• Energy Research

The paper reports the results of the experimental activities carried out within a Nationa Research Project to evaluate the agronomic, envoronmental and energy sustainability of the biomass production by no-food crops irrigated with different kinds of treated wastewater. Four different research units monitored the same four main herbaceous species. physical and chemical analyses were carried out on wastewater samples. Bio-agronomical analysis on the species placed on fields were made with the goal to evaluate the main parameters sich as the productivity and the heating values. The analysis of the combustion efficiency, the amount of ash, and the environmental impact of the combustion residual was executed ina small boiler. The results highlight attractive biomass yield and an interesting crop energy capability by using treated wastewater for irrigation.

The paper reports the results of the experimental activities carried out within a Nationa Research Project to evaluate the agronomic, envoronmental and energy sustainability of the biomass production by no-food crops irrigated with different kinds of treated wastewater. Four different research units monitored the same four main herbaceous species. physical and chemical analyses were carried out on wastewater samples. Bio-agronomical analysis on the species placed on fields were made with the goal to evaluate the main parameters sich as the productivity and the heating values. The analysis of the combustion efficiency, the amount of ash, and the environmental impact of the combustion residual was executed ina small boiler. The results highlight attractive biomass yield and an interesting crop energy capability by using treated wastewater for irrigation.

AbstractUnderstanding the effects of regionally available residues, wastes, and purpose‐grown energy crops on anaerobic microbes and corresponding digestion performance is important for designing and implementing suitable anaerobic digestion systems to manage them appropriately and to use them for bioenergy generation. This study analyzed and compared dynamic changes in anaerobic microbes and digestion performance using mixtures of six different materials (citrus pulp, olive pomace, cattle manure, poultry litter, whey, and corn silage) generated from Mediterranean agro‐industry. The results indicate that the feedstock mixture (FM3) with low citrus pulp (26% dry matter) and high olive pomace (18% dry matter) reached stable methane production of 210 mL methane/g volatile solids (VS) loading within 30 days after the start up. In contrast, the feedstock mixture (FM1) with high citrus pulp (44% dry matter) and low olive pomace (0% dry matter) required a longer time of at least 70 days to achieve a good methane production of 209 mL methane/g VS loading. The microbial community analysis and corresponding non‐metric dimensionless scaling (NMDS) analysis revealed dynamic relationships between microbial community, feedstock mixture, and digestion time. The feedstock mixtures with low citrus pulp content (FM2 and FM3) facilitated the accumulation of Archaea (i.e., Methanosarcinaceae), which led their digestion to reach stable methane production quicker than the digestion of FM1. This study provided useful information to valorize agricultural residues and wastes for bioenergy production in the Mediterranean region. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

AbstractUnderstanding the effects of regionally available residues, wastes, and purpose‐grown energy crops on anaerobic microbes and corresponding digestion performance is important for designing and implementing suitable anaerobic digestion systems to manage them appropriately and to use them for bioenergy generation. This study analyzed and compared dynamic changes in anaerobic microbes and digestion performance using mixtures of six different materials (citrus pulp, olive pomace, cattle manure, poultry litter, whey, and corn silage) generated from Mediterranean agro‐industry. The results indicate that the feedstock mixture (FM3) with low citrus pulp (26% dry matter) and high olive pomace (18% dry matter) reached stable methane production of 210 mL methane/g volatile solids (VS) loading within 30 days after the start up. In contrast, the feedstock mixture (FM1) with high citrus pulp (44% dry matter) and low olive pomace (0% dry matter) required a longer time of at least 70 days to achieve a good methane production of 209 mL methane/g VS loading. The microbial community analysis and corresponding non‐metric dimensionless scaling (NMDS) analysis revealed dynamic relationships between microbial community, feedstock mixture, and digestion time. The feedstock mixtures with low citrus pulp content (FM2 and FM3) facilitated the accumulation of Archaea (i.e., Methanosarcinaceae), which led their digestion to reach stable methane production quicker than the digestion of FM1. This study provided useful information to valorize agricultural residues and wastes for bioenergy production in the Mediterranean region. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

University wastewater is a type of wastewater with higher pollutants load and flow rate variability than typical domestic wastewater. Constructed wetlands (CW) could be used for university wastewater treatment and consequently for wastewater reuse. A hybrid CW pilot plant, at the University of Bologna (Italy), was monitored to assess its potential to be used at the university. Its treatment performance was monitored for one year and public acceptance explored through a survey. The pilot plant had two treatment lines, (1) a vertical flow CW (VFCW) and a planted horizontal flow CW (HFCW), and (2) the same VFCW and an unplanted horizontal flow filter (HFF). The HFCW achieved higher removals than the HFF, but it was also found to be prone to higher water losses. However, both treatment lines met the Italian limits for discharge in natural water bodies and some of the limits for wastewater reuse in Italy and the EU. The VFCW alone was not able to meet the same limits, demonstrating the advantages of hybrid over single stage CWs. A positive attitude towards CWs and wastewater reuse was found among the survey participants. Therefore, hybrid CWs (planted and unplanted) are considered a feasible technology for application at universities.

University wastewater is a type of wastewater with higher pollutants load and flow rate variability than typical domestic wastewater. Constructed wetlands (CW) could be used for university wastewater treatment and consequently for wastewater reuse. A hybrid CW pilot plant, at the University of Bologna (Italy), was monitored to assess its potential to be used at the university. Its treatment performance was monitored for one year and public acceptance explored through a survey. The pilot plant had two treatment lines, (1) a vertical flow CW (VFCW) and a planted horizontal flow CW (HFCW), and (2) the same VFCW and an unplanted horizontal flow filter (HFF). The HFCW achieved higher removals than the HFF, but it was also found to be prone to higher water losses. However, both treatment lines met the Italian limits for discharge in natural water bodies and some of the limits for wastewater reuse in Italy and the EU. The VFCW alone was not able to meet the same limits, demonstrating the advantages of hybrid over single stage CWs. A positive attitude towards CWs and wastewater reuse was found among the survey participants. Therefore, hybrid CWs (planted and unplanted) are considered a feasible technology for application at universities.

This study investigates carbon dioxide (CO2) and methane (CH4) emissions and carbon (C) budgets in a horizontal subsurface flow pilot-plant constructed wetland (CW) with beds vegetated with Cyperus papyrus L., Chrysopogon zizanioides (L.) Roberty, and Mischantus × giganteus Greef et Deu in the Mediterranean basin (Sicily) during the 1st year of plant growing season. At the end of the vegetative season, M. giganteus showed the higher biomass accumulation (7.4 kg m(-2)) followed by C. zizanioides (5.3 kg m(-2)) and C. papyrus (1.8 kg m(-2)). Significantly higher emissions of CO2 were detected in the summer, while CH4 emissions were maximum during spring. Cumulative CO2 emissions by C. papyrus and C. zizanioides during the monitoring period showed similar trends with final values of about 775 and 1,074 g m(-2), respectively, whereas M. giganteus emitted 3,395 g m(-2). Cumulative CH4 bed emission showed different trends for the three C4 plant species in which total gas release during the study period was for C. papyrus 12.0 g m(-2) and ten times higher for M. giganteus, while C. zizanioides bed showed the greatest CH4 cumulative emission with 240.3 g m(-2). The wastewater organic carbon abatement determined different C flux in the atmosphere. Gas fluxes were influenced both by plant species and monitored months with an average C-emitted-to-C-removed ratio for C. zizanioides, C. papyrus, and M. giganteus of 0.3, 0.5, and 0.9, respectively. The growing season C balances were positive for all vegetated beds with the highest C sequestered in the bed with M. giganteus (4.26 kg m(-2)) followed by C. zizanioides (3.78 kg m(-2)) and C. papyrus (1.89 kg m(-2)). To our knowledge, this is the first paper that presents preliminary results on CO2 and CH4 emissions from CWs vegetated with C4 plant species in Mediterranean basin during vegetative growth.

This study investigates carbon dioxide (CO2) and methane (CH4) emissions and carbon (C) budgets in a horizontal subsurface flow pilot-plant constructed wetland (CW) with beds vegetated with Cyperus papyrus L., Chrysopogon zizanioides (L.) Roberty, and Mischantus × giganteus Greef et Deu in the Mediterranean basin (Sicily) during the 1st year of plant growing season. At the end of the vegetative season, M. giganteus showed the higher biomass accumulation (7.4 kg m(-2)) followed by C. zizanioides (5.3 kg m(-2)) and C. papyrus (1.8 kg m(-2)). Significantly higher emissions of CO2 were detected in the summer, while CH4 emissions were maximum during spring. Cumulative CO2 emissions by C. papyrus and C. zizanioides during the monitoring period showed similar trends with final values of about 775 and 1,074 g m(-2), respectively, whereas M. giganteus emitted 3,395 g m(-2). Cumulative CH4 bed emission showed different trends for the three C4 plant species in which total gas release during the study period was for C. papyrus 12.0 g m(-2) and ten times higher for M. giganteus, while C. zizanioides bed showed the greatest CH4 cumulative emission with 240.3 g m(-2). The wastewater organic carbon abatement determined different C flux in the atmosphere. Gas fluxes were influenced both by plant species and monitored months with an average C-emitted-to-C-removed ratio for C. zizanioides, C. papyrus, and M. giganteus of 0.3, 0.5, and 0.9, respectively. The growing season C balances were positive for all vegetated beds with the highest C sequestered in the bed with M. giganteus (4.26 kg m(-2)) followed by C. zizanioides (3.78 kg m(-2)) and C. papyrus (1.89 kg m(-2)). To our knowledge, this is the first paper that presents preliminary results on CO2 and CH4 emissions from CWs vegetated with C4 plant species in Mediterranean basin during vegetative growth.