Anaerobic treatment of phenol in a two-stage anaerobic reactor

The inhibitory effects of phenol are problematic for the anaerobic treatment of wastewater. The purpose of this study is to demonstrate that a two-stage anaerobic digester (TSAD) can degrade phenol, reducing its toxic effects in the first acidogenic reactor (R1) before going into a methanogenic reactor (R2). The system consisted of two reactors in semi continuous operation. R1 was a Continuous Stirred Tank Reactor at pH 5.5± 0.5; R2 was a packet reactor at pH 8.4± 0.05. Both were operated at a hydraulic retention time (HRT) of 10 days and 35 0 C and fed with a nutritional supplement at organic loading rate (OLR) of 1.8 grams of COD per litre of reactor per day (LR -1 Day -1 ) until steady state conditions. Then one gram of phenol was fed daily over a period of 15 days. The performance of the system was monitored and analysed in terms of degradation of phenol and dissolved chemical oxygen demand (DCOD); concentration of organic acids (OA) and suspended organic carbon (SOC); biogas production and pH evolution. The removal of phenol and DCOD peaked at 99.7% and 70% respectively. The biogas production in the methanogenic reactor reached 0.8195 Lbiogas LR -1 Day -1 . These experiments demonstrate that, given the right conditions, a TSAD can degrade phenol without considerable inhibition

Tribological behaviour of copper oxide nanoparticle suspension

This work presents and discusses the tribological behaviour of nanoparticle suspensions in a polyalphaolefin (PAO6). CuO nanoparticles were separately dispersed at 0.5, 1.0 and 2.0% wt. in PAO6 using an ultrasonic probe for 2 minutes. AW properties were obtained using a TE53SLIM tribometer with a block-on-ring configuration and EP properties were obtained using a Four-Ball machine according to ASTM D2783. Wear surfaces were analyzed by SEM and EDS after tests. The study led to the following conclusions: nanoparticle suspensions exhibited reductions in friction and wear compared to the base oil; CuO suspensions showed the highest friction coefficient and lowest wear per nanoparticle content of 2%; all concentrations of nanoparticles improved the EP properties of PAO6; CuO showed better results at 0.5% wt. of nanoparticles; and the antiwear mechanism of nanoparticulate additive was produced by tribo-sintering

Tribological behaviour of polyalphaolefins: wear and rolling contact fatigue tests

Polyalphaolefin fluids are gaining rapid acceptance as high-performance lubricants and functional fluids because they have certain inherent, and highly desirable, characteristics relative to mineral oils. One of these characteristics is their low toxicity. It combined with excellent viscometrics and lubricity, have made low-viscosity PAO fluids an important component in lubricant formulations. Typical data found in product specifications for lubricants are the kinematic viscosity and the viscosity index. These values do not give enough information to choose the optimum lubricant for a lubricated contact. In mechanical systems take place rolling, sliding and rolling/sliding contacts, therefore lubricants have to work the best possible in these operation conditions. In this study are experimentally determined the L50, L10 and Weibull´s slope () of polyalphaolefins with two different viscosities. This test was made on a four-ball machine (Stanhope Seta). Wear test also was made on a four-ball tester (Roxana) in order to measure the wear scar diameter (WSD), and the flash temperature parameter (FTP). Lubricants were identified through infrared spectroscopy, and ball´s pittings were observed with SEM

Wear prevention characteristics of binary oil mixtures

This work presents the results of wear prevention tests carried out with mixtures of a polyalphaolefin (PAO 6) and two esters (TMP-05 and Sunflower oil, SO), on a four-ball machine tester. Results show that esters are excellent wear reducers when they are mixed with a low viscosity polyalphaolefin. The optimum ester percentages in PAO 6 were 5% and 15% for TMP-05 and SO, respectively. Better results than in pure PAO 6 occurred in all mixtures. The addition of esters (less than 15%) to PAO 6 hardly changed volume viscosity

Viscosity and tribology of copper oxide nanofluids

Nanofluids, a term proposed by Choi in 1995 [1], are composites consisting of solid nanoparticles with sizes varying generally from 1 to 100 nm dispersed in a liquid. Numerous nanoparticles used as oil additives have been investigated in recent years [2-7]. Results show that they deposit on the rubbing surface and improve the tribological properties of the base oil, displaying good friction and wear reduction characteristics even at concentrations below 2%wt. Although the viscosity of the nanofluids is a property of crucial importance for film forming, and hence friction and wear reduction, which are characteristic of lubricants, only Hwang et al. [8] have studied thermal characteristics, kinematic viscosity and tribological properties of nanofluids simultaneously. In this paper, we present measurements of dynamic viscosity of nanofluids formed by copper oxide nanoparticles dispersed in a polyalphaolefin, for temperatures and concentrations varying from 20 to 60ºC and 0.5 to 2% wt., respectively. Dependence of the nanofluid viscosity to the solid fraction and temperature was compared with existing models and its influence on lubrication was also analysed

Dry weight model, capacitance and metabolic data as indicators of fungal biomass growth in solid state fermentation

Developing improved industrial bioprocesses has been a driver for the growing research attention to solid state fermentation, in particular involving filamentous fungi. Accurate description of fungal growth in these systems is crucial and certainly needed to enable optimal deployment of subsequent engineering work. This manuscript proposes a model based on total dry weight measurement to describe biomass growth for Aspergillus awamori on wheat grains in two systems: Petri dishes and a 1L packed bed bioreactor. The proposed dry weight model can be used not only for identifying growth phases of the fungus but also to calculate key growth parameters such as specific growth rate and maximum biomass concentration. The use of techniques based on capacitance measurements and on metabolic data were also used in order to estimate fungal growth and to validate the proposed model

Some aspects of oil lubricant additivation with ZnO nanoparticles

This is a study on the tribological behaviour of ZnO nanoparticles as an additive in a polyalphaolefin (PAO6) and on the influence of dispersing agents (OL100 and OL300). Antiwear and extreme pressure tests were run on two four-ball machines. Firstly, it was demonstrated that OL300 has better dispersant properties than OL100, and also was found formation of aggregates for 1 and 1.5% of ZnO in PAO6 + 3% OL300 suspension. Ensuing SEM and EDS analysis of the worn surface highlighted a number of conclusions: OL100 and OL300 are potentially useful as wear reducer additives in PAO6, the non-coated ZnO nanoparticles had an abrasive behaviour, and ZnO nanoparticles do not act as anti-wear agent under certain conditions but in EP conditions they can decrease wear

Condition of Larval Red Snapper (\u3ci\u3eLutjanus campechanus\u3c/i\u3e) Relative to Environmental Variability and the Deepwater Horizon Oil Spill

The Deepwater Horizon oil spill(DWHOS)spatially and temporally overlapped with the spawning of many fish species, including Red Snapper, one of the most economically important reef fish in the Gulf of Mexico. To investigate potential impacts of the DWHOS on larval Red Snapper, data from a long-term ichthyoplankton survey off the coast of Alabama were used to examine: (1)larval abundances among pre-impact (2007–2009), impact(2010), and post-impact (2011, 2013) periods; (2) proxies for larval condition (size-adjusted morphometric relationships and dry weight) among the same periods; and (3) the effects of background environmental variation on larval condition. We found that larval Red Snapper were in poorer body condition during 2010, 2011, and 2013 as compared to the 2007–2009 period, a trend that was strongly (and negatively)related to variation in Mobile Bay freshwater discharge. However, larvae collected during and after 2010 were in relatively poor condition even after accounting for variation in freshwater discharge and other environmental variables. By contrast, no differences in larval abundance were detected during these survey years. Taken together, larval supply did not change relative to the timing of the DWHOS, but larval condition was negatively impacted. Even small changes in condition can affect larval survival, so these trends may have consequences for recruitment of larvae to juvenile and adult life stages

Extreme pressure behaviour of newly formulated oil-in-water emulsions

Oil-in-water (O/W) emulsions are broadly used in metal-machining processes, where combined lubrication and refrigeration are needed, such as in cutting, rolling, or grinding. These fluids consist of tiny oil droplets in water stabilised by small amounts of emulsifiers, namely surfactants. In an emulsion, oil is responsible for the lubricating properties, whereas water provides heat dissipation and fire resistance. Normally, emulsifiable metalworking oils are used in an oil concentration between 2 and 5 vol. %, depending on the application. Despite their wide use, the lubrication mechanisms of o/w emulsions have not been fully understood, mainly because of their complexity. Previous studies on oil-in-water emulsions showed that, in order to form thick lubricant films, oil droplets must wet the metal surfaces, displacing water. The ability of oil to wet is strongly dependent on the concentration of surfactant. Surfactant molecules tend to adsorb preferentially at the interface, modifying the nature of the layers adjacent to the metal surfaces and, thus, playing a key role in processes such as wettability, corrosion, or friction, as well as emulsion stability. The aim of this work is to study the influence of concentration of two different emulsifiers (anionic and non-inonic) on the wettability and extreme pressure properties of an oil-in-water emulsion. A mixture of a synthetic polyalphaolefin and a trimethylol propane ester was used as the base oil, and the concentrations of emulsifiers were below, equal to, and above their critical micellar concentrations (CMC). Extreme pressure tests (ASTM D 2783), which try to simulate the operating conditions of high speeds and pressures taking place in cutting processes, and contact angle measurements were carried out in order to establish a relationship between both properties and to evaluate the performance of these emulsions as lubricants

A Survey of High-Quality Computational Libraries and their Impactin Science and Engineering Applications

Recently, a number of important scientific and engineering problems have been successfully studied and solved by means of computational modeling and simulation. Many of these computational models and simulations benefited from the use of available software tools and libraries to achieve high performance and portability. In this article, we present a reference matrix of the performance of robust, reliable and widely used tools mapped to scientific and engineering applications that use them. We aim at regularly maintaining and disseminating this matrix to the computational science community. This matrix will contain information on state-of-the-art computational tools, their applications and their use