Received 26 February 2016; accepted 11 June 2016; published 14 June 2016
Solid waste has been produced since the beginning of civilization. During the earliest periods, solid wastes were conveniently and unobtrusively disposed of in large open land spaces, as the density of the population was low. As a result of rapid urbanization and changes in consumption of many cities in developing countries, waste generation has increased. However, the waste generated is, in most cases, not properly managed. Hence, this has huge consequences in terms of collection, disposal and the elimination of waste   . However, today, one of the consequences of global urbanization is an increased amount of solid waste. About 1.3 × 109 t of municipal solid waste (MSW) was generated globally in 1990  , and, at present, the annual generation is approximately 1.6 × 109 t. The urban population in Asia generates around 760 × 103 t of MSW per day, and this is expected to increase to 1.8 × 106 t by 2025   . In almost all developing countries, city solid waste constitutes a hazard, be it from the ecological point of view or the public health point of view. Almost everywhere, there is a distinct lack of policy on efficient waste collection and a total absence of its treatment  . Many experts from various cities in developing countries have expressed serious concerns about improper waste treatment and disposal in these countries   -  . In most developing countries, solid waste management is undertaken by the local authorities. These services include waste collection (either from households or district collection points) to final disposal. However, the low financial base and human resource capacity of these local authorities means that in most cases they are only able to provide a limited service  . Inadequate management of solid waste in most cities of developing countries leads to problems that impair human and animal health and ultimately result in economic, environmental and biological losses  -  . The quantity of municipal solid waste generated depends on a number of factors such as food habits, standard of living, with increasing urbanization and changing life styles, degree of commercial activities and seasons. A number of socioeconomic variables may affect the quantity of solid waste generated each day by a household. These include religion, family size, family employment, age, education; land status and duration of stay    . Data on quantity variation and generation are useful in planning for collection and disposal systems  . Today waste is also produced as a result of society’s attempt to solve other environmental problems such as water and air pollution. Some of these increasing amounts of waste give rise to new problems, such as sewage sludge and residues from cleaning of flue gases  . Solid waste management has several functional elements, including waste generation, waste handling and separation, storage and processing, collection, transfer and transport, and final disposal  . Solid waste management refers to all activities pertaining to the control, collection, transportation, processing and disposal of waste in accordance with the best principles of public health, economics, engineering, conservation, aesthetics and other environmental considerations. Its scope includes all attendant administrative, financial, legal, planning and engineering functions. To achieve the objectives of solid waste management and to overcome its problems,  proper management (storage, collection, and disposal) of solid waste requires accurate information regarding waste-generation rates, and quantities, composition, sources, and locations of waste. This type of information was not available for the cities in Libya. No studies were conducted on solid waste management in the past. There are no records indicating the amount of various types of waste collected and the volumes of waste generated per capita. Therefore, this study aimed to estimate the household solid waste generation, composition and density in Tripoli city in Libya as first step should lead to a better understanding of the solid waste management problems in Libya and estimate the effects of some socioeconomic factors on solid waste generation.
2. Place of Study
Tripoli is the capital city and the largest city of Libya. As of 2011, the Tripoli metropolitan area (district area) had a population of 2.2 million people. The city is located in the northwestern part of Libya on the edge of the desert, on a point of rocky land projecting into the Mediterranean and forming a bay. This study was conducted in three main parts of Tripoli city which have been chosen randomly.
The areas of study (area1, area 2 and area 3) have chosen according to the type of houses (old fashion houses, flats and modern houses) to be representing the low income, middle income and high income levels respectively. Equipment and collection route have been determined. Box volume has been measured and the workers instructed as to how should carry out their work. The plastic bags distributed in study areas.
4. Procedure of Study
The first phase of study carried out according to the Annex 2.1of: WHO (1996)  . Therefore, the plastic bags from houses collected according to the pre-specified collection route from (area1, area 2 and area 3) to the dump site where all measurements have been conducted. Each plastic bag weighed and recorded the weight in the data sheet according to the numbers assigned to households. 10 - 15 plastic bags chosen randomly of each sample area then opened and emptied in the boxes of volume unit it became full and then emptied, spread on the plastic sheet. Wastes separated into different types, weighted and recorded to be a composition of household wastes by weight. The volume of generated household solid waste measured by empting all plastic bags in the boxes and counting the number of boxes to be the total volume. This procedure repeated every day /week in summer, autumn and winter 2011/2012.
In the second phase of the study, a questionnaire survey was carried out on 150 randomly selected houses in various areas in the city. A questionnaire was prepared according to Raje et al. 2001  and Buenrostro et al. 2001  using door-to-door surveying in order to obtain data about household solid waste quantity, daily disposal, availability of containers, collection frequency and satisfaction level, etc. The data collected from the survey was analyzed using Microsoft Excel for calculating simple statistics.
5. Results and Discussion
From the data of collecting questionnaire, the responsive percentage to the study was 100% whereas 150 questionnaires have been distributed and collected in study places and the number of people was 947. Table 1 explains the concluding data. On the other side, the information about household solid waste services refers to, all chosen families in area 1 pay about 15 - 20 ?month for private companies for solid waste services twice a week and they are almost satisfy, and they prefer local services but there is no government company serving in this side of Tripoli. 50% of families produce 7 - 10 garbage bag per week, 30% producing 4 - 6 bags per week and 20% producing 0 - 3 bags. All chosen families in area 2 didn’t pay for private companies of solid waste services. 43% of families produce 7 - 10 garbage bag per week, 36% producing 4 - 6 bags per week and 21% producing 0 - 3 bags. 40% of chosen families in area 3 didn’t pay for private companies of solid waste services and 60% are paying. 60% of families produce 7 - 10 garbage bag per week, 30% producing 4 - 6 bags per week and 10% producing 0 - 3 bags.
6. Household Solid Waste Generation, Volume and Density in Places of Study
In order to determine generation, volume and density in places of study approximately 4650 kg household solid waste were collected from 150 Libyan families representing some 947 persons in (area1, area 2 and area 3) at Tripoli city during one week in summer, autumn and winter 2011/2012. From Table 2, the results shown that the total generation quantity, daily generation rate, total volume and density were 1464.5 kg, 0.66 kg/person/day, 19.73 m3 and 74.7 kg/m3 respectively in Tripoli city.
Comparisons between the Tripoli city results and those for African and Arabic countries, the generation rate agreed with All Arabic countries  , and Cameroon, Burkina Faso, Guinea, Namibia, Senegal and Zimbabwe  but it is higher than 0.39 reported in Allahabad, India  , 0.23 kg in Beijing  , 0.55 kg in Abuja  , 0.59 kg in Mexican city  , and the 0.4 kg in Dares Salaam  , but it is less than the 1.1 kg reported in Lagos  and 0.84 in Lahore city, Pakistan  .
Table 1. Families characteristic.
7. Household Solid Waste Generation According to the Family Size
The analysis of the 150 sample observations in the study areas indicates that an average household in the Tripoli Area generated 0.7 kg of wastes per day. It also reveals that the rate of waste generation varies in the different places studied, as shown in Tables 2-5, the waste generation rate was found to be 0.59 and 0.74 kg/capita/day in
Table 2. Average values of Tripoli city.
Table 3. Average values of Tripoli household solid waste during summer.
Table 4. Average values of Tripoli household solid waste during autumn.
Table 5. Average values of Tripoli household solid waste during winter.
Table 6. Solid waste generation according to the income level.
Table 7. Solid waste generation according to the family size.
Table 8. Household solid waste composition in Tripoli city in summer.
Table 9. Household solid waste composition in Tripoli city in autumn.
Table 10. Household solid waste composition in Tripoli city in winter.
Table 11. Household solid waste composition in Tripoli city.
Table 12. Household solid waste composition in Tripoli city (%).
area 1 and area 2 respectively and 0.78 kg/capita/day in area 3. The generation of household waste was found to be positively correlated with family size Table 4, which means families with more individuals generate a larger quantity of solid waste per day, the income level of family was also found to be positively correlated and the generation of solid waste, which reveals that families earning more per month have the tendency to generate a larger quantity of solid waste each day Table 6. An inverse correlation was found between the waste generation rate and families size as apparent in Table 7.
8. Composition of Household Solid Waste
In order to estimate the composition of household solid waste in Tripoli, 178.5 kg, 180.7 kg and 176.1 kg in summer, 168.3 kg, 180.1 kg and 169.4 kg in autumn and 173.5 kg, 183.7 kg and 179.1 kg in winter of waste mixed samples from (area 1, area 2 and area 3) were separated as groups and weighted. The results of the analyses show that household solid waste contains 36.3% organic matter as shown in Tables 8-12. The percentage of recyclable materials (glass, paper, plastic, metals) was 32.5%.
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