Even though low-income areas are grossly neglected by municipal collection services, low-income communities have proved willing to make some investments in cleaning up streets and improving drainage. The question is how much are they willing/able to pay, under what conditions and for what kind of service.

b) Operational inefficiencies

Although municipalities in DCs expend substantial resources on waste management (often 20 to 30 percent of municipal operating revenues), they tend to do a poor job operationally.

Operational inefficiency is due primarily to the inefficient institutional arrangements common to municipal governments in DCs. In addition, waste management services generally receive little attention from top city officials, and are usually assigned to the lower echelons of municipal government or to health departments. However, the more a city grows, the more the solid waste collection becomes complex and requires top level planning and sophisticated engineering and management skills.

c) Limited utilization of the capacity of the informal and formal private sector in recycling activities

The informal sector has been playing traditionally an important role in SWM schemes, especially with regard to recycling activities. However, while being basically beneficial to the environment and supporting large numbers of poor workers, these recycling activities by the informal sector can conflict with efficient waste management practices. These activities also pose serious health problems to the worker community. The formal private sector has so far been rather reluctant to participate in recycling activities, although the materials recovered from the waste stream are marketable.

The recovery of all kinds of material from municipal solid waste by the informal sector is not only a fact of life which cannot be ignored or even abolished, it also offers opportunities to incorporate resource recovery into solid waste management schemes. Scavenging as a whole not only provides a source of income to one of the poorest segments of the population, but it also reduces the need for highly sophisticated and costly recovery systems. Therefore, these recycling activities should by no means be discouraged, particularly since resource recovery is now becoming a recognized component of municipal solid waste management strategies in industrialized countries.

Although material recovery from the waste stream has a great potential for private sector involvement (the outputs are marketable), in industrialized countries as well as in DCs the formal private sector has been playing a minor role in recycling activities. The reasons are manifold and interrelated: (a) the market for recovered material, which is often controlled by cartels, leads to oligopolistic situations; (b) prices for recovered materials are subject to large fluctuations and are not predictable; (c) tipping fees are generally too low to create an economic incentive for private firms to reduce the volume of solid waste by material recovery and recycling of the putrescible components (composting). As long as this situation prevails, the formal private sector will probably only be involved through contractual agreements with municipalities.

d) Specific problems related to the final disposal of solid waste

The solid waste in DCs is generally disposed of in uncontrolled open dumps. Although the environmental consequences of inadequate disposal are often quite evident, they are seldom dealt with.

Financial and institutional constraints are the main reasons for such a situation. If financing of solid waste collection services poses a problem, the financing of safe disposal of solid waste poses an even greater problem. Although most people are willing to pay for the removal of the refuse from their immediate environment, they are generally not concerned with its ultimate disposal. In addition, since the important physical components of the environment (air, water, soil) are public goods, their utilization is not controlled by simple market mechanisms.

The present situation is expected to deteriorate even more. Due to rapid urbanization, the existing dumping sites, often former quarries originally located at a safe distance outside the municipal boundaries, are increasingly encircled by settlements and housing estates. They are subjected to growing opposition from the public. On the one hand, the central location of the dumping sites; i.e., close to the collection area, has enabled local governments to dispose the municipal SW at little cost. On the other hand, it is becoming increasingly difficult to find new landfill sites which find the approval of the public, and which are located at a reasonable distance from the collection area. Many of the recently selected landfill sites in larger cities (e.g. Jakarta, Manila) are in fact located at distances between 20 to 40 km from the central collection areas. This results in high transfer and transportation costs as well as in additional investments in the infrastructure of roads.

e) Problems related to collection and disposal of (non-industrial) hazardous waste

Although most hospitals officially require the burning of their pathogenic waste, most of the existing incinerators are out of order due to a lack of fuel and/or spare parts. Consequently, pathogenic waste products often enter the MSW stream and cause serious health risks.

Hospitals and especially the growing number of health institutions such as primary health care centres and dental and veterinary clinics spread throughout the cities and produce infectious medical waste. They generally lack appropriate collection and disposal services. Consequently, pathogenic waste products often enter the MSW stream and pose serious health risks to the public (e.g. children playing with toys recovered from MSW products), to scavengers and collection crews, and to workers at the landfill.

3. Possible approaches to solve the most urgent problems and need for future research

a) Increase in coverage

As long as solid waste collection services are not sustainable in the sense that the beneficiaries are not able/willing to pay for the kind of service offered to them, it is obvious that it will be increasingly beyond the resources of the municipal administrations to collect the growing amount of solid waste generated by the rapidly expanding cities in DCs. This basically means that the people in low-income communities have to assume the responsibility of the municipality with regard to the handling of their garbage, and to set up a system appropriate to their economic situation. This can take different forms; i.e., the community/neighbourhood is either paying private collectors, within or without the community, or the population will have to partly carry out the work themselves. In other words, those who cannot afford to pay in cash will still be provided with SWM services by paying in kind.

b) Improving operational efficiency

It is often argued that privatization of SWM activities is the best method to improve the poor efficiency of existing SWM systems. A preliminary study comparing the latest cost data of the urban waste management services in Rio de Janeiro and Sao Paulo revealed that taxpayers in Rio de Janeiro pay for a similar level of service at least twice as much as taxpayers in Sao Paulo. This difference is attributed to the fact that the services in Rio de Janeiro are provided by a government agency in contrast to Sao Paulo, where private firms have been contracted to collect the refuse and operate processing plants and disposal facilities. There is strong evidence that the productivity and efficiency of the services delivered by private firms in Sao Paulo is higher.

However, privatization has also serious limitations. Although in most cities of Francophone West Africa (e.g. Dakar, Abidjan, Lom‚, Douala), private firms have been in charge of SW services for many years, there is no indication that the municipal authorities and/or the taxpayers in these cities pay less for their SW services. This is probably because these private firms basically have a monopoly without any competition.

In this context, it is important to note that the organizational structure and management of the refuse collection agency are the most important factors affecting the efficiency of the system.

c) Better utilization of the capacity of the informal and formal private sector in resource recovery from MSW

The crucial question with regard to informal sector involvement in SWM systems is how can the above mentioned problems associated with scavenging be reduced or even eliminated without jeopardizing the benefits of these activities. A possible approach is to regard improved scavenging as an integral component of solid waste management planning and implementation.

The existing situation with regard to scavenging activities at dump sites and/or transfer stations/points could be improved significantly for example by (a) physically separating the area where scavenging is taking place from the actual disposal site. This would prevent interference with the tipping operation at the landfill; (b) providing manual or very simple mechanical sorting tools and operational training to the scavengers. Which would lead to more efficient material recovery; (c) incorporating processing activities to add market value to the recyclables; (d) providing washing and sanitary facilities in the areas where controlled scavenging is taking place; and (e) providing education, housing and health facilities to the scavenger community. In cases where collection and recovery are closely linked; i.e., where scavengers are actually given the task to collect the solid waste, it is essential to have formal agreements between the authority in charge of SWM, the households and the scavengers, and to put in place appropriate payment mechanisms. This again requires scavengers to be organized in formally acknowledged groups.

Since the formal private sector has so far been rather reluctant to enter the recycling market, investigations on market and price mechanisms of secondary raw materials are urgently needed. In this context, the question of prime interest is how do direct and indirect subsidies of virgin and/or imported raw material influence the prices of recyclables.

d) Improving the situation with regard to the final disposal of MSW

The following three basic measures are suggested to improve the present situation with regard to the final disposal of MSW in landfills: (a) Institutional and financial models for waste disposal activities as an integral part of SWM have to be found and applied. Landfill operation costs have to be covered by the collection fees. (b) Appropriate guidelines for the operation of landfills in DCs have to be developed. These guidelines should not be based primarily on the existing requirements of sanitary landfills in industrialized countries but mainly take into account the basically different physical and economic situation prevailing in DCs. (c) Increased recycling of the organic putrescible component, which accounts for the largest fraction of the MSW produced in DCs, will reduce the amount of waste to be disposed of, lower landfill operation costs and prolong their lifespan.

e) Improving the management of pathogenic hospital waste

Most of the wastes generated by hospitals and clinics are similar to the domestic and commercial wastes produced by other institutions; i.e., they are not hazardous and do not require special attention. In order to minimize the amount of waste to be handled in a special way, the small portion of infectious and hazardous waste should always be kept separate from the other waste stream (e.g. separation at the source). Nevertheless, appropriate guidelines have to be developed for the special handling and safe disposal of the relatively small portion of hazardous pathogenic waste from hospitals and clinics.

4. CONCLUSIONS

Urban SWM is one of the most serious environmental problems confronting the governments in DCs. Inadequate collection and disposal of solid waste are major reasons for the environmental degradation and health risks in the fast growing urban areas of DCs. The above mentioned five typical problem areas are related to institutional, financial and technical issues.

The most promising approach to improve the collection coverage is the introduction of community-based waste management schemes which involve the local communities in the collection, sorting and recycling activities. Research is needed to determine how such schemes can be implemented under different kinds of condition.

Operational efficiency of SW services can be improved by increasing the participation of the private sector. However, future research should not only address the question of what should be the role of the private sector in SWM, but also how the performance of public enterprises can be improved and what should be the role of the public (government) sector vis-…-vis the private sector.

The benefits of the recycling activities by the informal sector should be officially recognized. Instead of being outlawed, these activities should be improved and encouraged. However, informal recycling systems have to be thoroughly studied before changes are introduced. Investigation on market and price mechanisms of secondary raw materials are also necessary to determine how the capacity of the informal and formal private sector in resource recovery from municipal solid waste can be improved.

In order to improve the present situation of final disposal, three basic measures are suggested: (a) institutional and financial models for waste disposal activities as an integral part of SWM have to be found and applied; (b) appropriate guidelines for the operation of landfills in DCs have to be developed; and (c) recycling of the large organic putrescible MSW fraction needs to be increased.

There is a need for appropriate guidelines for the handling and safe disposal of hazardous pathogenic waste from hospitals and clinics in DCs.