The dewatering characteristics of polyaluminum chloride (Hyper⁺Ion 1050A) sludges were investigated using lab-scale tests including specific resistance to filtration (r*), capillary suction time (CST), and sludge pH. The effects of chemical conditioning (lime and cationic polymer) and mixing intensity (Gt) upon the sludge dewatering characteristics in a pilot-scale plate and frame press were also studied. The dewatering characteristics of the Hyper⁺Ion sludges were found to be dependent upon the influent water turbidity conditions; specifically, the ratio of aluminum coagulant to total dry solids in the sludge. Lime was an effective conditioner for doses that produced a sludge pH value in the range of 11.5 to 11.8 which, again, was a direct function of the aluminum coagulant fraction in the sludge. Cationic polymer and a combination of lime and polymer were also effective conditioning schemes when the appropriate dose and mixing intensity were applied. / Master of Science

Soluble manganese (Mn) is a common water contaminant which can cause discoloration of water and staining if not treated properly in a water treatment plant. The "natural greensand effect" is one of the proven methods for efficient removal of Mn from water. Therefore, research is ongoing to develop different ways to effectively create the natural greensand effect in a post-filtration sorptive contactor for application at water treatment facilities. The research reported by Zuravnsky (2007) focused on the use of oxide-coated media in a post-filtration contactor and served as a starting point for the research reported in this thesis. As a part of the work conducted by Zuravnsky (2007), a preliminary model was formulated to predict soluble Mn removal via adsorption and oxidation onto large-size MnOx(s)-coated media. A major part of the current research was to calibrate the proposed model in predicting the soluble Mn removal performance by incorporating a statistical non-linear regression method to estimate a best-fit value for the fitting parameter kr, the rate constant associated with Mn oxidation by free chlorine. The research work included an 18-week pilot-plant study conducted at a water treatment facility in Newport News, VA. A contactor column loaded with 27â of pyrolucite media was operated at varying applied water conditions. Hydraulic loading rate (HLR), temperature, pH and influent free chlorine concentration were the operational parameters that were varied and their effect on the Mn removal performance evaluated. The resulting data were then used in the model to aid in its calibration and to obtain the best-fit kr values corresponding to effective Mn removal for the various operating conditions. Soluble Mn removal in the contactor column was directly dependent on solution pH and initial free chlorine concentration. The applied water temperature and HLR also had a small impact on the Mn removal profiles observed. On analyzing the results obtained from the model, it was noted that the best-fit kr values for the pilot plant data increased with increasing solution pH (When temperature = 200C and the initial Cl levels were below 1.5mg/L). Also, the Mn uptake capacity of the pyrolucite media increased with both an increase in initial Mn concentration and solution temperature. Long-term operation of the contactor also resulted in significant head loss accumulation in the upper portion of the contactor column, most probably due to MnOx(s) deposition on the media and partial blockage of contactor void spaces. Media fluidization was necessary to address this operational issue. / Master of Science

The effects of four oxidants upon water treatment process parameters were investigated. The four oxidants under consideration were ozone, chlorine dioxide, potassium permanganate, and chlorine, Experimentation was directed towards the impact of these oxidants upon turbidity, TOC, and color removal, as well as reduced manganese oxidation. Studies were conducted with an experimental water with enhanced TOC levels. Experimentation was accomplished by a series of jar tests in which solution pH, coagulant dose, and oxidant dose were varied. Results show that, in general, oxidant application had either no impact or a negative impact upon TOC, turbidity, and color removal. Further deterioration of finished water quality was observed with increasing oxidant dose. Reduced manganese was oxidized by both potassium permanganate and chlorine dioxide. Ozone effectively oxidized reduced manganese in waters of low TOC, while chlorine was an ineffectual oxidant. Additionally, particle counts were conducted. Results show that the application of an oxidant increased the number of smaller particles present alter settling However, this immense of particles did not significantly alter settled turbidity levels. / Master of Science

In this study, the effects of organics removal efficiency, oxidant dose, and alum dose on aluminum hydroxide sludge characteristics were assessed. In order to maintain control over operating parameters, a continuous-flow laboratory-scale plant was operated in the laboratory with daily monitoring of pH, as well as influent and effluent turbidity, total organic carbon, and color. Sludge thickening and dewatering characteristics were found to worsen when increasing amounts of organic matter were incorporated into the sludge floe matrix. Sludge properties improved with increases in oxidant dose and decreases in alum dose and alum/influent turbidity ratio. Changes in coagulation mechanism from sweep to charge neutralization were hypothesized to be partially responsible for changes in sludge properties caused by changing alum dose. Improvements in thickening and dewatering characteristics were found to be heavily dependent upon increases in sludge floe density, as well as decreases in aggregate water content. / M.S.

No

Yes / The Sustainable Development Goal (SDG) 6.1, established by the United Nations General Assembly in 2015, targets universal and equitable access to safe and affordable drinking water for all by 2030. An essential factor in achieving this goal is the harnessing of “green” coagulants – naturally occurring, environmentally friendly materials which are effective coagulants for use in water treatment, with good availability in developing countries, inherent renewable properties and ease of biodegradation. In order to gain from these benefits, it is essential to fully understand how such coagulants may best be utilised, particularly concerning their practical application in developing countries. In this study, three different plant-based coagulation products (PCPs), namely Hexane (HxKP), saline (StKP) and crude (CrKP) extracts of Kenaf plant seed (Hibiscus cannabinus, a species of the Hibiscus plant), were applied to high (HTW), medium (MTW) and low (LTW) turbidity water in order to determine their performance and coagulation ability. The ability of the three Kenaf coagulant products (KCPs) to remove hydrophobic fractions of natural organic matter (NOM) was measured. The impact of KCPs on the treated water organic matter content (a known disinfection by-product (DBP) precursor) was examined using known surrogates of natural organic matter (NOM) i.e. the dissolved organic carbon (DOC), ultraviolet absorbance at 254 (UV254) and specific ultraviolet absorbance (SUVA254). Results obtained quantify the implications of using these coagulants during the water disinfection process. A parametric study, measuring the effect of different operating parameters, such as untreated water turbidity, pH, dosages, retention time, and KCP storage time, was completed. Turbidity removal performance for HxKP and StKP was very good with > 90% removal recorded for HTW and MTW, respectively, at pH seven within 2 hours retention time. Images obtained from scanning electron microscopy (SEM) analysis revealed a high likelihood of the coagulation mechanism of KCPs to be adsorption-interparticle bridging brought about by their flake-like structures and surfaces charges. Varying pH had no measurable influence on the coagulation performance of the KCPs. Comparing their efficiency with Moringa Oleifera (MO, a previously researched PCP) and alum showed that HxKP had a negligibly different particle removal as MO. StKP turbidity removal performance was below HxKP by 1% for HTW and LTW and 2% for MTW but performed higher than the CrKP by 5% and 7% in HTW and MTW, respectively. The optimum dosage of HxKP and StKP reduced DBP surrogate values, indicating that its precursor is also minimized, although a slight shift from this optimum dosage showed a significant rise in their concentration thus signifying a potential increase in DBPs during disinfection.

Yes / This study used fluorescence excitation-emission matrices (EEMs) analysis to investigate the characteristics of natural organic matter (NOM) in treated water using okra crude extract (OCE), sabdariffa crude extract (SCE) and kenaf crude extract (KCE) as coagulants. In addition, an assessment of the impact of purified okra protein (POP), purified sabdariffa protein (PSP) and purified kenaf protein (PKP) was undertaken. The performance evaluation of these coagulants in terms of increase or decrease in dissolved organic carbon (DOC) was compared with Peak T fluorescence intensity observed at excitation wavelength 220–230 nm, and emission wavelength 340–360 nm. Fluorescence analysis of water treated with the crude extracts identified the removal of DOC in peaks A and C region whereas the increase in DOC from the protein was predominantly found in peaks T and B region. Furthermore, it was observed that the purified proteins were noted to be capable of reducing the DOC concentration in raw water where all fluorophores were not detected. The application of OCE, SCE and KCE yielded an increase in DOC of 65, 61 and 55% respectively, corresponding to increases of 65, 29 and 54% in peak T fluorescence intensities, at 100 mg/l dose. Furthermore, DOC concentration was reduced by 25, 24 and 18% using POP, PSP and PKP respectively as coagulants with corresponding decreases in fluorescence intensity of 46%, 44 and 36% in POP, PSP and PKP, at a lower dose of 0.1 mg/l. Therefore, it is clear that Peak T fluorescence intensity could be used to characterise organic matter in treated water using natural extracts to assess final water quality. / Financial support given to this research work by the Nigerian Government through the Tertiary Education Trust Fund (TETfund/AST &D/2013/2014/CE/02)

Yes / This study used sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis and a jar test apparatus to investigate the molecular weight (MW) and turbidity removal potential of Hibiscus seeds. Three Hibiscus species were assessed: okra crude extract (OCE), sabdariffa crude extract (SCE), and kenaf crude extract (KCE). Furthermore, purified versions of each [i.e., purified okra protein (POP), purified sabdariffa protein (PSP), and purified kenaf protein (PKP)] obtained from anionic exchange were evaluated. The results show that whereas the crude extracts had multiple proteins with MW sizes between 11 and 82 kDa, the purified samples consisted of a single coagulant protein band around 39 kDa. In each case, significant turbidity removal was recorded with the purified proteins; POP, PSP and PKP achieved approximately 98%, 94%, and 90% removal, respectively, at a reduced dosage of ≤0.6  mg/L. However, OCE and SCE achieved lower turbidity removal of 86% and 85% using 40-mg/L doses, respectively, whereas KCE recorded only 73% turbidity removal with a 60-mg/L dose. Sludge generation by crude and purified proteins was approximately 25% of sludge produced by aluminum sulfate and had the additional benefit of being biodegradable. Therefore, the coagulant protein in Hibiscus plant seeds has potential applications for improvements to accessing clean water in developing countries.

The objectives were to evaluate permanganate and chlorine dioxide as preoxidants both when they were dosed individually and when they were dosed together, for their abilities to improve water treatment plant performance. The specific goals were to determine the effect of the preoxidant conditions on coagulant requirements, filter operation, and the removals of organic carbon, trihalomethane precursors, iron, and manganese. Also, the interaction of the preoxidants with each other when dosed together was investigated. The preoxidant conditions were evaluated on both plant- and laboratory-scale bases. The plant-scale study focused on the ability of the preoxidants to enhance those aspects of plant performance listed above. The laboratory-scale study reinforced the results of the plant-scale study and included investigations to the interactions between the two oxidants when they were dosed simultaneously. The plant-scale study yielded information regarding the extent to which these oxidants helped remove the raw water constituents listed previously. The laboratory-scale study expanded on these results and included information concerning the reasons why these oxidants performed in the manner that they did. During the period of lake stratification, when trihalomethane removal caused the greatest treatment concerns, chlorine dioxide provided the greatest removal efficiency (65 percent), but organic carbon removal suffered (45 percent), While the lake was mixing and reduced manganese posed the greatest treatment concerns, the simultaneous use of chlorine dioxide and permanganate resulted in the greatest removal efficiency (95 percent), however, objectionable tastes-and-odors were formed. In comparison, chlorine dioxide was more apt to oxidize organic compounds (including trihalomethane and taste-and-odor precursors), and permanganate was more apt to oxidize manganese(II). When the two oxidants were dosed simultaneously, chlorine dioxide had the capacity to maintain permanganate for extended periods, possibly beyond the hydraulic retention time of the plant. Methods were developed to measure 1) chlorite concentrations in the presence of oxidized forms of manganese and 2) the relative sizes and shapes of molecular—size distributions of naturally occurring organic matter. / Ph. D.

Water availability is presently under risk owing to the increased discharge of pollutants from both industrial and residential properties. A distinct category of pollutants known as "emerging contaminants" (ECs), whose hazards were either unknown before they were noticed, e.g., antibiotics, dyes, PFAS, etc. Most of the ECs are unregulated and pose a threat to aquatic and human life at even low doses. Our water treatment facilities are not designed to efficiently eliminate these toxic substances. Therefore, we need an economical tertiary treatment approach. Adsorptionis a sustainable, cost effective and simple technique, making it a viable technique for pollutants elimination on a worldwide scale. The removal of these ECs has been made possible by several commercially available adsorbents, however most of them are expensive. Adsorbents fabrication using, agricultural wastes is an effective waste management technique that helps reduce greenhouse gas emissions via carbon sequestration. The adsorption capability of adsorbents can be enhanced by further modification of its properties. This research study focuses on conversion of biomass into environmentally friendly adsorbents including biochar and nanocellulose aerogel. In the first study, a natural mineral dolomite (CaMg(CO3)2) modified biochar was fabricated from rice husk and used to remove anionic reactive dyes, Remazol Brilliant Blue (RBB) and Reactive Black 5 (RB-5) from synthetic wastewater. In the second study, a sustainable aminated/TEMPO cellulose nanofiber (Am/TEMPO-CNF) aerogel was fabricated and used to treat oxytetracycline (OTC) and chloramphenicol (CAP) contaminated water. The physiochemical properties of all adsorbents were studied using FTIR, SEM, TGA, elemental analyzer and N2 adsorption-desorption isothermal analyses. The contaminants were quantified using Ultraviolet–visible spectroscopy (UV-Vis) before and after the experiments. Kinetics, isothermal and thermodynamics modeling was applied to analyze the adsorption behavior and mechanism. In the third investigation, a novel In-situ UiO-66-NH2/TOCNF adsorbent was employed to remove the anionic azo dyes Orange II (ORII) and Congo Red (CR) from synthetic wastewater. We also looked at how pH, time, and initial concentration impacted CR and ORII adsorption. Research was conducted to assess the stability and adsorption potential under various situations by thermodynamics and regeneration.