土木環境工学ジャーナル

It is widely perceived that karst groundwater often has insufficient residence time for significant biodegradation of contaminants to occur. It is perhaps due to these perceptions that less research has been conducted for quantitative modeling of biodegradation in karst as compared to consolidated aquifers. Modeling biodegradation in karst is in the domain of non-ideal chemical reaction kinetics. The residence time distribution function (RTD) for tracer molecules in a single karst conduit or a complex system of conduits is a probability density function which can be interpreted to define the probability that contaminant molecules present at the influent at time equals zero will arrive at the effluent after a particular amount of time. To demonstrate this methodology the biodegradation rate of a contaminant (toluene) in raw karst groundwater from a BTEX impacted site in central Kentucky was quantitatively measured in batch microcosm studies and the extent of biodegradation of toluene in the same groundwater was measured for a complex flow system.The values of the pseudo first order rate constant (k’) obtained ranged from 0.017 (hr)-1 to 0.0210 (hr)-1 compared to 0.0186 (hr)-1 for the microcosm experiments. The close agreement between the values of k’ obtained from the static microcosms and the ADE model indicate that the model adequately describes the RTD for modeling biodegradation in karst aquifers. The values of k’ obtained correspond to a half-life of less than two days for toluene and this has major

In Egypt, Hydropower sector plays a key role in Climate smart technological solutions to mitigate and adapt climate change. Egypt intends to replace the existing Assiut barrage in Nile River with a new one incorporating a hydropower plant. The technical and economical feasibility of the rehabilitation of the existing barrage including the installation of a low head hydropower plant of about 32 MW is proved. The electricity production of about 250 GWh annually is planed. The optimization of hydropower output will be achieved through mitigation of project-related environmental and social impacts. The implementation of measures to predict, monitor and mitigate or avoid construction and operation impacts is planned. This Paper sets out information relating to the contribution of Hydropower plant of New Assiut Barrage Project towards Adaptation and sustainability options. The Paper assesses the socio-economic and environmental impact of the project, the indicators applicable to the scheme / community in question, and details of the method used to diagnose and monitor social-environmental performance. Where applicable, the diagnostic for the community must be presented separately from that carried out for the scheme. The Paper concludes that the Hydropower plant of the New Assiut Barrage Project has very promising positive aspects in relation to climate change mitigation and adaptation and sustainable development in Egypt.

The objective of this white paper is to explain the best way of using gate review as an effective tool for the optimal management of projects. Presented here are lessons learned during the past many years of managing/ coordinating million and billion dollar projects across North America. In all significant projects, a gate review is generally conducted using customized check lists to generate a qualitative or semi-quantitative information on the many levels of risks associated with each of the potential hazards and operability problems that could adversely impact the allocated budget, raise liability concerns, and delay in completing the project. The check lists serve as an event sieve incorporating all probable situations that may occur during the life of the project, and thereby making the gate review process meaningful and targeted in developing a risk matrix that quantify the likelihood and severity of a bad event happening. Thus having a reliable risk matrix brings substantial savings in completing the project on time, in safeguarding HS&E in the workplace & surrounding communities, and would bring down future operating costs in many ways from insurance premiums to O&M costs. Thus this white paper summarizes some of the best means to conduct an enhanced gate review prior to field implementing a project for achieving maximum benefits.

Study of indoor air quality (IAQ) has received attention of the researchers and policy makers over the last several years due to its affiliation with the adverse health effects and occupants’ discomfort. This article focuses on the importance and need of IAQ studies in Indian rural and urban indoor environments. A number of questions in this context are posed and addressed, together with identifying the allied research gaps and missing links in the existing literature. Also discussed are the technical challenges to carry out the IAQ studies in India, and the initiatives and future road map required to overcome them.

Odorous air emissions from confined animal feeding operation are causing public nuisance. Accordingly, different odor mitigation technologies were designed, developed, and evaluated in the last decades to reduce odor emissions. The purpose of this paper is to review the previous research related to odor mitigation from swine rearing facilities and provide information on the effectiveness of currently available and emerging odor mitigation technologies. This review focused on odor mitigation approaches at different stages of swine production, manure storage and handling, and land application. Several odor mitigation technologies have been suggested and evaluated including diet manipulation, solid-liquid separation, additives, aeration, anaerobic digestion, lagoon covers, biofilters, acid scrubbing, shelterbelts, and manure injection. The effectiveness of these mitigation technologies varied widely; however, diet manipulation, biofilters, shelterbelts, and direct injection of manure have shown advantages over other odor mitigation methods. Diet manipulation is the first line of defense for odor mitigation. Biofilters and shelterbelts provide solutions for treating the odorous air before releasing to atmosphere, whereas additives, lagoon covers, aeration, and anaerobic digestion reduce or control odor emissions during manure storage and treatment. Direct injection of manure provides ultimate disposal solution and can reduce odor significantly compared to surface application.

The solids that result from mine wastewater treatment usually contain elevated levels of contaminants that were originally contained in the wastewater. These must be carefully disposed or treated to avoid shifting of the original pollutants in the waste stream to the final disposal site where they may again become free to contaminate the environment. A more reasonable approach to ultimate solids disposal is to view the sludge as a resource that can be recycled or reused. In South Africa, reverse osmosis is already being used for desalination of mine water and huge sludge volumes are also produced. The Tshwane University of Technology-Magnesium-Barium-Oxide (TUT-MBO) process and its variations is an alternative technology that offers the benefit of lower cost as magnesium hydroxide, barium hydroxide and coal are the main process raw materials. In the first stage Mg(OH)2 is dosed to raise the pH of the acid mine drainage to 9 for removal of free acid, iron(II) oxidized to iron(III) and all other metals precipitated as metal hydroxides. In the second stage Ba(OH)2 is dosed for magnesium and sulphate removal as Mg(OH)2 and BaSO4 respectively. The resultant, mixed BaSO4/Mg(OH)2 sludge is treated in a thermal stage to produce BaS and MgO. The aim of this study was to separate magnesium hydroxide from barium sulphate, produced in the second stage of the TUT-MBO Process. Magnesium hydroxide is separated from barium sulphate through the dissolution of Mg(OH)2 with CO2 to Mg(HCO3)2. The results showed that: (a) By adding CO2 to a BaSO4/Mg(OH)2 sludge, selective dissolution of Mg(OH)2 occurred due to the relatively high solubility of Mg(HCO3)2 and the low solubility of BaSO4 and, (b) the solubility of Mg(HCO3)2 increased with decreasing temperatures and increasing pressures.

The aim of the study is to perform a potential health risk assessment on children in contracting respiratory symptoms due to inhaling traffic-generated nitrogen dioxide (NO2) in two typical high-rise naturally-ventilated residential building designs (slab and point block) located close to busy major expressways in a tropical climate. A total of six buildings were selected for the study. Ogawa passive samplers (PS-100) were used for NO2 measurements in each building over a period of 5 weeks during the predominant monsoon seasons. Health risk assessment showed children residing at the mid floors of the buildings had the highest health risk regardless of their age .i.e. infants, children (1 year and under), children (8-10 years)compared to those residents residing at the high and low floors. This was expected since the highest concentration of traffic-generated NO2 concentration occurred at the mid floors of the buildings. In a typical floor, children (1 year and under) had the highest followed by children (8-10 years) whilst new born infants had the least potential health risk in contracting respiratory symptoms. The reason might could be new born infants obtain passive immunity from their mothers and in children (1 year and under), the passive immunity fall during this age period as they are developing their very own immunity against respiratory symptoms. Children (8-10 years) had the their potential health risk to respiratory symptoms in between the other two age groups as these children could have developed more immunity against respiratory symptoms compared to the children (1 year and under) but less immunity compared to infants. Based on the mean overall HR values, children living in a slab block has about 1.27 times more risk in contracting a respiratory symptoms due to NO2 inhalation compared to those living in a point block.

Livestock operations have long been associated with unpleasant odors whether it is a swine, poultry, or dairy operation. Unpleasant odorous smell has been generally accepted as part of livestock operations in the past. However, as more and more animal production continues to evolve into major concentrated operations, odor emissions from these confined animal feeding operations (CAFOs) have caused persistent public concern and complaints. In addition, particulate matters and other gas emissions have also been a cause for environmental and health concerns. Therefore, a thorough understanding of air emissions from CAFOs is a first necessary step in formulating effective management strategies for dealing with these odor and air quality issues. In this study, the examination and characterization of volatile fatty acids (VFA), major components of odors from poultry operations, in suspended particulate matter (SPM) from a broiler house were carried out using particle trap impactors. The inhalable fractions (IH) of SPM from the particle trap impactors were extracted and analyzed for its VFA contents using High Performance Liquid Chromatography (HPLC). The results showed that proprionic and butyric acid are the major VFA found in the IH collected from the broiler house after a total cleanout. Their concentrations ranged from 80 to 382 μg/m3 for propanoic acid and 143 to 405 μg/m3 for butanoic acid. Trace amounts of other VFA (i.e., acetic acid, pentanoic acid, and hexanoic acid) were also observed from particulate matter (PM) analyses. The concentration profile of VFA appeared to reach a maximum at the middle of the flock age (e.g., when the birds reach about four to five-week old) and tapering off toward the end of the flock age. The mass fractions of VFA were also observed to be inversely proportional to PM concentrations.