Search results for "Science and technology"
showing 10 items of 1592 documents
Thermogravimetric analysis as express tool for quality assessment of refuse derived fuels used for pyro-gasification
2019
The development of pyro-gasification technologies makes necessary the development of new express analytical methods that are able to deal with the variability of feedstock and problems arising from it. Thermogravimetric proximate analysis of refuse derived fuels is a very fast, cheap and simple method for the determination of proximate and fractional composition. Development of this analytical approach may result in a very cost-effective method to describe wholesome composition and characteristics of feedstock used for pyrolysis and gasification processes in real time. The aim of this study was the development of such analytical method. Refuse derived fuel samples produced in Latvia and Est…
Integrating in situ measurements of an index of connectivity to assess soil erosion processes in vineyards
2020
In this research, we survey soil erosion processes using an index of connectivity and a non-invasive and long-term assessment in situ technique: the improved stock unearthing method (ISUM), for whi...
Fermentation and elutriation of primary sludge: Effect of SRT on process performance
2007
Abstract A primary sludge fermentation–elutriation pilot plant was operated using in-line and side-stream schemes. The influence of solids retention time, recirculation sludge flow-rate and solids concentration on the fermentation–elutriation process performance has been assessed in this paper. The use of high elutriation flows (12% of influent flow) improved the volatile fatty acids (VFA) concentration in the effluent stream. Suspended solids removal efficiency decreased in the primary settler when the solids retention time (SRT) was increased from 4 to 8 days. Disintegration step during hydrolysis process was pointed out as the main reason for that decrease. Maximum VFA productions were a…
Comparison between hybrid moving bed biofilm reactor and activated sludge system: a pilot plant experiment
2010
The paper presents the comparison between the traditional activated sludge system (AS) and a hybrid moving bed biofilm reactor (HMBBR). In particular, an experimental campaign has been carried out at the WWTP in Palermo (Italy), on a pilot plant consisting of two pre-anoxic schemes. The aerated tank of the HMBBR line was filled with suspended carriers (AnoxKaldnes™ K1), with a 30% filling ratio. The hydraulic load of the HMBBR line was increased up to two times the AS one. Further, in order to distinguish the additional contribution of the attached biomass for the HMBBR system, in the two lines the Mixed Liquor Suspended Solids (MLSS) was maintained as equal as possible. The monitoring peri…
Separate and combined sewer systems: a long-term modelling approach
2009
Sewer systems convey mostly dry weather flow, coming from domestic and industrial sanitary sewage as well as infiltration flow, and stormwater due to meteoric precipitations. Traditionally, in urban drainage two types of sewer systems are adopted: separate and combined sewers. The former convey dry and wet weather flow separately into two different networks, while the latter convey dry and wet weather flow together. Which is the best solution in terms of cost-benefit analysis still remains a controversial subject. The present study was aimed at comparing the pollution loads discharged to receiving bodies by Wastewater Treatment Plant (WWTP) and Combined Sewer Overflow (CSO) for different ki…
Thermophilic Anaerobic Digestion of Industrial Orange Waste
2006
Thermophilic anaerobic digestion of industrial orange waste (pulp and peel) with subsequent aerobic post-treatment of the digestate was evaluated. Methane production potential was first determined in batch assays and the effects of operational parameters such as hydraulic retention times (HRT) and organic loading rates (OLR) on process performance were studied through semi-continuous digestion. In batch assays, methane production potential of about 0.49 m(3) kg(-1) volatile solids (VS)(added waste) was achieved. In semi-continuous digestion, loading at 2.8 kgVS m(-3) d(-1) (2.9 kg total solids (TS) m(-3) d(-1)) and HRT of 26 d produced specific methane yields of 0.6 m(3) kg(-1) VS (added wa…
Fermentation of municipal primary sludge: effect of SRT and solids concentration on volatile fatty acid production
2002
Laboratory bench-scale experiments were conducted to investigate the performance of primary sludge fermentation for volatile fatty acids production. Primary sludges from two major wastewater treatment plants located in Valencia (Pinedo and Carraixet) were used. Experiments were performed at solids retention times between 4 and 10 days, and total volatile solids concentrations between 0.6% and 2.8%. Operation at two temperatures (20 degrees C and 30 degrees C) was also checked. Results indicated the importance of feed sludge characteristics on volatile fatty acids yields, being approximately double for the Carraixet wastewater treatment plant sludge than for the Pinedo plant. In both cases, …
A Survey of Multi-Label Topic Models
2019
Every day, an enormous amount of text data is produced. Sources of text data include news, social media, emails, text messages, medical reports, scientific publications and fiction. To keep track of this data, there are categories, key words, tags or labels that are assigned to each text. Automatically predicting such labels is the task of multi-label text classification. Often however, we are interested in more than just the pure classification: rather, we would like to understand which parts of a text belong to the label, which words are important for the label or which labels occur together. Because of this, topic models may be used for multi-label classification as an interpretable mode…
A GIS-based approach for gully erosion susceptibility modelling: a test in Sicily, Italy
2013
The aim of this study is to analyze the susceptibility conditions to gully erosion phenomena in the Magazzolo River basin and to test a method that allows for driving the factors selection. The study area is one of the largest (225 km2) watershed of southern Sicily and it is mostly characterized by gentle slopes carved into clayey and evaporitic sediments, except for the northern sector where carbonatic rocks give rise to steep slopes. In order to obtain a quantitative evaluation of gully erosion susceptibility, statistical relationships between the spatial distributions of gullies affecting the area and a set of twelve environmental variables were analyzed. Stereoscopic analysis of aerial …
The occurrence and bioavailability of retene and resin acids in sediments of a lake receiving BKME (bleached kraft mill effluent)
1999
Retene (7-isopropyl-1-methylphenantrene) is an alkyl substituted PAH derived primarily from bacterial aromatization of abietic type resin acids. Retene has been shown to induce cytochrome P450 1A in rainbow trout whereas e.g. dehydroabietic acid does not induce it. We analysed resin acids and retene in sediments from seven sites receiving pulp and paper mill effluents from 4 mills, and from two reference sites. All mills have employed treatment of waste waters by activated sludge. The highest concentration of retene measured in sediment was 1600 μg/g d.w. (11 700 μg/g organic carbon, OC) while the highest concentration of resin acids was 1500 μg/g d.w. (9 300 μg/g OC). Downstream from the p…