Search results for "Waste management"
showing 10 items of 1526 documents
The impact of noise on the population of an urban centre in Valencia (Spain)
1997
Acoustic contamination in residential areas is a generalized problem. This paper reports the results of a survey trying to evaluate this contamination in the historical center of Valencia and about its effects upon that district's residents. A total of 700 residents in 11 different neighbourhoods of the city of Valencia were interviewed; at the same time environmental noise was determined at 225 different points within the area of study. In the historical center of Valencia, there exists an important problem of environmental noise and the daily levels clearly exceed the recommended limits.
Eco-efficiency assessment of municipal solid waste services: Influence of exogenous variables.
2020
Abstract Improving the eco-efficiency of municipalities in the provision of municipal solid waste (MSW) services is fundamental in the context of a circular economy. This study evaluates the eco-efficiency of a sample of Spanish municipalities, integrating the total cost as input, recyclable waste as desirable output, and unsorted waste as undesirable output. Following a pioneering approach, the weighted Russell directional distance model (a non-radial data envelopment analysis model) was employed, which allowed us to obtain a global inefficiency score and individual inefficiency scores for each variable integrated in the model. In the second stage of analysis, the potential factors affecti…
Removal of bis (2-ethylhexyl) phthalate from reject water in a nitrogen-removing sequencing batch reactor.
2003
Reject water from sewage sludge processing may contain high concentrations of nutrients and organic pollutants and cause internal pollution load at a sewage treatment plant (STP) if circulated to the headworks of an STP. In the present study removal of nitrogen and bis (2-ethylhexyl) phthalate (DEHP) from reject water was studied in two sequencing batch reactors (SBRs) with different aerobic/anoxic periods during a 6-h total cycle period. Ammonia-nitrogen (NH(4)-N) was almost totally removed in both reactors, apparently by nitrification throughout the run, while denitrification declined with decreasing SCOD in the influent resulting in an increase in the effluent nitrate-nitrogen (NO(3)-N) …
Occurrence and removal of organic pollutants in sewages and landfill leachates
2002
Sewages of different composition and the effluents of four sewage treatment plants (STPs), plus sewage sludges were analysed for semivolatile organic priority pollutants. Furthermore, 11 landfill leachates were analysed to evaluate their contribution to sewage pollutants when co-treated. Bis(2-ethylhexyl) phthalate (DEHP) was the pollutant occurring at highest concentrations (up to 122 microg/l) and it was present in all sewages and leachates; concentrations of other phthalates were usually below 17 microg/l. Some polycyclic aromatic hydrocarbons (PAH) (<1 microg/l) and 2,6-dinitrotoluene (< or =5.9 microg/l) were also present in many of the sewages and leachates. Phthalates were present in…
Removal of bis(2-ethylhexyl) phthalate at a sewage treatment plant
2003
Bis(2-ethylhexyl) phthalate (DEHP) concentrations were measured at different stages in a full-scale sewage treatment plant (STP) and mass balances were calculated. The DEHP load to treatment process coming from the sewer system and the internal load comprising returned supernatants and filtrate from sludge treatment and excess secondary sludge were at the same level. The DEHP removal efficiency from the water phase at the STP was on average 94% of sewage DEHP, the main removal process being sorption to primary and secondary sludges. On average 29% of DEHP was calculated to be removed in the biological nitrifying-denitrifying activated sludge process, which was much less than expected from l…
Disintegration of Wastewater Activated Sludge (WAS) for Improved Biogas Production: A Mini Review
2018
Due to rapid urbanization, the quantity of wastewater treatment plants (WWTP) has increased, and with it the amount of waste generated by them. Sustainable management of this waste can lead to the creation of energy-rich biogas through the fermentation process. This review presents recent advances in the anaerobic digestion process resulting in greater biogas production. Disintegration techniques for enhancing waste activated sludge fermentation can be generally partitioned into biological, physical and chemical, each of which are covered in this review. These disintegration techniques were compared mainly in terms of their biogas yield. It was found that ultrasonic and microwave disintegra…
Impact of humic acids on EYL liposome membranes: ESR method
2015
Abstract In this paper, the effects of model (commercial) and natural (extracted from peat) humic substances on the membrane of liposomes formed with egg yolk lecithin (EYL) are presented. In our research, mass concentrations of fulvic and humic acids were used, which in relation to lecithin varied from 0% to 13%. To study membrane fluidity, electron spin resonance (EPR) was used with two spin probes, penetrating various regions of the lipid bilayer. The effects of model and natural humic substances (humic acids – HAs and fulvic acids – FAs) on the lipid membrane in different regions were researched: the lipid-water interphase, and in the middle of the lipid bilayer. It was shown that FA an…
MAJOR AND TRACE ELEMENTS GEOCHEMISTRY IN THE GROUND WATERS OF A VOLCANIC AREA: MOUNT ETNA (SICILY, ITALY)
1998
Thirty-five ground-water samples have been collected from wells, springs and drainage galleries on Mt Etna volcano for the determination of major, minor and trace elements in solution. Attention has been focused in particular on dissolved minor and trace elements, for most of which no data were available in the studied area. In general, dissolution of solids into Etna's ground waters follows from strong interaction between water of meteoric origin, CO2 gas of magmatic origin and the volcanic rocks of the aquifers. However, the R-mode analysis allowed to distinguish several sources of solutes: Al, Co, Ni, Fe, Si, As would derive mainly from alteration of the volcanic rocks of Etna; SO4=, K, …
Measuring and Modelling Evaporation Losses from Wet Branches of Lemon Trees
2022
Evaporation losses of rainfall intercepted by canopies depend on many factors, including the temporal scale of observations. At the event scale, interception is a few millimetres, whereas at a larger temporal scale, the number of times that a canopy is filled by rainfall and then depleted can make the interception an important fraction of the rainfall depth. Recently, a simplified interception/evaporation model has been proposed, which considers a modified Merrian model to compute interception during wet spells and a simple power-law equation to model evaporation from wet canopy during dry spells. Modelling evaporation process at the sub hourly temporal scale required the two parameters of …
Modeling the influence of potassium content and heating rate on biomass pyrolysis
2017
This study presents a combined kinetic and particle model that describes the effect of potassium and heating rate during the fast pyrolysis of woody and herbaceous biomass. The model calculates the mass loss rate, over a wide range of operating conditions relevant to suspension firing. The shrinking particle model considers internal and external heat transfer limitations and incorporates catalytic effects of potassium on the product yields. Modeling parameters were tuned with experimentally determined char yields at high heating rates (>200 K s−1) using a wire mesh reactor, a single particle burner, and a drop tube reactor. The experimental data demonstrated that heating rate and potassium …