Waste Management (WASTE MANAGE)

Publications in this journal

• Article: Development of numerical model for predicting heat generation and temperatures in MSW landfills.

  James L Hanson, Nazli Yeşiller, Michael T Onnen, Wei-Lien Liu, Nicolas K Oettle, Janelle A Marinos
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  ABSTRACT: A numerical modeling approach has been developed for predicting temperatures in municipal solid waste landfills. Model formulation and details of boundary conditions are described. Model performance was evaluated using field data from a landfill in Michigan, USA. The numerical approach was based on finite element analysis incorporating transient conductive heat transfer. Heat generation functions representing decomposition of wastes were empirically developed and incorporated to the formulation. Thermal properties of materials were determined using experimental testing, field observations, and data reported in literature. The boundary conditions consisted of seasonal temperature cycles at the ground surface and constant temperatures at the far-field boundary. Heat generation functions were developed sequentially using varying degrees of conceptual complexity in modeling. First a step-function was developed to represent initial (aerobic) and residual (anaerobic) conditions. Second, an exponential growth-decay function was established. Third, the function was scaled for temperature dependency. Finally, an energy-expended function was developed to simulate heat generation with waste age as a function of temperature. Results are presented and compared to field data for the temperature-dependent growth-decay functions. The formulations developed can be used for prediction of temperatures within various components of landfill systems (liner, waste mass, cover, and surrounding subgrade), determination of frost depths, and determination of heat gain due to decomposition of wastes.
  Waste Management 05/2013;
• Article: Simultaneous personnel and vehicle shift scheduling in the waste management sector.

  Gianpaolo Ghiani, Emanuela Guerriero, Andrea Manni, Emanuele Manni, Agostino Potenza
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  ABSTRACT: Urban waste management is becoming an increasingly complex task, absorbing a huge amount of resources, and having a major environmental impact. The design of a waste management system consists in various activities, and one of these is related to the definition of shift schedules for both personnel and vehicles. This activity has a great incidence on the tactical and operational cost for companies. In this paper, we propose an integer programming model to find an optimal solution to the integrated problem. The aim is to determine optimal schedules at minimum cost. Moreover, we design a fast and effective heuristic to face large-size problems. Both approaches are tested on data from a real-world case in Southern Italy and compared to the current practice utilized by the company managing the service, showing that simultaneously solving these problems can lead to significant monetary savings.
  Waste Management 05/2013;
• Article: Recycling and reuse of waste from electricity distribution networks as reinforcement agents in polymeric composites.

  Matheus V G Zimmermann, Ademir J Zattera
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  ABSTRACT: Of the waste generated from electricity distribution networks, wooden posts treated with chromated copper arsenate (CCA) and ceramic insulators make up the majority of the materials for which no effective recycling scheme has been developed. This study aims to recycle and reuse this waste as reinforcement elements in polymer composites and hybrid composites, promoting an ecologically and economically viable alternative for the disposal of this waste. The CCA wooden posts were cut, crushed and recycled via acid leaching using 0.2 and 0.4N H2SO4 in triplicate at 70°C and then washed and dried. The ceramic insulators were fragmented in a hydraulic press and separated by particle size using a vibrating sieve. The composites were mixed in a twin-screw extruder and injected into the test specimens, which were subjected to physical, mechanical, thermal and morphological characterization. The results indicate that the acid treatment most effective for removing heavy metals in the wood utilizes 0.4NH2SO4. However, the composites made from wood treated with 0.2NH2SO4 exhibited the highest mechanical properties of the composites, whereas the use of a ceramic insulator produces composites with better thermal stability and impact strength. This study is part of the research and development project of ANEEL (Agência Nacional de Energia Elétrica) and funded by CPFL (Companhia Paulista de Força e Luz).
  Waste Management 05/2013;
• Article: Diversity of bacterial isolates during full scale rotary drum composting.

  Akansha Bhatia, Sangeeta Madan, Jitendra Sahoo, Muntjeer Ali, Ranjana Pathania, Absar Ahmed Kazmi
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  ABSTRACT: Bacterial diversity of full scale rotary drum composter from biodegradable organic waste samples were analyzed through two different approaches, i.e., Culture dependent and independent techniques. Culture-dependent enumerations for indigenous population of bacterial isolates mainly total heterotrophic bacteria (Bacillus species, Pseudomonas species and Enterobacter species), Fecal Coliforms, Fecal Streptococci, Escherichia coli, Salmonella species and Shigella species showed reduction during the composting period. On the other hand, Culture-independent method using PCR amplification of specific 16S rRNA sequences identified the presence of Acinetobacter species, Actinobacteria species, Bacillus species, Clostridium species, Hydrogenophaga species, Butyrivibrio species, Pedobacter species, Empedobactor species and Flavobacterium species by sequences clustering in the phylogenetic tree. Furthermore, correlating physico-chemical analysis of samples with bacterial diversity revealed the bacterial communities have undergone changes, possibly linked to the variations in temperature and availability of new metabolic substrates while decomposing organics at different stages of composting.
  Waste Management 05/2013;
• Article: Biopotentiality as an index of environmental compensation for composting plants.

  Alberto Pivato, Stefano Vanin, Luca Palmeri, Alberto Barausse, Giovanni Mangione, Michele Rasera, Monego Gianluca
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  ABSTRACT: The Biopotentiality Index is a landscape ecology indicator, which can be used to estimate the latent energy of a given land and to assess the environmental impacts due to the loss of naturalness on a landscape scale. This indicator has been applied to estimate the effectiveness of the measures put in place to provide an environmental compensation for the revamping of a composting plant. These compensation measures are represented by a green belt with a minimum width of 25m all around the plant, representing both a windbreak and a buffer zone, and by two wide wooded zones acting as core natural areas. This case-study shows that the compensation index could be used as a key tool in order to negotiate the acceptance of waste treatment plant with the population.
  Waste Management 05/2013;
• Article: Energy implications of mechanical and mechanical-biological treatment compared to direct waste-to-energy.

  Ciprian Cimpan, Henrik Wenzel
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  ABSTRACT: Primary energy savings potential is used to compare five residual municipal solid waste treatment systems, including configurations with mechanical (MT) and mechanical-biological (MBT) pre-treatment, which produce waste-derived fuels (RDF and SRF), biogas and/or recover additional materials for recycling, alongside a system based on conventional mass burn waste-to-energy and ash treatment. To examine the magnitude of potential savings we consider two energy efficiency levels (state-of-the-art and best available technology), the inclusion/exclusion of heat recovery (CHP vs. PP) and three different background end-use energy production systems (coal condensing electricity and natural gas heat, Nordic electricity mix and natural gas heat, and coal CHP energy quality allocation). The systems achieved net primary energy savings in a range between 34 and 140MJprimary/100MJinput waste, in the different scenario settings. The energy footprint of transportation needs, pre-treatment and reprocessing of recyclable materials was 3-9.5%, 1-18% and 1-8% respectively, relative to total energy savings. Mass combustion WtE achieved the highest savings in scenarios with CHP production, nonetheless, MBT-based systems had similarly high performance if SRF streams were co-combusted with coal. When RDF and SRF was only used in dedicated WtE plants, MBT-based systems totalled lower savings due to inherent system losses and additional energy costs. In scenarios without heat recovery, the biodrying MBS-based system achieved the highest savings, on the condition of SRF co-combustion. As a sensitivity scenario, alternative utilisation of SRF in cement kilns was modelled. It supported similar or higher net savings for all pre-treatment systems compared to mass combustion WtE, except when WtE CHP was possible in the first two background energy scenarios. Recovery of plastics for recycling before energy recovery increased net energy savings in most scenario variations, over those of full stream combustion. Sensitivity to assumptions regarding virgin plastic substitution was tested and was found to mostly favour plastic recovery.
  Waste Management 05/2013;
• Article: Evaluation of Solvita compost stability and maturity tests for assessment of quality of end-products from mixed latrine style compost toilets.

  Geoffrey B Hill, Susan A Baldwin, Bjorn Vinnerås
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  ABSTRACT: It is challenging and expensive to monitor and test decentralized composting toilet systems, yet critical to prevent the mismanagement of potentially harmful and pathogenic end-product. Recent studies indicate that mixed latrine composting toilets can be inhibited by high ammonia content, a product of urea hydrolysis. Urine-diverting vermicomposting toilets are better able to accomplish the goals of remote site human waste management by facilitating the consumption of fecal matter by earthworms, which are highly sensitive to ammonia. The reliability of Solvita® compost stability and maturity tests were evaluated as a means of determining feedstock suitability for vermicomposting (ammonia) and end-product stability/completeness (carbon dioxide). A significant linear regression between Solvita® ammonia and free ammonia gas was found. Solvita® ranking of maturity did not correspond to ranking assigned by ammonium:nitrate standards. Solvita® ammonia values 4 and 5 contained ammonia levels below earthworm toxicity limits in 80% and 100% of samples respectively indicative of their use in evaluating feedstock suitability for vermicomposting. Solvita® stability tests did not correlate with carbon dioxide evolution tests nor ranking of stability by the same test, presumably due to in situ inhibition of decomposition and microbial respiration by ammonia which were reported by the Solvita® CO2 test as having high stability values.
  Waste Management 05/2013;
• Article: Dynamic of functional microbial groups during mesophilic composting of agro-industrial wastes and free-living (N2)-fixing bacteria application.

  Olimpia Pepe, Valeria Ventorino, Giuseppe Blaiotta
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  ABSTRACT: Although several reports are available concerning the composition and dynamics of the microflora during the composting of municipal solid wastes, little is known about the microbial diversity during the composting of agro-industrial refuse. For this reason, the first parts of this study included the quantification of microbial generic groups and of the main functional groups of C and N cycle during composting of agro-industrial refuse. After a generalized decrease observed during the initial phases, a new bacterial growth was observed in the final phase of the process. Ammonifiers and (N2)-fixing aerobic groups predominated outside of the piles whereas, nitrate-reducing group increased inside the piles during the first 23days of composting. Ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), showed an opposite trend of growth since ammonia oxidation decreased with the increase of the nitrite oxidation activity. Pectinolytics, amylolytics and aerobic cellulolytic were present in greater quantities and showed an upward trend in both the internal and external part of the heaps. Several free-living (N2)-fixing bacteria were molecularly identify as belonging especially to uncommon genera of nitrogen-fixing bacteria as Stenotrophomonas, Xanthomonas, Pseudomonas, Klebsiella, Alcaligenes, Achromobacter and Caulobacter. They were investigated for their ability to fix atmospheric nitrogen to employ as improvers of quality of compost. Some strains of Azotobacter chrococcum and Azotobacter salinestris were also tested. When different diazotrophic bacterial species were added in compost, the increase of total N ranged from 16% to 27% depending on the selected microbial strain being used. Such microorganisms may be used alone or in mixtures to provide an allocation of plant growth promoting rhizobacteria in soil.
  Waste Management 05/2013;
• Article: Anaerobic digestion in municipal solid waste management: Part of an integrated, holistic and sustainable solution.

  E Iacovidou, M Vlachopoulou, S Mallapaty, D G Ohandja, J Gronow, N Voulvoulis
  Waste Management 05/2013; 33(5):1035-6.
• Article: BMP tests of source selected OFMSW to evaluate anaerobic codigestion with sewage sludge.

  Valentina Cabbai, Maurizio Ballico, Eleonora Aneggi, Daniele Goi
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  ABSTRACT: The aim of this study is to characterize different types of source selected organic fraction of municipal solid waste (SS-OFMSW) in order to optimize the upgrade of a sewage sludge anaerobic digestion unit by codigestion. Various SS-OFMSW samples were collected from canteens, supermarkets, restaurants, households, fruit-vegetable markets and bakery shops. The substrates characterization was carried out getting traditional chemical-physical parameters, performing elemental analysis and measuring fundamental anaerobic digestion macromolecular compounds such as carbohydrates, proteins, lipids and volatile fatty acids. Biochemical methane potential (BMP) tests were conducted at mesophilic temperature both on single substrates and in codigestion regime with different substrates mixing ratios. The maximum methane yield was observed for restaurant (675NmlCH4/gVS) and canteens organic wastes (571 and 645NmlCH4/gVS). The best codigestion BMP test has highlighted an increase of 47% in methane production respect sewage sludge digestion.
  Waste Management 04/2013;
• Article: Study on the mechanical and environmental properties of concrete containing cathode ray tube glass aggregate.

  Diego Romero, Jacqueline James, Rodrigo Mora, Carol D Hays
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  ABSTRACT: Cathode ray tube (CRT) glass is considered a hazardous material due to its lead toxicity. In addition, current disposal practices are being phased out due to their adverse environmental impacts. In this project, CRT glass was used as a fine aggregate replacement in concrete. Life-cycle material characterization was conducted by evaluating the durability and strength of the CRT-Concrete. Leaching tests were also conducted to investigate whether the material meets drinking water limits for Pb. Test results show that the plastic state of the CRT-Concrete was affected by the angularity of the glass particles. Moreover, the compressive strength of CRT-Concrete met and exceeded that of the control specimen. However, CRT-Concrete was susceptible to expansive alkali-silica reactions when more than 10% CRT replacement was used. Environmental leaching results show that lead concentrations from CRT-Concrete are below the drinking water limits depending on the CRT volume replacement and if biopolymers are used.
  Waste Management 04/2013;
• Article: The evaluation of an analytical protocol for the determination of substances in waste for hazard classification.

  Pierre Hennebert, Arnaud Papin, Jean-Marie Padox, Benoît Hasebrouck
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  ABSTRACT: The classification of waste as hazardous could soon be assessed in Europe using largely the hazard properties of its constituents, according to the the Classification, Labelling and Packaging (CLP) regulation. Comprehensive knowledge of the component constituents of a given waste will therefore be necessary. An analytical protocol for determining waste composition is proposed, which includes using inductively coupled plasma (ICP) screening methods to identify major elements and gas chromatography/mass spectrometry (GC-MS) screening techniques to measure organic compounds. The method includes a gross or indicator measure of 'pools' of higher molecular weight organic substances that are taken to be less bioactive and less hazardous, and of unresolved 'mass' during the chromatography of volatile and semi-volatile compounds. The concentration of some elements and specific compounds that are linked to specific hazard properties and are subject to specific regulation (examples include: heavy metals, chromium(VI), cyanides, organo-halogens, and PCBs) are determined by classical quantitative analysis. To check the consistency of the analysis, the sum of the concentrations (including unresolved 'pools') should give a mass balance between 90% and 110%. Thirty-two laboratory samples comprising different industrial wastes (liquids and solids) were tested by two routine service laboratories, to give circa 7000 parameter results. Despite discrepancies in some parameters, a satisfactory sum of estimated or measured concentrations (analytical balance) of 90% was reached for 20 samples (63% of the overall total) during this first test exercise, with identified reasons for most of the unsatisfactory results. Regular use of this protocol (which is now included in the French legislation) has enabled service laboratories to reach a 90% mass balance for nearly all the solid samples tested, and most of liquid samples (difficulties were caused in some samples from polymers in solution and vegetable oil). The protocol is submitted to French and European normalization bodies (AFNOR and CEN) and further improvements are awaited.
  Waste Management 04/2013;
• Article: Thermal valorization of post-consumer film waste in a bubbling bed gasifier.

  S Martínez-Lera, J Torrico, J Pallarés, A Gil
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  ABSTRACT: The use of plastic bags and film packaging is very frequent in manifold sectors and film waste is usually present in different sources of municipal and industrial wastes. A significant part of it is not suitable for mechanical recycling but could be safely transformed into a valuable gas by means of thermal valorization. In this research, the gasification of film wastes has been experimentally investigated through experiments in a fluidized bed reactor of two reference polymers, polyethylene and polypropylene, and actual post-consumer film waste. After a complete experimental characterization of the three materials, several gasification experiments have been performed to analyze the influence of the fuel and of equivalence ratio on gas production and composition, on tar generation and on efficiency. The experiments prove that film waste and analogue polymer derived wastes can be successfully gasified in a fluidized bed reactor, yielding a gas with a higher heating value in a range from 3.6 to 5.6MJ/m(3) and cold gas efficiencies up to 60%.
  Waste Management 04/2013;
• Article: Management of agricultural biomass wastes: Preliminary study on characterization and valorisation in clay matrix bricks.

  Luisa Barbieri, Fernanda Andreola, Isabella Lancellotti, Rosa Taurino
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  ABSTRACT: In this work the feasibility of using woody agricultural biomass wastes as grapes and cherries seeds, sawdust, as pore forming agent, and sugar cane ash, as silica precursor, in bricks, were reported. Sawdust and grapes and cherries seeds, thanks to their organic substances content, during their combustion, bring an energetic support in the bricks firing phase and act as pore forming agent. Usually the addition of this kind of waste is limited to 10wt.% in order to reach an equilibrium between positive (weight and shrinkage decrease and porosity increase) and negative (increase of water absorption and mechanical resistance decrease) effects. The results show that grapes and cherries seeds, added in a percentage of 5wt.% to a brick formulation, have better influence with respect to the sawdust, maintaining the mechanical properties of the fired brick (950°C), showing modulus of rupture around 21-23MPa with a weight reduction of 3-10% (respect to the standard one). Regarding the sugar cane ash, the addition of 5wt.% improves the mechanical properties (modulus of rupture around 27MPa) and no weight decrease is observed. These results confirmed the role played by this kind of agricultural waste, which thanks to its high silica content (61wt.%) is capable to demonstrate a filler and plasticity reducing effect on the brick bodies. Tests carried out highlighted that the addition of these by-products (5wt.%) do not change negatively the main technological properties measured (water absorption, linear shrinkage, flexural resistance, etc.) and permit to hypothesize their use to obtain bricks with both insulating and higher mechanical properties using a pore agent forming or silica carrier alternative raw materials, respectively.
  Waste Management 04/2013;
• Article: Towards a coherent European approach for taxation of combustible waste.

  Maarten Dubois
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  ABSTRACT: Although intra-European trade of combustible waste has grown strongly in the last decade, incineration and landfill taxes remain disparate within Europe. The paper proposes a more coherent taxation approach for Europe that is based on the principle of Pigovian taxation, i.e. the internalization of environmental damage costs. The approach aims to create a level playing field between European regions while reinforcing incentives for sustainable management of combustible waste. Three important policy recommendations emerge. First, integrating waste incineration into the European Emissions Trading System for greenhouse gases (EU ETS) reduces the risk of tax competition between regions. Second, because taxation of every single air pollutant from waste incineration is cumbersome, a differentiated waste incineration tax based on NOx emissions can serve as a second-best instrument. Finally, in order to strengthen incentives for ash treatment, a landfill tax should apply for landfilled incineration residues. An example illustrates the coherence of the policy recommendations for incineration technologies with diverse environmental effects.
  Waste Management 04/2013;
• Article: Enhanced biodegradation at the Landgraaf bioreactor test-cell.

  Hans Oonk, André van Zomeren, Tristan C Rees-White, Richard P Beaven, Nanne Hoekstra, Luchien Luning, Maan Hannen, Hans Hermkes, Hans Woelders
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  ABSTRACT: From 2001 to 2011, a bioreactor demonstration was performed in a 25,000m(3) (8m deep, 3500m(2) surface) test-cell. In this bioreactor, biodegradation was enhanced by premixing and homogenizing of waste, recirculation of leachate and aeration. Anaerobic biodegradation was completed within four years and was followed by two years of aeration. Ultimately a residue was obtained that had lost approximately 95% of its biogas potential. Biodegradation resulted in a significantly reduced leaching potential for dissolved organic carbon (DOC) and specific heavy metals. For other inorganic components, less progress was achieved. Increased flushing would be required for further reduction of the leaching potential. A significant reduction in chemical oxygen demand (COD) and ammonia (NH4(+)) in leachate was not demonstrated during the relative short-term aeration: COD concentrations actually increased slightly and there was no effect on NH4(+). During the project, it became clear that moisture flow through the waste followed preferential flow paths. Therefore, attention was also paid to gain better understanding of leachate flows. From a tracer test, it was concluded that part of the waste contaminants are held in immobile blocks and are to a large extent unaffected by flow occurring in the surrounding preferential flow paths.
  Waste Management 04/2013;
• Article: Recovery of ammonia from poultry litter using flat gas permeable membranes.

  M J Rothrock, A A Szögi, M B Vanotti
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  ABSTRACT: The use of flat gas-permeable membranes was investigated as components of a new process to capture and recover ammonia (NH3) in poultry houses. This process includes the passage of gaseous NH3 through a microporous hydrophobic membrane, capture with a circulating dilute acid on the other side of the membrane, and production of a concentrated ammonium (NH4) salt. Bench- and pilot-scale prototype systems using flat expanded polytetrafluoroethylene (ePTFE) membranes and a sulfuric acid solution consistently reduced headspace NH3 concentrations from 70% to 97% and recovered 88% to 100% of the NH3 volatilized from poultry litter. The potential benefits of this technology include cleaner air inside poultry houses, reduced ventilation costs, and a concentrated liquid ammonium salt that can be used as a plant nutrient solution.
  Waste Management 04/2013;
• Article: Italian WEEE management system and treatment of end-of-life cooling and freezing equipments for CFCs removal.

  M Sansotera, W Navarrini, S Talaeemashhadi, F Venturini
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  ABSTRACT: This study presents and analyzes the data of the Italian system for take-back and recovery of waste electrical and electronic equipments (WEEEs) in the start-up period 2008-2010. The analysis was focused particularly on the data about the treatment of end-of-life cooling and freezing equipments. In fact, the wastes of cooling and freezing equipments have a high environmental impact. Indeed, in their compressor oil and insulation polyurethane (PU) foams chlorofluorocarbon (CFC) ozone-depleting gases are still present. In the period 2001-2004 Northern Italy resulted the main source in Europe of CFCs. The European Directive on WEEE management was enacted in 2002, but in Italy it was implemented by the legislative Decree in 2005 and it became operational in 2008. Actually, in 2008 the national WEEE Coordination Centre was founded in order to organize the WEEE pick-up process and to control collection, recovery and recycling targets. As a result, in 2010 the average WEEE collection per capita exceeded the threshold of more than 4kg per inhabitant, as well as cooling and freezing appliances represented more than one fourth of the Italian WEEE collection stream. During the treatment of end-of-life cooling and freezing equipments, CFCs were recovered and disposed principally by burner methods. The analyses of defined specimens collected in the treatment facilities were standardized to reliably determine the amount of recovered CFCs. Samples of alkaline solid salt, alkaline saline solution, polyurethane matrix and compressor oil collected during the audit assessment procedure were analyzed and the results were discussed. In particular, the analysis of PU samples after the shredding and the warm pressing procedures measured a residual CFCs content around 500-1300mg/kg of CFCs within the foam matrix.
  Waste Management 04/2013;
• Article: Treatment of digestate from a co-digestion biogas plant by means of vacuum evaporation: Tests for process optimization and environmental sustainability.

  A Chiumenti, F da Borso, R Chiumenti, F Teri, P Segantin
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  ABSTRACT: Vacuum evaporation consists in the boiling of a liquid substrate at negative pressure, at a temperature lower than typical boiling temperature at atmospheric conditions. Condensed vapor represents the so called condensate, while the remaining substrate represents the concentrate. This technology is derived from other sectors and is mainly dedicated to the recovery of chemicals from industrial by-products, while it has not been widely implemented yet in the field of agricultural digestate treatment. The present paper relates on experimental tests performed in pilot-scale vacuum evaporation plants (0.100 and 0.025m(3)), treating filtered digestate (liquid fraction of digestate filtered by a screw-press separator). Digestate was produced by a 1MWe anaerobic digestion plant fed with swine manure, corn silage and other biomasses. Different system and process configurations were tested (single-stage and two-stage, with and without acidification) with the main objectives of assessing the technical feasibility and of optimizing process parameters for an eventual technology transfer to full scale systems. The inputs and outputs of the process were subject to characterization and mass and nutrients balances were determined. The vacuum evaporation process determined a relevant mass reduction of digestate. The single stage configuration determined the production of a concentrate, still in liquid phase, with a total solid (TS) mean concentration of 15.0%, representing, in terms of mass, 20.2% of the input; the remaining 79.8% was represented by condensate. The introduction of the second stage allowed to obtain a solid concentrate, characterized by a content of TS of 59.0% and representing 5.6% of initial mass. Nitrogen balance was influenced by digestate pH: in order to limit the stripping of ammonia and its transfer to condensate it was necessary to reduce the pH. At pH 5, 97.5% of total nitrogen remained in the concentrate. This product was characterized by very high concentrations of total Kjeldhal nitrogen (TKN), 55,000mg/kg as average. Condensate, instead, represented 94.4% of input mass, containing 2.5% of TKN. This fraction could be discharged into surface water, after purification to meet the criteria imposed by Italian regulation. Most likely, condensate could be used as dilution water for digestion input, for cleaning floor and surfaces of animal housings or for crop irrigation. The research showed the great effectiveness of the vacuum evaporation process, especially in the two stage configuration with acidification. In fact, the concentration of nutrients in a small volume determines easier transportation and reduction of related management costs. In full scale plants energy consumption is estimated to be 5-8kWhe/m(3) of digestate and 350kWht/m(3) of evaporated water.
  Waste Management 04/2013;
• Article: Achieving sustainable biomaterials by maximising waste recovery.

  David Glew, Lindsay C Stringer, Simon McQueen-Mason
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  ABSTRACT: The waste hierarchy of 'reduce, reuse, recycle, recover' can be followed to improve the sustainability of a product, yet it is not applied in any meaningful way in the biomaterials industry which focuses more on sustainable sourcing of inputs. This paper presents the results of industry interviews and a focus group with experts to understand how waste recovery of biomaterials could become more widespread. Interview findings were used to develop three scenarios: (1) do nothing; (2) develop legislation; and (3) develop certification standards. These scenarios formed the basis for discussions at an expert focus group. Experts considered that action was required, rejecting the first scenario. No preference was apparent for scenarios (2) and (3). Experts agreed that there should be collaboration on collection logistics, promotion of demand through choice editing, product 'purity' could be championed though certification and there should be significant investment and research into recovery technologies. These considerations were incorporated into the development of a model for policy makers and industry to help increase biomaterial waste recovery.
  Waste Management 04/2013;