the environment as well as the health of the inhabitants. To decrease

pollutants by wastes affects, the plan to decrease these pollutants was by mixing one type of solid waste,

such as plastic, with bitumen. Plastics will increase the melting point of bitumen. The use of the innovative

technology will not only strengthen road construction but will also increase the road life as well as help to

improve the environment, and also create a source of income.

6. References

[1] Fangueiro, D., et al., Heavy metal mobility assessment in sediments based on a kinetic approach of the EDTA

extraction: Search for optimal experimental conditions. Analytica Chimica Acta, 2002. 459(2): p. 245-256.

[2] Dudka, S., Factor analysis of total element concentrations in surface soils of Poland. Science of the total

environment, 1992. 121: p. 39-52.

[3] Changli, L., et al., Experimental and numerical study of pollution process in an aquifer in relation to a garbage

dump field. Environmental geology, 2005. 48(8): p. 1107-1115.

[4] Tchobanoglous, G., H. Theisen, and S. Vigil, Integrated solid waste management: engineering principles and

management issues1993: McGraw-Hill, Inc.

[5] Romic, M. and D. Romic, Heavy metals distribution in agricultural topsoils in urban area. Environmental geology,

2003. 43(7): p. 795-805.

[6] Ebong, G., H. Etuk, and A. Johnson, Heavy Metals Accumlation by Talinum. Triangulare Grown on waster

Dumpsites in Uyo Metropolis Akwa Ibom State, Nigieria. J. Appl. Sci, 2007. 7(10): p. 1404-1409.

[7] Odukoya, O., O. Bamgbose, and T. Arowolo, Heavy metals in top soils of Abeokuta dump sites. Global Journal of

Pure and Applied Sciences, 2000. 6(4): p. 651-653.

[8] Verma, S., Roads from plastic waste. The Indian Concrete Journal, 2008: p. 43-44.

[9] Vasudevan, R., et al. Utilization of waste polymers for flexible pavement and easy disposal of waste polymers. in

International Conference on Sustainable Solid Waste Management. 2007.

[10] Liu, C., et al., Assessing pollutions of soil and plant by municipal waste dump. Environmental geology, 2007.

52(4): p. 641-651.

[11] Allen, S.E., et al., Chemical analysis of ecological materials1974: Blackwell Scientific Publications.

[12] Shacklette, H.T. and J.G. Boerngen, Element concentrations in soils and other surficial materials of the

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conterminous United States. 1984.

[13] Bradford, M.C. and M.A. Vannice, Catalytic reforming of methane with carbon dioxide over nickel catalysts II.

Reaction kinetics. Applied Catalysis A: General, 1996. 142(1): p. 97-122.

[14] Begum, A., et al., Analysis of heavy metals concentration in soil and litchens from various localities of Hosur

Road, Bangalore, India. Journal of Chemistry, 2009. 6(1): p. 13-22.

[15] Vasudevan, R., et al., A technique to dispose waste plastics in an ecofriendly way–Application in construction of

flexible pavements. Construction and Building Materials, 2012. 28(1): p. 311-320.

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