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In wetlands, a distinct zonation of plant species composition occurs along moisture gradients, due to differential flooding tolerance of the species involved. However, "flooding" comprises two important, distinct stressors (soil oxygen demand [SOD] and partial submergence) that affect plant survival and growth. To investigate how these two flooding stressors affect plant performance, we executed a factorial experiment (water depth x SOD) for six plant species of nutrient-rich and nutrient-poor conditions, occurring along a moisture gradient in Dutch dune slacks. Physiological, growth, and biomass responses to changed oxygen availability were quantified for all species. The responses were consistent with field zonation, but the two stressors affected species differently. Increased SOD increased root oxygen deprivation, as indicated by either raised porosity or increased alcohol dehydrogenase (ADH) activity in roots of flood-intolerant species (Calamagrostis epigejos and Carex arenaria). While SOD affected root functioning, partial submergence tended more to reduce photosynthesis (as shown both by gas exchange and 13C assimilation), leaf dark respiration, 13C partitioning from shoots to roots, and growth of these species. These processes were especially affected if the root oxygen supply was depleted by a combination of flooding and increased SOD. In contrast, the most flood-tolerant species (Juncus subnodulosus and Typha latifolia) were unaffected by any treatment and maintained high internal oxygen concentrations at the shoot : root junction and low root ADH activity in all treatments. For these species, the internal oxygen transport capacity was well in excess of what was needed to maintain aerobic metabolism across all treatments, although there was some evidence for effects of SOD on their nitrogen partitioning (as indicated by 865N values) and photosynthesis. Two species intermediate in flooding tolerance (Carex nigra and Schoenus nigricans) responded more idiosyncratically, with different parameters responding to different treatments. These results show that partial submergence and soil flooding are two very different stressors to which species respond in different ways, and that their effects on physiology, survival, and growth are interactive. Understanding species zonation with water regimes can be improved by a better appreciation of how these factors affect plant metabolism independently and interactively.

Abstract We propose an optimal control problem to determine the best aeration strategy for aerobic biodegradation in a composting cell. The goal is to minimize the deviation of the oxygen level from its reference value for the entire duration of the biodegradation process. The mathematical model includes several chemical phenomena, like the aerobic biodegradation of the soluble substrate by means of a bacterial biomass, the hydrolysis of insoluble substrate and the biomass decay. The oxygen and the optimal mechanical aeration time profiles are obtained and discussed. Finally, the plant performance is evaluated in absence and presence of external aeration by means of several specific indices.

In cement plants, the substitution of traditional fossil fuels not only allows a reduction of CO(2), but it also means to check-out residual materials, such as sewage sludge or municipal solid wastes (MSW), which should otherwise be disposed somehow/somewhere. In recent months, a cement plant placed in Alcanar (Catalonia, Spain) has been conducting tests to replace fossil fuel by refuse-derived fuel (RDF) from MSW. In July 2009, an operational test was progressively initiated by reaching a maximum of partial substitution of 20% of the required energy. In order to study the influence of the new process, environmental monitoring surveys were performed before and after the RDF implementation. Metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in soil, herbage, and air samples collected around the facility. In soils, significant decreases of PCDD/F levels, as well as in some metal concentrations were found, while no significant increases in the concentrations of these pollutants were observed. In turn, PM(10) levels remained constant, with a value of 16μgm(-3). In both surveys, the carcinogenic and non-carcinogenic risks derived from exposure to metals and PCDD/Fs for the population living in the vicinity of the facility were within the ranges considered as acceptable according to national and international standards. This means that RDF may be a successful choice in front of classical fossil fuels, being in accordance with the new EU environmental policies, which entail the reduction of CO(2) emissions and the energetic valorization of MSW. However, further long-term environmental studies are necessary to corroborate the harmlessness of RDF, in terms of human health risks.

The anaerobic digestion is a well-established process for the treatment of organic solid waste, pursuing its conversion into a methane rich gas destined to energy generation. Research has largely dealt with the enhancement of the overall bioconversion yields, providing several strategies to maximize the production of bio-methane from the anaerobic processing of a wide variety of substrates. Nevertheless, the valorization of the process effluents should be pursued as well, especially if the anaerobic digestion is regarded in the light of the circular economy principles. Aim of this work is in identifying the state of the art of the strategies to manage the digestate from the anaerobic processing of the organic fractions of municipal solid waste. Conventional approaches are described and novel solutions are figured out in order to highlight their potential scale up as well as to address future research perspectives.

With regard to renewable sources of energy, bioconversion of lignocellulosic biomass has long been recognized as a desirable endeavor. However, the highly heterogeneous structure of lignocellulose restricts the exploitation of its promising potential in biogas plants. Hence, effective pre-treatment methods are decisive prerequisites to overcome these challenges in order to improve the utilization ratio of (ligno) cellulosic substrates during fermentation. In the present study, the application of Trichoderma viride in an aerobic upstream process prior to anaerobic digestion led up to a threefold increase in the yield of methane and total gas in a lab-scale investigation. Due to its highly efficient cellulolytic activities, T. viride seemed to be responsible for an improved nutrient availability that positively influenced the anaerobic microbiocenosis. Aerobic pre-treatment of organic matter with T. viride is therefore a promising solution to achieve higher methane yields and degradation performances without any additional energy demand, nor undesired by-product inhibition.

The Indian Ocean Experiment (INDOEX) was an international, multiplatform field campaign to measure long-range transport of air pollution from South and Southeast Asia toward the Indian Ocean during the dry monsoon season in January to March 1999. Surprisingly high pollution levels were observed over the entire northern Indian Ocean toward the Intertropical Convergence Zone at about 6°S. We show that agricultural burning and especially biofuel use enhance carbon monoxide concentrations. Fossil fuel combustion and biomass burning cause a high aerosol loading. The growing pollution in this region gives rise to extensive air quality degradation with local, regional, and global implications, including a reduction of the oxidizing power of the atmosphere.

Abstract In this paper a thermoeconomic analysis of a novel hybrid Renewable Polygeneration System connected to a district heating and cooling network is presented. The plant is powered simultaneously by solar and geothermal sources, producing electricity, desalinated water, heat and cooling energy. System layout includes Parabolic Through Collector (PTC) field, geothermal wells, Organic Rankine Cycle (ORC) unit and a Multi-Effect Desalination (MED) system. Cooling and thermal demands are calculated by suitable building dynamic simulation models, calibrated for Pantelleria Island. Electrical demand is obtained by measured data. A detailed control strategy has been implemented in order to prevent any heat dissipation, to match the appropriate operating temperature levels in each component, to avoid a too low temperature of geothermal fluid reinjected in the wells and to manage the priority of space heating and cooling process. A 1-year dynamic simulation has been performed and results analyzed on daily, monthly and yearly basis. The system achieved an SPB equal to 8.50 and it resulted capable to cover the energy demands of a small community. Moreover, the plant is capable to cover the fresh water demand of the Pantelleria Island.