Sustainable waste management in Africa through CDM projects

Only few Clean Development Mechanism (CDM) projects (traditionally focussed on landfill gas combustion) have been registered in Africa if compared to similar developing countries. The waste hierarchy adopted by many African countries clearly shows that waste recycling and composting projects are generally the most sustainable. This paper undertakes a sustainability assessment for practical waste treatment and disposal scenarios for Africa and makes recommendations for consideration. The appraisal in this paper demonstrates that mechanical biological treatment of waste becomes more financially attractive if established through the CDM process. Waste will continue to be dumped in Africa with increasing greenhouse gas emissions produced, unless industrialised countries (Annex 1) fund carbon emission reduction schemes through a replacement to the Kyoto Protocol. Such a replacement should calculate all of the direct and indirect carbon emission savings and seek to promote public–private partnerships through a concerted support of the informal sector.     

Cost effective waste management through composting in Africa

Greenhouse gas (GHG) emissions per person from urban waste management activities are greater in sub-Saharan African countries than in other developing countries, and are increasing as the population becomes more urbanised. Waste from urban areas across Africa is essentially dumped on the ground and there is little control over the resulting gas emissions. The clean development mechanism (CDM), from the 1997 Kyoto Protocol has been the vehicle to initiate projects to control GHG emissions in Africa. However, very few of these projects have been implemented and properly registered. A much more efficient and cost effective way to control GHG emissions from waste is to stabilise the waste via composting and to use the composted material as a soil improver/organic fertiliser or as a component of growing media. Compost can be produced by open windrow or in-vessel composting plants. This paper shows that passively aerated open windrows constitute an appropriate low-cost option for African countries. However, to provide an usable compost material it is recommended that waste is processed through a materials recovery facility (MRF) before being composted. The paper demonstrates that material and biological treatment (MBT) are viable in Africa where they are funded, e.g. CDM. However, they are unlikely to be instigated unless there is a replacement to the Kyoto Protocol, which ceases for Registration in December 2012.     

Carbon emissions reduction strategies in Africa from improved waste management: A review

The paper summarises a literature review into waste management practices across Africa as part of a study to assess methods to reduce carbon emissions. Research shows that the average organic content for urban Municipal Solid Waste in Africa is around 56% and its degradation is a major contributor to greenhouse gas emissions. The paper concludes that the most practical and economic way to manage waste in the majority of urban communities in Africa and therefore reduce carbon emissions is to separate waste at collection points to remove dry recyclables by door to door collection, compost the remaining biogenic carbon waste in windrows, using the maturated compost as a substitute fertilizer and dispose the remaining fossil carbon waste in controlled landfills.     

Hospital solid waste management practices in Limpopo Province, South Africa: a case study of two hospitals

The shortcomings in the management practices of hospital solid waste in Limpopo Province of South Africa were studied by looking at two hospitals as case studies. Apart from field surveys, the generated hospital waste was weighed to compute the generation rates and was followed through various management practices to the final disposal. The findings revealed a major policy implementation gap between the national government and the hospitals. While modern practices such as landfill and incineration are used, their daily operations were not carried according to minimum standards. Incinerator ash is openly dumped and wastes are burned on landfills instead of being covered with soil. The incinerators used are also not environmentally friendly as they use old technology. The findings further revealed that there is no proper separation of wastes according to their classification as demanded by the national government. The mean percentage composition of the waste was found in the following decreasing order: general waste (60.74%)>medical waste (30.32%)>sharps (8.94%). The mean generation rates were found to be 0.60kg per patient per day.     

The costs of household food waste in South Africa

Food waste is problematic for a number of reasons, including the loss of a potentially valuable food source or resource for use in other processes (e.g. energy generation or composting), wasted resources and emissions in the food supply chain, and problems associated with the disposal of organic waste to landfill. This paper quantifies the household food waste stream in South Africa, in order to draw attention to the magnitude of the problem. In addition, it estimates the economic (monetary) value of the wasted food, as well as the costs associated with disposing putrescible food waste to landfill, in order to highlight the associated costs to society. Costs associated with the loss of a potentially valuable food source are valued using a weighted average market price of the wasted food. Costs associated with the disposal of food waste to landfill are quantified based on estimates of the financial and external costs associated with landfilling. For household food waste alone, the costs to society associated with these two food-waste related problems are estimated at approximately R21.7 billion (approximately US$2.7 billion) per annum, or 0.82% of South Africa’s annual GDP. These costs are therefore significant, particularly considering that household food waste accounts for less than 4% of total food losses across the food supply chain.     

Introducing mechanical biological waste treatment in South Africa: a comparative study

This paper presents the results of the first pilot project on mechanical biological waste treatment (MBWT) in South Africa. The study has shown that biological waste treatment in windrows using a passive aeration system that utilises thermal convection to drive the aeration process within a windrow of waste is appropriate for South Africa, in relation to low capital costs, low energy inputs, limited plant requirements and potential for labour-intensive operations. The influence of climate, waste composition and operational facilities was evaluated to optimise the treatment technique to local conditions. The maximum temperatures reached during the intensive thermophilic stage were effectively equivalent to the German experience. The lower CO2 production experienced in the South African trials was attributed to a different waste stream (high presence of plastics) due to the absence of a proper source separated waste collection system. An accurate adjustment of the input material (structural matter in particular) to the specific ambient conditions and irrigation during composting should result in higher organic carbon degradation efficiency in equivalent timeframes. This preliminary experience suggests that the applicability of MBWT in emerging countries, such as South Africa, is directly dependant on the mechanical treatment steps, available operational facilities and nature of the input material.     

Small-scale medical waste incinerators--experiences and trials in South Africa

Formal waste management services are not accessible for the majority of primary healthcare clinics on the African continent, and affordable and practicable technology solutions are required in the developing country context. In response, a protocol was established for the first quantitative and qualitative evaluation of relatively low cost small-scale incinerators for use at rural primary healthcare clinics. The protocol comprised the first phase of four, which defined the comprehensive trials of three incineration units. The trials showed that all of the units could be used to render medical waste non-infectious, and to destroy syringes or render needles unsuitable for reuse. Emission loads from the incinerators are higher than large-scale commercial incinerators, but a panel of experts considered the incinerators to be more acceptable compared to the other waste treatment and disposal options available in under-serviced rural areas. However, the incinerators must be used within a safe waste management programme that provides the necessary resources in the form of collection containers, maintenance support, acceptable energy sources, and understandable operational instructions for the incinerators, whilst minimising the exposure risks to emissions through the correct placement of the units in relation to the clinic and the surrounding communities. On-going training and awareness building are essential in order to ensure that the incinerators are correctly used as a sustainable waste treatment option.     

Part 1: The role of waste data in building knowledge: The South African waste information system

An empirical study was undertaken with 31 organisations submitting data to the South African Waste Information System (SAWIS) in order to explore the relationship between data and resultant waste knowledge generated through a process of learning. The results show that of the three constructs of knowledge (experience, data/information, and theory), experience has the greatest influence on building waste knowledge, nearly twice that of data/information and three times that of theory. Together the three constructs account for 54.1% of the variance in knowledge. Respondents from municipalities and private waste organisations reflect two distinct sub-groups in the data set. While the theoretical model remains the same for the two sub-groups, the way in which knowledge is constructed, and the variance in knowledge explained by the model, differs for the two. A mixed methods research design, combining quantitative statistical analysis and rich qualitative data, contributes to a comprehensive interpretation of the role of waste data in building knowledge in South Africa. While waste data has a minor influence on building knowledge, respondents acknowledge that waste data does have a positive impact on the way their organisations manage waste. However, it is not the data, but rather the resultant waste knowledge and raised level of awareness that causes the operational response. Experience is obtained predominantly through learning from others. Respondents in municipalities, emphasised learning from consultants, landfill site contractors, and colleagues in city-twinning programmes, while respondents in private waste companies, emphasised learning from experienced, senior colleagues.     

Costs of food waste along the value chain: Evidence from South Africa

In a previous paper (Nahman et al., 2012), the authors estimated the costs of household food waste in South Africa, based on the market value of the wasted food (edible portion only), as well as the costs of disposal to landfill. In this paper, we extend the analysis by assessing the costs of edible food waste throughout the entire food value chain, from agricultural production through to consumption at the household level. First, food waste at each stage of the value chain was quantified in physical units (tonnes) for various food commodity groups. Then, weighted average representative prices (per tonne) were estimated for each commodity group at each stage of the value chain. Finally, prices were multiplied by quantities, and the resulting values were aggregated across the value chain for all commodity groups. In this way, the total cost of food waste across the food value chain in South Africa was estimated at R61.5 billion per annum (approximately US$7.7 billion); equivalent to 2.1% of South Africa’s annual gross domestic product. The bulk of this cost arises from the processing and distribution stages of the fruit and vegetable value chain, as well as the agricultural production and distribution stages of the meat value chain. These results therefore provide an indication of where interventions aimed at reducing food waste should be targeted.     

Multiple system modelling of waste management

Due to increased environmental awareness, planning and performance of waste management has become more and more complex. Therefore waste management has early been subject to different types of modelling. Another field with long experience of modelling and systems perspective is energy systems. The two modelling traditions have developed side by side, but so far there are very few attempts to combine them. Waste management systems can be linked together with energy systems through incineration plants. The models for waste management can be modelled on a quite detailed level whereas surrounding systems are modelled in a more simplistic way. This is a problem, as previous studies have shown that assumptions on the surrounding system often tend to be important for the conclusions. In this paper it is shown how two models, one for the district heating system (MARTES) and another one for the waste management system (ORWARE), can be linked together. The strengths and weaknesses with model linking are discussed when compared to simplistic assumptions on effects in the energy and waste management systems. It is concluded that the linking of models will provide a more complete, correct and credible picture of the consequences of different simultaneous changes in the systems. The linking procedure is easy to perform and also leads to activation of project partners. However, the simulation procedure is a bit more complicated and calls for the ability to run both models.     

Flow analysis of metals in a municipal solid waste management system

This study aimed to identify the metal flow in a municipal solid waste (MSW) management system. Outputs of a resource recovery facility, refuse derived fuel (RDF) production facility, carbonization facility, plastics liquefaction facility, composting facility, and bio-gasification facility were analyzed for metal content and leaching concentration. In terms of metal content, bulky and incombustible waste had the highest values. Char from a carbonization facility, which treats household waste, had a higher metal content than MSW incinerator bottom ash. A leaching test revealed that Cd and Pb in char and Pb in RDF production residue exceeded the Japanese regulatory criteria for landfilling, so special attention should be paid to final disposal of these substances. By multiplying metal content and the generation rate of outputs, the metal content of input waste to each facility was estimated. For most metals except Cr, the total contribution ratio of paper/textile/plastics, bulky waste, and incombustible waste was over 80%. Approximately 30% of Cr originated from plastic packaging. Finally, several MSW management scenarios showed that most metals are transferred to landfills and the leaching potential of metals to the environment is quite small.     

韩国包装废物管理制度

介绍了韩国固体废物的管理中针对包装废物的管理体制和制度。韩国固体废物的主要监管执行部门是环境资源公社。韩国固体废物管理制度按照循环经济3R原则,制订了生产者责任延伸制度、废物付费制度、押金返还制度、分类排放标识制度及事业场废物减量化制度,在控制韩国包装废物产量和提高回收中起到了很好的作用。     

Towards zero discharge of chromium-containing leather waste through improved alkali hydrolysis

The treatment of chromium-containing leather waste (CCLW), the major solid waste generated at the post-tanning operations of leather processing, has the potential to generate value-added leather chemicals. Various alkali and enzymatic hydrolysis were compared, and calcium oxide was found to be important for effective (but still incomplete) hydrolysis. Three possible reasons are given for the incomplete hydrolysis under alkaline conditions. Data for 19 amino acids are presented for four different treatment products. On the basis of the results, a novel three-step CCLW treatment process is proposed. The gelatin extracted in the first step is chemically modified to produce leather finishing agents. The collagen hydrolysates isolated in the second step are used as proteinic retanning agents by chemical modification. The remaining chrome cake is further hydrolyzed with acids in the third step, and the obtained chromium-containing protein hydrolysates could be used for the preparation of chromium-containing retanning agents for leather industry. The proposed three-step process provides a feasible zero discharge process for the treatment of CCLW.     

Development and operation of a waste management system in Alberta,Canada

The successful hazardous waste treatment facility siting program in the Province of Alberta, Canada, provides an impressive example of comprehensive planning and implementation. Near Swan Hills, 250 km northwest of Edmonton, North America's first integrated Province (or State)- wide treatment and disposal facility, sited by both environmental and social criteria, was officially opened in September of 1987. Alberta's program is unique in that the public was involved from the outset and played a major role in the decision-making process.The $CDN 50M facility receives organic and inorganic wastes from Alberta generators. Treatment by incineration, physical/chemical treatment and stabilization destroys approximately 15,000 tonnes of waste annually. Inert residues are landfilled and treated wastewaters disposed of down a deep well. The facility is fed directly from large industry and indirectly, from small industry and households, via a system of collection and transfer stations located throughout the province.     

Optimization of regional hazardous waste management systems: an improved formulation

The planning and design of regional hazardous waste management system (RHWMS) involves selection of treatment and disposal facilities, allocation of hazardous wastes and waste residues from generator to the treatment and disposal sites and selection of the transportation routes. An improved formulation based upon multi-objective integer programming approach is presented to arrive at the optimal configuration of RHWMS components. This formulation addresses important practical issues like unique characteristics of the hazardous wastes reflecting on waste–waste and waste–technology compatibility. A utility function approach is presented to integrate both cost and risk related objectives. An illustrative case example is presented to demonstrate the usefulness of the improved formulation as a tool which can be used by environmental planning agencies in regional planning for hazardous waste management.     

Implementing separate waste collection and mechanical biological waste treatment in South Africa: A comparison with Austria and England

The degradation of organic compounds found in municipal solid waste (MSW) under the anaerobic landfill conditions produces gas and liquid emissions that can protract well into the landfill after-care period. The European Landfill Directives regulate the amount and nature of the organic compounds disposed into landfills. In South Africa and other developing countries, MSW is still landfilled without any kind of pre-treatment. This paper presents a pilot project of mechanical biological waste treatment (MBWT) in South Africa implemented at municipal level in the city of Durban using passively aerated open windrows. Based on case studies from Austria, England and South Africa, a waste minimisation model which can facilitate full-scale implementation of MBWT in developing countries is presented. MSW was treated in open windrows for 8 weeks. Composting temperature reached a maximum of 65 °C in less than 10 days. The results of eluate tests on waste samples from the windrows at the end of composting show a reduction of BOD₅ and BOD₅/COD ratios equal to 35.7% and 16.7%, respectively. The percent waste composition of the treated MSW was 28.3% putrescibles, 17.4% garden refuse, 13.3% plastic, 12.4% fabrics, 12% paper and other elements. The waste composition shows that more than 40% of un-treated organic material and also more than 40% non-biodegradable and recyclable materials are still landfilled without any form of biological treatment or resource recovery. A simple wet and dry waste collection model can promote recycling, treatment of biological waste before landfilling, resource recovery, labour intensive jobs and hence sustainable landfilling in the South African scenario as well as in similar developing countries.     

The effect of dynamic scheduling and routing in a solid waste management system

Solid waste collection and hauling account for the greater part of the total cost in modern solid waste management systems. In a recent initiative, 3300 Swedish recycling containers have been fitted with level sensors and wireless communication equipment, thereby giving waste collection operators access to real-time information on the status of each container. In this study, analytical modeling and discrete-event simulation have been used to evaluate different scheduling and routing policies utilizing the real-time data. In addition to the general models developed, an empirical simulation study has been performed on the downtown recycling station system in Malmoe, Sweden. From the study, it can be concluded that dynamic scheduling and routing policies exist that have lower operating costs, shorter collection and hauling distances, and reduced labor hours compared to the static policy with fixed routes and pre-determined pick-up frequencies employed by many waste collection operators today. The results of the analytical model and the simulation models are coherent, and consistent with experiences of the waste collection operators.