Immersion frying for the thermal drying of sewage sludge: an economic assessment

This paper presents an economic study of a novel thermal fry-drying technology which transforms sewage sludge and recycled cooking oil (RCO) into a solid fuel. The process is shown to have significant potential advantage in terms of capital costs (by factors of several times) and comparable operating costs. Three potential variants of the process have been simulated and costed in terms of both capital and operating requirements for a commercial scale of operation. The differences are in the energy recovery systems, which include a simple condensation of the evaporated water and two different heat pump configurations. Simple condensation provides the simplest process, but the energy efficiency gain of an open heat pump offset this, making it economically somewhat more attractive. In terms of operating costs, current sludge dryers are dominated by maintenance and energy requirements, while for fry-drying these are comparatively small. Fry-drying running costs are dominated by provision of makeup waste oil. Cost reduction could focus on cheaper waste oil, e.g. from grease trap waste.     

UV-C as an efficient means to combat biofilm formation in show caves: evidence from the La Glacière Cave (France) and laboratory experiments

Environmental Science and Pollution Research - Ultra-violet C (UV-C) treatment is commonly used in sterilization processes in industry, laboratories, and hospitals, showing its efficacy against...     

Polynomial Surrogates for Open-Channel Flows in Random Steady State

Assessing epistemic uncertainties is considered as a milestone for improving numerical predictions of a dynamical system. In hydrodynamics, uncertainties in input parameters translate into uncertainties in simulated water levels through the shallow water equations. We investigate the ability of generalized polynomial chaos (gPC) surrogate to evaluate the probabilistic features of water level simulated by a 1-D hydraulic model (MASCARET) with the same accuracy as a classical Monte Carlo method but at a reduced computational cost. This study highlights that the water level probability density function and covariance matrix are better estimated with the polynomial surrogate model than with a Monte Carlo approach on the forward model given a limited budget of MASCARET evaluations. The gPC-surrogate performance is first assessed on an idealized channel with uniform geometry and then applied on the more realistic case of the Garonne River (France) for which a global sensitivity analysis using sparse least-angle regression was performed to reduce the size of the stochastic problem. For both cases, Galerkin projection approximation coupled to Gaussian quadrature that involves a limited number of forward model evaluations is compared with least-square regression for computing the coefficients when the surrogate is parameterized with respect to the local friction coefficient and the upstream discharge. The results showed that a gPC-surrogate with total polynomial degree equal to 6 requiring 49 forward model evaluations is sufficient to represent the water level distribution (in the sense of the \(\ell _2\) norm), the probability density function and the water level covariance matrix for further use in the framework of data assimilation. In locations where the flow dynamics is more complex due to bathymetry, a higher polynomial degree is needed to retrieve the water level distribution. The use of a surrogate is thus a promising strategy for uncertainty quantification studies in open-channel flows and should be extended to unsteady flows. It also paves the way toward cost-effective ensemble-based data assimilation for flood forecasting and water resource management.     

Evaluation of adsorption capacities of humic acids extracted from Algerian soil on polyaniline for application to remove pollutants such as Cd(Ⅱ), Zn(Ⅱ) and Ni(Ⅱ) and characterization with cavity microelectrode

The adsorption capacities of new humic acids isolated from Yakouren forest (YHA) and Sahara (Tamenrasset: THA) soils (Algeria) and commercial humic acid (PFHA) on polyaniline emeraldine base (PEB) were studied at pH 6.6. Also the adsorption of heavy metals such as Cd2+, Zn2+ and Ni2+ on humic acid-polyaniline systems (HA-PEB) was investigated at the same conditions. HA-PEB compounds were characterized by scanning electron microscopy (SEM), infrared spectrometry and cavity microelectrode. In addition, batch adsorption and cavity microelectrode were used in the adsorption study of Cd2+, Zn2+ and Ni2+ on HA-PEB. To develop biocaptors of polluting metals using a cavity microelectrode modified by HA-PEB systems, the adsorption kinetic and adsorption capacity were investigated. The SEM analysis showed that the presence of humic acid affected the PEB surface and caused the formation of a granular morphology. The maximum adsorption capacities (qmax) of PFHA, THA and YHA determined by adsorption isotherms were 91.31, 132.1 and 151.0 mg/g, respectively. Batch adsorption results showed that qmax of Cd2+, Zn2+ and Ni2+ on HA-PEB followed the order: THA-PEB > YHA-PEB > PFHA-PEB. The voltammograms obtained with HA-PEB modified cavity microelectrode showed the appearance of new redox couples reflecting the adsorption of HA on PEB. Metal-humic acid-polyaniline voltammograms were characterized by appearance of oxidation-reduction couples or reduction wave corresponding to metal. Finally, the result may be exploited to develop a biocaptor based on the cavity microelectrode amended by THA-PEB and YHA-PEB.     

CO2 storage capacity estimation: Methodology and gaps

Implementation of CO₂ capture and geological storage (CCGS) technology at the scale needed to achieve a significant and meaningful reduction in CO₂ emissions requires knowledge of the available CO₂ storage capacity. CO₂ storage capacity assessments may be conducted at various scales—in decreasing order of size and increasing order of resolution: country, basin, regional, local and site-specific. Estimation of the CO₂ storage capacity in depleted oil and gas reservoirs is straightforward and is based on recoverable reserves, reservoir properties and in situ CO₂ characteristics. In the case of CO₂-EOR, the CO₂ storage capacity can be roughly evaluated on the basis of worldwide field experience or more accurately through numerical simulations. Determination of the theoretical CO₂ storage capacity in coal beds is based on coal thickness and CO₂ adsorption isotherms, and recovery and completion factors. Evaluation of the CO₂ storage capacity in deep saline aquifers is very complex because four trapping mechanisms that act at different rates are involved and, at times, all mechanisms may be operating simultaneously. The level of detail and resolution required in the data make reliable and accurate estimation of CO₂ storage capacity in deep saline aquifers practical only at the local and site-specific scales. This paper follows a previous one on issues and development of standards for CO₂ storage capacity estimation, and provides a clear set of definitions and methodologies for the assessment of CO₂ storage capacity in geological media. Notwithstanding the defined methodologies suggested for estimating CO₂ storage capacity, major challenges lie ahead because of lack of data, particularly for coal beds and deep saline aquifers, lack of knowledge about the coefficients that reduce storage capacity from theoretical to effective and to practical, and lack of knowledge about the interplay between various trapping mechanisms at work in deep saline aquifers.     

Elemental and isotopic determination of lead (Pb) in particulate matter in the Brazilian city of Goiânia (GO) using ICP-MS technique

Environmental Science and Pollution Research - The toxic metal lead (Pb) can be harmful to human health in various manners, but is also considered as a distinguished tracer of environmental...     

The impact of nitrogen deposition on acid grasslands in the Atlantic region of Europe

A survey of 153 acid grasslands from the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is changing plant species composition and soil and plant-tissue chemistry. Across the deposition gradient (2-44 kg N ha⁻¹ yr⁻¹) grass richness as a proportion of total species richness increased whereas forb richness decreased. Soil C:N ratio increased, but soil extractable nitrate and ammonium concentrations did not show any relationship with nitrogen deposition. The above-ground tissue nitrogen contents of three plant species were examined: Agrostis capillaris (grass), Galium saxatile (forb) and Rhytidiadelphus squarrosus (bryophyte). The tissue nitrogen content of neither vascular plant species showed any relationship with nitrogen deposition, but there was a weak positive relationship between R. squarrosus nitrogen content and nitrogen deposition. None of the species showed strong relationships between above-ground tissue N:P or C:N and nitrogen deposition, indicating that they are not good indicators of deposition rate.