The New Nation - Internet Edition

Taieba Ahmad Ireen

Solid waste and its generation are unavoidable. Since human beings have been inhabited on the earth, they have generated, produced, manufactured, excreted, discarded and otherwise disposed of all manner of waste. By definition, solid waste is useless, unwanted and discarded non-liquid waste materials arising from domestic, trade, commercial, industrial, agriculture, as well as public services. It is inextricably linked with resource consumption, urban lifestyle, attitude, education, regulation and economic activity.

Solid waste is one of the most visible and pressing urban environmental problems in both developed and developing countries. Urbanization, demographic growth and economic development all contribute to the generation of waste, which overloads the capacities (budget, personnel and infrastructure) of the local authorities. As long as, solid waste is not managed properly, it could have effect on health and environment. Solid Waste Management in mere practice refers to the activities of collection, transportation and disposal of waste. But in a modern and broader definition - Solid waste management refers to all activities such as generation, storage, collection, transportation, processing, treatment as well as disposal in accordance with the best principle of public health, economics, engineering, conservation, aesthetic and other favorable environmental considerations in the framework of administrative, financial, legal, planning and engineering functions.

Compared to developed countries, the developing countries produce less per-capita solid waste, but the capacity of the developing countries to collect, process and dispose waste is limited in terms of inadequate infrastructure, finance, political priority and awareness.

Solid waste generation is an inevitable consequence of production and consumption activities. Population growth can increase the amount of municipal solid waste significantly. The waste generation rate varies between 0.47 to 0.50 kg/cap/day in the developing countries like Bangladesh. However, the generation can also vary with the level of income, urbanization trend, changing food habit, social and cultural habits, and lifestyle changes. Seasonal variations also can influence the amount of waste generation. During the rainy season, the waste becomes wet and heavy. Plenty of vegetables and seasonal fruits grow and lead to an incremental variation in waste amount. The rate of waste generation is found to be higher in wet season and lower in the dry season.

Residential wastes are the main sources of MSW in Bangladesh. The other important sources are commercial wastes including markets, hotels, restaurants etc. Institutional wastes include the wastes from school, college and universities as well as the offices. Municipal services wastes include wastes from street sweeping and drain cleaning.

Municipal solid waste is a heterogeneous mixture of wastes; organic and inorganic, rapidly and slowly biodegradable, hazardous and non-hazardous generated from various sources due to human and industrial activities. In major cities of Bangladesh, it is observed that food and vegetable wastes are the dominant component in the waste stream. Other waste components are paper & paper products, polythene & plastics, textile & woods, rubber & leathers, metal & tins, glass & ceramics, brick & concrete, dust & soil etc. These components vary with the sources such as residential, commercial, industrial and institutional. In the residential area, food & vegetable waste dominates but in the institution paper waste is more. As the inorganic wastes are picked up by the scavengers from the secondary storage points, the organic waste is found more in the disposal ground.

The pH, moisture content, bulk density and particle size are the physical characteristics of municipal solid waste. The pH of organic material ranges from 5.5 and 8.5 and a good indicator for decomposition. For aerobic composting, the organic mass has to attain a pH

value of 6.0 and 7.5. A moisture content of 50-60% of the total weight of waste is considered ideal for the developing countries. Higher moisture content indicates the possibility of the development of anaerobic conditions that causes obnoxious odors and quicker rotting. The bulk density of waste is an important criterion for the design of storage, collection and transportation equipment as well as for the landfill. The low income level country contains higher concentration of vegetable materials but lower density of packaging materials. For the low income countries, the bulk density of waste accounts for 300-600 kg/m3 and for the middle and high income countries, the bulk density reduces to 200-300 and 100-150 kg/m3 respectively. The particle size is important to determine mass to surface ratio for expose to microbial attack.

The organic matter content in the waste material is important for the potential possibility of composting and biogas as a waste management option. Apart from the fraction of the organic wastes, the concentration of Carbon and Nitrogen and the consequent C/N ratio, the Potassium (K) and Phosphorus (P) is important. In addition the feasibility of combustion depends on moisture content, volatile combustible matter, fixed carbon and ash. The combustion is expressed by the term calorific value of waste, which is the quantitative estimation of heat energy released by burning. Higher calorific value indicates the combustion of waste with a lesser amount of auxiliary fuel support. To facilitate self-combustion of waste, it requires 5024 kJ/kg and at least 6280 kJ/Kg for power generation. But in Bangladesh, the calorific value is lower 2303-3559 kJ/Kg which indicates that the waste does not sustain combustion.

Kitchen is the main source of waste production. Households keep small containers to store the waste in the kitchen, hand over them to the collection workers who then dispose them into vans and return the empty container. The mixed wastes are mostly collected from the households. The separation of waste at source into organic, inorganic and hazardous are not practiced. Motivation, awareness and commitment is highly required for source- separation. However, the waste which is dry and has a recycle value are stored at households and sold them to itinerant buyers in exchange of money or household utensils.

Primary waste collection is the responsibility of the waste generators. Having this in mind or with the dissatisfaction of the municipal cleansing services, the community based solid waste collection system has been introduced in most part of the cities with the involvement of some CBOs and NGOs. With transforming into this new system of door-to-door waste collection system from the traditional practice, people are now accustomed to the practice of keeping waste into bins or bags and handed over them to the waste collection crews and contributed to the system by paying service charges. Where, door-to-door collection systems are not available, people carry wastes to nearby municipal secondary bins, from where the municipal trucks load the wastes for ultimate disposal. Rickshaw vans are usually used to operate the collection system which can carry waste nearly 250-280 kg/van/trip. The secondary bins are placed usually on the main road selected based on population, space availability, accessibility or other local factors. Sometimes, the locations of the bins are opposed by the nearby households commonly known as NIMBY (Not In My Backyard) syndrome.

City authorities are responsible for the waste transportation by trucks. The different types of truck such as open, closed and tipping with varying capacities are engaged for waste transportation into the disposal site. The trucks are normally assigned for a particular area with two or three trips per day. However, the waste transportation system is inefficient in its management namely due to off route of vehicles for repairing, poor maintenance, under loaded by waste, skip trip for illegal dumping etc.

Waste disposal is the end of journey for waste management. The disposal is commonly practice in low lying areas for the reclamation of lands. But this practice is unsound and unsustainable in terms of pollution of surface and underground water resources, green house gas emission and the discharge of toxic leachate in the nearby lands. The discharge of leachate contaminates the water bodies dangerous for fish and aquatic lives by reducing the amount of oxygen in water. So in the landfill (controlled or sanitary), waste are deposited onto and into lands in such a way that the environmental risks are controlled at an appropriate and acceptable level. Provisions are kept to minimize risks from leachate and gas production.

The treatment of waste and use its byproduct is not economic in true sense until or unless it is subsidized. The processes such as composting, biogas generation, waste-to energy, refused derived fuel etc. can be produced from waste. But it can be examined through technological, financial and socio-economic consideration. The key considerations in solid waste disposal are:

(i) Municipal capacity (ii) Political commitment (iii) Finance and cost recovery (iv) Technical guidelines (v) Institutional roles and responsibilities (vi) Location

The informal sectors play an important role in waste reduction and recycling. The waste picking from the secondary and final disposal sites are concerns in terms of health and livelihood issue.

In Bangladesh, recovery and recycling occurs in three phases. In the first phase, the waste generators separate waste which has higher market value such as newspaper, bottles, and plastic containers and sell them to street hawkers. In the second phase, the scavengers are rummage through the wastes near the bins for collecting recyclable materials of low market value such as broken glass, cans, polythene which are discarded by households.

The final phase is the collection of recyclable materials by the waste pickers from the waste vehicles immediately after unloading at dumpsites. Scavenging from an economic and social point of view, it economizes on resource use, reduces burden of waste disposal and contributes to environmental conservation. However, they work in wastes in a risky environment without due consideration to their occupational health and safety.

The waste management policy is virtually insufficient and ineffective. The few clauses of the municipal ordinances are the basis for waste management. The responsibility of the waste generators and the municipality are not mentioned in detail which limits the activities of the local authority as well as make them responsive to the people. People are not also aware of or more careful about the keeping of waste properly into dustbin. Basically the conservancy department is in charge of solid waste management in the municipality. However, solid waste management is a multi-disciplinary activity of conservancy, transport and engineering. It needs a coordinated effort. Solid waste management has given low priority and provided limited funds than the other municipal services. The municipalities have lack of capacity, legal framework, coordination and effective financial management system.

Solid waste management is the most visible urban environmental problem. The ever increasing solid waste, accelerating cost, ineffective legislation and inefficient institutional image has made solid waste management a very challenging task for the local authorities. It is recognized that the local authorities, the private sector and the community can not alone be able to improve the waste situation of their own. Its' need a collaborative effort of all stakeholders in the development paradigm. A rapid growth of community based activity in solid waste management is being seen in recent years. New forms of civic engagement are emerging, resulting in community people increasingly getting involved in the decision making process of solid waste management. Local government support and acknowledgement is imperative in the community-based initiative, it can increase public trust and legitimacy to the initiatives. The local authority can take a leading role to institutionalize the informal community-based activities within their formal waste management services. As such the political motivation of the local authority is essential.

Local government authorities are generally responsible for the provision of solid waste collection and disposal services. Beside, their statutory obligations, the local authorities are motivated by political concerns to provide solid waste services. They are lacking in both financial and institutional capacities to provide efficient solid waste management services. There is no institutional culture in the local government to train its fellow personnel to build knowledge and capacity in waste management. Poor government policy and response, lack of political priority, lack of transparency in budget use, bureaucratic and top down approach in decision making process has made solid waste management a complex activity. Effective decentralization can make solid waste management more flexible, efficient and responsive to local requirements and potentials. Devolution of responsibilities, authorities, decision making power and financial management can reduce the work load of the local authority and can foster more demand-oriented solid waste management services.

(Taieba Ahmad Ireen, Dept. of Environmental Science and Resource Management, Mawlana Bhashani Science and Technology University, Santosh, Tangail.)