31 research outputs found

    Characterization of odorous compounds and odor load in indoor air of modern complex MBT facilities

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    Gaseous emissions and chemical compounds responsible for odor nuisance are the most common social concerns arising from modern municipal mechanical-biological waste treatment (MBT) facilities. Regarding to this, an inventory of indoor concentrations of hydrogen sulfide and volatile organic compounds (VOCs) along with odor analyses were carried out at three different full-scale MBT facilities. 48-h profiles of total volatile organic compounds (tVOCs) and hydrogen sulfide were performed in selected areas (reception warehouse, pretreatment, anaerobic digestion and composting areas) and a complete gases and odor characterization were performed at two selected moments of the day according to maximum and minimum tVOCs concentrations, which corresponded to day/night variations. Terpenoids, aromatic hydrocarbons and aliphatic hydrocarbons were the families of VOCs more often detected. The average percentage of contribution of these three VOCs families was 32, 21 and 24%, respectively, while the average percentage of contribution of other VOCs families ranged from 0.2 to 5.5%. A multiple regression method was developed as a simple tool for odor modeling and prediction, showing that 98.5% (p < 0.001) of the variance in odor concentration could be explained by the concentrations of hydrogen sulfide and tVOCs. Results obtained suggested that optimization of indoor ventilation systems and, concomitantly, operational costs of MBT facilities was possible in certain locations where ventilation could be reduced up to 20-25% during night hours

    Analysis of MSW full-scale facilities based on anaerobic digestion and/or composting using respiration indices as performance indicators

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    The Landfill Directive (1999/31/EC) forces European States to reduce the amount of biodegradable municipal waste landfilled to 35% of 1995 levels. Mechanical-Biological Treatment (MBT) plants are the main alternative to waste incineration and landfilling. In this work, the waste treatment efficiency of six full-scale MBT facilities has been analysed using respiration indices (Dynamic Respiration Index and Cumulative Oxygen Consumption) to monitor plant performance. MBTs relying on anaerobic digestion plus composting achieved a high grade of stability on final compost (0.24 ± 0.09 mg O2 g⁻¹ DM h⁻¹ and 20 ± 9 mg O2 g⁻¹ DM for dynamic respiration and cumulative consumption, respectively). On the contrary, MBTs relying only on composting showed a poor performance (1.3 ± 0.2 mg O2 g⁻¹ DM h⁻¹ and 104 ± 18 mg O2 g−1 DM for dynamic respiration and cumulative consumption, respectively). These results highlight the usefulness of respirometric balances to assess the performance of MBT full-scale plants

    Analysis of MSW full-scale facilities based on anaerobic digestion and/or composting using respiration indices as performance indicators

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    The Landfill Directive (1999/31/EC) forces European States to reduce the amount of biodegradable municipal waste landfilled to 35% of 1995 levels. Mechanical-Biological Treatment (MBT) plants are the main alternative to waste incineration and landfilling. In this work, the waste treatment efficiency of six full-scale MBT facilities has been analysed using respiration indices (Dynamic Respiration Index and Cumulative Oxygen Consumption) to monitor plant performance. MBTs relying on anaerobic digestion plus composting achieved a high grade of stability on final compost (0.24 ± 0.09 mg O2 g⁻¹ DM h⁻¹ and 20 ± 9 mg O2 g⁻¹ DM for dynamic respiration and cumulative consumption, respectively). On the contrary, MBTs relying only on composting showed a poor performance (1.3 ± 0.2 mg O2 g⁻¹ DM h⁻¹ and 104 ± 18 mg O2 g−1 DM for dynamic respiration and cumulative consumption, respectively). These results highlight the usefulness of respirometric balances to assess the performance of MBT full-scale plants

    Pig slurry fertilization in a double-annual cropping forage system under sub-humid mediterranean conditions

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    In areas of Southern Europe with very intensive pig production, most of the pig slurry (PS) is applied asfertilizer. However, in the European Union, no more than 170 kg N ha−1year−1can be applied in nitratevulnerable zones (NVZs) from livestock manures. In this context, a six-year trial was conducted for amaize-triticale double-annual forage cropping rotation under rainfed conditions. Four different N rateswere applied (0, 170, 250 and 330 kg N ha−1year−1), to evaluate their effect on crop yield, N uptake, unre-covered N and soil nitrate content. The corresponding PS rates were defined as zero (PS 0), low (PSL)medium (PSM) and high (PSH). The annual average dry matter (DM) yields (maize + triticale) for the PSfertilization treatments PS0, PSL, PSM and PSH were 12.6, 17.7, 20.2 and 22.0 Mg DM ha−1, respectively.Maize DM yield was influenced mainly by weather conditions, and triticale DM yield was clearly influ-enced by initial soil NO3−-N and PS fertilization rates. Unrecovered N was affected by PS fertilizationrate and initial soil NO3−-N content. A residual effect of the PS when applied to maize had an importanteffect on soil NO3−-N and subsequent triticale DM yield. Moreover, total annual average unrecoveredN, considering the sum of both crops (maize + triticale), were 91, 144, and 222 kg N ha−1in PSL, PSMand PSH, respectively. In order to avoid part of this unrecovered N, mainly by lixiviation of nitrates, PSfertilization in triticale should be applied as side dressing at tillering. The application of N, in the formof PS, at rates higher than the legally permitted maximum of 170 kg N ha−1year−1, may result in betteryields. However, high rates of PS fertilization may originate in significantly lower N use efficiency anda higher potential environmental impact in double-cropping systems, practiced in rainfed sub-humidMediterranean conditions

    Saving freshwater from salts. Ion-specific standards are needed to protect biodiversity

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    TECNIOspring ProgramMany human activities—like agriculture and resource extraction—are increasing the total concentration of dissolved inorganic salts (i.e., salinity) in freshwaters. Increasing salinity can have adverse effects on human health (1); increase the costs of water treatment for human consumption; and damage infrastructure [e.g., amounting to $700 million per year in the Border Rivers catchment, Australia (2)]. It can also reduce freshwater biodiversity (3); alter ecosystem functions (4); and affect economic well-being by altering ecosystem goods and services (e.g., fisheries collapse). Yet water-quality legislation and regulations that target salinity typically focus on drinking water and irrigation water, which does not automatically protect biodiversity. For example, specific electrical conductivities (a proxy for salinity) of 2 mS/cm can be acceptable for drinking and irrigation but could extirpate many freshwater insect species (3). We argue that salinity standards for specific ions and ion mixtures, not just for total salinity, should be developed and legally enforced to protect freshwater life and ecosystem services. We identify barriers to setting such standards and recommend management guidelines
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