The use of seawater in cooling towers for industrial applications has much merit in the Gulf Cooperation Council countries due to the scarcity and availability of fresh water. Seawater make-up in cooling towers is deemed the most feasible because of its unlimited supply in coastal areas. Such latent-heat removal with seawater in cooling towers is several folds more efficient than sensible heat extraction via heat exchangers. Operational challenges such as scaling, corrosion, and biofouling are a major challenge in conventional cooling towers, where the latter is also a major issue in seawater cooling towers. Biofouling can significantly hamper the efficiency of cooling towers. The most popular methods used in cooling treatment to control biofouling are disinfection by chlorination. However, the disadvantages of chlorination are formation of harmful disinfection byproducts in the presence of high organic loading and safety concerns in the storage of chlorine gas. In this study, the research focuses on biofouling control in seawater cooling towers by investigating two different approaches. The first strategy addresses the use of alternative oxidants (i.e. ozone micro-bubbles and chlorine dioxide) in treatment of cooling towers. The second strategy investigates removing nutrients in seawater using granular activated carbon filter column and ultrafiltration to prevent the growth of microorganisms. Laboratory bench-scale tests in terms of temperature, cycle of concentration, dosage, etc. indicated that, at lower oxidant dosages (total residual oxidant (TRO) equivalent = 0.1 mg/l Cl2), chlorine dioxide had a better disinfection effect than chlorine and ozone. The performance of oxidizing biocides at pilot scale, operating at assorted conditions, showed that for the disinfectants tested, ozone could remove 95 % bioactivity of total number of bacteria and algae followed by chlorine dioxide at 85%, while conventional chlorine dosing only gave 60% reduction in bioactivities. Test results of GAC bio-filter showed that around 70 % removal of total organic carbon in the seawater feed was achieved and was effective in keeping the microbial growth to a minimum. The measured results from this study enable designers of seawater cooling towers to manage the biofouling problems when such cooling towers are extrapolated to a pilot scale.

In situ chemical oxidation using permanganate is an increasingly employed approach to organic contaminant remediation at hazardous waste sites. Manganese dioxide (MnO2) particles form as a by-product of the reaction of permanganate with contaminants and naturally-reduced subsurface materials. These particles are of interest because they have the potential to deposit in the subsurface and impact the flow regime in/around permanganate injection, including the well screen, filter pack, and the surrounding subsurface formation. Control of these particles can allow for improved oxidant injection and transport, and contact between the oxidant and contaminants of concern. Sodium hexametaphosphate (HMP) has previously been identified as a promising aid to stabilize MnO2 in solution when included in the oxidizing solution, increasing the potential to inhibit particle deposition and impact subsurface flow. The goal of the experimental studies described herein was to investigate the ability of HMP to prevent particle deposition in transport studies using four different types of porous media. Permanganate was delivered to a contaminant source zone (trichloroethylene) located within four different media types with variations in sand, clay, organic carbon, and iron oxides (as goethite) content. Deposition of MnO2 within the columns was quantified with distance from the source zone. Experiments were repeated in replicate columns with the inclusion of HMP directly with the oxidant delivery solution, and MnO2 deposition was again quantified. While total MnO2 deposition within the 60 cm columns did not change significantly with the addition of HMP, deposition within the contaminant source zone decreased by 25-85%, depending on the specific media type. The greatest differences in deposition were observed in the goethite-containing and clay-containing columns. Columns containing these two media types experienced completely plugged flow in the oxidant-only delivery systems; however, the addition of HMP prevented this plugging within the columns, increasing the oxidant throughput.

No description available.

Organic carbon and nitrogen content in low-strength wastewaters can be removed by conventional aerobic processes such as Modified Ludzak Ettinger (MLE), but these treatment methods are not appropriate for treating strong wastewaters. Treatment of highly polluted effluents from slaughterhouse, food processing, brewery, dairy, landfill leachates, etc., which are rich in organic matter and nutrients requires specific considerations. The main removal pathways in the aerobic processes are bacterial assimilation and complete nitrification-denitrification for nitrogen content removal which is accompanied by organic carbon removal during this process. Various biological aerobic treatment processes and operations have been tried in the past to effectively treat strong streams, but high energy requirement and sludge production are serious drawbacks. Anaerobic digestion (AD) is the best alternative to the aerobic processes for treatment of strong wastewaters but biological nutrient removal is not possible, and needs further treatment. In high-strength wastewater treatment, neither aerobic nor anaerobic treatment methods alone as a single-process can produce treated effluents complying with discharge standards. Therefore, existing conventional technologies for treatment of highly polluted streams are combined systems. These conventional combined systems are a pair of at least two separate processes in series. Most of the combined systems are applying the AD as a head system which is followed by a polishing aerobic process such as conventional activated sludge. Synchronizing two different processes in a series in combined systems is expensive and complicated with intensive operation and maintenance requirements. Hence, in order to prevail these difficulties, it is paramount to develop an efficient and less expensive single-process technology with simple operation and maintenance. In this thesis, a conventional MLE system as a single-process was modified for treating highly polluted wastewaters, with a performance similar to the combined systems. This modified system is referred to throughout the thesis as SAO/PND (Simultaneous Anaerobic Oxidation/Partial Nitrification–Denitrification). After several unsuccessful modifications were tried, the main successful modifications were increasing the hydraulic retention time (HRT) in the pre-anoxic reactor, and decreasing the solids retention time (SRT) to create favorable conditions for anaerobic oxidation and partial nitrification-denitrification. A laboratory-scale of SAO/PND was used to conduct the experiments in this research. SAO/PND looks like the MLE process regarding the reactor configurations and recycle and return lines. Ammonia concentrations above 150 mg/L can be toxic for the MLE system, but SAO/PND improves the situation so that ammonia concentration is not toxic until close to 290 mg/L. Another issue with MLE process is that it requires high amounts of oxygen and alkalinity which results in high amounts of sludge production. But, SAO/PND produces less sludge, and does not need high amounts of oxygen and alkalinity. The results showed more than 95% chemical oxygen demand (COD) and 90% total inorganic nitrogen (TIN) removal from synthetic wastewater, respectively, in our laboratory environment. In addition, volumetric design loading rates determined as 11.80 kg COD/(m3.d) and 0.63 kg TIN/(m3.d) with synthetic solution as a feed. Furthermore, the results showed high performance of the system in treating dairy and brewery industry effluents. In this modified single-process system, organic carbon was removed through anaerobic oxidation, assimilation, P–uptake by polyphosphate accumulating organisms (PAOs) and denitrifying PAOs (DPAOs), aerobic heterotrophs, and denitrification by DPAOs and denitrifying ordinary heterotrophic organisms (OHOs). Nitrogen content removal mechanisms were assimilation, partial nitrification–denitrification, anaerobic ammonium oxidation (anammox), and small portion uncharacterized processes. 95% and 90% less oxygen requirements along with 60% and 44% less sludge production compared to the conventional aerobic processes and conventional combined systems, respectively, resulted in significant potential cost savings by this modified system. Finally, the applied modified single-process system in this thesis is found as a sustainable, robust, cost-effective, and small footprint process with less intensive operation and maintenance requirements which will yield new insights into the design of treating highly polluted streams in the future.

No description available.

Volatile organic compounds (VOCs) are those chemical species having sufficiently high vapor pressures to exist largely or entirely in the gaseous phase, whereas reactive organic carbon (ROC) encompasses all organics except methane. ROC can be emitted biogenically and anthropogenically, usually in a pure hydrocarbon form that is susceptible to reaction with common atmospheric oxidants such as hydroxyl and ozone in the initial steps to the formation of particulate matter, the criteria pollutant most strongly implicated in human mortality. The diversity of both the emitted VOCs and their possible atmospheric reactions yields countless different compounds existing in the atmosphere with a correspondingly wide range of volatility, solubility, reactivity, etc.. Moreover, the temporal and spatial variability of a given analyte is often large. Real-time chemical characterization of gaseous and particulate organic compounds can be achieved by instrumentation utilizing chromatographic and/or mass spectrometric techniques, but these methods are expensive, often logistically challenging, and require high levels of skills for both operation and data analysis. Conversely, filter-based measurements for organic particulates are inexpensive and straightforward, but do not give real-time data and analytes may be lost or transformed before analysis. There is a niche for robust, low-maintenance, moderate-cost instrumentation that offers chemical information on atmospheric carbon. Presented here are two projects that develop and validate instrumentation for measuring ROC. The first combines flame ionization detection (FID) with a CO2 detector to estimate the O/C ratios of sampled gases and particulates. O/C ratios are a particularly valuable piece of chemical information as higher ratios give lower volatility and higher solubility, meaning increased propensity to partition into the condensed phase. The second project utilizes portable VOC samplers with sorbent tubes that trap and protect analytes for detailed analysis. The samplers' portability and programmable microcontrollers offers the investigator great flexibility, both spatially and temporally. A third project analyzed the chemical composition of commercially available fragrance mixtures and modeled their emissions' impact on oxidant reactivity. It was observed that terpenes, despite their low mole fractions in the mixtures, represent the vast majority of emitted reactivity and are quantitatively evolved from the mixtures in a matter of hours. / Doctor of Philosophy / Organic (i.e., carbon-containing) compounds are emitted into the atmosphere from a variety of natural and anthropogenic sources. Respective examples would include the agreeable aroma of a pine forest (from terpene compounds) or the pungent smell of gasoline (from additives such as toluene). These emitted compounds are often pure hydrocarbons (molecules formed of carbon and hydrogen atoms), and the category VOCs (volatile organic compound) encompasses hydrocarbons and the products of their chemical reactions with atmospheric oxidants like the hydroxyl radical and ozone. In the presence of pollutant nitrogen oxides, oxidants modify these VOCs; adding oxygen lowers the VOCs' vapor pressure and increases aqueous solubility, resulting in higher likelihood of condensation from the gaseous phase into particulates (liquid or solid phases). "Smog" is a colloquial term for the entire suite of noxious chemical compounds produced in the air from reactions of largely anthropogenic organic precursors. Particulates, a.k.a. aerosols, are the most concerning atmospheric pollutant due to deleterious effects on respiratory and cardiovascular health and has shown strong correlations with increased mortality in exposed groups such city dwellers. Determining the chemical identities of the VOCs is useful for pollution forecasting and possibly identifying and quantifying VOC sources. Current methods for chemical identification are cumbersome, expensive, complex, and wholly unsuitable for many investigators. In this work, we introduce two new approaches to gathering chemical information about organic gases and particulates. The first instrument has been demonstrated to give accurate estimates of oxygen/carbon (O/C) ratios; higher O/C ratios represent higher propensities to condense into particulate forms. The second instrument developed is a portable VOC sampler, which traps (and prevents reaction of) a broad range of organics on a sorbent (such as activated charcoal) in a small metal tube. After sampling in remote locales, the tubes can be analyzed in the lab and the VOCs identified and quantified. The third study investigated the chemical composition of fragrance mixtures (present in perfumes, cleaning agents, etc.) and modeled (i.e., estimated) VOC emissions based on the fragrance components as well as the effects on atmospheric oxidant levels. Fragrance mixtures represent a significant source of atmospheric carbon, so a more thorough understanding of the fragrances' impacts on oxidant levels gives further insight into atmospheric processes and aerosol formation.

Rivers are a significant source of particulate and dissolved organic carbon (POC, DOC) into inland waters and coastal systems and provide a fundamental linkage between the terrestrial, oceanic, and atmospheric carbon reservoirs. Recent studies have examined the relationship between the quantity and form (POC vs. DOC) of carbon delivered to the aquatic system; however, little is known about the age of POC and DOC exported and how the radiocarbon age may vary with latitude, topographic gradient, vegetation, and land use. I provide the first global synthesis of published radiocarbon values of POC and DOC (∆14C). Inclusion of DOC and POC parameters (µM, δ13C, ∆14C) reveal significant driving forces of DOC (µM), latitude, and elevation (m) as capable of explaining 25% of the variability in DO14C in rivers and POC (µM) and latitude accounting for 15% of the variability in PO14C. When δ13C of DOC and POC and latitude were incorporated with ∆14C of DOC observations, 61% of the variability in DOC age was explained revealing the necessity to include dissolved and particulate fractions of organic carbon to yield the most robust predictive models. This study found a global trend of increasing age of DOC and increasing δ13C of DOC and POC with increasing latitude. My study suggests future research should incorporate both particulate and dissolved OC parameters along with elevation, vegetation, land cover, and climate zones to increase understanding of what drives the age of carbon exported in riverine systems.

Because of high intense population is in Taiwan, households water use requires a considerable amount. It is substantially reduce daily water use to share primary water resources, if we can reclaim domestic wastewater properly and make it support. Currently, reclaiming water is an emerging requirement for management and application. If we can adequately monitor and treat reclaimed water, reducing environmental contaminants, costs, and environmental feedback is possible. The study treated domestic wastewater of Feng-Shan river using GAC trickling filter with two column in a series and the removal efficiency of organic carbon was observed. The experimental results indicated that removal efficiency of organic carbon concentration was decreased as the empty-bed contact time (EBCT) increased. The best average removal efficiency of TOC and DOC was about 72% and 78%. According to the TOC removal rates using GAC at different temperatures, the TOC removal rates at room temperature and 4¢Jwere respectively 95% and 90% in the first column of the experiment and 85% and 80% in the second column. The removal rates of dissolved organic carbon (DOC) using GAC folter system at room temperature and 4¢J were respectively 95% and 90% in the first column of the experiment and 90% and 87% in the second column. Obviously,the TOC removal rate treated using GAC filter system at room temperature was superior to that treated at 4¢J In comparing treated water and recycled water,most of the water quality parameters (temperature¡BSuspended solids¡BBOD¡BCOD¡BpH) were to meet recycled water quality standards.However, the system due to use GAC trickling filter system treatment that easily decrease dissolved oxygen in treated water but conductivity in treated water without changes. These two water parameters were failed to meet the recycled water standards. By the way, we found trained GAC through SEM irradiation the biofilm area of trained GAC surface at 25¢Jwas superior to that treated at 4¢J. It corresponds to the removal efficiency of organic carbon, the removal efficiency of 25¢J was higher than result of 4¢J. Therefore, a certain relationship between the biofilm area and removal efficiency of organic carbon is existed in this work.

The Bryan/College Station (B/CS) region has been reported to have elevated concentrations of dissolved organic carbon (DOC) in surface water. Increased DOC concentrations are worrisome as DOC has been shown to be an energy source for the recovery and regrowth of E. coli and many watersheds are impaired by high bacteria levels. To examine the sources and fates of DOC in rural and urban regions to better understand DOC movement though the environment, seven watersheds were studied. To investigate source, streams were analyzed using diffuse reflectance near infrared spectroscopy (DR-NIR) and carbon isotopes. Fate of DOC was determined through monthly streams samples, gathered between March 2011 and February 2012, which were incubated for biodegradable DOC (BDOC). Soil in the region was sampled based on land use categories. Soil was analyzed for DOC and BDOC as well as DOC adsorption, the other major fate of DOC. Above ground vegetation was sampled in conjunction with soil and analyzed for BDOC. Data indicated that fecal matter from cliff swallows provided considerable organic material to streams in the B/CS region as shown through DR-NIR. Carbon isotope values in streams ranged from -23.5 +/- 0.7% to -26.8 +/- 0.5%. Stream spectra may be able to predict carbon isotope values in streams (Adj. R2 = 0.88). Mean annual stream DOC concentrations ranged from 11 +/- 3 mg/L to 31 +/- 12 mg/L, which represents a significant decrease in DOC between 2007 and 2011. Concurrent increases in pH and conductivity were also recorded. The decrease in DOC and the increases in pH and conductivity may be due to impacts of high sodium irrigation tap water. Biodegradable DOC was low in streams, which is likely due to DOC being present in streams in refractory forms that are resistant to microbial breakdown. Soil chemistry, including soil adsorption, was greatly influenced by sodium. The elevated adsorption coefficients and release values seen in highly developed and urban open areas can be attributed to frequent exposure to high sodium irrigation water. The results indicate that sodium is a major driver of DOC in the system. Sound management decisions concerning irrigation water chemistry and urban development might eventually emerge to protect water quality as a result of this research.

Reductive dechlorination is a significant natural attenuation process in chloroethene-contaminated aquifers where organic carbon combined with reducing redox conditions support active dechlorinating microorganisms. At sites where natural organic carbon (NOC) associated with the aquifer matrix provides fermentable organics, the ability to measure the NOC is needed to assess the potential for the long-term sustainability of reductive dechlorination. This study focused on developing a method to measure the potentially bioavailable organic carbon (PBOC) associated with aquifer sediment. To measure NOC and evaluate its biodegradability, liquid extraction techniques on aquifer sediment were investigated. Single extractions with different extracting solutions showed that extractable organic carbon associated with the sediment ranged from 1-38% of the total organic carbon content (TOCs). Bioassay experiments demonstrated that 30-60% of the extractable organic carbon can be utilized by a microbial consortium. Alternating between 0.1% pyrophosphate and base solutions over multiple extractions increased the rate of removal efficiency and targeted two organic carbon pools. The result of the investigation was a laboratory method to quantify organic carbon from the aquifer matrix in terms of the PBOC. In the second part, the extractable PBOC was shown to biodegrade under anaerobic conditions, to produce H2 at levels necessary to maintain reductive dechlorination, and to support reductive dechlorination in enrichment cultures. For the third part of the research, the difference in extractable organic carbon inside and outside of a chloroethene-contaminated plume was examined through the combination of PBOC laboratory data and field parameters. Supported by ground-water constituent data, the PBOC extraction and bioassay studies showed that less extractable organic carbon was present inside than outside of the chloroethene plume. The final part of the research investigated the distribution of PBOC extractions across six contaminated sites. PBOC extractions were directly correlated to the TOCs, soft carbon content, and level of reductive dechlorination activity at the sites. Based on these correlations, a range for organic carbon potentially available to subsurface microorganisms was proposed where the upper bound consisted of the soft carbon and the lower bound consisted of the PBOC. / Ph. D.