FG Abfallwirtschaft (ehemals)
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The Anaerobic Sequencing Batch Reactor (ASBR) operates by sequential batches, has been studied as an alternative treatment for different systems because of their versatility. The ASBR is applicable for the conversion of a wide variety of organic wastewaters to methane and carbon dioxide (biogas). The main factors affecting the overall performance of the ASBR are: agitation, Substrate/Biomass ratio, geometric configuration of the reactor and the feeding strategy. In this research the strategy agitation was carried out by used of a gaslift system coupled to an ASBR. The aim of the research was the creation of bases for the design and process control of an Anaerobic Sequencing Batch Gaslift Reactor on a laboratory scale in order to find the optimal operating regime and optimize the process. The type of gaslift system to be used is an internal loop with a concentric draught tube configuration, which enables the gas may be sparged either the draught tube or the annulus. The simple design of a gas lift reactor permits less expensive operation, requires less maintenance, low investment costs, low interference and low power consumption.
Scientific and technical objectives of the research include the analysis of macro geometric dimensions of the reactor, developing innovative solutions for optimization of mixing process (gaslift mixing), analysis of the hydrodynamics and the homogenization inside of the reactor.
This study also includes the flow determination in the riser, the evaluation of the liquid circulation velocity in the downcomer and the influence of the vertical draft tube and the effect of top and bottom clearance. Also, the goal was to find an adequate mixture to not destroy microorganisms but to allow the sedimented biomass and undigested solids may rise quickly and mixed with the feed substrate.
The unprecedented population growth, rising in community living standard and urbanization have left most municipalities in African Countries grappling to find viable solutions to their waste management problems. Improper waste management is attributed to systemic failure of policy makers and municipal authorities to identify the most sustainable approach to dealing with it so as to meet environmental and socio-economic aspirations. This study aims to find a new approach involving people of different social, ethnic, gender and religious groups in the reconstruction of local waste management systems creating typical win-win situations. The main objectives of this research are as follows: • Investigates how gender affects solid waste planning and the influence of different social status of the community especially the role of households. • Examines the level of community involvement in solid waste management in terms of policy formulation, implementation and evaluation. The case study area Cameroon “Africa in miniature” is used to highlight waste management burdens and challenges which are characteristic of most African cities. This research sought to answer one principal question: Can top-down approaches in municipal solid waste management be successful without sufficient community engagement and sense of ownership? Top-down approaches where considered in terms of policies and technology transfer. An integrated methodology was used involving a desk study, field survey for situation analysis, household questionnaire survey, habitat scale, “waste to cash seminar” for stakeholders’ analysis and focus group discussion. The outcome of this holistic investigation reveals a strong concern for a clean environment thus citizens’ participation and awareness creation is so vital to take the message to grass roots level. Municipal waste collection services are more effective when they work in collaboration with community led primary collection from households. It is clear that where a reliable service can be guaranteed communities are willing to pay for it. Building the capacity of communities implies empowering community to sustainably manage their waste. An integration of several factors is vital to increase sustainability. However, this does not undermine the fact that the best implementation in some situations is some sort of a middle ground between Top-down and Bottom-up.
Thermal recycling of plastic waste using pyrolysis-gasification process for energy production
(2012)
The disposal of mixed waste in landfills, dump sites and open burning without material and energy recovery leads to resource loss, causes health problems, pollution and littering. Increasing energy demand for industrial and domestic application with rising costs due to scarcity motivates a constant search for alternative clean energy sources. Recovering energy from waste presents various incentives e.g. creating jobs, alleviating poverty, combating and mitigating climate change, protecting the environment and reducing dependence on traditional fuels sources. Hence, plastics end up in landfills, surface waters and ocean bed with serious negative impact on terrestrial and aquatic biodiversity. Plastic waste with high calorific value (36-46MJ/kg) occupies the greatest portion of landfill space. Hence, using an appropriate technology to transform waste plastic to a hot gaseous mixture which is burned in-situ produces enormous amount of energy without pollution. Based on this hypothesis, the study objectives accomplished were to: 1.Characterise, quantify and classify waste fractions and plastic components common in MSW by manual sorting 2.Evaluate options for sustainable plastic waste management especially for developing countries 3.Design, construct, test and optimize an appropriate technology that applies pyrolysis and gasification processes to convert non-PVC plastic waste to energy 4.Assess the efficiency of the technology based on the functioning, the engineering, mass and energy analysis including socioeconomic and environmental impacts An integrated methodology involving review of current literature, field and laboratory experiments on mixed waste and plastic waste analysis was used. In addition, the pyrolysis-gasification technology (PGT) was conceptualised, designed, constructed, tested and optimised at BTU Cottbus, Germany; Lagos, Nigeria and Dschang, Cameroon. Field studies involving natural observation, interviews, personal discussions and visits to waste management organisations and disposal sites were conducted in various cities in the three case study countries. A resource-oriented manual sorting using the resource-recovery scavenging approach (RESA) simulating integration of scavenger’s activities in waste sorting was conducted at BTU and Lagos. Major results obtained include: •Characterization, quantification and classification of a dry sample of commingled MSW at Cottbus gave major waste fractions in order of decreasing abundance as 23.15% of residue waste, 19.75% of paper and cardboards, 17.80% of plastics, 14.63% of textiles and diapers, 10.06% of food waste and 9.55% of glass. An overall 33.21% of waste sample is compostable for manure, 52.2% usable as feedstock in the PG technology and 99.81% of total sample having a material or energy recovery potential. In Lagos, Nigeria main fractions were 29% of plastics, 36% of residue waste, 17% of soil/sand, 7% of paper with overall 41% usable as feedstock in PG technology, 39% compostable, 3% of recyclable (metal and glass). Sand can be recovered from the soil/sand fraction for construction. Excluding the sand/soil mixture, 83% of the total waste sample has potential for material and energy value. •An appropriate technology that applies principles of pyrolysis and gasification to convert non-PVC plastic waste to energy was designed, constructed, tested and optimized with respect to: (i) Successful functioning with conversion of averagely 98.51% of input constituting of 82.78-98.21% of charcoal and 96.72-99.27% of plastic to heat energy (ii) Evaluation of socioeconomic and environmental impacts based on pyrolysis and exhaust gas and ash residue analysis showed absence of VOCs, heavy metals and pollutant organic and inorganic compounds; (iii) Safety and risk assessment to indoor pollution is very low; (iv) Assessment of the WTA and WTP indicated that 94% of respondents in Lagos, Nigeria and Porto Novo, Benin were willing to accept and pay for this technology. Using the PG technology improves local communities’ ability to achieve clean, efficient and safe cooking and heating energy with potential for combine heat power generation.
While much is known about ISO 14001 and EMAS environmental management systems in general, comparatively little knowledge is about the application of these management instruments in non-industrial sectors, including the municipal waste sector. Consequently, the intention of this paper is to assist municipal waste treatment facilities with the development of environmental management systems in which the continual improvement of environmental performance can be coupled with an increased economic efficiency and quality of delivered services. For this purpose, a manual that provides sample polices, programmes and approaches to the successful realisation of the ISO 14001 environmental management system was written. Due to more stringent requirements for the sound management of municipal solid waste, a growing number of Polish municipal waste treatment facilities have implemented or intend to implement the ISO 14001 system. By the end of 2005, 25% of facilities were formally certified to the ISO 14001 EMS, 60% of which have integrated it with the ISO 9001 QMS. The facilities, despite encountering a number of difficulties, for instance during the identification and assessment of significant environmental aspects, are also gaining numerous benefits, resulting in an improved environmental performance. Ipso facto, 37.5% of municipal waste treatment facilities in Poland have admitted that the environmental-improvement potential of EMSs is higher than economic-human costs related to its introduction and operation. All the presented information, if other sources are not adequately referenced, are based upon the author’s research, encompassing quantitative and qualitative study methods, conducted among municipal waste treatment facilities in Poland in years 2004 – 2006. The response rate of 68% guarantees credibility of the collected data.
In the quest of finding sustainable solution to solid waste management problems in Ghana, this research formulated as its goal, to mitigate policy constraints to sustainable solid waste management in Ghana. This research goal and objectives were addressed through an empirical study that involved interviews and administration of two sets of questionnaires, one set to members of parliament and the other to members of the general public. The development of questionnaires was influenced by a conceptual policy development model “The Bridge Model of Policy Development”. Administration of questionnaires to members of the general public was accomplished through random sampling within churches and mosques in three cities in Ghana; Accra, Kumasi, and Takoradi. The percentage response for members of the general public was 38.9% and that for members of parliament was 18%. Prioritization of policy options was achieved through “Differentiated Perception Ranking”, a method devised by this research process. The results revealed the relative importance of constraints to sustainable solid waste management in Ghana, the relative difficulty of mitigating constraints, and the relative difficulty of implementing policy options among others. These results were integrated with the principles of sustainability into producing a policy package for sustainable solid waste management in Ghana.
Aim of the study In this thesis, the recovery of biogas from Unsorted Municipal Solid Waste with high methane content was investigated. Special attention was given to unsorted municipal solid waste since its management is posing a big challenge for solid waste management authorities especially in developing countries (e.g. Accra, Ghana). Common solid waste management practice in most of the communities involves having the entire components of the waste mixed together and deposited in bins or on a bare ground at locations within communities and subsequently hauled to the dumpsite by the waste authority. In a laboratory study, a simulated waste was developed representing the real waste situation in Accra, Ghana to leach out the biodegradable organic fraction and subsequent biogas recovery. Method of investigation In order to optimize the biodegradation of Unsorted Municipal Solid Waste, the double-stage anaerobic digester with optimum design capability and with both intra and inter liquid recirculation, and microaerophilic hydrolysis conditions was employed. In order to biomethanize the waste, the following hypotheses were tested: · Effect of water flow rate (dilutions) on the extent of hydrolysis/ liquefaction. · Solid retention time and biodegradation. · Temperature on the extent of hydrolysis. · Effect of preprocessed feeding material on hydrolysis and gas yield. Results and technical applicability The results indicate that the various conditions tested are effective in determining the biogas production from the Unsorted Municipal Solid Waste. Following several runs for the optimization process, volume and mass reduction of 30±19% and 42±13% was achieved respectively. Importantly, almost 42% of the organic total solids reduction with equivalent of methane yield of 232±66 l CH4/kg OTS was obtained. A concept is developed for the application of the double-stage digester for the biomethanization of Unsorted Municipal Solid Waste. This concept involves the appropriate optimum conditions required for the biodegradation process. Finally the potential of using Unsorted Municipal Solid Waste for commercial biogas production was emphasized.