OPTIMAL CAPACITY-EXPANSION PLANNING IN MULTIAQUIFER SYSTEMS

Three models were developed and tested for the optimal capacity expansion planning in a hypothetical multiaquifer system. The response of the system was included in the models using response matrices. All models are 0/1 mixed-integer programming models and enable the determination of minimum capital investment and operation costs of well fields and associated pipeline facilities while satisfying a set of system constraints. The performances of the models are compared in terms of computational requirements and approximation to pumpage costs under three water-demand schedules. Multiobjective analyses were conducted to develop trade-off curves relating pumpage to drawdown. The sensitivity of the capacity expansion policies to variations in demand requirements, interest rates, and system parameters are analyzed. The first model produces minimum total drawdowns and requires lesser computation time while the remaining two models yield minimum total costs but require more computation time. The variations in demand requirements, interest rates and system parameters causes variations in selection of the potential well fields, their completion time, resulting total costs and minimum total drawdowns

Selection of waste disposal sites using GIS

Geographic Information Systems (GIS) technology is used to identify candidate sites for a solid waste disposal facility in the Golbasi region of Turkey that has suffered from the negative impact of a current but poorly-located open-dump site on the environment. The municipality of Galbasi has noticed its deleterious effect on the environment, and has thus decided to dismiss this open-dump site and search for new landfill sites. In this study, the procedure followed under a GIS framework rejects the unacceptable sites considering environmental factors exclusively, other than economic and political issues, contained in the form of multiple layers of attribute information to select the candidate sites for landfilling wastes through an overlay analysis performed by GIS software, ARC/INFO V 7.1. For the spatial data requirements of GIS, a number of thematic map layers (ground water, wetlands and swamp areas, surface water, roads, topographic contours, ecological features, settlements, erosion susceptibility zones, and soil type) are prepared in digital form. In this application, GIS is considered as a screening tool in a site selection process to narrow the number of candidate sites, subsequently leading to one or more sites for detailed investigation. Preliminary ranking for a group of potential sites is done on the basis of simple calculations coupled with on-site field studies

Density fluctuations in lattice-Boltzmann simulations of multiphase fluids in a closed system

A two-dimensional single component two-phase lattice Boltzmann model was used to simulate the Rayleigh-Taylor instability in a closed system. Spatiotemporally variable densities were generated by gravity acting on the fluid density. The density fluctuations were triggered by rapid changes in the fluid velocity induced by changes in the interface geometry and impact of the dense fluid on the rigid lower boundary of the computational domain. The ratio of the maximum density fluctuations to the maximum fluid velocity increased more rapidly at low velocities than at high velocities. The ratio of the maximum density fluctuations in the dense phase to its maximum velocity was on the order of the inverse of the sound speed. The solution became unstable when the density-based maximum local Knudsen number exceeded 0.13

Stochastic Conjunctive Management of Water Resources in Yolo County

Two management models are developed to determine the optimal operating policies for hydraulically connected time-variant surface and ground water supplies in a hypothetical system. The system involves a multipurpose reservoir, a hydraulically connected stream and aquifer, agricultural plot, water supply and observation wells, and an artificial recharge zone so as to address various hydrologic components experienced in Yolo County in the management models. The first model minimizes deviations from a set of rule curves defined for storage in the reservoir and along stream course so as to consider possibilities for storage excess water in wet periods and its distribution in subsequent dry periods. The second model, in addition to the objective of the first model, minimizes total operational costs of surface and subsurface water storages (pricing) while meeting the target storage levels in the surface water supplies. The first model is formulated as a linear programming model whereas the second one is formulated as a nonlinear programming model and a []-form approximating model is employed in the solution phase.The hypothetical system is divided into components which are subsequently integrated using numerically-generated response functions that relate the system's behavior to various system excitations. The management model is formulated and solved for monthly time steps, which include both dry and wet conditions, to determine reservoir release, pumpage rate from supply wells, artificial recharge rate, water diversion from reservoir and stream to the demand area, and storage both in the reservoir and along the stream course at an optimal level in each time step over a six-month planning horizon. Sensitivity analysis of the first management plan with respect to potential use of groundwater supplies is performed to analyze the latter's impact on the operating policies. Furthermore, the performance of the []-form approximating model for conjunctive management models applied to the hypothetical system is found to be promising

Modeling the inactivation of microorganisms occluded in effluent wastewater particles to enhance operation of filtration and disinfection systems

In disinfection systems, incomplete penetration of chlorine into effluent wastewater particles can result in a residual population of viable microorganisms. In this work, a combined experimental and numerical approach was used to quantify inactivation of microorganisms in effluent particles and identify combinations of particle removal and chlorine dose that would result in a reduction of occluded microorganisms for six full-scale facilities in the United States with different nitrification levels. The results reveal that combined chlorine is more effective for inactivating occluded microorganisms than free chlorine; model calibration results suggest that free chlorine is less effective because it is more reactive. However, nitrified effluents appear to have lower effluent particle concentrations, and decreases in particle concentrations significantly reduce the chlorine required. Additionally, in disinfection systems that are designed and operated based on inactivation of indicator organisms, the chlorine dose may be insufficient to inactivate occluded pathogens to levels consistent with current regulations

Integração de critérios técnicos, ambientais e sociais em estudos de alternativas locacionais para implantação de aterro sanitário Integrating technical, environmental and social criteria in landfill sitting studies

A Política Nacional do Meio Ambiente tem como objetivo a conciliação do desenvolvimento econômico e social com a qualidade ambiental, e dispõe de vários instrumentos que procuram contemplara capacidade de suporte do meio. Assim, a discussão sobre a localização das atividades é uma etapa importante para a avaliação da viabilidade ambiental de um determinado empreendimento, notadamente em processos de licenciamento ambiental. O trabalho apresenta uma abordagem metodológica para integração de critérios técnicos, ambientais e sociais em estudos de alternativas de localização de aterros sanitários, com especial atenção à interação entre os aspectos ambientais e os elementos fundamentais de um projeto (a saber, requisitos locacionais e concepção tecnológica), aplicado em um estudo de caso em São Carlos (SP). Como resultados principais, destacam-se o maior foco nos impactos significativos e a possibilidade de envolvimento de segmentos importantes da sociedade previamente à elaboração dos estudos ambientais.<br>The National Environment Policy aims to reconcile economic and social development with environmental quality and has several instruments to address environmental issues within the decision making processes. Thus, the discussion about the location of activities is an important step in the evaluation of the environmental acceptability of aparticular activity, even though the systematic procedures do not require neither to the entrepreneur or to the government studies of sitting alternatives. This paper presents the integration of technical, environmental and social criteria in a landfill sitting study, in order to present a systematic integration of environmental factors and applies in a case study in São Carlos, Brazil. The results allowed the development of an environmental impact statement more focused on significant impacts and the participation of segments of society at early stages of project's development