13,078 research outputs found
Interfactory and Intrafactory Water Network System To Remodel a Conventional Industrial Park to a Green Eco-industrial Park
No full textWater network synthesis is to optimize a water supply system by connecting water sources to sinks in order to maximize water reuse. This synthesis has been applied within a factory to reduce freshwater Consumption. This study illustrates (i) the synthesis and design of an interfactory and intrafactory water network system for an eco-industrial park (EIPWNS) utilizing more opportunities for water reuse within an industrial park, and (ii) an environmental and economic feasibility Study to demonstrate benefits from industrial symbiosis. An EIPWNS is synthesized, designed, and compared to conventional water system (CWS). The feasibility Study using life cycle assessment and life cycle costing shows that the total environmental impacts of the EIPWNS are 7.5% to 16.0% less than those or the CWS, and the life cycle cost of the EIPWNS is 15.6% less. Therefore, the EIPWNS can be employed in remodeling a conventional industrial park to an eco-industrial park. This study provides a good example for disseminating EIPWNSs.X112226sciescopu
Consideration of the methods for evaluating the Cr(VI)-removing capacity of biomaterial
No full textOver the last few decades, many researchers have tested various biomaterials for the removal of toxic Cr(VI) from aquatic systems. It is now widely accepted that the mechanism of Cr(VI) biosorption is not 'anionic adsorption' but 'adsorption-coupled reduction'. Unfortunately, however, many researchers have still used common equilibrium isotherm models, such as Langmuir and Freundlich ones, based on 'anionic adsorption' mechanism in order to evaluate the Cr(VD-removing capacity of biomaterial tested. In this study, a fermentation waste of Corynebacterium glutamicum, capable of removing Cr(VI) efficiently, was used as a model biomaterial to show why equilibrium isotherm models cannot be used to evaluate the Cr(VI)-removing capacity of biomaterial. Meanwhile, some alternative methods considering the mechanism of Cr(VI) biosorption were suggested; the maximum Cr(VI)-removing capacity of the biomaterial could be evaluated by a Cr(VI)-biosorption experiment under biomaterial-limited condition as well as by a simplified kinetic model based on the reduction mechanism of Cr(VI).11sciescopuskc
Enhanced biological phosphorus removal in a sequencing batch reactor supplied with glucose as a sole carbon source
No full textMetabolism of enhanced biological phosphorus removal (EBPR) in an anaerobic/aerobic sequencing batch reactor (SBR) was investigated when glucose was supplied as, a sole carbon source. There have been several reports claiming that the EBPR could not be accomplished with glucose feed as a carbon source due to the dominating growth of so-called "G-bacteria" which do not accumulate polyphosphate and take up glucose without ortho-phosphate release under anaerobic condition. However, in our work, high EBPR could be achieved even with the use of glucose as a sole carbon source following completely different mechanisms From previous reports. Glucose disappearance and glycogen accumulation rapidly occurred, which coincided with other reports. But the release of ortho-phosphate and synthesis of poly 3-hydoxy alkanoic acids (PHAs) were related to total organic carbon (TOC) concentration rather than glucose concentration. The fate of glucose in annerobic/aerobic stags H-as investigated by supplying all C-13-labelled glucose at the beginning of anaerobic stage which was traced by C-13-NMR spectroscopy. Results showed that the EBPR with glucose supply was accomplished at least by two kinds of microbial populations, a lactic acid producing organism (LPO) and a polyphosphate accumulating organism (PAO). During the anaerobic stage, about 0.42-C mmol of PHAs was synthesized from 1 C-mmol of glucose while 0.12 P-mmol of phosphate was released at pH 6.9. The amount of phosphate release was proportional to the FH value. The amount of PHAs synthesized was less than the amount of glucose added since glucose was converted to the other storage compound (inferred as lactic acid polymer) by the LPO in addition to the PHAs by PAO. During the aerobic phase, PHAs and storage compounds in cells were metabolized and phosphate uptake occurred. In this work, a probable metabolic pathway of PHA synthesis and phosphorus removal was proposed in a SBR supplied with glucose as a sole carbon source. (C) 2000 Elsevier Science Ltd. hll rights reserved.X1162sciescopu
Neural network modeling for on-line estimation of nutrient dynamics in a sequentially-operated batch reactor
No full textIn monitoring and controlling wastewater treatment processes, on-line information of nutrient dynamics is very important. However, these variables are determined with a significant time delay. Although the final effluent quality can be analyzed after this delay, it is often too late to make proper adjustments. In this paper, a neural network approach, a software sensor, was proposed to overcome this problem. Software sensor refers to a modeling approach inferring hard-to-measure process variables from other on-line measurable process variables. A bench-scale sequentially-operated batch reactor (SBR) used for advanced wastewater treatment (BOD plus nutrient removal) was employed to develop the neural network model. In order to improve the network performance, the structure of neural network was arranged in such a way of reflecting the change of operational conditions within a cycle. Real-time estimation of PO43-, NO3-, and NH4+ concentrations was successfully carried out with the on-line information of the SBR system only. (C) 1999 Elsevier Science B.V. All rights reserved.X1164sciescopu
Estimation of oxygen transfer in soil slurry bioreactor
No full textThe apparent volumetric O-2 transfer coefficient in a soil slurry bioreactor was significantly affected by the particle size of the soil and its clay content but less affected by the concentration of organic matter. The k(L)a values in the slurry of 40% (w/v) soil content ranged from 60% to 80% of that in water. O-2 requirement was estimated for a bioremediation: O-2 was limiting in heavily contaminated soil and in soil with high clay content.X117sciescopu
Evaluation of drum bioreactor performance used for decontamination of soil polluted with polycyclic aromatic hydrocarbons
No full textA laboratory-scale drum bioreactor system was used to study engineering aspects of soil bioremediation. Polycyclic aromatic hydrocarbons (PAHs) were chosen as contaminants in soil. In the operation of the reactor, different mixing strategies were applied according to the size of soil without separate washing of sand. The effect of the water content of the soil mixture on solid mixing time and phenanthrene degradation rate was of particular interest. At 20% water content, which was below the saturation level, the mixing effficiency of soil and the degradation rate of phenanthrene was lower than those at 30% or 40% water content. Optimal water content was variable according to the soil texture. The drum bioreactor was operated under optimal water content and PAH concentration (fluorene, phenanthrene, anthracene, pyrene) and microbial numbers were measured in each soil phase (sediment and suspension). Over 95% of PAHs with three or four rings (fluorene, phenanthrene, anthracene, pyrene) were degraded at 270 mgkg(-1) soil within 20 days. The degradation rate of PAHs in the suspension phase was higher than that in sediment phase. (C) 1999 Society of Chemical Industry.X1127sciescopu
One-dimensional mixed-culture biofilm model considering different space occupancies of particulate components
No full textA new one-dimensional mixed-culture biofilm model was derived based on a hypothesis that each particulate component would have different space occupancy within biofilm. Contrary to conventional density-based modeling approaches, in this model the volume change of the biofilm. is described with the space occupancies of the particulate components, new model parameters introduced here. The unique feature of this model is that internal pore development during biofilm growth can be predicted implicitly so that the changes of effective diffusivities of soluble components depending on internal porosity are readily implemented in the model. Simulation studies revealed that the presented biofilm model could reasonably describe several important aspects of biofilm growth phenomena. In a mixed-culture biofilm system where heterotrophs and autotrophs were involved, the overall biofilm growth pattern was governed by microbial competition depending on influent composition. In a thick heterotrophic biofilm, a simulated biomass distribution and internal porosity profile showed higher total biomass concentration, lower active cell fraction, and lower internal porosity in the bottom layers of the biofilm, which are well coincident with the experimental data reported previously. All these phenomena can be explained by the proceeding of biofilm consolidation, which happens due to the inter-conversions of the particulate components having different space-occupancy values. The presented biofilm model suggests that the space occupancy of EPS may be a key model parameter to decide the overall biofilm growth pattern by regulating the extent of biofilm consolidation. (C) 2007 Elsevier Ltd. All rights reserved.X1118sciescopu
Synthesis of an environmentally friendly water network system
No full textWater network synthesis contributes to cost reduction and the conservation of water resources by reducing water consumption. A mathematical optimization model is developed in this study to synthesize an environmentally friendly water network system (WNS) by minimizing environmental impacts of a WNS. The concept of life cycle assessment (LCA) is integrated into the objective function of the model to evaluate the environmental effect scores (EESs) of principal contributors to the environmental impacts of a WNS and to optimize tradeoffs among their EESs. The mass balances are formulated from the superstructure model, and the constraints are formulated to take into account the real situation in industrial plants. A case study demonstrates the effect of the objective function on the configuration and environmental performance of a WNS and validates the mathematical optimization model. This model can be used for the design for environment (DfE) of WNSs in the context of sustainable development.X111617sciescopu
Environmental and economic analysis of a water network system using LCA and LCC
No full textWater network synthesis has been used to conserve water resources and reduce costs. The objective of this study was to verify the higher eco-efficiency of a water network system (WNS), and to identify principal contributors to environmental burdens and economic costs using life cycle assessment (LCA) and life cycle costing (LCC). The WNS was compared to the conventional water system (CWS). LCA and LCC results showed that the total environmental burdens and life cycle cost of the WNS were lower than those of the CWS. The consumptions of industrial and ionized water were principal contributors to the environmental and economic burdens. The third principal contributor to the environmental burdens was electricity consumption, but that to the economic costs was piping cost. These principal contributors can be employed to obtain the simple and practical mathematical optimization models synthesizing the most environmentally friendly, economical, or sustainable WNSs. (c) 2007 American Institute of Chemical Engineers AIChE J, 53: 3253-3262, 2007.X112121sciescopu
GROWTH OF IMMOBILIZED PLANT-CELLS IN RETICULATE POLYURETHANE FOAM MATRICES
No full textX1126sciescopu
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