INTEGRATING COMPOSTING AND ANAEROBIC DIGESTION OF ORGANIC WASTES IN THE TROPICS: THE CASE OF A COMMUNITY BASED PILOT PLANT IN KAKIRI, KAMPALA, UGANDA

The absence of proper waste and wastewater management strategies is one of the most relevant issues faced in developing countries, where wastes are often abandoned along the roadsides with serious detrimental effects on hygienic conditions and aesthetics of urban areas, as well as on soil and groundwater quality. As organic waste (consisting of food wastes, mainly peelings, commingled with human and animal faeces) accounts for more than 70% by wet weight of the overall waste amount generated in low and medium income countries, abandoned waste heaps can be regarded as a source of insects, mosquitoes, flies and rats, so that health protection programmes should not neglect actions devoted to put into operation a valid waste management strategy and a proper wastewater collection system. As stated by a number of researchers, proper management of the organic fraction represents a relevant step towards the implementation of a sustainable waste management system and may contribute to make waste management sustainable from an economical point of view. As thermal treatment is hardly used due to the high water content of the material as well as the complexity of such a technology, biological stabilization processes are recognized to be the most promising options for organic waste management both in urban and in peri-urban areas of low and medium income countries. However, looking at the results from surveys carried out on the status of the composting plants built in low and medium income countries, it can be argued that the absence of both design criteria and operation guidelines specifically derived for these areas adversely affected the performances of the composting plants and led to the closure of most of them. The present research is aimed at contributing to the generation of a consistent and large database on the composting process evolution and yield through the execution of a wide pilot-scale experimental programme. The pilot area was also intended for public sensitization on waste managementrelated problems, for training of waste operators, for contacting potential stakeholders as well as for demonstrating to politicians and decision-makers the role of composting in a waste management system. In addition to the composting reactors, the pilot plant area was equipped with tower gardens for grey water treatment, a bio-latrine coupled with a fixed dome anaerobic digester to supply biogas to the kitchen at the pilot plant. The overall research target was to determine optimal conditions for generation of a synergistic interaction between the two biostabilisation processes of different kinds of organic wastes, utilising the biogas generated by the anaerobic process to overcome the problems related to the scarcity of reliable energy sources. Research activities are carried out by a team of Professors, esearchers and Students of Makerere niversity, in the framework of a cooperation with the Department of Civil and Environmental ngineering of the University of Rome “La Sapienza” and with the conomical and logistic support of the Italian ooperation Office. The present paper provides the results gained from the first two years of the experimental campaign carried out on the pilot plant.