Mass Balance

The first industrial process in which sugar cane undergoes is the extraction of juice. The purpose of this step is to separate the sucrose contents from the fiber and other components as it goes along several mills in the tandem. A mathematical model involving mass, brix, pol and fiber balances has been developed in order to predict a handful of factors important in the process, such as pol extraction and bagasse moisture. This is all done considering the extensively used compound imbibition and screened fiber returning to the second mill. Feedstock characteristics and mill parameters are varied and compared to actual process results to ratify the effectiveness of the model.

The effect of manure-screening on the biogas yield of dairy manure was evaluated in batch digesters under mesophilic conditions (35°C). Moreover, the study determined the biogas production potential of different mixtures of unscreened dairy manure and food waste and compared them with the yield from manure or food waste alone. A first-order kinetics model was developed to calculate the methane yield from different mixtures of food waste and unscreened dairy manure. The methane yields of fine and coarse fractions of screened manure and unscreened manure after 30 days were 302, 228, and 241 L/ kgVS, respectively. Approximately 93%, 87%, and 90% of the biogas yields could be obtained, respectively, after 20 days of digestion. Average methane content of the biogas was 69%, 57%, and 66%, respectively. Based on mass balance calculations, separation of the coarse fraction of manure would sacrifice about 32% of the energy potential. The methane yield of the food waste was 353 L/kgVS after 30 days of digestion. Two mixtures of unscreened manure and food waste, 68/32% and 52/48%, produced methane yields of 282 and 311 L/kgVS, respectively after 30 days of digestion. After 20 days, approximately 90% and 95% of the final biogas yield could be obtained, respectively. Therefore, a hydraulic retention time (HRT) of 20 days could be recommended for a continuous digester. The average methane content was 62% and 59% for the first and second mixtures, respectively. The predicted results from the model showed that adding the food waste into a manure digester at levels up to 60% of the initial volatile solids significantly increased the methane yield for 20 days of digestion.

The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield was significantly higher in the lower hydraulic loading rate. Fish production, plant growth and percentage nutrient removal were highest at hydraulic loading rate of 1.28 m/day. The ratio of fish to plant production has been calculated to balance nutrient generation from fish with nutrient removal by plants and the optimum ratio was 15-42 gram of fish feed/m 2 of plant growing area. Each unit in RAS was evaluated in terms of oxygen demand. Using specified feeding regime, mass balance equations were applied to quantify the waste discharges from rearing tanks and treatment units. The waste discharged was found to be strongly dependent on hydraulic loading rate.

The Ernest Henry Cu-Au deposit was formed within a zoned, post-peak metamorphic hydrothermal system that overprinted metamorphosed dacite, andesite and diorite (ca 1740-1660 Ma). The Ernest Henry hydrothermal system was formed by two cycles of sodic and potassic alteration where biotite-magnetite alteration produced in the first cycle formed ca 1514±24 Ma, whereas paragenetically later Na-Ca veining formed ca 1529 +11/À8 Ma. These new U-Pb titanite age dates support textural evidence for incursion of hydrothermal fluids after the metamorphic peak, and overlap with earlier estimates for the timing of Cu-Au mineralization (ca 1540-1500 Ma). A distal to proximal potassic alteration zone correlates with a large (up to 1.5 km) K-Fe-Mn-Ba enriched alteration zone that overprints earlier sodic alteration. Mass balance analysis indicates that K-Fe-Mn-Ba alteration-largely produced during pre-ore biotite-and magnetite-rich alteration-is associated with K-Rb-Cl-Ba-Fe-Mn and As enrichment and Na, Ca and Sr depletion. The aforementioned chemical exchange almost precisely counterbalances the mass changes associated with regional Na-Ca alteration. This initial transition from sodic to potassic alteration may have been formed during the evolution of a single fluid that evolved via alkali exchange during progressive fluidrock interaction. Cu-Au ore, dominated by co-precipitated magnetite, minor specular hematite, and chalcopyrite as breccia matrix, forms a pipe-like body at the core of a proximal alteration zone dominated by K-feldspar alteration. Both the core and K-feldspar alteration overprint Na-Ca alteration and biotite-magnetite (K-Fe) alteration. Ore was associated with the concentration of a diverse range of elements (e.g. Ca). Mineralization also involved the deposition of significant barite, K(-Ba)-feldspar, calcite, fluorite and complexly zoned pyrite. The complexly zoned pyrite and variable K-(Ba)-feldspar versus barite associations are interpreted to indicate fluctuating sulphur and/or barium supply. Together with the alteration zonation geochemistry and overprinting criteria, these data are interpreted to indicate that Cu-Au mineralization occurred as a result of fluid mixing during dilation and brecciation, in the location of the most intense initial potassic alteration. A link between early alteration (Na-Ca and K-Fe) and the later K-feldspathization and the Cu-Au ore is possible. However, the ore-related enrichments in particular elements (especially Ba, Mn, As, Mo, Ag, U, Sb and Bi) are so extreme compared with earlier alteration that another fluid, possibly magmatic in origin, contributed the diverse element suite geochemically independently of the earlier stages. Structural focussing of successive stages produced the distinctive alteration zoning, providing a basis both for exploration for similar deposits, and for an understanding of ore genesis.

Many of the popular building energy simulation programs around the world are reaching maturity Ð some use simulation methods (and even code) that originated in the 1960s. For more than two decades, the US government supported development of two hourly building energy simulation programs, BLAST and DOE-2. Designed in the days of mainframe computers, expanding their capabilities further has become dif®cult, time-consuming, and expensive. At the same time, the 30 years have seen signi®cant advances in analysis and computational methods and power Ð providing an opportunity for signi®cant improvement in these tools.

Mass balance is an important concept in pharmaceutical development, but it often proves challenging to assess accurately. This article explores the various methods by which mass balance can and should be measured, expressed, and evaluated in conjunction with degradation chemistry. Causes of mass-balance issues and potential solutions are summarized, as are the advantages and the disadvantages of various detection strategies. The importance of reactants other than the parent drug, reaction stoichiometry, response factors, and assay variability are discussed, and recommendations for obtaining reliable and informative mass-balance information are provided.

In this paper, a mathematical model for a counter¯ow wet cooling tower is derived, which is based on one-dimensional heat and mass balance equations using the measured heat transfer coecient. The balance equations are solved numerically to predict the temperature change of air and water, as well as the humidity as a function of the cooling tower high. Experimental measurements on two pilot-scale cooling towers were carried out in order to analyze the performance of dierent cooling tower ®lling materials. Also, the performance of other cooling tower elements, such as droplet separators and water spray nozzles, was investigated in the pilot experiments. The¯ow distribution, i.e. the velocity ®eld, upstream to the ®lling material was predicted using the three-dimensional version of the computational¯uid dynamics (CFD) code Fluent/UNS UNS, version 4.2. The calculated¯ow ®elds are presented for dierent distances between the inlet of the air and the ®lling material. In addition, the two-dimensional version of the CFD code Fluent/ UNS UNS , version 4.2, was applied to predict the external air¯ow around the cooling tower and the back¯ow in dierent weather conditions in summer and winter. The research project was carried out in connection to an industrial cooling tower installation. Ó

A comparison of computer simulation results of reactive distillation obtained by ASPEN PLUS and HYSYS software was done. Esterification of acetic acid and 1-butanol was chosen as the model reaction proceeding in a reactor and reactive distillation column (RD) system. A nearly equimolar reaction mixture was fed into the equilibrium fixed bed reactor and the liquid product was continuously fed into reaction zone of the reactive distillation column. The same mass balance in the reactor and reactive distillation column was used to compare the adequacy of chosen simulation systems. The results of computer simulation have been consequently compared with pilot plant experimental data. A good agreement was reached.

In this paper, a mathematical model for a counter¯ow wet cooling tower is derived, which is based on one-dimensional heat and mass balance equations using the measured heat transfer coecient. The balance equations are solved numerically to predict the temperature change of air and water, as well as the humidity as a function of the cooling tower high. Experimental measurements on two pilot-scale cooling towers were carried out in order to analyze the performance of dierent cooling tower ®lling materials. Also, the performance of other cooling tower elements, such as droplet separators and water spray nozzles, was investigated in the pilot experiments. The¯ow distribution, i.e. the velocity ®eld, upstream to the ®lling material was predicted using the three-dimensional version of the computational¯uid dynamics (CFD) code Fluent/UNS UNS, version 4.2. The calculated¯ow ®elds are presented for dierent distances between the inlet of the air and the ®lling material. In addition, the two-dimensional version of the CFD code Fluent/ UNS UNS , version 4.2, was applied to predict the external air¯ow around the cooling tower and the back¯ow in dierent weather conditions in summer and winter. The research project was carried out in connection to an industrial cooling tower installation. Ó

In the electric arc furnace (EAF) steel production processes, scrap steel is principally used as a raw material instead of iron ore. In the steelmaking process with EAF, scrap is first melted in the furnace and then the desired chemical composition of the steel can be obtained in a special furnace such as ladle furnace (LF). This kind of furnace process is used for the secondary refining of alloy steel. L F furnace offers strong heating fluxes and enables precise temperature control, thereby allowing for the addition of desired amounts of various alloying elements. It also provides outstanding desulfurization at high-temperature treatment by reducing molten steel fluxes and removing deoxidation products. Elemental analysis with mass balance modeling is important to know the precise amount of required alloys for the L F input with respect to scrap composition. In present study, chemical reactions with mass conservation law in EAF and L F were modeled altogether as a whole system and chemical compositions of the final steel alloy output can be obtained precisely according to different scrap compositions, alloying elements ratios, and other input amounts. Besides, it was found that the mass efficiency for iron element in the system is 95. 93%. These efficiencies are calculated for all input elements as 8. 45% for C , 30. 31% for Si, 46. 36% for Mn, 30. 64% for P, 41. 96% for S , and 69. 79% for Cr, etc. These efficiencies provide valuable ideas about the amount of the input materials that are vanished or combusted for 100 kg of each of the input materials in the E A F and L F system.

Interaction strength Ecopath with Ecosim a b s t r a c t Keystones are defined as relatively low biomass species with a structuring role in their food webs. Thus, identifying keystone species in a given ecosystem may be formulated as: (1) estimating the impact on the different elements of an ecosystem resulting from a small change to the biomass of the species to be evaluated for its 'keystoneness'; and (2) deciding on the keystoneness of a given species as a function of both the impact estimated in (1) and its own biomass. Experimental quantification of interaction strength necessarily focus on few species, and require a priori assumptions on the importance of the interactions, which can bias the identification of keystone species. Moreover, empirical measurements, although very important, are expensive and time consuming and, owing to the spatio-temporal heterogeneity of habitats, physical conditions, and densities of organisms, published results tend to be case-specific and context-dependent.

Many numerical methods use characteristic analysis to accommodate the advective component of transport. Such characteristic methods include Eulerian-Lagrangian methods (ELM), modified method of characteristics (MMOC), and operator splitting methods. A generalization of characteristic methods can be developed using an approach that we refer to as an Eulerian-Lagrangian localized adjoint method (ELLAM). This approach is a space-time extension of the optimal test function (OTF) method. The method provides a consistent formulation by defining test functions as specific solutions of the localized homogeneous adjoint equation. All relevant boundary terms arise naturally in the ELLAM formulation, and a systematic and complete treatment of boundary condition implementation results. This turns out to have significant implications for the calculation of boundary fluxes. An analysis of global mass conservation leads to the final ELLAM approximation, which is shown to possess the conservative property. Numerical calculations demonstrate the behaviour of the method with emphasis on treatment of boundary conditions. Discussion of the method includes ideas on extensions to higher spatial dimensions, reactive transport, and variable coefficient equations.

A new model filtration equation which incorporates the input variable, sludge concentration (C.,); the state variable, specific resistance (R); and the output variables, cake concentration (C) and filtrate concentration (C) was derived by material balance and regression analysis. On verification using experimental data from treatment plants, the theoretical predictions of the new equation agreed closely with the practical values, yielding a correlation coefficient of 0.98. For the experimental curve, the slope and intercept are 2.5 x 10 ~ m.h. and 0.02, respectively whereas the corresponding values for the theoretical curve are 2.75 x 10 ~5 m.h. and 0.017, respectively. The graphical optimum dosage of ferric chloride for conditioning for both the Carman's and the new equation was found to be the same, 16% of the sludge solids by weight in each case.

Many of the popular building energy simulation programs around the world are reaching maturity Ð some use simulation methods (and even code) that originated in the 1960s. For more than two decades, the US government supported development of two hourly building energy simulation programs, BLAST and DOE-2. Designed in the days of mainframe computers, expanding their capabilities further has become dif®cult, time-consuming, and expensive. At the same time, the 30 years have seen signi®cant advances in analysis and computational methods and power Ð providing an opportunity for signi®cant improvement in these tools.

Within the context of current international initiatives on the control of persistent organic pollutants (POPs), an overview is given of the scientific knowledge relating to POP sources, emissions, transport, fate and effects. At the regional scale, improvements in mass balance models for well-characterised POPs are resulting in an ability to estimate their environmental concentrations with sufficient accuracy to be of help for some regulatory purposes. The relevance of the parameters used to define POPs within these international initiatives is considered with an emphasis on mechanisms for adding new substances to the initial lists. A tiered approach is proposed for screening the large number of untested chemical substances according to their long-range transport potential, persistence and bioaccumulative potential prior to more detailed risk assessments. The importance of testing candidate POPs for chronic toxicity (i.e. for immunotoxicity, endocrine disruption and carcinogenicity) is emphasised as is a need for the further development of relevant SAR (structure activity relationship) models and in vitro and in vivo tests for these effects. Where there is a high level of uncertainty at the risk assessment stage, decision-makers may have to rely on expert judgement and weight-of-evidence, taking into account the precautionary principle and the views of relevant stake-holders. Close co-operation between the various international initiatives on POPs will be required to ensure that assessment criteria and procedures are as compatible as possible.

1] A new software, PetroGraph, has been developed to visualize, elaborate, and model geochemical data for igneous petrology purposes. The software is able to plot data on several different diagrams, including a large number of classification and ''petrotectonic'' plots. PetroGraph gives the opportunity to handle large geochemical data sets in a single program without the need of passing from one software to the other as usually happens in petrologic data handling. Along with these basic functions, PetroGraph contains a wide choice of modeling possibilities, from major element mass balance calculations to the most common partial melting and magma evolution models based on trace element and isotopic data. Results and graphs can be exported as vector graphics in publication-quality form, or they can be copied and pasted within the most common graphics programs for further modifications. All these features make PetroGraph one of the most complete software presently available for igneous petrology research.

A mathematical model of biomass gasification in bubbling fluidized gasifier has been developed. It is a one-dimensional, two-phase (bubble and emulsion), two-zone (bottom dense bed and upper freeboard), steady state model. The model is based on global reaction kinetic, mass and energy balances and is capable of predicting temperature, solid hold ups and gas concentration along the reactor's major axis. The overall model has sub-models to deal with biomass pyrolysis, gasification, bed hydrodynamics, material classification and property calculation. A sub-model for tar generation and cracking is included in this study. The model is capable of dealing with wide variety of biomasses and fluidizing agents, i.e. air, oxygen, steam or a mix of these gases. Results show that during devolatilization step, gases release and mixing are sensitive and critical parameters. They have a strong influence on the overall performance of a gasifier. A comparison with experimental data from numerous literature works was done, which showed fairly good agreement. The model can be used to study and optimize the operation of bubbling fluidized bed gasifier. However, further validation with diverse data will help to fine-tune the model.

The aim of this paper is to present a new database on the chemical composition of suspended matter in World Rivers, together with the associated elemental fluxes. There is a lack of any recent attempt in the literature to update the pioneering work of Martin and Meybeck [Martin, J.-M., Meybeck, M., 1979. Elemental mass balance of material carried by major world rivers. Mar. Chem. 7, 173-206.] and Martin and Whitfield [Martin, J.-M., Whitfield, M., 1983. The significance of the river input of chemical elements to the ocean. Trace metals in sea water Wong, Boyle, Bruland, Burton, Goldberg (Eds) Plenum Publishing Corporation.] regarding the worldwide average major and trace element chemistry of riverine particulate matter.

An Environmental Management Accounting (EMA) framework is applied to the 2000 year-end financial report for the Mackenzie Paper Division paper mill owned and operated by Abitibi-Consolidated Inc. of Montreal, Quebec. A conventional reading of the obvious environmental costs from this financial report is Cdn$2,196,838. This figure is derived from an analysis of effluent treatment costs and other line item environmental costs. There is no “environmental account” category that breaks out either costs or the mass balance of inputs and outputs. For the most part, environmental costs are rolled up into overhead accounts such as administration, infrastructure and materials accounts.

Application of the EMA framework is based on assigning environmental costs to one of four categories for which a tentative breakdown is as follows: (1) waste and emission treatment costs ($3,348,902); (2) prevention and environmental management costs ($270,109); (3) material purchase value of non-product output costs ($946,799); and (4) processing costs of non-product output ($2 92,943). There is also a category called Environmental Revenues, of which none were reported. Conservative estimates thus place the total environmental costs at $4,858,753.

What is significant about this result is that the environmental costs under EMA are at least twice as much as would normally be reported. This supports the view that environmental costs are much higher than generally considered and makes it clear that many important environmental costs as well as benefits are “hidden” in other accounts. More studies of a similar design are required to confirm the validity of the EMA methodology reported here.

Keywords
Environmental Management Accounting; Environmental costs; Environmental benefits; Hidden costs; Cleaner production; Waste and emission treatment; Pollution prevention and environmental management; Material purchase value of non-product output; Processing costs of non-product output

The supercritical fluid extraction (SFE) of oil from ground black pepper, using supercritical carbon dioxide (SC CO 2 ) as a solvent, is presented in this study. The effect of process parameters, namely pressure (90, 100, 150 bar) and temperature (40, 50°C) of extraction, and solvent flow rate (1.1, 2, 3 kg/h), on the extraction rate was examined in a series of experiments conducted in a bench scale apparatus. The results indicated a significant increase of extraction rate with increase of pressure or decrease of temperature. A similar effect was observed with the increase of solvent flow rate. The experimental data were satisfactorily correlated by two mass balance models. The first one is based on the LackÕs plug flow model, which accounts for both the solubility and diffusion controlled regimes of the extraction, and the second one on the adsorption-desorption equilibrium of solute from solid tissue, the diffusion of the solute dissolved in the supercritical solvent to the surface and the mass transfer through the external film into the bulk.

Global synthesis of the findings from ¾140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40-374 000 km 2 ) range from 0Ð2 to 35 mm year 1 , representing 0Ð1-5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to ¾720 m year 1 , results from focussed recharge beneath ephemeral streams and lakes and preferential flow mostly in fractured systems. System response to climate variability and land use/land cover (LU/LC) changes is archived in unsaturated zone tracer profiles and in groundwater level fluctuations. Inter-annual climate variability related to El Niño Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Niños relative to periods dominated by La Niñas (1941)(1942)(1943)(1944)(1945)(1946)(1947)(1948)(1949)(1950)(1951)(1952)(1953)(1954)(1955)(1956)(1957). Enhanced recharge related to ENSO is also documented in Argentina. Climate variability at decadal to century scales recorded in chloride profiles in Africa results in recharge rates of 30 mm year 1 during the Sahel drought (1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986) to 150 mm year 1 during non-drought periods. Variations in climate at millennial scales in the SW US changed systems from recharge during the Pleistocene glacial period (½10 000 years ago) to discharge during the Holocene semiarid period. LU/LC changes such as deforestation in Australia increased recharge up to about 2 orders of magnitude. Changes from natural grassland and shrublands to dryland (rain-fed) agriculture altered systems from discharge (evapotranspiration, ET) to recharge in the SW US. The impact of LU change was much greater than climate variability in Niger (Africa), where replacement of savanna by crops increased recharge by about an order of magnitude even during severe droughts. Sensitivity of recharge to LU/LC changes suggests that recharge may be controlled through management of LU. In irrigated areas, recharge varies from 10 to 485 mm year 1 , representing 1-25% of irrigation plus precipitation. However, irrigation pumpage in groundwater-fed irrigated areas greatly exceeds recharge rates, resulting in groundwater mining. Increased recharge related to cultivation has mobilized salts that accumulated in the unsaturated zone over millennia, resulting in widespread groundwater and surface water contamination, particularly in Australia. The synthesis of recharge rates provided in this study contains valuable information for developing sustainable groundwater resource programmes within the context of climate variability and LU/LC change.

Mass flow rate of solids is probably the most important parameter in pneumatic conveying systems. It is a challenging task to measure this parameter in gas–solid flows.A new and simple model is presented and described to calculate the mass flow rate of solids in pneumatic conveying systems, based on air flow and pressure measurements. The principle of the model is conservation of mass, and it is applied in a horizontal straight pipe section. Two tests need to be performed on the actual conveying rig to be used for calibration of the model. Due to the kind of sensors used to carry out the necessary measurements, application of the model is rather inexpensive and non-intrusive.The model has been validated successfully with data from two different single blow tank conveying systems and in dense and dilute phase conveying. Four test materials were used for validation of the model: alumina, baryte, cement and dextrose.Provided that the requirements to apply the air mass balance model are...

Increasing growth in the aquaculture industry demands ecosystem-based techniques for management if that growth is to be ecologically sustainable and promote equity among users of the ecosystems in which it occurs. Models of carrying capacity can be used to responsibly limit the growth of aquaculture in increasingly crowded coastal areas. Narragansett Bay, Rhode Island, USA is one such crowded coastal region experiencing a rapid increase in bivalve aquaculture. An ecosystem mass-balance model was used to calculate the ecological carrying capacity of bivalve aquaculture. Cultured oyster biomass is currently at 0.47 t km −2 and could be increased 625 times without exceeding the ecological carrying capacity of 297 t km −2 . This translates to approximately 38,950 t of harvested cultured oysters annually which is 4 times the total estimated annual harvest of finfish. This potential for growth is due to the high primary productivity and large energy throughput to detritus of this ecosystem. Shellfish aquaculture has potential for continued growth and is unlikely to become food limited due, in part, to the large detritus pool.

Semivolatile organic compounds (SVOCs) are ubiquitous in indoor environments, redistributing from their original sources to all indoor surfaces. Exposures resulting from their indoor presence contribute to detectable body burdens of diverse SVOCs, including pesticides, plasticizers, and flame retardants. This paper critically examines equilibrium partitioning of SVOCs among indoor compartments. It proceeds to evaluate kinetic constraints on sorptive partitioning to organic matter on fixed surfaces and airborne particles. Analyses indicate that equilibrium partitioning is achieved faster for particles than for typical indoor surfaces; indeed, for a strongly sorbing SVOC and a thick sorptive reservoir, equilibrium partitioning is never achieved. Mass-balance considerations are used to develop physical-science-based models that connect source-and sink-rates to airborne concentrations for commonly encountered situations, such as the application of a pesticide or the emission of a plasticizer or flame retardant from its host material. Calculations suggest that many SVOCs have long indoor persistence, even after the primary source is removed. If the only removal mechanism is ventilation, moderately sorbing compounds (K oa > 10 10 ) may persist indoors for hundreds to thousands of hours, while strongly sorbing compounds (K oa > 10 12 ) may persist for years. The paper concludes by applying the newly developed framework to explore exposure pathways of building occupants to indoor SVOCs. Accumulation of SVOCs as a consequence of direct air-to-human transport is shown to be potentially large, with a maximum indoor-air processing rate of 10-20 m 3 /h for SVOC uptake by human skin, hair and clothing. Levels on human skin calculated with a simple model of direct air-to-skin transfer agree remarkably well with levels measured in dermal hand wipes for SVOCs possessing a wide range of octanol-air partition coefficients.

The presence of bioactive trace pollutants such as pharmaceuticals and ingredients of personal care products (PPCPs) in different environmental compartments (rivers, lakes, groundwaters, sediments, etc.) is an emerging issue due to the lack of existing information about the potential impact associated with their occurrence, fate and ecotoxicological effects. Due to the low PPCP concentrations reported in wastewaters (ppb or ppt) and their complex chemical structure, common technologies used in sewage and drinking water treatment plants may not be efficient enough to accomplish their complete removal. Information about physico-chemical characteristics such as acidity, lipophilicity, volatility and sorption potential is a useful tool to understand the different removal patterns observed. In order to perform an accurate overall mass balance along the different units of sewage treatment plants, it is necessary to gather information not only about the presence of micropollutants in the aqueous phase, but also on the fraction sorbed onto solids. Since only some PPCPs are very well eliminated by conventional sewage treatment configurations, new strategies such as modification of operating conditions (e.g. solids retention time), implementation of new technologies (e.g. biomembrane reactors) or additional advanced post-treatment steps (e.g. oxidation, adsorption, membranes) have been suggested for an increased efficiency.

Cut-and-fill type fluvial terraces are ubiquitous in the Lesser Himalayan zone of the AlaknandaeGanga (Ganges) rivers system, which flows perpendicular to Himalayan lithotectonic units and traverses a steep climatic gradient. Lithofacies analysis of the sedimentary sequences of cut-and-fill terraces indicated that the valley aggradation took place via (1) channel bar development and excess sediment supply, (2) debris flows composed of mixed rounded to sub-rounded lithoclasts, resulting from episodic high intensity rainfalls in the upper catchment or (3) debris flows or rockfalls generated by local landslides. The luminescence chronology indicates that valley aggradation took place in two phases: w49e25 ka and 18e11 ka. The incision of the fill started soon after 11 ka. Paleoclimatic records from marine sediments indicate that the aggradation and incision in the AlaknandaeGanga River has oscillated in-phase with global climatic variations. Glaciationedeglaciation processes in the upper catchment produced huge amounts of sediment between 63 and 11 ka, which was fluvially transferred to the lower valley via several cycles of erosion and deposition, leading to extensive aggradation. The climatic amelioration at w11 ka and the completion of deglaciation processes led to increased fluvial discharge and decreased sediment supply, conditions conducive for incision of the alluvial fills. Records from the Indo-Gangetic plain and the Ganga Delta demonstrate that the phase of aggradation was regional but that incision in the foreland started at least 2e3 ka later, after 7 ka.

Planning for "water-sensitive" cities has become a priority for sustainable urban development in Australia. There has been little quantification of the term, however. Furthermore, the water balance of most cities is not well known. Following prolonged drought, there has also been a growing need to make Australian cities more water self-reliant: to source water from within. This article formalizes a systematic mass-balance framework to quantify all anthropogenic and natural flows into and out of the urban environment. Quantitative performance indicators are derived, including (1) degree of system centralization;

Tibesti volcanoes (Chad) are poorly documented, as much for volcanological evolution as for mineralogy and geochemistry. Emi Koussi volcano is a wide ignimbritic shield-like volcano that results from the succession of three eruptive sequences, each one related to a caldera collapse. Activity occurred from 2.4 Ma to the recent Quaternary. The continental alkaline volcanics of Emi Koussi exhibit two bimodal lava series, silica-saturated (up to 11% normative quartz) and silica-undersaturated (up to 29% normative nepheline). Basanite and tephrite, trachyte and phonolite are dominant while trachyandesite is very scarce. The basanites and tephrites contain olivine, diopside, plagioclase, nepheline, kaersutite and titanomagnetite. The trachytes contain alkali feldspar, plagioclase, Na^Ca amphibole (kataphorite, richterite), mica, augite, aegirine augite, titanomagnetite and ilmenite. In phonolites, alkali feldspar, andesine, nepheline or sodalite, hedenbergite, aegirine augite, amphibole (ferropargasite and kaersutite), titanite and titanomagnetite occur. Trachyandesite contains olivine, augite, edenite, phlogopite, andesine, alkali feldspar, titanomagnetite and ilmenite. The two suites exhibit a wide compositional gap of about 10% SiO 2 . Trachytes are peralkaline and comenditic. Major and trace element data are compatible with differentiation dominated by fractional crystallisation. The fractional crystallisation has been modelled using major-element least-squares mass balance models. Crystal fractionation involving olivine, clinopyroxene, amphibole and plagioclase is the best way to explain the petrogenesis of the undersaturated suite. The silica-saturated suite recorded removal of olivine, pyroxene, amphibole, mica, plagioclase, alkali feldspar, magnetite and apatite. Trace element data, including rare earth elements, calculated using the Rayleigh equation, confirm the models for the undersaturated suite, because there is a close agreement between the observed and calculated data. But the petrogenesis of the silica-saturated suite is probably related to other processes, such as crustal contamination. ß

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 laboratory biodegradation studies described in literature. Monoethylhexyl phthalate, the primary biotransformation product of DEHP, was not detected at any treatment stage. Approximately 32% of DEHP in sewage was removed during anaerobic digestion of the sludge, while 32% remained in the digested a...

In order to assess the applicability at industrial-scale of the anaerobic ammonium oxidation (Anammox) process it is necessary to study the toxic effects on the maximum specific Anammox activity (SAA) of different compounds commonly present in industrial effluents. The present study was focused on the application of batch tests to determine the maximum SAA in different conditions. The batch tests were based on the measurement of nitrogen gas production. The initial conditions for the tests established to obtain the maximum value of the measured SAA were: 30 • C, pH 7.8, shaking speed 150 rpm, and biomass concentration 1 g VSS L −1 . The accuracy of the method was evaluated by mass balances of the nitrogen compounds and the obtained errors were smaller than 7%. Neither the initial biomass concentrations tested (0.5-2.0 g VSS L −1 ) nor the S 0 /X 0 ratio between 0.018 and 0.140 g NO 2 − -N g VSS −1 had significant influence on the estimated SAA. The addition of a second feeding tended to increase it around 20 ± 10%. The developed method is afterwards applied to the study of the inhibition caused on the Anammox process by different compounds (NH 4 + , NO 2 − , NO 3 − , NaCl, SO 4 2− , S 2− , flocculant, etc.). The effects of chloramphenicol (inhibitor of the denitrifying process) and allylthiourea (inhibitor of the nitrifying process) were tested in order to be used to distinguish between the Anammox activity from nitrifying and denitrifying activities. The developed batch experiments were found suitable to establish not only the maximum SAA of certain sludge but also the inhibitory effects of certain tested compounds.

An alternative potential feedstock for bioethanol in the automotive sector is citrus peel waste (CPW), which can be processed through enzymatic hydrolysis and fermentation. The present work considers mathematical modeling of orange peel wastes (OPW) hydrolysis with the use of free enzymes and compares the performance of batch, fed-batch and continuous well-mixed reactors after introducing appropriate rate equations in dynamic mass balances. MATLAB ® was used for model implementation.

Groundwater inflow and outflow contributions to the hydrologic budget of lakes can be determined using a stable isotope ( 18 O/ 16 O) mass balance method. The stable isotope method provides a way of integrating the spatial and temporal complexities of the flow field around a lake, ...

A mathematical model of biomass gasification in bubbling fluidized gasifier has been developed. It is a one-dimensional, two-phase (bubble and emulsion), two-zone (bottom dense bed and upper freeboard), steady state model. The model is based on global reaction kinetic, mass and energy balances and is capable of predicting temperature, solid hold ups and gas concentration along the reactor's major axis. The overall model has sub-models to deal with biomass pyrolysis, gasification, bed hydrodynamics, material classification and property calculation. A sub-model for tar generation and cracking is included in this study. The model is capable of dealing with wide variety of biomasses and fluidizing agents, i.e. air, oxygen, steam or a mix of these gases. Results show that during devolatilization step, gases release and mixing are sensitive and critical parameters. They have a strong influence on the overall performance of a gasifier. A comparison with experimental data from numerous literature works was done, which showed fairly good agreement. The model can be used to study and optimize the operation of bubbling fluidized bed gasifier. However, further validation with diverse data will help to fine-tune the model.

In this study, the supercritical carbon dioxide extraction of essential oils from plants which contain secretory ducts as essential oil reservoirs was investigated and modelled. Supercritical carbon dioxide extraction of essential oils from Asteraceae family species, marigold and chamomile, indicated that particle size had no significant influence on the extraction rate in two outermost cases: fine milled plant material and plant material cut to particle length of 5 mm. This confirmed previously reported phenomenon that in some cases particle size had no influence on the rate of supercritical extraction process. In order to explain this behavior, the mathematical model which took into consideration the phenomena occurring on the secretory duct scale, was developed and applied to simulate experimental data of marigold and chamomile supercritical carbon dioxide extraction. Proposed model was also applied to the literature experimental data of fennel fruit supercritical fluid extraction where the same phenomenon had been observed. To obtain information regarding secretory structure, scanning electron microscopy investigation of the plant material was performed. Very good agreement of the model results and experimental data in the case of different plant species, extraction conditions and particle sizes, confirmed the basic hypothesis of the model.

A mass-balance study was carried out to investigate the transformation of nitrogenous pollutants in vertical flow wetlands. Landfill leachate containing low BOD, but a high concentration of ammonia, was treated in four wetland columns under predominately aerobic conditions. Influent total nitrogen in the leachate consisted mainly of ammonia with less than 1% nitrate and nitrite, and negligible organic nitrogen. There was a substantial loss of total nitrogen (52%) in one column, whereas other columns exhibited zero to minor losses (<12%). Net nitrogen loss under study conditions was unexpected. Correlations between pH, nitrite and nitrate concentrations indicated the removal of nitrogen under study conditions did not follow the conventional, simplistic, chemistry of autotrophic nitrification. Through mass-balance analysis, it was found that CANON (Completely Autotrophic Nitrogen-removal Over Nitrite) was responsible for the transformation of nitrogen into gaseous form, thereby causing the loss of nitrogen mass. The results show that CANON can be native to aerobic engineered wetland systems treating wastewater that contains high ammonia and low BOD.

Contamination caused by pesticides in agriculture is a source of poor environmental water quality in some of the European Union countries. Without treatment or targeted mitigation, this pollution is diffused in the environment. Pesticides and their metabolites are of increasing concern because of their potential impacts on the environment, wildlife and human health. Within the context of the European Union (EU) Water Framework Directive and to promote low-pesticide-input farming and best management practices, the EU LIFE project ArtWET assessed the efficiency of ecological bioengineering methods using different artificial wetland (AW) prototypes throughout Europe. We optimized physical and biological processes to mitigate agricultural nonpoint-source pesticide pollution in AW ecosystems. Mitigation solutions were implemented at full-scale demonstration and experimental sites. We tested various bioremediation methods at seven experimental sites. These sites involved (1) experimental prototypes, such as vegetated ditches, a forest microcosm and 12 wetland mesocosms, and (2) demonstration prototypes, such as vegetated ditches, three detention ponds enhanced with technology of constructed wetlands, an outdoor bioreactor and a biomassbed. This set-up provides a variety of hydrologic conditions, with some systems permanently flooded and others temporarily flooded. It also allowed to study processes both in field and controlled conditions. In order to compare the efficiency of the wetlands, mass balances at the inlet and outlet of the AW will be used, taking into account the partitioning of the studied compound in water, sediments, plants and suspended solids. The literature background necessary to harmonize the interdisciplinary work is reviewed here and the theoretical framework regarding pesticide removal mechanisms in AWs is discussed. The development and the implementation of innovative approaches concerning various water quality sampling strategies for pesticide load estimates during flood, specific biological endpoints, innovative bioprocesses applied to herbicide and copper mitigation to enhance the pesticide retention time within the AW, modelling the transport and the fate of pesticides using a 2D mixed hybrid finite element model are introduced. These future results will be useful to optimize hydraulic functioning, e.g. pesticide resident time, and biogeochemical conditions, e.g. dissipation, inside the AWs. Hydraulic retention times are generally too low to allow an optimized adsorption on sediment and organic materials accumulated in AWs. Absorption by plants is also not effective (VanBeinum et al., 2006). The control of the hydraulic design and the use of adsorbing materials can be useful to increase the pesticide’s residence time and the contact between pesticides and biocatalyzers. Pesticide fluxes can be reduced by 50–80% when hydraulic pathways in AWs are optimized by increasing ten times the retention time, by recirculation of water, and by deceleration of the flow. Thus, using a bioremediation method should lead to an almost complete disappearance of pesticide pollution. To retain and to treat agricultural nonpoint-source pollution at the upstream of the hydrosystems form a part of the management of the environmental activities and thus represents a major stake for a sustainable development.

This study assesses the environmental effects of brine discharge into the Arabian/Persian Gulf and the option of mixing with wastewater to reduce the salt content in the discharge. The Arabian Gulf region occupies about 3.3% of the world area and has 1.0, 2.0 and 2.2% of the total world population in the years 1950, 2008 and 2050 (prognosis) respectively. The study area desalination capacities were obtained as 50, 40 and 45% of total world capacity at the end of 1996, 2008 and 2050 (prognosis) respectively. The trend towards increased recovery ratio in the desalination plants was considered as one important environmental factor. This will significantly increase the brine salt concentration from 1.5 to more than 2 times the seawater. The allocation of wastewater and brine is important for the Arabian Gulf. Straightforward water and salt mass balances were used to calculate residual flow, exchange flow and exchange time in the Arabian Gulf. For example, at zero wastewater discharge from 1996 to 2008, the net volume in the Arabian Gulf decreased by 7.4 million m 3 /d, the exchange volume increased by 69 million m 3 /d, and the mixing time decreased by 22.5 d. Discharging a mix of brine and wastewater in the Arabian Gulf reduces the water and salt exchange between the Gulf and the Indian Ocean. Nutrients in wastewater may cause problems such as eutrophication in the Gulf if the exchange of water is low or if wastewater is discharged to the Gulf with insufficient treatment.

CITATIONS 44 READS 743 5 authors, including: Some of the authors of this publication are also working on these related projects: iMB(TM): Intelligent Bio-engineered Microalgae Harvester View project Corrosion, Fluid Power, Marine Technology, Renewable Energy, Bio Fuel View project Azizah Endut Universiti Sultan Zainal Abidin | UniSZA The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.

While marine aquaculture has grown rapidly, so have concerns regarding the environmental impacts caused by the industry. In particular, increasing discharges of solid and dissolved fish excretions, nutrients and therapeutic chemicals have coincided with greater public awareness of the possibility of environmental damage. This has stimulated a number of criticisms, drawn from a wide spectrum of interests, ranging from the use of natural fish stocks to produce fish meal for aqua feeds to the effects of enhanced nutrient input on the coastal marine environment. The present study reviews available information on the environmental effects of feeding practices in salmonid aquaculture in Europe. Accumulation of waste food and fish faecal material results in changes in the sediment under fish cages, characterized by a low redox potential, high content of organic material and accumulation of nitrogenous and phosphorous compounds. Although significant environmental impacts have been reported in the literature at distances of up to 100 m from the cages, in general such impacts are reported to be localized to within 20-50 m around the cages. For farmed salmon and trout, mass balance models have been developed for nitrogen and phosphorus, indicating that 50% of the nitrogen and 28% of the phosphorus supplied with the food is wasted in dissolved form. The maximum nutrient release can be estimated from the hydrographic conditions in the immediate vicinity of the farm, such as water volume, tidal water exchange and currents. At present production levels, improvements in the feeding efficiency and Ó Springer Science+Business Media B.V. 2006 feed quality of aquafeeds could reduce waste and consequent environmental impacts.