1,720,961 research outputs found
Evaluation of phytodepuration intensified systems for the treatment of agricultural and livestock wastewaters
Full text linkThe intensification of Italian pig breeding over the years has resulted in high livestock concentrations in some parts of the country, especially in the north, increasing environmental pollutions threats. The potential environmental hazards caused by these activities regard surface water or groundwater eutrophication, emission of ammonia with consequent problems of acid deposition due to rainfall, other gases, odours, and accumulation risk of heavy metals and salts in agricultural soils. In addition, the proliferation over time of biogas plants in the livestock and agricultural field has led to a rapid and significant increase in the digestate quantities produced. The wastewaters from these activities are distributed on fields according to the European Directive (91/676 EC), which often results in an increase in the demand for available surfaces for the distribution of the effluent. However, when the land for spreading is not sufficient, other solutions must be found, that breeders solve by relocating the wastewater in other areas, incurring high transport costs. In recent years phytodepuration has proved to be of substantial interest as a system for the treatment of animal wastewater liquid fraction, representing a valid solution for its disposal when the surface area is not adequate.
This work examined phytodepuration intensified systems for the treatment of agricultural and livestock wastewaters, based on low-cost solutions and reduction of the area required for treatment. The research concerned in particular the study of pilot filter systems using recycled and sustainable materials for the pretreatment of piggery wastewater and digestate, in order to purify wastewater for the phytodepuration treatment. A vertically arranged phytodepuration system was also investigated, where both wetland and halophytic plant species have been tested for the treatment of piggery wastewater. Lastly, a secondary part of this research was devoted to the hydraulics study of filters used for phosphorus treatment, and to the growth of algae on pretreated piggery wastewater to analyze the chemical removal and possible accumulation of astaxanthin. The pretreatment systems proved to be suitable for digestate and piggery wastewater depuration, with higher removal for NH4-N, COD and total N than other chemicals. The phytodepuration highlighted the potential of several plants and the weaknesses of others for the treatment of piggery wastewater, showing highest concentration abatements of NH4-N (69-99%) and lower abatements of the other chemicals
Valutazione delle prestazioni della fitodepurazione per alleviare il carico di azoto nella frazione fluida dell'allevamento suinicolo.
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Biomass production and soil organic carbon accumulation in a free water surface constructed wetland treating agricultural wastewater in North Eastern Italy
No full textFree water surface constructed wetlands (FWSs) play an important role in wastewater pollutants removal and, at the same time, vegetated wetlands can act as carbon sinks. In this study we measured biomass production and soil carbon content variations over five years in a FWS with fluctuating hydroperiod treating agricultural drainage water to evaluate its role in the carbon dioxide cycle. During the study flooding occurred with a yearly average of 28 days. Annual dry matter production, from 2008 to 2011, ranged between 50 and 60 Mg ha−1. The highest C storage was concentrated in the belowground biomass. 83% of total belowground biomass was measured in the 0–20 cm soil layer. During the 2007–2012 period the organic carbon (OC) concentration in the 0–20 cm soil layer slightly increased from 12.3 to 13.1 g kg−1 and bulk density from 1.38 to 1.66 Mg m−3. In the 20–50 cm soil layer, monitored only in 2009 and 2012, OC concentration was lower and steady (8.8 g kg−1). The total soil C accumulation in the five years was 110.73 Mg ha−1 of equivalent CO2(eq). Given the positive C balance FWSs can be considered a CO2 sink
A simplified process of swine slurry treatment by primary filtration and Haematococcus pluvialis culture to produce low cost astaxanthin
No full textA simplified process for treating swine slurry through primary filtration and subsequent depuration of thefiltrate with the astaxanthin-rich microalga Haematococcus pluvialis is proposed. The first step comprisesa low-cost filtration system capable of reducing 66% of ammonia, 7% of phosphorus and 19% of chemicaloxygen demand, and increasing the concentration of nitrate, being this useful for subsequent growthof the algae. The second step comprises the discontinuous cultivation of H. pluvialis in diluted filteredslurry. The optimal dilution was researched by testing undiluted and 2, 4 and 8-fold diluted filtrate. Thisstep led to a drastic reduction in macro and micronutrients concentration (up to 99% for NO3-N andNH4-N, 98% for TP and 26% for chemical oxygen demand). After H. pluvialis growth the accumulation ofastaxanthin took place for 14 d in nutrient-deprived conditions: an astaxanthin accumulation of 1.27%on a dry weight basis was measured. These results indicate the possibility to couple low-cost filtrationand microalgae production to recover nutrients from swine wastewaters and to add value by producingvaluable astaxanthin for the feed market or for an on-farm utilization as feed addictive
La fitodepurazione per il trattamento di acque di origine agricola e di reflui zootecnici. Quaderno progetto AQUA, Veneto Agricoltura, ISBN 978-88-6337-107-9, 44 p. DOI: 10.13140/2.1.5081.9527
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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