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Performance of hybrid constructed wetland for piggery wastewater treatment
Full text linkThe environmental impact of the livestock sector in North-East Italy directly affects water (nitrates accumulation and eutrophication). Through the “Nitrate Directive” (91/676/EEC), the EU aims to reduce water pollution caused or induced by nitrates from agricultural sources. Disposal of animal wastewater is a common problem among local farmers. Land spreading is the usual disposal method but requires sufficient land area in close proximity to the farm. Problems associate with animal wastewater treatment and land application has prompted an urgency to find alternative treatment systems that are technically feasible and economically viable. Hybrid constructed wetlands (HCW) are being considered as an alternative method for livestock wastewater disposal which could reduce the amount of land necessary for terminal land application. This work presents the results of monitoring a full-scale hybrid wetland system operating on a swine farm. The HCW system was composed of three vertical-subsurface flow wetlands (VF) in parallel with a total area of 30 m2, followed by one horizontal-subsurface flow wetland (HF) connected in series (100 m2). During the experimentation (2010-2012), HCW operated under different conditions: seasonal variations (temperature), pollutants concentrations, hydraulic loading rate (HLR), hydraulic retention time (HRT), feeding mode and operational regimes. During the first period (April 2010-July 2010) the system was loaded with 5m3/d of pre-treated piggery wastewater and VF system worked like a “biological filter”. During the second period (October 2010-April 2011), the system was loaded with 5m3/d of raw piggery wastewater, a sequential batch (feed-stay-drain-rest) feed mode in VF system was used. To determine if winter climate conditions influence treatment effectiveness, during the third period (May 2011-July 2012) the system was loaded with 1.7 m3/d of synthetic wastewater. VF system was fed with sequential batch mode with two different operational regimes. Overall concentration reduction obtained by HCW system for COD ranged from 46 to 56%, for total nitrogen from 40 to 54%, for ammonia nitrogen from 43 to 60%, for nitric nitrogen from 21 to 55%, for total phosphorus from 32 to 35% and for orthophosphate from 24 to 34%
Performance of a hybrid constructed wetland treating piggery wastewater
No full textA full-scale hybrid constructed wetland (HCW) designed to treat 5 m3/d of piggery wastewaters built in
2008 on a private pig farm in northern Italy was monitored from May to December 2009 to determine
its efficiency in treating COD, total nitrogen (TN), ammonia nitrogen (NH4–N), nitrate nitrogen (NO3–N)
and total phosphorus (TP). In situ measurements were also taken of pH, electrical conductivity (EC),
dissolved oxygen (DO) and temperature (T). The system was composed of three vertical-subsurface flow
wetlands (VF) (10 m2 each, one planted with Canna indica and the other two with Symphytum officinale)
working in parallel, followed by one horizontal-subsurface flow wetland (HF) connected in series (100 m2
planted with Phragmites australis). The system was fed with pre-treated piggery wastewater with the total
daily load (5 m3) divided in two batches 11 h apart. Wastewater samples were collected at the inflow
(IN), outflow of VF unit (OUT-VF) and outflow HF unit (OUT-HF). Median COD concentration decreased
from 1126 at the inlet to 235 mg/L at the outlet (79% abatement). TN concentration was abated by 64%
(671–240 mg/L). NH4–N and NO3–N median inflow concentrations (390 and 6.61 mg/L) were reduced by
63% and 53%, respectively, with median outflow concentrations of 145 and 3.14 mg/L. Inflow phosphorus
concentration of 23 mg/L was abated by 61%. Average daily mass removal rates were 31.4 g/m2 for COD,
17.5 g/m2 for TN and 0.54 g/m2 for TP.
The HF unit was more efficient than VF in reducing COD concentration; VF and HF gave similar abatements
for TN and TP, but VF occupied a quarter of the surface of the HF.
The results show that the HCW is an effective solution for treating the excess pollutants deriving from
animal wastewaters where sufficient land is not available for spreading
Temperature influence on nitrogen removal in a hybrid constructed wetland system in Northern Italy.
No full textThe objective of this research was to investigate the efficiency and seasonal performance of a full-scale
hybrid constructed wetland system (HCW) in reducing total nitrogen (TN), ammonia nitrogen (NH4-N)
and nitrate nitrogen (NO3-N). HCW with a total area of about 130 m2 and hydraulic load of 2 m3/day was
composed of three subsurface
flow vertical systems (VF), working in parallel and one horizontal (HF)
connected in series. The system was loaded daily with synthetic wastewater having an average
concentration of TN of 250 mg/L (about 125 mg/L of NH4-N and 125 mg/L of NO3-N). Water samples were
collected and analyzed from May to July 2011 and from January 2012 to July 2012. Variations were
observed in nutrient removal performance related to temperature.
During the whole monitoring period median reduction efficiency (RE) in the HCW was TN 95%, NH4-N
95% and NO3-N 93%, although three sub-periods characterized by different performances have been
observed. During the
first period (from May to July 2011) the RE was positive for the three nitrogen forms
considered, whereas from January to the end of March 2012 the RE was lower, particularly for TN and
NO3-N. From April 2012, when the temperature rose above 14.8 C, there was an increase in the
performance that reached the 2011 values.
Internal production of NO3-N was observed, mainly in the VF systems between January and March
2012. The median removals of mass pollutants per m2 of HCW per day were TN 3.1 g/m2/d, NH4-N 1.5 g/
m2/d, NO3-N 1.5 g/m2/d. Segmented regression analysis identified a breakpoint at 14.2 C for wastewater
temperature that caused variations in TN and NO3-N concentration reduction performances. According to
this approach the abatement was always positively correlated with temperature, but different regression
slopes were obtained below and above the breakpoint. In particular, with lower temperature the
abatement of NO3-N and TN increased by 1.7 and 2.0% per C of temperature increase; with temperature
higher than 14.2 C the increase in abatement due to increased temperature was sharper, especially for
NO3-N
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
No full text
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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