1,720,973 research outputs found
Aerobic solid-state processes to mitigate greenhouses gas emission in municipal solid waste management
No full textWith increasing the greenhouse gases (GHGs) gas emissions into the atmosphere and the possible consequence for the global climate change, there has been a growing interest in develop efficacy management strategies of reducing anthropogenic GHGs emissions. Municipal solid waste (MSW) management plays an important role in the GHGs emission. The contribution of the landfilled MSW to GHGs it was reported to be of 5% of the total GHGs emitted and of the 13% of the methane from anthropogenic fonts (USEPA, 2003; IPCC, 2006). The compute of the total GHG emissions is determined quantifying the GHG gases from all human activity as credits and debits. Debits are the GHG emitted in the atmosphere; on the other hand, the credits are the storage on C in stable forms (C-based systems) (IPCC, 2006; Brown et al., 2008). Because the production of CH4 vs CO2 during MSW degradation depends by aerobic vs anaerobic conditions, the possibility to manage MSW organic fraction by aerobic biological process, i.e. composting and mechanical biological treatment, avoiding methane production in landfill, reduce GHGs emission due to MSW management. The potential reduction of the methane emission and the possibility to store C in landfill and soil under recalcitrant forms, is extensively discussed in this chapter, reporting both literature and new data
Solid and liquid fractionation of digestate: Mass balance, chemical characterization, and agronomic and environmental value
No full textSolid-liquid (S/L) separation of digestate (D) represents a simple technology able to produce two fractions having different composition. The aim of this work was to study the effect of S/L separation on dry matter (DM), nitrogen (TKN), phosphorus (P2O5) and heavy metals (HM) repartition into these two fractions and to characterize them. Therefore, thirteen full-scale digestion plants were studied and D, LF and SF were collected during three seasons of the year. Results obtained indicated that unexpectedly, on a mass balance, the liquid fraction still contains the majority of DM, i.e. 67% of the total of D. LF also contained 87% and 71% of TKN and P2O5respectively. HM contents were in line with typical NP-organic fertilizers. Chemical characterization suggested that the LF can be used as a substitute for mineral N fertilizers because of its high N content, while SF can be proposed as an NP-organic fertilizer
On-field study of anaerobic digestion full-scale plants (Part II) : New approaches in monitoring and evaluating process efficiency
No full textBiogas plants need easy and practical tools for monitoring and evaluating their biological process efficiency. As soon as, in many cases, biomass supply present considerable costs, full-scale anaerobic digestion (AD) processes must approach, as much as possible, the potential biogas yield of the organic mixture fed to the biodigesters. In this paper, a new indicator is proposed (the bio-methane yield, BMY), for measuring the efficiency in full-scale AD processes, based on a balance between the biochemical methane potential (BMP) of the input biomass and the residual BMP of the output materials (digestate). For this purpose, a one-year survey was performed on three different full-scale biogas plants, in the Italian agro-industrial context, and the bio-chemical processes were fully described in order to calculate their efficiencies (BMY. = 87-93%) and to validate the new indicator proposed, as useful and easily applicable tool for full-scale AD plants operators
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Potential odour emission measurement in organic fraction of municipal solid waste during anaerobic digestion : relationship with process and biological stability parameters
Get PDFThe aim of the present study is to investigate the correlation between microbial activity, i.e., biological stability measured by aerobic (OD(20) test) and anaerobic tests (ABP test), and odour emissions of organic fraction of municipal solid waste during anaerobic digestion in a full-scale treatment plant considering the three stages of the process (input, digested and post-digested waste).
The results obtained indicated that the stabilization of the treated material reduces the odour impact measured by the olfactometric approach. Successive application of gas chromatography mass spectrometry (GC-MS) and electronic nose (EN) allowed the characterization of the different groups of volatile organic compounds (VOCs) responsible of odour impacts determining, also, their concentration. Principal component and partial least squares analyses applied to the EN and GC-MS data sets gave good regression for the OD(20) vs the EN and OD(20) vs the GC-MS data. Therefore, OD(20) reduction could be used as an odour depletion indicator. (C) 2010 Elsevier Ltd. All rights reserved
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