In search of a reliable technique for the determination of the biological stability of the organic matter in the mechanical-biological treated waste

Composting Research Group, Chemical Engineering Department, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola, 08193 Barcelona, Spain.
Journal of Hazardous Materials (Impact Factor: 4.53). 07/2008; 162(2-3):1065-72. DOI: 10.1016/j.jhazmat.2008.05.141
Source: PubMed


The biological stability determines the extent to which readily biodegradable organic matter has decomposed. In this work, a massive estimation of indices suitable for the measurement of biological stability of the organic matter content in solid waste samples has been carried out. Samples from different stages in a mechanical-biological treatment (MBT) plant treating municipal solid wastes (MSW) were selected as examples of different stages of organic matter stability in waste biological treatment. Aerobic indices based on respiration techniques properly reflected the process of organic matter biodegradation. Static and dynamic respirometry showed similar values in terms of aerobic biological activity (expressed as oxygen uptake rate, OUR), whereas cumulative oxygen consumption was a reliable method to express the biological stability of organic matter in solid samples. Methods based on OUR and cumulative oxygen consumption were positively correlated. Anaerobic methods based on biogas production (BP) tests also reflected well the degree of biological stability, although significant differences were found in solid and liquid BP assays. A significant correlation was found between cumulative oxygen consumption and ultimate biogas production. The results obtained in this study can be a basis for the quantitative measurement of the efficiency in the stabilization of organic matter in waste treatment plants, including MBT plants, anaerobic digestion of MSW and composting plants.

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    • "Some runs were terminated earlier than others since the critical respiration indices (DRI 24 , AT 4 ) could be anyway calculated. Other calculated parameters relevant in respiration activity were: (d) the maximum value of the average of instantaneous OUR measurements in one hour (DRI 1 ) (Barrena et al., 2009), (e) the lag time (hours), finishes when the observed respiration activity is, at least, the 25% of the respiration activity observed during the largest increase in the oxygen consumption within the first 4 days (Federal Government of Germany, 2001) and (f) the times needed to reach the first and second (if existed) instantaneous peak in the OUR profile (Berthe et al., 2007). "
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    ABSTRACT: The aim of this study was to assess the effect of different air flowrates and different aeration modes on the respiration activity of three organic substrates of different stability degree: (i) a constant flowrate and (ii) a continuously adjusted air flowrate that optimized the oxygen uptake rate (OUR). Above 20L air kg(-1)DMh(-1), at the constant flow regime, the resulting dynamic respiration index at 24h (DRI24) and the cumulative respiration at four days (AT4) were statistically similar. At the OUR based aeration regime, the DRI24 and AT4 were statistically similar at all initial flowrates tested. Above a minimum threshold, cumulative air flow of around 3000Lairkg(-1) DM during a 5day period, the respiration activity was similar, particularly for the two less active substrates. This study highlights the importance of selecting the aeration to obtain reliable measures of biological activity and stability in organic wastes. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · Aug 2015 · Bioresource Technology
    • "This result is consistent with some previous BMP studies performed on aerobically treated MBT wastes. For instance, Barrena et al. (2008) measured a total gas production of 187 ± 16 Nl/kgTS, with an average methane content of 57% v/v, from MBT wastes after 32 days of aerobic treatment . Bayard et al. (2010) analysed the gas generation potential of different flows in a French MBT plant; they observed that the intermediate fraction (<50 mm), after 6 weeks forced-aerobic treatment, still exhibited high gas generation potential (232 ± 23 Nl/kgTS). "
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    ABSTRACT: In this work, the influence of different operating conditions on the biogas production from mechanically-biologically treated (MBT) wastes is investigated. Specifically, different lab-scale anaerobic tests varying the water content (26-43% w/w up to 75% w/w), the temperature (from 20 to 25°C up to 55°C) and the amount of inoculum have been performed on waste samples collected from a full-scale Italian MBT plant. For each test, the gas generation yield and, where applicable, the first-order gas generation rates were determined. Nearly all tests were characterised by a quite long lag-phase. This result was mainly ascribed to the inhibition effects resulting from the high concentrations of volatile fatty acids (VFAs) and ammonia detected in the different stages of the experiments. Furthermore, water content was found as one of the key factor limiting the anaerobic biological process. Indeed, the experimental results showed that when the moisture was lower than 32% w/w, the methanogenic microbial activity was completely inhibited. For the higher water content tested (75% w/w), high values of accumulated gas volume (up to 150Nl/kgTS) and a relatively short time period to deplete the MBT waste gas generation capacity were observed. At these test conditions, the effect of temperature became evident, leading to gas generation rates of 0.007d(-1) at room temperature that increased to 0.03-0.05d(-1) at 37°C and to 0.04-0.11d(-1) at 55°C. Overall, the obtained results highlighted that the operative conditions can drastically affect the gas production from MBT wastes. This suggests that particular caution should be paid when using the results of lab-scale tests for the evaluation of long-term behaviour expected in the field where the boundary conditions change continuously and vary significantly depending on the climate, the landfill operative management strategies in place (e.g. leachate recirculation, waste disposal methods), the hydraulic characteristics of disposed waste, the presence and type of temporary and final cover systems. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · Jul 2015 · Waste Management
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    • "Biological tests are, therefore, suitable to realistically assess the achievement of the biological stability after a composting process. Such tests can be performed in either aerobic (Scaglia et al., 2007, 2011) or anaerobic (Barrena et al., 2009) environment as well as under static or dynamic conditions (Scaglia et al., 2000). Respiration techniques, in particular, have been reported to provide the more detailed compost stability characterization (Barrena et al., 2014). "
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    ABSTRACT: Composting represents the most common option to recover material from the organic fraction of municipal solid waste, due to the possibility to use compost as a fertilizer. To this end the assessment of compost quality needs to be adequately enforced in national regulations. This work aims at reviewing European regulations regarding compost quality, in order to identify the most common parameters used to define compost characteristics as fertilizer. It was found that the majority of European States requires the fulfilment of specific criteria, but a lack of uniformity in regulations and guidelines can be observed. In particular the approach to the evaluation of stability and maturity, which account for compost safe use on soils, shows great heterogeneity throughout Europe. As stability and maturity go hand in hand, the proper characterization of compost toxicity should rely on the determination of both parameters. The results of an annual monitoring of compost under the Italian regulation highlighted, indeed, that the evaluation of the germination index can provide only partial information on the product maturity but not reliable operating indication on compost inhibitory properties.
    Full-text · Article · Jan 2015 · Resources Conservation and Recycling
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