Garbage Management
Garbage Management getting rid of waste materials or domestic refuses. The word garbage is generally used to indicate solid household wastes which are generally composed of a few types of unwanted material produced through day-to-day household activities. Such garbage is also called residential waste. A similar type of garbage is also produced by commercial sources such as hotels and restaurants, shops, offices and other business outlets, which is referred to as commercial waste. The third type of waste is industrial waste, the nature of which is determined by the type of industry concerned. In Bangladesh, by the term 'garbage' one largely means city garbage because the socio-economic conditions of the villages is such that there is little scope for generation of city type garbage from day-to-day domestic activities of village people.
In cities, residential and commercial wastes are disposed of by the city's municipal administration, but industrial waste is discharged into water bodies or dumped near the site where the industry is located. Although disposal of industrial waste is to be made in a manner that does not constitute a threat to environment, it is frequently not practised with sufficient stringency. Consequently, industrial pollution is today a major environmental threat in many countries including Bangladesh.
Municipal waste produced in the capital city Dhaka may be taken to be representative of the main cities and towns of Bangladesh in its material composition. Residential waste of Dhaka consists of about 80% food waste, 10% metal and glass, 7% paper and polyethylene bags, and 1.5% cloth. Commercial waste is generally similar in composition with the exception that food waste comprises about 85%, largely due to the contribution of many diverse types of food outlets ranging from street vendors to big restaurants and hotels, while metal and glass wastes are somewhat less, at about 5.5%.
With its population of about 10 million, Dhaka city at present generates approximately 1,500 m tons of garbage per day. Similarly, Chittagong, Khulna, Rajshahi, Barisal and Sylhet produce substantial quantities of garbage daily. In all these cities, the garbage is dumped in land filling areas located in the vicinity of the town with antecedent health hazards and creation of unaesthetic conditions for the public.
Recently, research work has been carried out by BCSIR at its laboratories in Dhaka to examine the possibility of using city garbage for biogas and fertiliser production through anaerobic fermentation. Based on the laboratory results, a pilot project involving a batch type 85 M3 digester was constructed in Sydabad near Dhaka city. The pilot project indicates a good potential for biogas production by using city's domestic and commercial waste. A careful cost-benefit analysis is, however, required. An operating strategy for such batch type digesters need to be adopted, for instance separation of plastic, glass and metal objects from the garbage and improvement of the digestion process by using more efficient bacterial inoculum.
Separation of non-biodegradable material from the city garbage at the site of the plant, that is, after collection of the garbage is a significant disincentive, but such separation at the domestic level such as placing plastic, glass and metal wastes separately from the rest of the garbage would require both resource mobilisation and awareness creation among the city dwellers. It is believed that private sector involvement in this venture may prove productive at the small-scale community level, but for this a careful cost-benefit analysis and a well thought out operating strategy is needed. [Zia Uddin Ahmed]
See also toxic and hazardous waste.
