PCDD/PCDF reduction by the co-combustion process

A novel process, termed the co-combustion process, has been developed and designed to utilise the thermal treatment of municipal solid waste (MSW) in cement clinker production and reduce PCDD/PCDF emissions. To test the conceptual design; detailed engineering design of the process and equipment was performed and a pilot plant was constructed to treat up to 40 tonnes MSW per day. The novel process features included several units external to the main traditional cement rotary kiln: an external calcinations unit in which the hot gas calcined the limestone thus making significant energy savings for this chemical reaction; the lime generated was used in a second chamber to act as a giant acid gas scrubber to remove SOx and particularly HCl (a source of chloride); an external rotary kiln and secondary combustion unit capable of producing a hot gas at 1200 degrees C; a gas cooler to simulate a boiler turbogenerator set for electricity generation; the incorporation of some of the bottom ash, calcined lime and dust collector solids into the cement clinker. A PCDD/PCDF inventory has been completed for the entire process and measured PCDD/PCDF emissions were 0.001 ng I-TEQ/Nm(3) on average which is 1% of the best practical means [Hong Kong Environmental Protection Department, 2001. A guidance note on the best practicable means for incinerators (municipal waste incineration), BPM12/1] MSW incineration emission limit values.     

Ozone uptake by citrus trees exposed to a range of ozone concentrations

The Citrus genus includes a large number of species and varieties widely cultivated in the Central Valley of California and in many other countries having similar Mediterranean climates. In the summer, orchards in California experience high levels of tropospheric ozone, formed by reactions of volatile organic compounds (VOC) with oxides of nitrogen (NO_x). Citrus trees may improve air quality in the orchard environment by taking up ozone through stomatal and non-stomatal mechanisms, but they may ultimately be detrimental to regional air quality by emitting biogenic VOC (BVOC) that oxidize to form ozone and secondary organic aerosol downwind of the site of emission. BVOC also play a key role in removing ozone through gas-phase chemical reactions in the intercellular spaces of the leaves and in ambient air outside the plants. Ozone is known to oxidize leaf tissues after entering stomata, resulting in decreased carbon assimilation and crop yield. To characterize ozone deposition and BVOC emissions for lemon (Citrus limon), mandarin (Citrus reticulata), and orange (Citrus sinensis), we designed branch enclosures that allowed direct measurement of fluxes under different physiological conditions in a controlled greenhouse environment. Average ozone uptake was up to 11 nmol s^?1 m^?2 of leaf. At low concentrations of ozone (40 ppb), measured ozone deposition was higher than expected ozone deposition modeled on the basis of stomatal aperture and ozone concentration. Our results were in better agreement with modeled values when we included non-stomatal ozone loss by reaction with gas-phase BVOC emitted from the citrus plants. At high ozone concentrations (160 ppb), the measured ozone deposition was lower than modeled, and we speculate that this indicates ozone accumulation in the leaf mesophyll.     

A tool to aid emergency managers and communities in appraising private dam safety and policy

Issues concerning dam safety and equitable sharing of catchment run-off are receiving more attention throughout the world. This paper assesses these matters in the context of Australia, and the need for policy responses. Landholders often overlook the common law obligation to review/design dams to current standards because of high costs, leaving them vulnerable to litigation if their dam fails. The paper reports on an innovative spillway design/review procedure, applicable to southeast Australia, but transferable to any region worldwide. Dam safety policy models and guidelines derived from international best practice are linked to the procedure and intended to aid government decision-making. The procedure minimises costs to landholders and provides an acceptable level of safety assurance to downstream communities. Also discussed are recent surveys testing community attitudes to the procedure and implemented dam safety and water allocation policies. These further guide any government wanting to implement this'integrated engineering and community partnerships'approach to preventing potential disasters due to private dam failure and achieving sustainable and safe water storage and use.     

MODELING THE IMPACT OF SUBSURFACE NUTRIENT FLUX ON WATER QUALITY IN THE LOWER TRUCKEE RWER,NEVADA1

ABSTRACT: The impacts of regional groundwater quality and local agricultural activities on in-stream water quality in the Lower Truckee River, Nevada, were assessed through a detailed program of monitoring and computer simulation. An agricultural diversion and return-flow were monitored in great detail to determine mass loading rates of nutrients from agriculture in the area. Once characterized, the cumulative impacts of agricultural diversions and return-flows were evaluated using the Water Quality Assessment Program (WASP) to model nitrogen, phosphorus, periphyton, and dissolved oxygen. Monitoring showed that a significant proportion of the water diverted for agricultural purposes returned to the river as surface point return-flow (estimated at 13.9 percent $ 0.1 percent), and as groundwater diffuse return-flow (estimated at 27 percent $ 6 percent). Modeling efforts demonstrated the significant effect of assumed regional groundwater quality (nitrate) upon predicted periphyton growth and associated diel fluctuations of dissolved oxygen.     

Photochemical generation of reactive intermediates from urban-waste bio-organic substances under UV and solar irradiation

Singlet oxygen (¹O₂), hydroxyl radicals (^•OH), and excited triplet states of organic matter (³OM^*) play a key role in the degradation of pollutants in aquatic environments. The formation rates and quantum yields (Φ) of these reactive intermediates (RI) through photosensitized reactions of dissolved organic matter (DOM) have been reported in the literature for decades. Urban biowaste-derived substances (UW-BOS), a form of organic matter derived from vegetative and urban waste, have recently been shown to be efficient sensitizers in the photo-degradation of different contaminants. Nevertheless, no quantitative measurements of photo-oxidant generation by UW-BOS have been reported. In this study, the formation quantum yields of ¹O₂ and ^•OH, as well as quantum yield coefficients of TMP degradation (indicative of ³OM^* formation), were quantified for two UW-BOS samples, under 254-nm UV radiation or simulated sunlight and compared to a DOM standard from the Suwanee River (SRNOM). Values of Φ for UW-BOS samples ranged from Φ(+¹O₂) = 8.0 to 8.8 × 10⁻³, Φ(+^•OH) = 4.1 to 4.3 × 10⁻⁶, and f _TMP = 1.22 to 1.23 × 10² L Einstein⁻¹ under simulated sunlight and from Φ(+¹O₂) = 1.4 to 2.3 × 10⁻², Φ(+^•OH) = 1.3 to 3.5 × 10⁻³, and f _TMP = 3.3 to 3.9 × 10² L Einstein⁻¹ under UV. Although UW-BOS are not necessarily better than natural DOM regarding photosensitizing properties, they do sensitize the production of RI and could potentially be used in engineered treatment systems.

     

Development and testing a diagnostic capacity tool for improving socio-ecological system governance

The capacity to sustainably govern complex socio-ecological systems (SES) has been identified as a necessary but daunting task by SES scholars, resource stewards and stakeholders. This research sought to inform the question: What are determinant capacities and functional linkages that can be incorporated into diagnostic tools for analysts seeking to improve sustainable socio-economic system SES governance? Literature was used to identify and translate determinant capacities and functional linkages into a quantifiable metric of governance quality. The tool was developed from ecological, business, governance and decision science literature. This tool recognizes the dynamic and systemic linkages between the resources and the social systems that use and govern them for improving systems thinking and SES outcomes. The tool was tested to determine its ability to capture perceived characteristics of governance quality and problem management using Michigan’s cleanup and redevelopment program. The results of this research indicated that the exploratory tool was reliable and valid. This research contributes to the evolving body of SES frameworks, specifically the study of individual and organizational capacities for improved SES outcomes. The implications of this research suggest participatory network-based governance with higher levels of resource exchange, in the form of interdependency, trust, diplomacy and reciprocity, aligns with practitioners’ perceptions of improved program performance. Further, while some capacities and related findings of this research may be context specific, concepts associated with the development and testing of this diagnostic tool, such as the use of systems thinking, participatory network-based governance, and related competencies, may have more universal application.     

Medical investigation after a motorcoach strikes the rear of a tractor semitrailer parked on the highway; 13 fatal

Abstract

Objective: The objective of this study was to examine the medical conditions of 2 commercial drivers and the effects of physical barriers to occupant egress in a crash involving a tractor trailer and a motorcoach in order to assess and identify the factors that caused the crash and had a significant effect on occupant extrication.

Methods: Physical evidence from the scene, video evidence, commercial driver information, phone records, toxicology findings, autopsy results, and personal medical information were reviewed.

Results: On October 23, 2016, at 5:16 a.m., a motorcoach carrying a driver and 42 passengers struck the rear of a stopped semitrailer occupied by its driver in the center-right lane of Interstate 10 at highway speed outside Palm Springs, California. The motorcoach driver and 12 passengers died; 11 passengers were seriously injured.

All traffic had been stopped on I-10 early that morning to allow electrical lines to be strung over the highway. Security camera footage showed that the truck arrived at the end of a traffic queue 2?min before traffic flow resumed. Physical evidence indicated that the truck’s parking brake was still engaged at the time of the collision about 2?min later. The truck driver had a body mass index (BMI) between 45.6 and 50?kg/m², which placed him at very high risk of moderate to severe obstructive sleep apnea; he also inaccurately recalled that he had been stopped for 20–25?min and had placed the vehicle in gear just before the collision.

The motorcoach driver was on the return leg of an overnight trip to a casino. Based on his phone records, known driving time, and security camera footage, at the time of the collision he had had 4?h of sleep opportunity in the preceding 35?h. There was no evidence that the motorcoach driver attempted any evasive action before the collision. In addition, postmortem testing revealed a hemoglobin A1C of 11.4%, indicating poorly controlled diabetes; this was apparently undiagnosed prior to the crash.

The motorcoach was equipped with a single loading door at the front of the vehicle; it was rendered inoperable by the collision. Emergency egress was initially carried out through the emergency exit windows, but they repeatedly swung shut, impeding passengers’ efforts to exit. Emergency responders eventually cut open the bus wall to create a larger means of egress. Overall, it took almost 3?h to extricate the occupants from the vehicle.

Conclusions: The National Transportation Safety Board (NTSB) determined that the probable cause of the accident was the truck driver’s falling asleep, most likely due to undiagnosed moderate-to-severe obstructive sleep apnea, and the motorcoach driver’s failure to identify the stopped truck as a hazard requiring evasive action, most likely as the result of fatigue. Additional easy-to-use emergency exits would have decreased the time to extricate the occupants.     

Efficacy of Bacteroides measurements for reducing the statistical uncertainty associated with hydrologic flow and fecal loads in a mixed use watershed

This paper presents an analysis of the occurrence and uncertainty of source-specific Bacteroides and Escherichia coli in a stream in a mixed land-use watershed with human, cattle, and wildlife fecal inputs located in a karstic geologic region during baseflow conditions. The objectives of the study were to evaluate the occurrence, hydrologic significance, and source of fecal mass in the stream using assays for total Bacteroides (AllBac) and bovine-specific Bacteroides (BoBac), and then to compare these measurements with E. coli densities and loads. Samples were collected during baseflow conditions over several months at seven different main channel sites in the Stock Creek watershed, a 49.3 km2 basin located in Knoxville, TN (USA). We determined instantaneous loads for total fecal loads, bovine fecal loads, and E. coli from measured flow rates and the representative Bacteroides fecal masses and/or E. coli densities. The study indicated a strong correlation between total fecal load (kg d(-1)), bovine fecal load (kg d(-1)), E. coli load rate (CFU d(-1)), 7-d antecedent precipitation, and turbidity. The various datasets were used to establish parameter correlations and spatial dependencies throughout the watershed. The data analysis demonstrated two prevalent patterns throughout the watershed: (i) a runoff-dominated transport and occurrence; and (ii) potential groundwater-dominated transport and occurrence.