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Substantial environmental contamination has occurred from coal tar creosote and pentachlorophenol (C5P) in wood preserving solutions. The present studies focused on the characterization and remediation of these contaminants. The first objective was to delineate a sequence of biological changes caused by chlorinated phenol (CP) exposure. In Clone 9 cells, short-term exposure to 10 ?M C5P decreased pH, GJIC, and GSH, and increased ROS generation. Long-term exposure caused mitochondrial membrane depolarization (25 ?M), increased intracellular Ca2+ (50 ?M), and plasma membrane depolarization (100 ?M). Cells were affected similarly by C5P or 2,3,4,5-C4P, and similarly by 2,3,5-C3P or 3,5-C2P. Endpoints were affected by dose, time, and the number of chlorine substituents on specific congeners. Thus, this information may be used to identify and quantify unknown CPs in a mixture to be remediated. Due to the toxic effects observed due to CP exposure in vitro, the objective of the second study was to develop multi-functional sorbents to remediate CPs and other components of wood preserving waste from groundwater. Cetylpyridinium-exchanged low pH montmorillonite clay (CP-LPHM) was bonded to either sand (CP-LPHM/sand) or granular activated carbon (CP-LPHM/GAC). Laboratory studies utilizing aqueous solution derived from wood preserving waste indicated that 3:2 CP-LPHM/GAC and CP-LPHM/sand were the most effective formulations. In situ elution of oil-water separator effluent indicated that both organoclay-containing composites have a high capacity for contaminants identified in wood preserving waste, in particular high molecular weight and carcinogenic PAHs. Further, GAC did not add substantial sorptive capacity to the composite formulation. Following water remediation, the final aim of this work was to explore the safety of the parent clay minerals as potential enterosorbents for contaminants ingested in water and food. Calcium montmorillonite and sodium montmorillonite clays were added to the balanced diet of Sprague-Dawley rats throughout pregnancy. Based on evaluations of toxicity and neutron activation analysis of tissues, no significant differences were observed between animals receiving clay supplements and control animals, with the exception of slightly decreased brain Rb in animals ingesting clay. Overall, the results suggest that neither clay mineral, at relatively high dietary concentrations, influences mineral uptake or utilization in the pregnant rat.

Monitoring for pollutants in potable water is an area of interest and concern for water supply companies. Supply of sub-standard water can draw complaints from public and industrial customers. Water and water tainted with pollutants were used to assess the application of a non-specific chemical sensor array (eNose) to monitor for changes in the headspace generated from a flow-cell by means of statistically designed experiments. 2-chlorophenol and diesel were used to further assess trends in headspace generation during trials where different combinations of sampling parameters were applied. Field trials were conducted in accordance with the most suitable methodology determined during initial studies under laboratory conditions. The headspace is generated by bubbling nitrogen through the flow-cell containing a water sample. The liquid sample is flushed and regenerated after each sensor acquisition cycle. The resultant headspace sample is transferred to the sensor array module where the resistance of the conducting polymer sensors is monitored as they are exposed to each respective headspace sample. The change in each sensor resistance after 60 seconds of exposure is used to represent the headspace character. Subsequent acquisitions are added to a data set and then presented graphically. Sudden changes in the sensor resistance plots represent changes in water quality. The results showed that the developed apparatus and sampling methodology can determine the presence or absence of pollution in a water matrix. Laboratory analysis showed that detection levels for 2-chlorophenol and diesel were both <5 ppm in the mixed stream. Future developments should focus on increasing the sensitivity of the system by concentrating the pollutants in either the liquid or gas phase or by modifying the sampling protocol to enable sensor recognition at lower concentration levels. The sensor array could act as a screening technique to support quantitative and characterising analytical equipment at the abstraction point. Establishing a pollution alarm limit, within the bounds of acceptable system variation, would enable conventional analytical techniques to remain on standby until activated by a statistically significant change in water quality. Once established continued testing would enable alarm levels to be incorporated into a contaminant database for additional pollutant compounds and combinations of known taste and odour causing compounds.

Yes / The total energy consumption of many Reverse Osmosis (RO) plants has continuously improved as a result of manufacturing highly impermeable membranes in addition to implementing energy recovery devices. The total energy consumption of the RO process contributes significantly to the total cost of water treatment. Therefore any way of keeping the energy consumption to a minimum is highly desirable but continues to be a real challenge in practice. Potential areas to explore for achieving this include the possibility of optimising the module design parameters and/or the associated operating parameters. This research focuses on this precise aim by evaluating the impact of the design characteristics of membrane length, width, and feed channel height on the total energy consumption for two selected pilot-plant RO process configurations for the removal of chlorophenol from wastewater. The proposed two configurations, with and without an energy recovery device (ERD), consist of four cylindrical pressure vessels connected in series and stuffed with spiral wound membranes. A detailed steady-state model developed earlier by the authors is used here to study such impact via repetitive simulation. The results achieved confirm that the overall energy consumption can be reduced by actually increasing the membrane width with a simultaneous reduction of membrane length at constant membrane area and module volume. Energy savings of more than 60% and 54% have been achieved for the two configurations with and without ERD respectively using process optimization. The energy savings are significantly higher compared to other available similar studies from the literature.

Membrane assisted passive sampler (MAPS) is an informative, cost-effective and environmentally friendly approach for monitoring of ionisable organic compounds in water bodies. The sampler uses no organic solvent. By adjusting the pH of the acceptor phase, both acidic chlorophenols and basic triazine model compounds were extracted. The sampler was optimized under laboratory conditions followed by field applications on the same compounds. The optimised parameters were temperature of the water body, turbulence, protective cover, biofouling, matrix effects such as humic substances, degree of trapping in the acceptor phase and exposure time. It was found that the sampling kinetics of most of the tested analytes are dependent on temperature and on the hydrodynamic conditions. Also, a strong dependence of the sampling rates reduction on sample matrix and protective cover used was noted. The chemical uptake of both the acidic chlorophenols and basic triazine compounds into the passive sampler remained linear and integrative through out the exposure periods. The amounts quantified in the MAPS had relative standard deviations mostly between 10 % and 20 % (from repeat determinations) and did in no case exceed 30 %. The behaviour of the MAPS to monitor ionisable triazine compounds in dam water of the Hartebeespoort was compared to Chemcatcher and solid phase extraction technique with C18 sorbents of spot samples. Similarly, the behaviour of the MAPS to monitor ionisable chlorophenol compounds in wastewater of the Goudkoppies Wastewater Treatment Plant was compared to solid phase extraction technique. There were no triazine and chlorophenol compounds detected in any of the deployed passive samplers in the field applications. The same results were obtained in grab samples extracted with solid phase extraction under laboratory conditions. However, data from laboratory studies support the feasibility of MAPS to measure the freely dissolved fraction of ionisable organic chemicals in water. Using water from the Hartebeespoort dam spiked with 50 μg L-1 triazine, the detection limits of triazine compounds ranged from 11.38 to 61.86 μg L-1 for direct injection, 1.082 to 23.077 μg L-1 for MAPS, 0.892 to 5.769 μg L-1 for Chemcatcher and 1.482 to 7.410 μg L-1 for SPE. While using water from Goudkoppies Wastewater Treatment Plant spiked with 100 μg L-1 chlorophenols, the detection limits of the passive sampler were comparable with that of solid phase extraction and were around 1.5 μg L-1. Estimation and interpretation of enrichment factors in the passive samplers and SPE were generally comparable ranging from 46 to 295 for chlorophenol compounds. Also, for triazine compounds, the obtained enrichment factors in the passive samplers and SPE are generally comparable with the exception of enrichment factors of propazine, ametryn terbuthylazine, prometryn and terbutryn compounds which were higher for the MAPS ranging from 46 to 65.

2,4,6-trichlorophenol (TCP) is a pervasive carcinogenic water contaminant found in a wide variety of water and waste systems and is a pertinent model compound of broader aromatic organics, specifically organo-halide pesticides. These compounds are persistent in the environment and show resilience to regular water and waste treatment protocols thus warranting the development and implementation of novel treatment materials for improved contaminant removal. Zero-valent iron (ZVI) has demonstrated the ability to remove or degrade a wide variety of inorganic and organic water contaminants, including chlorophenols, and has been widely applied for in-situ groundwater remediation where contamination is often localised in a low-oxygen environment. ZVI's broader applications in water treatment have remained mainly limited due to corrosion, particle dispersion, and confinement issues in deployment. This work, therefore, explored the development, functionality, and potential application of new modified nZVI materials (nZVI-Osorb) and assessed their potential to improve iron's intrinsic functionality while also gauging the material's viability for TCP remediation in water and waste systems. Materials produced in this thesis were prepared utilising three different embedment procedures (1-pot, multiple additions, oxygen-free). All embedment methods resulted in tightly bound composites featuring high surface areas (340.2-449.1 sq. m/g) with net iron composition ranging from 10% to 29.78% by mass. Electron imaging microscopy verified even dispersion of iron throughout the substrate. Composite materials did not exhibit a delayed rate of atmospheric corrosion over nZVI controls evincing an 18% nZVI0 loss per day until reaching a stabilised concentration (7%) after 48 hrs. nZVI-Osorb composites did produce more favourable iron oxide species which remain conducive to electron transfer from core Fe0 atom. After 50 days, a majority of nZVI in nZVI-Osorb had oxidised to maghemite (30%) and magnetite (26%) compared to control nZVI producing 19% and 12% respectively. Unreactive hematite accounted for 47% of the control and just 36% of the composite. While 1-pot embedment allowed the most substantial control over final iron composition, the oxygen-free method allowed the most reliable preservation of initial nZVI0 concentrations through restricted oxidation. Materials generated through oxygen-free embedment were utilised in the following water treatment trials with TCP. Parameters related to sorption and degradation mechanisms of TCP by nZVI-Osorb were tested in aerobic conditions, e.g. surface and potable water. nZVI-Osorb materials demonstrated high extraction capacity for TCP from aqueous solutions (Qe=1286.4 ± 13.5 mg TCP/g Osorb, Qe=1253 ± 106.7 mg TCP/g nZVI-Osorb, pH 5.1, 120mg/L TCP) and followed pseudo second order kinetics. In the broader class of chlorophenols, sorptive affinity mirrored partitioning values with highly substituted chlorophenols displaying the highest sorption capacities. Degradation of TCP by nZVI-Osorb or nZVI controls was not observed due to corrosive hindrance and inadequate reductive capacity, suggesting that materials may not be suitable for highly aerated surface and potable water treatment systems. Environmental conditions pertinent to sorption and degradation mechanisms were evaluated to improve understanding and robustness of functionality in low-oxygen applications, such as wastewater and anaerobic digesters, where nZVI-Osorb treatment is anticipated to be advantageous to TCP sorption and methane production. pH was found to influence sorption dramatically. Acidic solutions below 5 found sorption > 90%. This capacity was reduced to < 30% when pH was raised above TCP pKa value (6.23) to 7 and above. Further trials found a positive effect on TCP sorption (+7.55%) linked to net pH reduction (5.1 to 3.3) with the addition of secondary acids (volatile fatty acids: acetic, propionic, butyric, 3x 100mg/L) commonly found in anaerobic digester systems. Salinity did not affect TCP sorption. The removal of dissolved and atmospheric oxygen increased total sorption (40ppm-+1.94%, 100ppm- +7.93%, 200ppm- +0.89%, 400mg/L- +14.59%) through reduced iron corrosion and the production of favorable iron oxides, but did not facilitate contaminant degradation. Biodegradation mechanisms for TCP have broadly been established, and new research has supported the improved cometabolic degradation of recalcitrant contaminants like TCP and PCP in nZVI-dosed anaerobic digesters. Model anaerobic digester systems (3.9 g/L nZVI-Osorb, 25mg/L TCP, 240 mg/L acetic, 120mg/L propionic, 120mg/L butyric acid) containing bioreactor sludge (62.5%) were observed through standard water quality diagnostics (pH, ORP, COD, head pressure) for 14 days and suggested that nZVI-Osorb did not inhibit cellular processes. Increased electron activity from iron corrosion and hydrogen gas production, increased overall pH and decreased total ORP in these AD systems. TCP degradation by-products (DCP, CP) were detected in dilute concentrations (< 0.01 mg/L) with poor recovery by LC-MS/MS. Results suggest that nZVIOsorb may be well-suited additive for AD systems. This study contributes to knowledge of the properties, functionality, and treatment mechanisms of metal-sorbent composites with a model chlorinated aromatic water contaminant in aerobic and anaerobic environments. The work identifies favourable environmental and process conditions to apply these materials in larger scale applications, particularly, anaerobic digestion and provides support for the continued refinement and improvement of nZVI based remediation systems.

No description available.

Yes / The successful use of Reverse Osmosis (RO) process has increased significantly in water desalination, water treatment and food processing applications. In this work, the economic feasibility of a multi-stage RO process including both retentate and permeate reprocessing for the removal of chlorophenol from wastewater is explored using simulation and optimisation studies. Firstly, a mathematical model of the process is developed based on the solution diffusion model, which was validated using experimental chlorophenol removal from the literature, is combined with several appropriate cost functions to form a full model package. Secondly, for a better understanding of the interactions between the different parameters on the economic performance of the process, a detailed process simulation is carried out. Finally, a multi-objective optimisation framework based on Non-Linear Programming (NLP) problem is developed for minimising the product unit cost, the total annualised cost, the specific energy consumption together with optimising the feed pressure and feed flow rate for an acceptable level of chlorophenol rejection and total water recovery rate. The results clearly show that the removal of chlorophenol can reach 98.8% at a cost of approximately 0.21 $/m³.

Yes / Reverse Osmosis (RO) can be considered as one of the most widely used technologies used to abate the existence of highly toxic compounds from wastewater. In this paper, a multilayer artificial neural network (MLANN) with Genetic Algorithm (GA) have been considered to build a comprehensive mathematical model, which can be used to predict the performance of an individual RO process in term of chlorophenol removal from wastewater. The MLANN model has been validated against 70 observational experimental datasets collected from the open literature. The MLANN model predictions have outperformed the predictions of several structures developed for the same chlorophenol removal using RO process based on performance in terms of coefficient of correlation, coefficient determination (R2) and average error (AVE). In this respect, two structures (4-2-2-1) and (4-8-8-1) were also used to study the effect of a number of neurons in the hidden layers based on the difference between the measured and ANN predicted values. The model responses clearly confirm the successfulness of estimating the chlorophenol rejection for network structure 4-8-8-1 based on a wide range of the control variables. This also represents a high consistency between the ANN model predictions and the experimental data.

Yes / Reverse Osmosis (RO) is one of the most widely used technologies for wastewater treatment for the removal of toxic impurities, such as phenol and phenolic compounds from industrial effluents. In this research, performance of multi-stage RO wastewater treatment system is evaluated for the removal of chlorophenol from wastewater using model-based techniques. A number of alternative configurations with recycling of permeate, retentate, and permeate-retentate streams are considered. The performance is measured in terms of total recovery rate, permeate product concentration, overall chlorophenol rejection and energy consumption and the effect of a number of operating parameters on the overall performance of the alternative configurations are evaluated. The results clearly show that the permeate recycling scheme at fixed plant feed flow rate can remarkably improve the final chlorophenol concentration of the product despite a reduction in the total recovery rate.