Search results for "wage"
showing 10 items of 731 documents
A Noxious Weed Ambrosia artemisiifolia L. (Ragweed) as Sustainable Feedstock for Methane Production and Metals Immobilization
2023
Plants of the Ambrosia genus are invasive and cause many ecological problems, including the oppression of the growth of agricultural crops and native plants, land depletion, and the production of strong allergens. The use of weeds as a sustainable feedstock for biogas production, either methane or hydrogen, is a promising way to fulfill the energy needs of the current generation, eliminate the depletion of non-renewable carbon resources, and preserve the ecosystem degradation caused by invasive species impacts. A diversified microbial community was used as inoculum and Ambrosia artemisiifolia L. biomass as a substrate for anaerobic degradation and methane production. In this regard, the dev…
Biological nutrient removal in membrane bioreactors: denitrification and phosphorus removal kinetics.
2007
The impact of including membranes for solid liquid separation on the kinetics of nitrogen and phosphorus removal was investigated. To achieve this, a membrane bioreactor (MBR) biological nutrient removal (BNR) activated sludge system was operated. From batch tests on mixed liquor drawn from the MBR BNR system, denitrification and phosphorus removal rates were delineated. Additionally the influence of the high total suspended solids concentrations present in the MBR BNR system and of the limitation of substrate concentrations on the kinetics was investigated. Moreover the ability of activated sludge in this kind of system to denitrify under anoxic conditions with simultaneous phosphate uptak…
Co-treatment of landfill leachate in laboratory-scale sequencing batch reactors: analysis of system performance and biomass activity by means of resp…
2014
Aged or mature leachate, produced by old landfills, can be very refractory; for this reason mature leachate is difficult to treat alone, but it can be co-treated with sewage or domestic wastewater. The aim of the study was to investigate the feasibility of leachate co-treatment with synthetic wastewater, in terms of process performance and biomass activity, by means of respirometric techniques. Two sequencing batch reactors (SBRs), named SBR1 and SBR2, were fed with synthetic wastewater and two different percentages of landfill leachate (respectively 10% and 50% v v−1 in SBR1 and SBR2). The results showed good chemical oxygen demand (COD) removal efficiency for both reactors, with average C…
Application of Electronic Nose for Evaluation of Wastewater Treatment Process Effects at Full-Scale WWTP
2019
This paper presents the results of studies aiming at the assessment and classification of wastewater using an electronic nose. During the experiment, an attempt was made to classify the medium based on an analysis of signals from a gas sensor array, the intensity of which depended on the levels of volatile compounds in the headspace gas mixture above the wastewater table. The research involved samples collected from the mechanical and biological treatment devices of a full-scale wastewater treatment plant (WWTP), as well as wastewater analysis. The measurements were carried out with a metal-oxide-semiconductor (MOS) gas sensor array, when coupled with a computing unit (e.g., a computer with…
Should the government pay more to public sector employees? Impact of subjective, stereotypicalwage and core self-evaluations on job satisfaction and …
2018
There are many stereotypes about work in public sector. It is supposedly more stable, less hectic but in the same time offers smaller wages in comparison to a work in private sector. But does it provide more satisfaction to employees? The current study compares work satisfaction (Warr, Cook, & Wall, 1979) and subjective Well-being (Diener, Emmons, Larsen, & Griffin, 1985) as dependent on subjective and objective wage evaluations (Brown, Gardner, Oswald, & Qian, 2008; Walczak, 2017) and Core Self-Evaluations (Judge, Locke, & Durham, 1997; Walczak & Derbis, 2015). On a sample of N=625 employees (of which 18%; n=118 were employed in public sector) an impact of subjective (rather than objective…
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…
How does the age structure of worker flows affect firm performance?
2016
We develop a method for decomposing firm performance to impacts coming from the inflows and outflows of workers and apply it to study whether older workers are costly to firms. Our estimation equations are derived from a variant of the decomposition methods frequently used for measuring micro-level sources of industry productivity growth. By using comprehensive linked employer–employee data, we study the productivity and wage effects, and hence the profitability effects, of the hiring and separation of younger and older workers. The evidence shows that the separations of older workers are profitable to firms, especially in the manufacturing ICT-industries. To account for the correlation of …
Conventional Theory’s Relevance: Evidence from Japan
2019
Abstract The formidable surge in the volume of international trade after 1960 stimulated surveys designed to ascertain to what degree the commercial flows among nations reflected the structure of their economies, in other words, how tight was the correlation between international exchanges and the specific attributes of participating nations. In fact, scholars were keen to test the relevance of the conventional Heckscher-Ohlin theory, that is, to what extent did nations’ exports reflect their endowment with factors of production, more specifically, whether their exports used their abundant factors intensively. I try to show that, although most of the tests reached their purpose in that they…