Search results for "Environmental engineering"
showing 10 items of 2674 documents
The role of metallothionein and selenium in metal detoxification in the liver of deep-sea fish from the NW Mediterranean Sea
2014
8 pages, 1 figure, 5 tables
Use of Algae in Active Biomonitoring of Surface Waters
2015
Abstract Biomonitoring studies have been carried out in three retention reservoirs located in the Opole Province (southern Poland): Turawa reservoir, Nysa reservoir and Otmuchow reservoir. The increases of concentrations of Mn, Fe, Cu, Zn, Cd and Pb in fresh water algae Spirogyra sp. and sea water Palmaria palmata (Linnaeus) Weber & Mohr, exposed in the analysed waters, were determined by the atomic absorption spectrometry method (AAS). Also the waters pH, conductivity and Mn and Fe concentrations were determined. The concentrations of Cu, Zn, Cd and Pb in the analysed waters were lower than the method limit of determination. The analyses were carried out during the period from June to …
Residues of planar polychloroaromatic compounds in Baltic fish and seal
1990
Abstract Polychlorinated dibenzo-p-dioxins, dibenzofurans, coplanar PCBs and other dioxin-type of toxins have been analyzed in Baltic salmon, cod, ringed seal and grey seal and in Arctic cod.
Economic Aspects of the Conjunctive Use of Ground and Surface Water
1989
Abstract The different structure of the costs of ground and surface water and the different and complementary characteristics of both kinds of resources make it possible to solve the specific needs of water quantity and quality more adequately and economically if both resources are used conjunctively. Higher discount rates favour the inclusion of elements involving lower initial investment and generally with higher groundwater components. Lower discount rates favour a higher participation of surface water. The external factors produced by groundwater pumping must be taken into consideration in any economic analysis. Examples of external factors are water level descents, surface water flow r…
Particle size distribution and biomass growth in a submerged membrane bioreactor
2006
Submerged membrane bioreactors (MBR)associate in a single treatment unit a process ofbiological treatment and a phase of solid/liquidseparation by membrane filtration. Due to reduced membrane porosity, suspendedsolids and large amount of bacteria and virusesmay be retained in the reactor; consequently, highbiomass concentration is generally established inthe system. Indeed, this latter circumstance leadsto obtain a system able to operate with a low F/Mand high SRT and hence, as a result, a low sludgeproduction. In technical literature, the definition of fou-lants in MBR systems is a controversial task.More specifically, the influence of TSS onmixed liquor filterability has not been yet full…
Study of aerobic granular sludge stability in a continuous-flow membrane bioreactor.
2015
A granular continuous-flow membrane bioreactor with a novel hydrodynamic configuration was developed to evaluate the stability of aerobic granular sludge (AGS). Under continuous-flow operation (Period I), AGS rapidly lost their structural integrity resulting in loose and fluffy microbial aggregates in which filamentous bacteria were dominant. The intermittent feeding (Period II) allowed obtaining the succession of feast and famine conditions that favored the increase in AGS stability. Although no further breakage occurred, the formation of new granules was very limited, owing to the absence of the hydraulic selection pressure. These results noted the necessity to ensure, on the one hand the…
Optimization of the coagulation–flocculation treatment: influence of rapid mix parameters
1999
[EN] Turbid waters, containing suspended and colloidal particles, are normally treated by coagulation–flocculation followed by clarification; the process usually consists of the rapid dispersal of a coagulant into the raw water followed by an intense agitation commonly defined as rapid mixing. Rapid mixing is influenced by chemical and physical parameters and the final result of the whole treatment depends on this step. The study focused on the most important parameters of rapid mix design: velocity gradient and rapid mix time. Wastewaters from a tannery processing stored ovine hides were treated with aluminium(III) or iron(III) salts. Experimental results indicate that rapid mix time has a…
Step-by-step analysis of drinking water treatment trains using size-exclusion chromatography to fingerprint and track protein-like and humic/fulvic-l…
2019
This paper provides a glimpse into the removal of dissolved organic matter (DOM) during conventional drinking water treatment and evaluates the potential of high-performance size-exclusion chromatography (HPSEC) as a supplementary tool for routine monitoring of drinking water treatment plants (DWTPs). Two DWTPs in Central Finland were systematically evaluated using HPSEC with simultaneous UV and fluorescence detection. For tyrosine-like, tryptophan-like, and humic/fulvic-like DOM fractions of various molecular weight (MW) values, the total and step-by-step removal efficiencies were estimated along the treatment trains. Overall, both DWTPs removed ∼70% of dissolved organic carbon (DOC) and r…
Comparative study of laboratory-scale thermophilic and mesophilic activated sludge processes.
2005
Laboratory-scale mesophilic (20-35 degrees C) and thermophilic (55 degrees C) activated sludge processes (ASPs) treating diluted molasses wastewater were compared in effluent quality, removal of different COD fractions, sludge yield, floc size, and sludge settleability. The effect of polyaluminium chloride (PAC) with high cationic charge on sludge settleability and effluent quality was also studied. In the ASPs, the hydraulic retention time was 12h in both processes, corresponding to a volumetric loading rate of 3.2+/-1.0 kg COD(filt) m(-3)d(-1). The mesophilic ASP gave 79+/-18% and 90+/-2% and the thermophilic ASP gave 50+/-6% and 67+/-11% total COD (COD(tot)) and GF/A-filtered COD (COD(fi…
Experimental analysis of the effect of vegetation on flow and bed shear stress distribution in high-curvature bends
2016
The cross-sectional circulation, which develops in meandering bends, exerts an important role in velocity and the boundary shear stress redistributions. This paper considers the effect of vegetation on cross-sectional flow and bed shear distribution along a high-curvature bend. The analysis is conducted with the aid of data collected in a large-amplitude meandering flume during a reference experiment without vegetation and an experiment with vegetation on the bed. The results show that the presence of vegetation modifies the curvature-induced flow pattern and the directionality of turbulent structures. In fact, in the presence of vegetation, the turbulent structures tend to develop within a…