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Post-tensioned concrete masonry walls provide improved seismic performance, but have had limited application in seismic regions because of a lack of research pertaining to their in-plane response. Following focused research over recent years, a consortium of product suppliers has collaborated with the University of Auckland to construct New Zealand’s first post-tensioned concrete masonry house. A feature of this innovative design was that all incorporated products were commercially available, with no proprietary products being specifically developed for the prestressed masonry system used. Consequently, it is hoped that this house will be a showcase, and provide exposure for the technology in New Zealand and elsewhere. This paper provides a brief review of previous post-tensioned concrete masonry research applications, then discusses post-tensioning details and their application to house design and construction.

The issue regarding the corrosion of steel ties connecting brick veneer to its structural backing is well known and well documented. However, none of the research to date has developed field-calibrated corrosion rate and service life models specific to wall ties in brick veneer steel stud (BVSS) wall systems. In this paper, corrosion rate and service life estimates produced by two models generated by the International Organization for Standardization (ISO) were compared with the empirically determined corrosion rates (CRs) and service lives of nine zinc galvanized tie specimens inspected at five buildings in four different Canadian cities. The best estimate, obtained using actual environmental data, was found to be the ISOCORRAG formula. However, the maximum difference between predicted and actual service life was still significant, indicating that a better understanding of the mechanics governing the corrosion of a tie embedded in mortar is still needed.

The mechanics of masonry structures have been underdeveloped for a long time in comparison with other fields of knowledge. Presently, nonlinear analysis is a popular field in masonry research and homogenization techniques play a major role despite the mathematical and conceptual difficulties inherent to this approach. This paper addresses different homogenization techniques available in published literature, aiming at defining a first catalogue and at discussing the advantages and disadvantages of the different approaches. Finally, special attention is given to a micromechanical based model and a model based on a polynomial expansion of the microstress field. These seem promising and accurate strategies for advanced structural analysis.

Change in flow regime from subcritical to supercritical flow or opposite can be met during a dam break flow propagation but also during floods in urban areas, particularly near crossroads. Detailed laboratory measurements of flow discharge distribution and flow depths are carried out for transcritical dividing flows in a 90° sharp-edged, rectangular junction formed by horizontal open-channels of equal width. These measurements are used to assess the uncertainty of numerical predictions obtained using a two-dimensional (2-D) depth-averaged model. A sensitivity analysis to four parameters, i.e., space step, friction coefficient, diffusion coefficient, and downstream boundary condition, is carried out. For the water depths in the vicinity of the intersection, uncertainty linked to the calibration of the four aforementioned parameters can be higher than 50% because of the difficulty in representing the location and amplitude of the hydraulic jumps while, for the flow ratio between the downstream branches, uncertainty is limited to 10%.

Within the larger domain of risk or environmental assessment, uncertainty treatment is gaining growing interest in the fields of hydrological and hydraulic modeling. A generic approach to quantitative uncertainty is suggested, putting together the applicable decision-making framework and associated probabilistic formulations involving uncertainty modeling (possibly through an inverse approach), uncertainty propagation, and the ranking of importance or sensitivity analysis. Accordingly, a number of generic statistical, physical, and numerical methods could be more largely disseminated in the water domain. Two axes of particular potential interest are outlined: the tricky choice of differentiating according to the epistemological nature of the uncertainty, with considerable impact on the formulation of the risk criterion and the associated level of complexity; the challenges posed by uncertainty modeling in the context of data scarcity, and the corresponding calibration and inverse probabilistic techniques, bound to be developed to best value hydro-monitoring and data acquisition systems under uncertainty.

This work forms part of a general research effort into developing a methodology for reliability estimates of results obtained in numerical hydrodynamic computations. We consider the possibility of overtopping at the crest of a dyke of height h0positioned on a river with several uncertain parameters, such as discharge, Manning coefficient, bathymetry, etc. The estimation model is based either on the first-order reliability method (FORM), on the multi-form method, or on the importance sampling methods and is coupled with algorithms for the resolution of an adjoint optimization problem. Numerical tests are carried out on flows over a channel with a bump and on a river. The results obtained with our algorithms are compared with those obtained with the commercial software Nessus®and with the Monte Carlo method. The proposed multi-form approach combined with a robust optimization algorithm provides reliable results within reasonable computation times.

Interest in the actual estimation of the uncertainty affecting flood hazard assessments is increasing within the scientific community and among decision makers. Several works may be found in the hydrological and hydraulic literature listing the sources of uncertainty affecting the estimation of extreme flood levels. Here, a well-assessed uncertainty treatment procedure is applied to carry out a complete flood hazard assessment study to encompass both the hydrological and hydraulic components. In particular, the focus is on modeling the sources of uncertainty via a direct (for discharge) or inverse (for roughness hydraulic coefficient) approach. The results illustrate the relative importance of the hydraulic and hydrological uncertainty sources on the final uncertainty. The solution of the inverse problem for the calibration of the roughness coefficient proves useful for several reasons, including the quantification of model error.

Increasingly, an understanding of flood risk across regions and nations, and an ability to explore how these might change in time, is seen as a prerequisite to effective and efficient flood risk management. In response, specific flood risk analysis methods have been developed that are both accurate and fast to run. Although widely acknowledged as desirable, it has not previously been possible to quantify the uncertainty associated with the assessed flood probability, consequence, or risk. To help overcome this deficiency, an efficient method for the propagation of epistemic uncertainties through large-scale flood risk system models has been developed and trialed for three pilot catchments. The approach is allied to an efficient sensitivity analysis that enables the influence of individual uncertainties on the output quantity of risk to be isolated, enabling future research, development, and data-gathering efforts to be focused.

This study aims to investigate treatment performance of the two-stage upflow anaerobic sludge blanket (UASB) applied to concentrated latex processing wastewater in Thailand. First, optimal conditions including the hydraulic retention time (HRT) in the acid tank and the UASB tank, pH, and temperature (mesophilic and thermophilic) were determined. It was found that the HRT at 24 h and 48 h were the optimal HRT for the acid tank and the UASB tank, respectively. The pH of the system should be controlled at 7 to prevent rubber coagulation and to achieve high treatment performance, and the mesophilic condition (35°C) was found to be the optimal temperature. Second, the two-stage UASB was applied with the optimal conditions mentioned earlier with real wastewater at a latex mill. It was found that methane production was about 0.116 L CH4/g COD removed (16.3–22.8 m3CH4/d), and average chemical oxygen demand (COD) and suspended solids (SS) removal efficiency were about 82% and 92%, respectively. In case of SS removal, the results revealed that the two-stage UASB was capable of overcoming the limitations of the single-stage UASB in treating concentrated latex effluent. The results indicated that application of the two-stage UASB to concentrated latex processing wastewater is feasible. Nevertheless, combination with other treatment systems (e.g., oxidation pond, aerated lagoon) is necessary to meet Thailand's industrial effluent standards (in the case of COD).

A continuous flow mode of the microwave enhanced advanced oxidation process (MW/H2O2-AOP) was used for sludge treatment as opposed to a batch operation mode from past studies. The effects of pre-microwave heating, microwave irradiation and post-microwave holding on organic matter solubilization were studied. Pre-microwave heating did not improve the overall orthophosphate solubilization, but helped in organic matter solubilization. Nutrients and organic matter were found to have increased during the post-microwave holding period, indicating overall sludge solubilization can be more effective when maintained at a high temperature after treatment with the MW/H2O2-AOP. It was beneficial to operate a continuous mode of the MW/H2O2-AOP at a longer retention time for organic matter solubilization, and at a shorter retention time for orthophosphate solubilization. Sludge settleability was greatly improved with the microwave treatment, with or without the addition of H2O2. The pre-heating of sludge before treatment with the microwave process by the means of heat exchange can be beneficial for the overall organic matter solubilization in the MW/H2O2-AOP.

Swine wastewater is not easy to dispose of in usual biological wastewater treatment plants. One reason is that some antibiotics are not easily degradable in the normal treatment system and suppress or inhibit microorganisms in the treatment system. Specifically tetracycline, sulfathiazole, and ampicillin have been widely used as antibiotics in pig feed. For treating disposal and spillage of these antibiotics biologically, a special enzyme based method is needed. Detoxifying enzymes caused the antibiotics to be bio-converted in this experiment and degraded them in this biological experiment. The glutathione S-transferases (GSTs) catalyzed the conjugation of glutathione (GSH) to a number of hydrophobic electrophilic substrates. In this study, we hypothesized that the microorganisms with GSTs degraded the representative manure antibiotics. The initial concentrations of tetracycline, sulfathiazole, and ampicillin were 100 mg/L, 100 mg/L, and 50 mg/L, respectively. These concentrations of antibiotics in pig feed are typical levels. Evaluation of the biodegradation feasibility of antibiotics was carried out by three bacteria possessing glutathione S-transferases under the strong concentration of antibiotics (standards for livestock pharmaceuticals in pig feed).

The aim of this study was to determine the impact of microwave radiation on the efficiency of nitrification and on the percentage of ammonia-oxidizing bacteria in biofilm and to study the possibility of the occurrence of nonthermal effects caused by the interaction of microwaves and biofilm. Eight trickling filters with a biofilm were used in the experiment: four were exposed to microwave radiation, and four were heated with warm air as a control group. Microwave radiation at a frequency of 2.45 GHz was applied at an intensity of 18 W (0.01 W·cm–3of the reactor packing), which increased the biofilm temperature by 6 °C compared with the ambient temperature. The hydraulic loading averaged 0.30 m3·m–2·h–1, and the organic loading equalled 1.93 g chemical oxygen demand (COD)·m–2·d–1. Microwave radiation had an effect on the concentration of nitrogen compounds in the biofilm, and microwave heating triggered alterations within the biofilm that increased the efficiency of both nitrification and denitrification and the percentage of ammonia-oxidizing bacteria.

A horizontal subsurface flow constructed wetland (HSSFCW) was employed to remove tannins from the effluent of a tannins extracting company. Two HSSFCW cells with hydraulic retention time (HRT) of 9 d and packed with limestone were used. One cell without macrophytes was used as a control, while the second cell was planted with Phragmites mauritianus . Results indicated that HSSFCW was capable of treating tannin wastewater that has been seeded with primary facultative pond sludge. Tannins and chemical oxygen demand (COD) removal efficiency of 95.9% and 90.6% with outlet concentration of 27 mg/L and 86 mg/L, respectively, were obtained in the planted cell; while the tannins and COD removal efficiency of 91.1% and 89.5% with outlet concentration of 57 mg/L and 96 mg/L, respectively, were obtained in the control cell.

The spatio-temporal variation in ammonium-nitrogen (NH4-N) profiles was investigated in the North Basin of Lake Biwa in 2002, 2004, and 2005 and in the Uso River in 2004–2005. The in-lake concentration of NH4-N was low throughout the water column, except between late April and mid-June, when a distinct maximum developed between 10 and 25 m depth, in and below the thermocline. This layer extended offshore from both east and west boundaries to the center of the lake. By comparing water temperature estimates from the Uso River with water temperatures measured in the lake, we hypothesize that cooler water intrudes into the lake during the night at depths between 8 and 28 m. The intrusions are likely more pronounced from mid to late May when the NH4-N concentration in the Uso River is highest. This suggests that riverine input is an important factor in the formation of the mid-depth ammonium maximum in Lake Biwa. These findings underscore the importance of fluvial discharge and lateral transport of dissolved nutrients in temperate lakes.

A coupled advanced regional prediction system – community multi-scale air quality (ARPS–CMAQ) modeling system was applied to develop an abatement strategy for air pollutant emission in the Handan region of the northern China. The system was evaluated by comparing the simulated concentrations of particulate matter less than 10 µm (PM10) with the observed results in the study area during the four representative months in 2005. A process of planning emission abatement was applied by gradually reducing PM10 emissions from the original GIS-based emission inventory until a modeling emission scenario was obtained under which the simulated PM10 concentrations could satisfy the desired air quality objective. The air quality objective was represented by an air quality guideline satisfaction ratio of 80% to reach a daily PM10 concentration of 150 µg/m3 after the year 2010. The modeling system and results could provide sound basis for decision makers to develop an effective air quality management strategy.

Growing evidence suggests that inhalation exposure to diesel exhaust, including diesel particulate matter (DPM), causes acute and chronic health effects. As a result, interest in monitoring diesel exhaust has increased. Maps of emissions sources, emissions activity data, and meteorology were combined within a geographic information system (GIS) suitability model to produce a composite map identifying areas where DPM emissions are likely to be high. The results of the GIS model were compared with (i) the locations of existing monitoring sites in Phoenix, Arizona, and (ii) the spatial distribution of population. The results indicate that two existing sites are located in areas where DPM emissions are predicted to be high; however, incorporating meteorology as a factor showed that one site is located upwind of a predicted high DPM area. Consideration of population density showed high density in two areas that appear to be moderately influenced by DPM.

The purpose of this study was to evaluate different effluent treatment options for Atlantic Canadian seafood processing plants. Bench-scale testing with a 25-mesh screen, sedimentation (SED), and dissolved air flotation (DAF) was conducted. Treatment by SED and DAF was successful in reducing contaminant concentrations with maximum observed percent reductions: biochemical oxygen demand, BOD5 (90%); chemical oxygen demand, COD (60%); turbidity (99%); total suspended solids, TSS (95%); and ammonia nitrogen, NH3-N (50%). Bench-scale 25-mesh screen runs for select effluent types showed poor reduction efficiencies and appeared to provide inadequate removal of contaminants. Sedimentation and DAF using alum were effective at removing solids but less effective at removing soluble effluent components. Improved performance may be possible with further treatment technology optimization on an effluent specific basis.

A semi-industrial bioscrubber was developed to treat a complex mixture of volatile organic compounds (VOCs), including oxygenated, aromatic, and chlorinated compounds. Packed and atomizing columns were used for the bioscrubber. For an applied inlet load of around 850–870 g VOCs·m–3 packing material·h–1, the various performances of the bioscrubber were equivalent (around 50%), regardless of the selected absorption column. Only the removal efficiency of oxygenated compounds was found to be reasonable, close to 80%–85%. For the bioscrubber equipped with an atomizing column, a doubling of the inlet load involved a decrease in the removal efficiency of the VOC mixture (35%) and oxygenated compounds (from 80% to 55%). As the transferred compounds were biodegraded, the limits could be explained by the hydrodynamic characteristics of the atomizing column. Furthermore, these results demonstrate the necessity of optimizing the gas–liquid mass transfer step. Two-phase partitioning bioreactors seem to represent an attractive option, even though knowledge of the transfer of compounds and biodegradation mechanisms is required prior to scale-up and industrial use.

Air quality in workplaces is a main concern for industrial hygienists and occupational health specialists. Aerosolization of microorganisms or their by-products from contaminated material can significantly decrease the air quality and expose the workers’ health to potentially harmful effects. To identify the risks and elaborate safe exposure thresholds, the microbiology of air samples from industrial workplaces must be characterized, which means the airborne microorganisms must be identified and quantified. This review summarizes, for nonbiologist specialists, the principal sampling and analysis techniques for air sample characterization regarding microbiological contamination. A survey of the literature regarding levels of airborne bacteria, fungi, and viruses in agricultural industries, waste management plants, peat and wood processing facilities, and other industries is also provided. This review shows that very complex bioaerosol sources are present in industrial settings, and variable and hardly predictable biodiversity is expected in such environments.

An upflow lab-scale biofilter was operated with an inorganic filter material to control methane emissions. The influence of the inlet load on methane removal was investigated and the maximum elimination capacity obtained was 36 g/(m3·h) for an inlet load of 95 g/(m3·h). The influence of the nitrogen concentration, which was provided in the form of nitrate through a nutrient solution, was also determined. We established that the optimum nitrogen concentration required for biofilter operation decreases with the methane inlet load. In fact, it was around 0.75 g/L for inlet loads comprised between 55 and 95 g/(m3·h) and of 0.50 g/L when the inlet load was comprised between 20 and 55 g/(m3·h). During this study, a nitrogen concentration of 1.00 g/L inhibited methane removal in the biofilter. In addition, the use of a nitrogen concentration superior to its optimum level can cause, in the long-term run, severe damages to the biofilter performance.

A dechlorinated drinking water distribution system simulator containing 15-year old unlined iron pipe was contaminated with Bacillus globigii spores. Bulk phase spore density decreased by 1.5–2.0 log105 min after injection and declined by 1.8–3.4 log10after 4 d. Spores were detected on the iron pipe interior at 2 and 22 CFU/cm2after it was decontaminated and disassembled. These results support previous bench-scale studies that show that spores can persist on corroded surfaces in a drinking water environment.

On the basis of previous work by the late Professor M. Selim Yalin and the author, the process of self-formation of alluvial streams and the final (equilibrium or regime) geometry of the self-formed stream are considered in the light of thermodynamic principles, including the first and second laws, and the Gibb’s equation; the stream is treated as an isolated and irreversible system. The present analysis suggests that stream self-formation is guided by the need of the stream to progressively decrease its average flow velocity to accommodate the increase in the entropy of the system with the passage of time. The reduction in flow velocity is achieved by an appropriate alteration of stream slope, cross-sectional geometry, and effective roughness, the regime development being the process of this appropriate alteration. A method is presented for the computation of regime width, depth, and slope. The method rests on the channel formation criterion derived from thermodynamic principles and the expression of regime flow width determined on the basis of zero net cross sediment transport rate at the regime state. The regime channels computed from this method are compared with field and laboratory data from various sources.

A two-dimensional model was developed in this study. The model predicts the performance of a full-scale aerated grit chamber for grit removal from wastewater. The model numerically integrates Poisson’s equation, which describes the motion of the liquid induced by the rising air bubbles. The model makes use of finite element algorithms available in Mathcad to solve Poisson’s equation. The model was developed for predicting the velocity field in the chamber. The model was used to perform a sensitivity analysis of the design variables that affect the performance of an existing grit chamber at the Moose Jaw Wastewater Treatment Plant. The results of the sensitivity analysis indicate that predictions of velocity field are highly sensitive to energy transfer efficiency, air flowrate, and particle settling velocity but less sensitive to variations of wastewater flowrate, diffuser depth, and grid spacing.

Conventional gas chromatography (GC) analysis of hydrocarbons displaying one broad peak provides limited information. Two GC analytical protocols using two-peak and three-peak approaches were developed to investigate transformer oil components and their degradation in soil by hydrogen peroxide. The two-peak method revealed transformer oil to be composed of 27 wt.% F2 fraction and 73 wt.% F3 fraction hydrocarbons. The three-peak method segregated the transformer oil into 40 wt.% light, 40 wt.% medium, and 20 wt.% heavy hydrocarbon fractions. In contrast to reports of success with several classes of lighter hydrocarbons, only limited degradations of transformer oil in soils by 15% and 30% hydrogen peroxide treatment was indicated by conventional one-peak analysis; two-peak analysis showed varying F2 and F3 fraction degradations with F2 fraction degradation being higher; three-peak analysis offered a richer understanding of the relative degradations of light, medium, and heavy fractions. The effect of a low pH environment on the degradation of transformer oil by hydrogen peroxide was evaluated using the three-peak method. It emerged that the degradation of the medium and heavier fractions of transformer oil was higher at pH 2.0.

The present study was conducted to determine the effect of analgesics (aspirin and salicylic acid) on heterotrophic organisms and ammonia-oxidizing bacteria (AOB) resistance to antibiotics (amoxicillin, ciprofloxacin, and nalidixic acid) using the spread plate method. The bacteria were cultured from a biological graywater reclamation system. The results indicate an increase in ciprofloxacin resistance of AOB at concentrations of 0.5 and 1 mmol/L salicylic acid and aspirin. An increase in resistance of heterotrophic organisms and AOB in the presence of salicylic acid and aspirin was observed at 0.064 and 0.107 mmol/L of nalidixic acid. However, the effect of salicylic acid and aspirin on amoxicillin resistance of heterotrophic organisms and AOB was minimal. This study is important because it focuses on the antibiotic resistance of the less studied environmental microbes by considering the impact of compounds other than antibiotics to induce antibiotic resistance.

Accurate analysis of reinforced concrete (RC) structures under blast loading is very complicated due to the nonlinear behaviour of concrete and reinforcement and the various failure modes to be considered. Although blast loads can excite a large number of modes due to their high frequency content, practical computational tools are usually limited to single-degree-of-freedom (SDOF) models. In addition to oversimplification, SDOF models are known to give inaccurate prediction for shear forces and support reactions. This is because accurate shear force prediction typically requires accounting for modes higher than the fundamental mode. In this study, a multi-degree-of-freedom (MDOF) model is developed that takes into account the nonlinear behaviour of RC structures and the material strength and deformation dependency on the strain rate. Using this model, a series of dynamic analyses were carried out for two typical structural members, with different combination of blast pressure and impulse. The effect of varying the number of degrees of freedom (DOF) was investigated through increasing the number of nodes used to descretize each structural member. The results of the developed MDOF model were compared to the results of available SDOF models which demonstrated the deficiencies of the latter. The developed MDOF model, with few DOF, was found to be capable of accurately predicting the dynamic shear of the modeled structural members. The model was also compared to available experimental results and showed good agreement. Changing the number of DOF also affected the pressure–impulse (P–I) diagrams for the structural member significantly, especially in the impulsive regime.

The blast response and ultimate resistance of reinforced concrete slabs externally strengthened with carbon fibre reinforced polymer (CFRP) laminates were investigated. Five square slab specimens, 1 m on a side, were retrofitted with 500 mm wide CFRP laminates bonded to their top and bottom surfaces. Another four nominally identical unretrofitted slabs were used as control specimens. Four of the retrofitted and the four control slabs were first subjected to the detonation of either 22.4 or 33.4 kg of explosive at a stand-off distance of 3.0 m. For reference, the fifth retrofitted slab was only statically tested to failure. Blast pressures and impulses and slab deformations were measured. After exposure to the blast, the slabs that were not completely damaged were statically tested to failure. Overall the retrofitted slabs performed better than the control slabs, but one retrofitted slab completely failed under the blast load while none of the control slabs experienced complete failure under similar load.

Recent bomb attacks on buildings have raised awareness about the vulnerability of structures to blast effects. The resiliency of structures against blast-induced impulsive loads is affected by structural characteristics that are also important for seismic resistance. Deformability and continuity of structural elements, strength, stiffness, and stability of the structural framing system and resistance to progressive collapse are factors that play important roles on the survivability of buildings under both blast and seismic loads. The significance of these structural parameters on blast resistance of reinforced concrete buildings is assessed through structural analysis. Both local element performance and global structural response are considered while also assessing the progressive collapse potential. The buildings under investigation include 10-storey moment resisting frames with or without shear walls. The blast loads selected consist of different charge-weight and standoff distance combinations. The results are presented in terms of ductility and drift demands. They indicate improved performance of seismic-resistant buildings when subjected to blast loads, in terms of local column performance, overall structural response, and progressive collapse potential.

In-line addition of alum and ferric chloride was conducted at a hollow-fibre immersed ultrafiltration (UF) membrane pilot plant, using secondary effluent from a municipal wastewater treatment plant (WWTP) as the feed. The objective of such pretreatment was to remove phosphorus from the feed from an initial concentration of approximately 5 mg/L to below 0.3 mg/L. The simplified in-line coagulant addition process involved hydraulic mixing of the coagulant into the feed and subsequent flocculation, and a greatly reduced (12–14 min) flocculation time relative to conventional coagulation-flocculation-settling treatment. Both alum and ferric chloride effectively removed phosphorus to below the 0.3 mg/L threshold when applied as a pretreatment at optimized doses, both of which were below the WWTP’s current coagulant dose (as ferrous chloride). This simplified pre-treatment scheme provided consistent enhanced removal of phosphorus and organic compounds. These results suggest that simplified in-line coagulant addition in advance of immersed UF membranes enhances the ability to produce treated effluent suitable for water-reuse applications.

Photocatalytic decolourization of textile dye X3B in aqueous solutions was investigated, using iron-rich montmorillonite (MMt, 2.24%Fe2O3) under a 15 W low-pressure UV lamp (λ = 254 nm, I = 48.4 μW/cm2). Hydroxyl radicals (•OH) were detected by tert-butyl alcohol (TBA) in aqueous MMt suspensions under UV irradiation and were found to be responsible for the degradation of X3B. Free iron ions dissolved in MMt suspensions, structural iron in the MMt solid, and the charged surface of nano clay are responsible for hydroxyl radical (•OH) production. Low pH values are favorable for the decolourization of X3B. The •OH concentration increased with increasing aqueous MMt concentrations in the range of 0 – 2.0 g/L; higher concentrations, for example, 5.0 g/L MMt, inhibited the •OH production. The addition of oxalate was favorable for X3B photodegradation in acid-washed MMt suspensions. This study shows that iron-rich MMt is a potential photocatalyst for the treatment of dye wastewater.

A field trial involving 50 separate releases of inert aerosol (kaolin) was conducted to determine the concentration distribution within aerosol puffs resulting from near-instantaneous releases. Atmospheric conditions during the trial fell within Pasquill stability classes A and B (very and moderately unstable, respectively). Aerosol concentration measurements were made using a scanning lidar system operating at 1.06 μm. Artificial neural network (ANN) models were developed using the data to predict concentration distributions, given a number of meteorological parameters. The ANN predictions were compared to those from traditional Gaussian puff models, and provided better predictions than the Gaussian model parameterizations examined. The ANN models were also used to develop Gaussian fitting parameters to replace traditional Pasquill and Slade dispersion coefficients. The ANN-derived dispersion coefficients provided better predictions of measured puff concentration distributions than either the Pasquill or Slade parameterizations, though the full multi-input ANN models provided even better predictions than the Gaussian puff model using ANN-derived dispersion coefficients.

Rural wastewater containing low chemical oxygen demand (COD), but relatively high concentration of total nitrogen comprised of dominant ammonia-nitrogen, was treated in two vertical flow wetland systems whose effluent were discharged intermittently. A substantial loss of total nitrogen (30.3%) was found in a modified wetland system, which introduced an air pipe to enhance oxygen transfer, whereas only a minor loss (17.9%) in the conventional wetland. The correlation between pH, nitrite and nitrate concentrations, ammonia-nitrogen and nitrate-nitrogen distribution along with the depth in the wetlands indicated that the removal of total nitrogen did not follow the classic nitrification and denitrification pathway in the modified wetland system. Through mass balance calculation and theoretical analysis, it was found that simultaneous nitrification and denitrification (SND) was responsible for the transformation of soluble nitrogen into gaseous nitrogen in the modified wetland, thereby causing the loss of total nitrogen. The results showed that SND can be stimulated in aerobic wetland systems and its occurrence may depend on the biofilm thickness, the hydraulic detention time, and the type and population of microorganisms present in the wetland systems.

The goal of this research was to remove arsenic from groundwater supplies via adsorption into media obtained from waste material generated as by-products from glass recycling programs and the seafood industry such as crushed glass and scallop shells. During the course of this research four new adsorbents were developed: ferric hydroxide coated crushed glass (FHCCG); ferric oxide coated crushed glass (FOCCG); ferric hydroxide coated scallop shells (FHCSS); and ferric oxide coated scallop shells (FOCSS). The adsorbents were characterized through evaluation of their structure, surface area, chemical composition, iron content, and coating stability. Efficiency of the adsorbents to remove arsenic from water was examined through batch kinetic and isotherm adsorption experiments. The adsorption capacity of the adsorbents was also evaluated by performing column experiments using real ground waters and a synthetic water. Arsenic removal to a concentration less than 10 μg/L was achieved with the FHCSS and more than 9000 bed volumes of water were treated before the breakthrough point was reached. The research results revealed that scallop shells coated with ferric hydroxideperformed better than crushed glass coated with ferric hydroxide. Both FOCCG and FOCSS had poor arsenic removal compared with FHCSS and granular ferric hydroxide (GFH). Ferric hydroxide coated scallop shells performed similarly to GFH.

This bench-scale study investigated whether strains of Escherichia coli that are resistant to two common types of antibiotics, ampicillin and trimethoprim, possess increased resistance to two common disinfectants in water and wastewater treatment, free chlorine and ultraviolet disinfection, relative to an antibiotic-sensitive strain of E. coli isolated from sewage sludge. Trimethoprim-resistant E. coli was slightly more resistant to chlorine than the antibiotic-sensitive isolate and the ampicillin-resistant E. coli under the study conditions (95% confidence), however this difference would not be important under normal chlorination conditions applied in practice. There were no statistically significant differences between the ultraviolet dose-response profiles of the antibiotic-resistant and antibiotic-sensitive E. coli strains over the ultraviolet dose range tested.

Bench scale experimentation was completed to assess the potential of using a short residence time pretreatment reactor upstream of aerobic digestion to enhance the destruction of pathogens. The impact of aeration, temperature, hydraulic residence time (HRT), solids concentration, and feeding frequency on the pretreatment process was investigated. Subsequent testing evaluated pathogen destruction resulting from the operation of selected pretreatment conditions in a staged configuration with conventional aerobic digesters. Either highly oxidative or highly reductive conditions were observed to be most effective in reducing the concentrations of E. coli. and Salmonella spp. in the pretreatment reactor. When operated in series with the aerobic digesters, the more highly reducing conditions in pretreatment were found to enhance die-off of the microorganisms in subsequent aerobic digestion compared to the control.

The removal effect on nitrate and phosphate of a sulphur-based autotrophic denitrifying bioreactor in composite packing of sulphur with coral stone were investigated on a pilot scale. The results showed that the optimal influent loading rate of the bioreactor (the ratio of sulphur volume to coral stone volume was 1:1) was in the range of 0.080–0.244 kg NO3–-N/(m3·d) when the water temperature was 29 ± 1 °C. In this range, the removal efficiency of nitrates was higher than 95% and no nitrite accumulation occurred in the effluent. The maximum nitrate volumetric removal rate of 0.594 kg NO3–-N / (m3·d) was achieved at an influent loading rate of 0.716 kg NO3–-N/(m3·d) with obvious nitrite accumulation in the effluent. Along with the autotrophic denitrifying reaction, an influent loading rate between 0.070–0.210 kg PO43–-P/ (m3·d) achieved the removal efficiency and volumetric removal rate of phosphates were 50.5%–89.2% and 0.045–0.179 kg PO43–-P/(m3·d), respectively. The phosphates related to the resistance ability of the bioreactor (the ratio of sulphur volume to coral stone volume was 1:1) was stronger than that of bioreactors (the ratio of sulphur volume to coral stone volume was 1:2 and 1:4).

In this study, the impact of black liquor shocks on multiple stage biological treatment plant was studied. The tests were carried out in a lab scale plant and using a mathematical simulation model. The results showed good relation to a parallel situation at the Gruvön Mill. The MultiBio concept is persistent to short-term black liquor spills due to the design where the black liquor is diluted between every compartment. According to the lab scale trials, short-term shocks (5 and 10 h) of black liquor addition reduce bio activity in the first part of the MultiBio plant. Oxygen uptake rate and chemical oxygen demand (COD) degradation decreased during high concentrations of black liquor and increased when the black liquor concentration declined. Protozoas disappeared from compartments exposed to high concentrations of black liquor. A long-term trial encompassing 24 h of black liquor addition inhibited the COD reduction in the whole plant for several weeks.

Inspired by an analogy to AM radio signals, amplitude modulation (AM) is proposed here as a useful view of nonstationary environmental periodicities, and applied to hydrologic and air quality datasets. Both example time series considered exhibit seasonally evolving diel cycles, with large (small) daily cycle amplitudes in summer (winter). The carrier wave is taken to be a sinusoidal daily cycle; this is multiplied by an information signal consisting of a sinusoidal annual cycle, forming an envelope to the diel variations. Our results suggest that amplitude modulation may offer a novel, compact, and accessible perspective, both qualitatively and quantitatively, on the net phenomenological behaviour arising from highly complex, nonlinear, and diverse environmental process dynamics. Physical interpretations, synergies with common environmental time series processing or analysis methods (Kolmogorov-Zurbenko filtering, classical spectral analysis, and singular systems analysis), and potential future research directions are also explored.

The electrochemical oxidation of aqueous wastes polluted with 4-nitrocathecol has been studied on boron-doped diamond electrodes in an acidic medium. The voltammetric results showed that 4-nitrocathecol is oxidized in the potential region where the supporting electrolyte is stable. Galvanostatic electrolysis study showed that the oxidation of these wastes in a single-compartment electrochemical flow cell with boron-doped diamond anodes results in the complete mineralization of the organics. Cathecol, benzoquinone, 4-aminocathecol, maleic and oxalic acids have been detected as soluble organics, polymeric product as solid product at the cathode surface and NO3– as mineral product during the electrolysis of 4-nitrocathecol. The electrochemical oxidation of 4-nitrocathecol consists of a sequence of steps: release of NO2 and (or) hydroxylation of the aromatic ring; formation of quinonic compounds; oxidative opening of aromatic ring to form carboxylic acids; and oxidation of carboxylic acids to carbon dioxide. Both direct and mediated oxidation processes are involved in these stages.

Laboratory experiments are conducted to determine the liquid–liquid phase separation behavior of six three-component systems with each system comprised of a common alcohol (namely ethanol, isopropanol, or methanol), water, and one of two engineered dense nonaqueous phase liquids (DNAPLs) manufactured by the 3M™ Corporation (namely methoxy-nonafluorobutane (HFE-7100) or ethoxy-nonafluorobutane (HFE-7200)). The experimental results are presented on ternary phase diagrams and compared against available published experimental data where tetrachloroethylene (PCE) and (or) trichloroethylene (TCE) is the dense nonaqueous phase liquid (DNAPL). Results show that the two engineered fluids exhibit similar phase separation behavior in the presence of the same alcohol. Furthermore, these engineered fluids exhibit similar phase separation behavior to that of PCE, but relatively dissimilar phase separation behavior to that of TCE.

Utilization of zeolite industrial wastewater as a sorbent and (or) precipitant to remove Cu and Zn from copper-brass pipe industrial wastewater was conducted. These wastewaters were sampled and values for pH, temperature, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), and heavy metals were determined. In addition, the sorption isotherms of Cu and Zn in copper-brass pipe industrial wastewater onto solids of zeolite industrial wastewater at various dilutions of copper-brass pipe industrial wastewater were explored. The relationship between Cu and Zn concentrations and their removal efficiencies under different conditions of wastewater pH, contact times, and ratios between copper-brass pipe industrial wastewater and zeolite industrial wastewater was examined. Zeolite industrial wastewater contained various carbonate compounds that contributed to high pH and TDS values, and low heavy metals contamination whereas copper-brass pipe industrial wastewater had a low pH value and was contaminated with heavy metals, especially Cu and Zn. Application of zeolite industrial wastewater significantly increased the pH of copper-brass pipe industrial wastewater and consequently removed Cu and Zn. The increase in pH of the wastewater mixture significantly enhanced the heavy metals removal. The Langmuir equation described sorption isotherms of Cu and Zn onto solids of zeolite industrial wastewater at neutral pH (6–7) while the Freundlich equation fitted well at pH > 12. The maximum Cu (97%–98%) and Zn (92%–96%) removal efficiencies occurred at the original pH 12.8 of zeolite industrial wastewater, at the ratio of copper-brass pipe industrial wastewater to zeolite industrial wastewater 3:1 (vol.:vol.) and at 30 min contact time.

Synthetic wastewaters simulating physically pre-treated low-loaded winery effluents were treated for four months with five pilot-scale horizontal subsurface flow constructed wetlands (HSSF-CWs) using different plants. Species under study were Phragmites australis (HSSF-CW2), Lythrum salicaria (HSSF-CW3), Cladium mariscus (HSSF-CW4), and Iris pseudacorus (HSSF-CW5). The designation HSSF-CW1 was not planted, and was used as a control. The mean dissolved oxygen and oxidation–reduction potential values in all HSSF-CWs indicated anaerobic conditions in the bulk liquid. High pollutant-removal efficiencies were obtained. Apparently, the species with higher growth (Phragmites, Lythrum, and particularly Iris) improved total nitrogen (TN) and nitrogen as ammonium (N-NH4+) removals, but adversely affected sulphate (SO42–) anaerobic reduction. Chemical oxygen demand (COD) removal efficiencies were high, although there were no clear indications how the kinds of plants might have influenced this parameter. A statistical analysis of variance indicated that only N-NH4+ removal efficiencies were statistically different owing to the influence of the different plants. In a second 6 month experimental period, polyphenols (13 mg L–1) were added to the synthetic wastewater to study possible inhibition effects. The addition of polyphenols did not seem to cause inhibition effects on COD, TN, and N-NH4+ removals, but clearly negatively affected SO42– removal. A new two-way analysis of variance confirmed that only SO42– removal was negatively affected by polyphenols, while the effects of the different plants were only significant for N-NH4+ removal. Polyphenols were nearly completely removed. First order rate constants obtained for COD, TN, SO42–, and polyphenol removals were similar to those reported by other authors.

A fuzzy logic model was developed to simulate the effect of leachate recirculation and sludge addition on the biogas generation in anaerobic bioreactor landfills. The model was designed using a fuzzy logic system (FLS) which incorporated 3 input variables (time, leachate recirculation, and sludge addition) and a single manipulated output (biogas generation rate). The biogas production rate was measured during the experiment and was increasing proportionally with the rate of both leachate recirculation and sludge addition. The experimental work involved the operation of six simulated laboratory-scale bioreactors for over a year under different operating schemes. The experimental results were employed in formulating the fuzzy rule base, calibrating the model, and verifying its predictions. Then, the model was validated against other measured data that was compiled from published studies. The FLS model simulations demonstrated high correlation with the experimental observations.

Small angle neutron scattering (SANS) data are reported from a system that models the contamination of a clay – organic matter soil from a fuel spillage. The soil was represented as an aqueous dispersion of the synthetic clay mineral Laponite coated with lysine, and the contaminant was a representative jet fuel, quadricyclane, mixed with the detergent cetyltrimethylammonium bromide (CTAB). The adsorbed surface coverage on the clay was estimated. It is shown that the presence of adsorbed lysine considerably enhances the subsequent adsorption of both CTAB and quadricyclane. It is demonstrated that the SANS technique can contribute to the general problem of environmental remediation and retention by probing the interactions of pollutants and clay surfaces.

The present study investigates the electrocoagulation treatment of two different wastewaters, namely sawmill wastewater and ship waste effluent, charged with organic matter. Monopolar electrode configuration was studied for both types of effluents at current intensity of 2.0 A for a total treatment time of 90 min. Soluble chemical oxygen demand (CODs) removal was very low (12.5% to 13.6%) for sawmill effluent in comparison to 74.7% to 75.4% obtained for ship effluents. Thus, ship effluent was further examined in details for its treatment efficacy in terms of electrode configuration and type, current intensity, treatment time, and pH. It was observed that bipolar electrode configuration using the Al electrode at 0.3 A gave the highest CODsremoval of 77%. Effluent pH increased rapidly in the initial 20 min with a concomitant decrease in CODsconcentration. Electrocoagulated-flocculated ship effluent improved performance relative to simple flocculation with respective removals of 86% of turbidity, 56% of CODs; 69% of total COD (CODt), 90% of oil and grease, 94% of C10-C50hydrocarbons and 89% of biochemical oxygen demand (BOD5). Residual Al3+concentration in the solution followed a linear trend with treatment time. Meanwhile, the sludge production increased progressively during 60 min of treatment time. Total cost for treatment of ship effluent, including energy, electrodes, and sludge disposal fee is estimated between CAN$1.34 and CAN$2.40m–3.

Study of the chemical dispersion of crude oil using size distribution methods can provide important information needed for oil-spill response strategy, which is lacking in the more commonly used mass–concentration methods. Therefore, identification of a reliable method or methods that can provide accurate information regarding droplet size and the mass of oil dispersed is necessary. This research compared four such methods. Gravimetric analysis of the oil mass dispersed was biased low due to loss of volatile components, whereas UV spectroscopy provided accurate results. Size–distribution data obtained using an optical particle counter (OPC) produced accurate estimates of oil mass dispersed, but microscopic examination produced inaccurate and poorly reproducible estimates. Although size–distribution metrics (e.g., estimates of the mean diameter of the size distribution) produced by the two methods were similar, microscopic examination gave unreliable estimates of the number concentration of dispersed oil droplets due to the relatively small number of observations relative to the OPC.

Dissolution kinetics of struvite are important for optimizing intentional struvite crystallization, as well as for ensuring the efficient use of the crystallized products. Dissolution experiments were carried out for struvite pellets grown in a pilot-scale fluidized bed reactor. To determine the kinetics and mechanism of the dissolution process in a batch reactor system, two different theoretical models were tested. The experimental values were found to fit well with both models. In a mixed flow-through reactor system, the constituents release became stoichiometric when the input solution had an alkaline pH. The dissolution rates for struvite pellets were found to decrease with increasing pH due to proton promoted dissolution. After a transition from around 7.5 to 8, the rate of dissolution increased with the increase in pH, because of the hydroxyl promoted dissolution.

Data from five residential urban arid catchments were used to develop regression equations for predicting mean concentrations of selected heavy metals in the stormwater runoff from duststorm and stormwater flow properties. The selected metals are copper (Cu), lead (Pb), nickel (Ni), zinc (Zn), and iron (Fe). The concentrations of the selected metals were predicted through two groups of equations. The first group of equations relates concentrations of suspended sediment with duststorm and stormwater parameters, whereas the second group relates the concentrations of the suspended sediment with those of heavy metals in the stormwater runoff. The results of the predictions encouraged recommendations on the use of the equations in the investigated catchments and identified the relative importance of the stormwater runoff and duststorms on the accumulation and transportation of heavy metals in the stormwater runoff. Based on the obtained results, recommendations concerning water quality control in arid areas are made.

Tanning wastewater was subjected to different unit operations to select the best treatment sequences. Textile membrane filtration (TMF), microfiltration (MF), and ultrafiltration (UF) were complemented by screening, flocculation or flotation operations. The general chemical characterization determined that the wastewater had a high organic load. The ecotoxicological study classified the wastewater as highly ecotoxic. The sequence of screening–TMF–UF was found to be the optimal treatment for wastewaters of the first and second soaking stages, while the sequence of screening–TMF–flotation–UF proved to be adequate for the liming wastewater concerning productivity and water quality. Larger pore sizes MF membrane or higher molecular weight cut off (MWCO) UF membranes with higher permeability to pure water showed lower permeation fluxes for tanning wastewater. After membrane treatments, a decrease in the ecotoxicity was measured. The use of membrane treatment technology showed to be promising in removing organic pollutants and allowing the reuse of water and chemicals in the process.

Humic substances (HS) can be isolated in preparative quantities from low rank coal, peat, and soil. Traditionally, treatment with solutions of NaOH, KOH, or metal salts (K4P2O7) has been used for their isolation. The aim of this article is to study the effectiveness of different technologies in extracting HS from peat as well as the impact of the different extractive technologies on the properties of the isolated HS. Yields of HS depend very much on the extraction process (extractant, temperature, pretreatment procedures, solvent, mixing intensity); however, the properties of the substances obtained (molecular mass, number of functional groups, spectral characteristics) differ significantly. Yields of HS can be associated with the degree of destruction of the peat fibres and intensive destruction technologies provide opportunities to obtain HS from peat in higher yields than traditional extraction methods. However, during the extraction process, significant degradation of the humic molecules takes place.