93,001 research outputs found
Simulation of Alachlor fate and transport: model calibration and sensitivity analysis
No full textSpraying of agricultural chemicals result in their travel downward through the unsaturated zone and adsorption on the surrounding soil. Infiltration from rainfall and irrigation solubilize these chemicals and carry the dissolved components to the ground water. This process can cause soil and ground water contamination the extent of which is greatly influenced by soil characteristics, the rate and method of chemical application. This paper presents experimental and mathematical results describing the transport of the herbicide Alachlor in laboratory soil columns with variable length, initial moisture content, and Alachlor application rate and method. The laboratory time-dependent distribution of Alachlor concentration is used to calibrate a numerical flow and transport model. The model was also used to conduct a sensitivity analysis with respect to soil and chemical properties and identify parameters value ranges controlling Alachlor transport in porous media
Aerobic vs. anaerobic biological processes for the treatment of organically contaminated groundwater
No full textThis paper describes laboratory scale results of aerobic and anaerobic biological treatment studies conducted to evaluate the feasibility of treating ground water contaminated with an organic solvent consisting of an equal weight-mixture of methylethylketone and cyclohexanone. For this purpose, three alternatives were considered, namely a single-stage anaerobic baffled reactor, an activated sludge system, and an aerated lagoon. The study focused on determining and comparing the treatment efficiency of each of the three treatment processes under similar operating conditions. Aerobic processes proved to be more effective in treating the organically contaminated groundwater
Environmental remediation of fire damaged buildings
No full textThe potential presence of indoor air pollutants in fire-damaged buildings stemming primarily from fire soot deposits, raises major environmental concerns in relation to potential long term health impacts on building occupants. Litigation claims often occur as a result of perceived ineffective remedial activities and the potential risk hazards of indoor air quality after the remediation is completed. This paper describes environmental remediation activities at an office building in the China Basin district of the City of San Francisco following a fire accident at a nearby wharf, which severely damaged the building. Based on an air quality sampling and chemical analysis program, a health-based risk assessment was conducted to evaluate the health effects of indoor air quality on building occupants. The risk assessment consisted of a toxicity definition of measured indoor air pollutants and an exposure assessment including the characterization of the exposure setting, the identification of exposure pathways, and the quantification of exposure. The results of the exposure assessment are combined with chemical-specific toxicity information to characterize the potential health risks at fire-damaged building
Comparative assessment of EIA systems in MENA countries: challenges and prospects
No full textEnvironmental impact assessment (EIA) was devised as a decision tool in response to the grand swell of ecocentric concerns to mediate between the technocentric view of continued development and the ability to create economic growth while overcoming environmental problems. The assimilation of the philosophy and practice of EIA into a broad range of cultures and political systems reflects the desire and need to integrate environmental considerations into the decision-making process. This paper unveils the status of EIA systems in countries of the Middle East and North Africa region through a comparative assessment of existing and planned legislation and procedure
Grade separations for traffic congestion relief: air quality and noise implications
No full textTraffic congestion at major intersections is typically an accumulation of the effects of several factors, including short-sighted urban planning and ineffective enforcement of traffic regulations. This paper evaluates air quality and noise implications at a typical intersection where a grade separation is proposed to relief traffic congestion. For this purpose, traffic counts, air quality characterization, and noise level measurements were conducted to define existing conditions. Mathematical simulations were performed to evaluate the future evolution of the site with and without a grade separation. Potential impacts are evaluated by comparing simulated exposure levels of air quality and noise indicators with relevant environmental standards. Mitigation measures in the context of constructing grade separations in urban areas are also outlined
Environmental impact assessment of traffic improvement in highly congested urban areas: the Beirut Urban Transport Project
No full textAfter nearly two decades of civil unrest, Lebanon launched a reconstruction and development initiative. Environmental impact assessments (EIAs) were introduced primarily to secure international financing and assistance. This report discusses an EIA for the proposed Beirut Urban Transport Project. The Lebanese Government is seeking to finance the project through a loan from the World Bank. Since traffic congestion has reached unsustainable levels in recent years, the main objective of the project is to improve traffic management within the City and its surrounding areas. Environmental management and monitoring are emphasized within the context of the EIA proces
Settlement in municipal solid waste landfills: I. Field scale experiments
No full textThe biodegradation of organic matter in MSW landfills increases the void ratio and weakens the structural strength of the refuse within a landfill leading to a substantial loss of volume and settlement. Development of completed landfill sites which is highly desirable particularly in land-limited locations, is invariably hindered by these settlements. Estimating long term landfill settlements becomes an integral part towards final site closure and ultimate usage. The rate and magnitude of these settlements depend primarily on refuse composition and operational-management practices which affect bio-degradation and stabliization processes within landfills. Field scale experiments were conducted to measure refuse settlements rates under different operational management practices including leachate recirculation, addition of water, buffer and microbial seed. The effect of these practices on settlement rates and magnitudes is evaluated. The field test data are used to calibrate mathematical models that are traditionally used in soil consolidation. The models can be applied to simulate landfill settlement rates and correlate these rates to refuse biodegradation and stabilization processes within landfills. The present research work is presented in series of two papers: I. field scale experiments II. mathematical modeling of settlement behaviour
Phase-out of leaded gasoline: approaches and prospects for Lebanon
No full textAir pollution from urban traffic is a growing environmental problem worldwide. Emissions of lead resulting from the usage of leaded fuel are of particular concern due to associated health hazards. While many countries have accomplished or are in the process of phasing-out leaded gasoline, others continue to rely to a large extent on the use of high lead-content gasoline. Such is the case of Lebanon where the use of unleaded gasoline is hindered not only by the lack of direct governmental endorsement but also by the price difference in favour of leaded gasoline. While the phase-out of leaded gasoline is economically feasible, several measures should be undertaken for a successful transition to unleaded gasoline. This paper reviews the problem of lead addition into gasoline and the international experience in its phase-out. Policy measures and technical considerations for a successful transition to unleaded gasoline are described. Available data for Lebanon about the vehicle fleet characteristics, gasoline consumption and quality as well as lead emissions and concentrations in various environments are presented. This information forms the basis for developing a phase-out action plan outlining the interrelation and responsibilities of various agencies as well as measures to be adopted for a successful phase-out process
Effect of food waste disposers on municipal solid waste and wastewater management
No full textThis paper examines the feasibility of introducing food waste disposers as a waste minimization option within urban waste management schemes, taking the Greater Beirut Area (GBA) as a case study. For this purpose, the operational and economic impacts of food disposers on the solid waste and wastewater streams are assessed. The integration of food waste disposers can reduce the total solid waste to be managed by 12 to 43% under market penetration ranging between 25 and 75%, respectively. While the increase in domestic water consumption (for food grinding) and corresponding increase in wastewater flow rates are relatively insignificant, wastewater loadings increased by 17 to 62% (BOD) and 1.9 to 7.1% (SS). The net economic benefit of introducing food disposers into the waste and wastewater management systems constitutes 7.2 to 44.0% of the existing solid waste management cost under the various scenarios examined. Concerns about increased sludge generation persist and its potential environmental and economic implications may differ with location and therefore area-specific characteristics must be taken into consideration when contemplating the adoption of a strategy to integrate food waste disposers in the waste–wastewater management syste
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