Dissertations and Theses of Interest
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ItemHydraulic Parameter Estimation Using Aquifer Tests, Specific Capacity, Ocean Tides, and Wave Setup for Hawai'i Aquifers(Water Resources Research Center, University of Hawaii at Manoa, 2007-12)The islands of Hawaii face increasing ground-water demands due to population growth in the last decades. Analytical and numerical models are essential tools for managing sustainable ground-water resources. The models require estimates of hydraulic properties, such as hydraulic conductivity and storage parameters. Four methods were evaluated to estimate hydraulic properties for basalts on the island of Maui. First, unconventional step-drawdown tests were evaluated. The results compare favorably with those from classical aquifer tests with a correlation of 0.81. Hydraulic conductivity is log-normally distributed and ranges from 1 to 2,500 m/d with a geometric mean of 276 m/d and a median of 370 m/d. The second approach developed a simplified parameter-estimation scheme through an empirical relationship between specific capacity and hydraulic parameters that utilized Hawaii's state well database. For Maui's basalts, the analysis yields a geometric-mean and median hydraulic conductivity of 423 and 493 m/d, respectively. Results from aquifer tests and specific-capacity relationships were used to generate island-wide hydraulic-conductivity maps using kriging. The maps are expected to be of great benefit in absence of site-specific field assessments. In the third approach, ocean-tide responses in the central Maui aquifer were used to estimate an effective hydraulic diffusivity of 2.3 x 10^7 m^2/d. The position of the study area necessitated refining the existing analytical solution that considers asynchronous and asymmetric tidal influence from two sides in an aquifer. Finally, measured ground-water responses to wave setup were used to estimate hydraulic parameters. Setup responses were significant as far as 5 km inland and dominated barometric-pressure effects during times of energetic swell events. The effective diffusivity estimated from setup was 2.3 x 10^7 m^2/d, matching that based on tides. Additionally, simple numerical ground-water flow models were developed to assess the accuracy of results from analytical solutions for step-drawdown tests, dual-tides and wave setup, and to evaluate sediment-damping effects on tidal propagation. The estimated mean hydraulic conductivities of the four methods range between 300 and 500 m/d for basalts in Maui. The results of different methods are consistent among each other and match previous estimates for basalts.
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ItemFate and Transport of Selected Endocrine Disrupting Chemicals in Recycled Water Through a Tropical Soil(Water Resources Research Center, University of Hawaii at Manoa, 2006-08)Endocrine disrupting chemicals (EDCs) are a group of synthetic and natural chemicals that have the potential to mimic the hormone-like activities in the human body. This study was conducted to recognize whether recycled water (a source of EDCs) has the potential to contaminate the environment when such water is used for irrigation purposes. Batch sorption and miscible displacement experiments were conducted to elucidate the fate and transport of four EDCs including estrone, 17β estradiol, octylphenol and nonylphenol in a soil from Hawaii. The sorption capacity of the soil from two depths (2 ft as topsoil and 15 ft as saprolite) was estimated using recycled water and deionized water as the mobile phases. The transport parameters of these contaminants were obtained by using the inverse modeling approaches as provided in the HYDRUS 1D code. All four EDCs sorbed significantly on the soil. Octylphenol and Nonylphenol rapidly degraded during sorption. The Freundlich model was suitable to describe the sorption isotherm. The sorption nonlinearity was relatively higher for saprolite compared to topsoil. Both physical and chemical non-equilibrium processes were found to affect the mobility of the EDCs in the soil. The migration of EDCs in the soil was enhanced in recycled water due to the presence of dissolved organic carbon and elevated salt concentration. The ambient pH had little effect on sorption of EDCs on the soil from either depth.
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ItemAssessing the Source of Fecal Contamination in Streams on Kaua'i Based on Concentration and Genotypes of FRNA Bacteriophages(Water Resources Research Center, University of Hawaii at Manoa, 2005-08)Extensive data from O'ahu indicate that all streams on this island consistently exceed the USEPA standards (200 fecal coliform/100 ml, 33 enterococci/100 ml) for water quality. Soil was determined to be the source of the elevated counts of these bacteria. In tropical areas, as Hawai'i, these bacteria are able to survive and multiply in the soil. Thus, these bacteria can end up in nearby streams after heavy rains or due to erosion. As a result, the USEPA recommended indicator bacteria (fecal coliform, enterococci) cannot be used to reliably determine when waters in tropical areas are fecally contaminated. Several alternative indicators have been proposed for such areas such as C. perfringens and FRNA coliphages. Extensive monitoring data does not exist for the other islands of Hawai'i. Kaua'i differs from O'ahu in that it is older, wetter and contains an abundance of cesspools. The Nawiliwili Watershed, on the island of Kaua'i, was chosen for this study. Sampling was conducted over a period of one year, and all samples were assayed for the traditional USEPA indicators (fecal, coliform, enterococci) as well as two alternative indicators (C. perfringens, FRNA coliphages). Of the 14 sites sampled, 12 contained levels of fecal coliform and enterococci that exceeded the USEPA standards (200 fecal coliform/100 ml and 33 enterococci/100 ml. This is similar to what has been documented in O'ahu streams. Based on the concentrations of these indicator bacteria, the USEPA would deem these sites as sewage contaminated. However, monitoring of these same sites for C. perfringens indicated that there was no sewage contamination (geometric mean values fell below the proposed standard of 50 CFU/100 ml). FRNA coliphage data indicate that cesspools may be leaching into nearby streams. Two streams (Nawiliwili, Papakōlea) had geometric mean levels greater than the 50 PFU/100 ml (based on O'ahu streams). Other streams in the watershed may be sporadically contaminated by cesspool because elevated FRNA coliphage levels were detected on occasion. Genotyping these FRNA coliphage isolates furthered supported the theory that cesspools were contaminating these sites because 98% of the FRNA isolates were typed as human while only 2% were typed as of animal origin. Current USEPA standards (fecal coliform, enterococci) are not reliable indicators of sewage pollution in tropical areas, thus, alternative indicators such as C. perfringens and FRNA coliphages may prove to be better indicators in these areas.
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ItemAre Fecal Sterols a Possible Alternative Indicator of Human Waste Contamination in Hawaiian Recreational Waters?(Water Resources Research Center, University of Hawaii at Manoa, 2005-08)Many of Hawaii’s recreational streams and beaches contain high fecal indicator bacteria levels that are not indicative of sewage pollution. Instead, this pollution is due to environmental sources of fecal bacteria which reside and multiply in tropical soils. Current EPA fecal indicator bacteria are no longer representative of human fecal contamination in tropical waters. Fecal sterols have been used as chemical indicators of fecal pollution in many parts of the world. The primary sterol found in human feces is coprostanol. Detection and quantification of coprostanol and related sterols using GCMS analysis provides a fingerprint that can be used to characterize fecal contamination. The objective of this study was to assay for fecal sterols as an independent method to determine whether streams in Hawaii are contaminated with sewage. This method was applied to ambient streams, a stream recently contaminated by a sewage spill, and a stream suspected to be affected by a sewage line leak. The results of this study showed that some ambient streams in Hawaii contain high levels of fecal indicator bacteria, but low concentrations of coprostanol (<10 ng/L). A stream contaminated with sewage during a sewage spill event contained high concentrations of coprostanol (18,000 ng/L) in the first 24 hours after contamination, but this level dropped to ≤ 60 mg/L after 72 hours. A stream suspected to be contaminated with sewage contained significant levels of coprostanol (>1000 ng/L) when fecal indicators were also high, confirming a possible sewage line leak. This study demonstrated that coprostanol is a useful and independent measurement of sewage pollution. It is best used in conjunction with other fecal indicators and human fecal markers if confirmation of human fecal pollution is sought.
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ItemPolyacrylamide (PAM) Effects on Viruses and Bacteria Transport in an Unsaturated Oxisol(Water Resources Research Center, University of Hawaii at Manoa, 2001-05)Experiments were to study the effects of anionic polyacrylamide (PAM) on viruses and bacteria movement in soil. A water pollution problem which affects all areas with significant rainfall is soil erosion and subsequent transport of soil and all land-based pollutants. In recent year, high molecular weight polymers, such as anionic polyacrylamides (PAMs), have been used for soil erosion control and subsequent environmental problems. PAM is found to enhance infiltration. Land application of manure, sludge, and wastewater is common in many areas of the world, including the United States. Bacteria, viruses and other pathogens can be found in these waste materials. Studies must be conducts to evaluate if the use of polymers will allow water pollution constituents such as chemicals, pesticides, and microbial pathogens to reach groundwater in aquifer.
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ItemAssessing the Persistence and Multiplication of Fecal Indicator Bacteria in Hawai'i Soil Environment(Water Resources Research Center, University of Hawaii at Manoa, 2000-12)Traditional fecal indicator bacteria such as fecal coliform, E.coli and enterococci have been shown to be unreliable indicators of the hygienic quality of recreational waters under tropical conditions. One of the major reasons for considering these bacteria as ineffective indicators of water quality in warm, tropical regions is that they are consistently found in natural environments (plants, soil, water) in the absence of any significant contamination of these environments. Since preliminary studies conducted in Hawaii had indicated soil as the major environmental source of elevated concentrations of these bacteria in environmental waters, the aim of this study was to focus on the soil environment to specifically address two assumptions made by regulatory agencies in using fecal bacteria as indicators of water quality: first, there should not be an environmental source of these indicator bacteria unrelated to sewage or fecal matter contamination, and second, the indicator bacteria do not multiply in the environment. To determine the validity of these two assumptions under tropical conditions in Hawaii and possibly other tropical locations, various experiments were conducted. The major findings are as follows. 1) Analysis of soil samples collected from various locations representing major soil groups on the island of Oahu showed that fecal indicator bacteria are naturally found in most of the soil environments, indicating that the fecal bacteria have adapted to the soil conditions to become part of soil biota. 2) Evidence was obtained to show that the soil contains adequate nutrients to sustain the populations of these bacteria. 3) Growth and multiplication of fecal indicator bacteria in natural soil was dependent on available nutrients (particularly carbon), moisture and competing microorganisms. In conclusion, tropical soil conditions are suboptimal for the multiplication of fecal indicator bacteria. Consequently, these bacteria in natural soil conditions will probably grow and multiply sporadically when conditions are relatively optimal. Although concentrations of fecal indicator bacteria in soil represent only a small fraction of the microbiota, their counts are significant enough in numbers not only to impact the quality of recreational waters but also to nullify two of the assumptions used in the application of recreational water quality standards. Thus, there is a need for an alternate and more reliable indicator of water quality in Hawaii and other tropical locations.
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ItemSimultaneous Removal of Carbon and Nitrogen by Using a Single Bioreactor for Land Limited Application(Water Resources Research Center, University of Hawaii at Manoa, 1998-05)An Entrapped-Mixed-Microbial-Cell (EMMC) process was investigated for its simultaneous removal of carbon and nitrogen in a single bioreactor with the influent COD/N ratio varying from 4 to 15 and influent alkalinity of 140 mg CaCO3/L and 230 mg CaCO3/L. The reactor was operated with alternate schedules of intermittent aeration. Two different sizes of carriers (10 * 10 * 10 mm3 and 20 * 20 * 20 mm3) were studied. The medium carrier (10 * 10 * 10 mm3) system presents higher nitrogen removal and COD removal compared to the large carrier system. The nitrogen removal efficiency is related to the ratio of COD/N in the influent. With the increase of the COD/N ration in the influent, the nitrogen removal efficiency is increased. The average reductions of nitrogen were over 92% and the average reductions of SCOD and BOD5 are over 95% and 97%, respectively, in the medium carrier system. This is operated at the HRT of 12 hours and 0.5 hour aeration and 2 hours of non-aeration, and the COD/N ratio of 15 in the influent. Changing alkalinity from 140 to 230 mg CaCO3/L has no effect in both large and medium carriers for the nitrogen removal efficiency. The pH, oxidation – reduction potential (ORP) and dissolved oxygen (DO) were used to monitor the biological nitrogen removal. It was found that the ORP (range from -100 to 300 mV) can be used to provide better effluent quality measured as total-nitrogen of less than 10 mg/L. Also, the impact of influent COD/N ratio on the effluent quality (measured as Inorg.-nitrogen) for the EMMC process is very important. Compared to other two compact biological wastewater treatment processes, membrane bioreactor (MBR) and moving bed biofilm reactor (MBBR), the EMMC process with the intermittent aeration has higher removal efficiencies of carbon and nitrogen, easier operation, lower O&M cost, lower energy requirement, and more compact. The total cost requirement is less than $3.27 per 1000 gallons (3.785 m 3) of treated settled domestic sewage per day. It is apparent that the EMMC process is technically feasible for the simultaneous removal of carbon and nitrogen under the operation on a schedule of intermittent aeration and suitable to be used for replacement or upgrading of existing treatment plant at land limited area.
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ItemEffect of bioaugmentation and diesel fuel type on soil bioremediation(Water Resources Research Center, University of Hawaii at Manoa, 1998-08)The enhancement of bioremediation by bioaugmentation in soil contaminated with diesel fuel No. 2 and No. 6 (Bunker C) is uncertain. A clayey soil was contaminated with 6,000 mg of either diesel fuel per kg of soil and seeded (5 x 10-7 cells/g of soil) with a Hawaii soil bacterium (UH138) known to utilize several hydrocarbons. The soil was limed, fertilized, and incubated in jars at 30°C for several months. The concentrations of total petroleum hydrocarbons (TPH) and of polycyclic aromatic hydrocarbons (PAH) in soil were measured by gravimetry and immunoassay, respectively. Poisoned controls (0.6% HgCl2) were used to determine the extent of hydrocarbon degradation due to microbial activity. A rapid first order biodegradation of TPH (84% in 23 days) occurred in soil contaminated with diesel fuel No. 2, regardless of bacterial seeding. Biodegradation of PAH was linear and reached 84% by day 98 in both seeded and unseeded treatments. Bioaugmentation had no effect on bioremediation of diesel fuel No.2. The decrease in TPH and PAH was paralleled by an increase in populations of total bacteria, phenanthrene-degrading bacteria and microorganisms capable of utilizing hexadecane and diesel fuel No. 2 as well as by an enhancement in CO2 evolution by the soil. Indigenous Zygomycetes grew profusely in diesel fuel No. 2 contaminated soil. Cunninghamella echinulata var. echinulata was isolated from the soil and was shown to be able to utilize several hydrocarbons. Thus, Zygomycetes may have contributed to the rapid decrease in contaminant. In soil contaminated with diesel fuel No. 6, the measurements of TPH and PAH were more variable due to the uneven distribution of the product. No biodegradation of the contaminant occurred over a period of 138 days. The growth of Zygomycetes was scant. The counts of total bacteria remained unchanged after the addition of diesel fuel No. 6. However, counts of the indigenous phenanthrene-degrading bacteria increases dramatically ( 4 log units) during the first 54 days whereas the level of the seeded bacteria remained stable. The counts of mineral oil degraders decrease by 2 log units after day 2. Co2 evolution from the soil confirmed that diesel fuel No. 6 was not degraded by either the indigenous microflora or the seeded bacterium. Thus, diesel fuel No. 2 was highly degradable by the indigenous population, however, diesel fuel No. 6 was recalcitrant.
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ItemIntegrating an Intermittent Aerator for a Swine Wastewater Treatment System(Water Resources Research Center, University of Hawaii at Manoa, 1997-05)Integrating an intermittent aeration for the treatment of combined dilute and anaerobic digested swine wastewater in a field swine wastewater treatment system was investigated. Four operations models in term of ratio of aeration to no-aeration of 60:36, 5:1, 4:2 and 3:3 hour were evaluated. At the HRT of 3.2 days and ration of aeration to non-aeration of 3:3, the removal efficiency of BOD5, Total-N, TSS and Total-P of 98.0%, 92.4%, 95.6% and 59.4% could be achieved, respectively. The effluent quality of BOD5, NO3ˉ–N, NH4+–N and TSS concentrations were 35±12mg/l, 2.6±0.8 mg/l, 36±28 mg/l and 78±13 mg/l, respectively. The operational criteria were developed for integrating the intermittent aeration in the swine wastewater treatment system (including anaerobic reactors and sedimentation unit). Economical evaluation of the swine wastewater treatment system integrating the intermittent aeration unit was conducted. It was found that break even point was the operation of 166 pigs if the biogas and stabilized sludge were utilized. If the byproducts were not utilized, the cost of the treatment system are $12.30, $7.92, $7.21, $7.06 and $6.09 for the operation of 300, 1000, 2000, 3000 and 5000 pigs per year, respectively. Integrating the intermittent aeration unit in the swine waste treatment system provides the effective odor control, reduction of energy cost and treated wastewater reuse without creating the deterioration of environmental quality.
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ItemAssessment of nitrate leaching in the unsaturated zone on Oahu(Water Resources Research Center, 1996-12)Groundwater contamination caused by agricultural fertilization is a widely recognized problem. In Hawaii, nitrogen fertilization from pineapple and sugarcane fields has posed a threat to several basal aquifers and has been implicated in coastal algae blooms. The concentration of nitrate-N in the Pearl Harbor basin on the island of Oahu was below 2.3 mg/L in the 1950’s and 1960’s, and has increased to as much as 7.6 mg/L in 1992 to 1994. The objective of this dissertation research is to develop a practical methodology for realistically estimating nitrate leaching from fertilized agricultural lands. Numerous mechanisms have impact on the distribution and migration of nitrate in the soil. Nitrogen fertilizer undergoes many N transformations and interactions with the soil and the plant after applications. In this study, an analysis of soil samples was performed to understand the leaching process of nitrate in the root zone of three different cropped fields in Hawaii. A detailed discussion is given to address various factors which control the nitrate transport process. To judge the sampling plan in relation to spatial variation, the field measurements were evaluated statistically by an uncertainty index, which is represented as the density of samples required for the estimate of sample mean of the nitrate concentration to fall within a defined limit of accuracy. In order to predict the effect of nitrogen fertilization on the groundwater contamination with very limited input data, a simple, analytical, lumped parameter model (LPM), was developed. The model can estimate the average nitrate leaching from the root zone in response to agricultural practices, N transformations and other related processes. The model was tested against the field data and two detailed numerical models, LEACHM-N and CERES-Maize. It provides an alternative way to assess nitrate leaching from the root zone with acceptable accuracy. A listing of the program is provided in Appendix 2. Owing to the complex nature of nitrogen behavior in the unsaturated zone, some degree of uncertainty is involved in the development of modeling approaches. In this study, five major sources of uncertainty were identified. These are: uncertainty due to spatial variation, uncertainty related to the accuracy of the input data, uncertainty due to simplifications in the development of the models, uncertainty due to the modeling parameters, and uncertainty due to the complexity of the unsaturated zone in Hawaii. The impact of these uncertainties on simulation results is evaluated.