Waste Management & Research: The Journal for a Sustainable Circular Economy

A complex treatment of agricultural waste including the following major steps: anaerobic fermentation of suitable waste, cogeneration of the obtained biogas and growth of microalgae consuming the CO₂ from biogas and flue gas was verified under field conditions in a pilot-scale photobioreactor. The growth kinetics of microalgae Chlorella sp. consuming mixture of air and carbon dioxide (2% (v/v) of CO₂), or flue gas (8—10% (v/v) of CO₂) was investigated. The results obtained in the pilot photobioreactor were compared with results previously measured in laboratory photobioreactors. The field tests were performed in a pilot-scale outdoor solar-bubbled photobioreactor located at a biogas station. The pilot-scale photobioreactor was in the shape of a flat and narrow vertical prism with a volume of 300 L. The microalgae growth rates were correlated with empirical formulas. Laboratory analyses of the produced microalgae confirmed that it meets the strict EU criteria for relevant contaminants level in foodstuffs. Utilization of flue gases from cogeneration therefore was not found to be detrimental to the quality of microalgal biomass, and may be used in these types of bioreactors.

Renewable energy sources (RES), excluding large hydroelectric plants, currently produce 4.21% of total electricity production in Greece. Even when considering the additional production from large hydroelectric plants, which accounts for some 7.8%, the distance to be covered towards the objective of 20% electricity produced from RES by 2010 and respectively towards 20% of total energy production by 2020 is discouraging. The potential, however, does exist; unfortunately so do serious barriers. On the other hand, solid waste management (SWM) is an issue that generates continuously increasing interest due to the extra amounts of solid waste generated; the lack of existing disposal facilities with adequate infrastructure and integrated management plans, also often accompanied by legislative and institutional gaps. However, socio-economic and public awareness problems are still met in the planning and implementation of RES and SWM projects, together with the lack of a complete national cadastre and a spatial development master plan, specifying areas eligible for RES and SWM development. Specific barriers occur for individual RES and the on-going inclusion of waste-derived renewable energy in the examined palette further increases the complexity of the entire issue. The consolidated study of this broad set of barriers was a main task of the present study which was carried out within the frame of a Hellenic—Canadian research project; the main results will be discussed herein.

The problem of odour nuisances in Greece was explored using: (a) field measurements of a range of malodorous compounds (hydrogen sulfide, ammonia, benzene, toluene, xylenes, formaldehyde, acetaldehyde, acetone, methyl-mercaptan and carbonyl sulfide) from selected wastewater treatment plants and composting facilities; and (b) questionnaires, completed by wastewater treatment plant operators, to investigate potential odour problems, the odour abatement technologies used, and potential interest and motives for adopting such technologies. The sparse information available in the literature is also exploited. Results indicate that on several occasions there was an odour problem, often stemming from the uncontrolled city sprawl, which results in mixed and often conflicting land uses. This is particularly true for wastewater treatment plants, which tend to be built close to built-up areas and highlights the importance of town planning as a tool to minimize odour problems. Measurement of odours and/or odour related gases is not commonly practised in Greece, while the odour abatement systems currently used are often considered inadequate by plant managers who do have an active interest in using more efficient and effective technologies. To our knowledge, this is the first systematic effort to monitor the odour nuisance in the country.

Waste management has become a great social concern for modern societies. Landfill emissions have been identified among the major contributors of global warming and climate changes with significant impact in national economies. The energy industry constitutes an additional greenhouse gas emitter, while at the same time it is characterized by significant costs and uncertain fuel prices. The above implications have triggered different policies and measures worldwide to address the management of municipal solid wastes on the one hand and the impacts from energy production on the other. Emerging methods of energy recovery from waste may address both concerns simultaneously. In this work a comparative study of co-generation investments based on municipal solid waste is presented, focusing on the evolution of their economical performance over time. A real-options algorithm has been adopted investigating different options of energy recovery from waste: incineration, gasification and landfill biogas exploitation. The financial contributors are identified and the impact of greenhouse gas trading is analysed in terms of financial yields, considering landfilling as the baseline scenario. The results indicate an advantage of combined heat and power over solely electricity production. Gasification, has failed in some European installations. Incineration on the other hand, proves to be more attractive than the competing alternatives, mainly due to its higher power production efficiency, lower investment costs and lower emission rates. Although these characteristics may not drastically change over time, either immediate or irreversible investment decisions might be reconsidered under the current selling prices of heat, power and CO ₂ allowances.

The Kirki project aimed to identify, among the mining waste abandoned at a mine and processing plant, the most critical potential pollution sources, the exposed milieus and the main pathways for contamination of a littoral area. This was accompanied by the definition of a monitoring network and remedial options. For this purpose, field analytical methods were extensively used to allow a more precise identification of the source, to draw relevant conceptual models and outline a monitoring network. Data interpretation was based on temporal series and on a geographical model. A classification method for mining waste was established, based on data on pollutant contents and emissions, and their long-term pollution potential. Mining waste present at the Kirki mine and plant sites comprises (A) extraction waste, mainly metal sulfide-rich rocks; (B) processing waste, mainly tailings, with iron and sulfides, sulfates or other species, plus residues of processing reagents; and (C) other waste, comprising leftover processing reagents and Pb—Zn concentrates. Critical toxic species include cadmium and cyanide. The stormy rainfall regime and hilly topography favour the flush release of large amounts of pollutants. The potential impacts and remedial options vary greatly. Type C waste may generate immediate and severe chemical hazards, and should be dealt with urgently by careful removal, as it is localised in a few spots. Type B waste has significant acid mine drainage potential and contains significant amounts of bioavailable heavy metals and metalloids, but they may also be released in solid form into the surface water through dam failure. The most urgent action is thus dams consolidation. Type A waste is by far the most bulky, and it cannot be economically removed. Unfortunately, it is also the most prone to acid mine drainage (seepage pH 1 to 2). This requires neutralisation to prevent acid water accelerating heavy metals and metalloids transfer. All waste management options require the implementation of a monitoring network for the design of a remediation plan, efficiency control, and later, community alert in case of accidental failure of mitigation/remediation measures. A network design strategy based on field measurements, laboratory validation and conceptual models is proposed.

A comprehensive life-cycle inventory of all consumptions and emissions of environmental relevance was made for the windrow composting plant treating garden waste in Aarhus (Denmark). The flows of materials and substances within the facility were balanced using the mass-balance model STAN. The overall fuel and electricity use at the facility (3.04 L diesel Mg^—1 wet waste (ww) and 0.2 kWh Mg^—1 ww) was low whereas the emissions of CH ₄ and N₂O from the windrows (2.4 ± 0.5 kg CH ₄—C Mg^—1 ww and 0.06 ± 0.03 kg N₂O—N Mg^—1 ww) were relatively high compared to data reported in similar studies. The loss of carbon during the 14-month-long composting was 56%. CH₄ made up 2.1% of the C lost. Loss of nitrogen-containing compounds was identified as the most sensible and uncertain parameter and could be relevant for global warming (N ₂O emissions), acidification (NH₃ emissions), and eutrophication (NH₃ and NO₃ emissions). The compost produced had a very low content of heavy metals and was suitable for use in gardens and/or agriculture.

A rational approach for developing optimal municipal solid waste (MSW) management plans comprises the strategic and the detailed planning phases. The present paper focuses on the former, the objective of which is to screen management alternatives so as to select the ones that are able to fulfil all legal and other management requirements with reasonable cost. The analysis considers the transportation, treatment and final disposal of the commingled wastes that remain after the application of material recovery at the source programmes and comprises 10 elements, four of which are region-dependent and the remaining ones application-dependent. These elements and their inter-dependencies are described and the entire methodology is applied to Greece. The application considers the existing regional plans and shows that they are incompatible with the existing EU Directives, as well as overly expensive. To address this problem, a new plan is developed in accordance with the rational planning principles of the present methodology. The comparative evaluation of the above alternatives shows that the existing regional plans, in addition to being incompatible with the applicable EU Directives, require 4.3 to 4.8 times (3.7 to 4.4 billion ) higher capital investment and their annual cost is at least 2.1 to 2.3 times (590 to 735 million year ^—1) higher in comparison with the new national plan.

In this study, a survey containing 28 questions concerning general information about the healthcare services, waste collection, training, waste quantities, storage and general evaluation was applied to 311 healthcare services. The response rate was 82%, which was considered acceptable for the evaluation of the results. The separate collection of medical waste and sharps was completely achieved in all of the healthcare services participating in the survey and 82.6% of the healthcare services used containers for separate collection of medical waste. Only 5% of the containers used for waste collection and temporary storage were inappropriate for collecting medical waste. Almost 33% of healthcare services organized courses monthly, 40% quarterly and 20% at least twice a year. A total of 88% of the hospitals have temporary storage depots for medical waste and all of these depots complied with the Medical Waste Control Regulation. The results of this study showed that the medical waste generation rate was 2.35 kg bed^-1 day^-1. The amount of liquid waste and sharps was determined for the first time in Turkey. The rate of separate collection for recyclables increased to 94%, having been 83% in 2006. The results indicate that in the period 2006—2009, the healthcare services conformed completely to the Medical Waste Control Regulation as it applied. Any deficiencies observed will be satisfied by precautionary actions that will be taken by hospital managers and local administrations.

As a result of urbanization and economic prosperity, which has accelerated the generation of municipal solid waste (MSW) along with its organic fraction, the management of MSW is a challenge faced by urban centres worldwide, including the European Union (EU) and Canada. Within a concept of waste recovery, the source separation and on-site treatment of urban organic waste (UOW) can resolve some of the major economic issues faced by urban centres along with the environmental and social issues associated with landfilling. In this context and in a comparison with the traditional landfilling practice, this paper examines on-site UOW composting strategies using a combination of centralized composting facilities, community composting centres and home composting. This study consisted of a feasibility and economic study based on available data and waste management costs. The results indicate that on-site treatment of UOW using practices such as home and community composting can lower management costs by 50, 37 and 34% for the rich European countries (annual GDP over US$25 000), the poorer European countries (annual GDP under US$25 000), and Canada, respectively. Furthermore, on-site composting can reduce greenhouse gas emissions by 40% for Europe and Canada, despite gas capture practices on landfill sites. However, the performance of home composters and the quality of the compost products are issues to be further addressed for the successful implementation of UOW on-site composting.