A pilot plant study was conducted in Newport News, Virginia to investigate the effectiveness of powdered activated carbon [PAC] and granular activated carbon [GAC], with and without preoxidation, for reducing trihalomethane [THM] precursor concentrations in Harwood's Mill Reservoir water. Preoxidation with ozone followed by GAC is referred to as the "biological activated carbon" [BAC] process. This study showed that the GAC and BAC processes obtained the same level of organic removal; however, BAC would provide longer bed life and require less carbon than the GAC process. PAC treatment of alum coagulated water provided significantly higher TOC and THMFP removals than alum coagulation alone. The use of a preoxidant (ozone) with PAC slightly improved the organic removal efficiency. While treatment by PAC increased THMFP removals, it was not as efficient as the GAC and BAC processes. UV absorbance measured at 254 nm and TOC were found to be good surrogates for THMFP in the GAC column, but not in the BAC column. / Master of Science

Typescript (photocopy). / Digitized by Kansas Correctional Industries

The capacity and efficiency of melter slag (provided by New Zealand Steel) to remove heavy metals and suspended solids from stormwater samples are studied in this thesis. A series of batch tests were carried out to investigate the adsorption-desorption mechanism of the slag to remove heavy metals (Cd2+, Zn2+ and Cu2+) from working solutions. The results showed that all the tested metallic ions could be removed by mixing the melter slag with the working solutions. Adsorption and ion exchange are the dominant mechanisms in this process. The adsorption capacity follows the descending order of Cu2+ > Zn2+ = Cd2+. Varied binding energy of different metallic ions to the slag resulted in competitive adsorption between ions.A variety of substances: inorganic salts (KCl, NaCl, KNO3 and sea water), organic acids (citric and tartaric) and inorganic acids (nitric and carbonic), were tested as desorbing agents to recover the used slag. Citric acid in sea water was found to be the best in terms of desorption efficiency and cost-effectiveness.The column tests were carried out to simulate the filtration bed in laboratory conditions. Stormwater samples were collected from residential and commercial areas in Auckland. The synthetic stormwater samples were prepared from clay and metallic ion solution. Both samples were used as feeding solutions in the tests. The removal efficiencies of suspended solids and metallic ions (Zn2+, Cd2+ and Cu2+) vary depending on different operation conditions. They are in inverse proportion to the grain size of the melter slag and the influent flow rate. The higher removal efficiency of Zn2+ than that of suspended solids infers that metallic ions are removed by both precipitation and adsorption.

M. Tech. Environmental Management / Investigates the possibility of using maize tassel powder as a solid phase extraction sorbent for the recovery of Ag, Au and Cu from aqueous solution. The surface characteristics of maize tassel and its ability to remove Ag, Au and Cu from aqueous solutions needed to be established before the preparation of maize tassel beads.

Permeable reactive barriers are considered among the most promising technologies for contaminated soil and groundwater remediation. Zero-valent iron (ZVI), hydroxyapatite (HA), and organic compost, with (OM) and without (OMx) dextrose/sulfate were assessed in column studies for their ability to attenuate chromium (Cr) or cadmium (Cd). PVC columns were packed with the reactive media and Cr or Cd solutions were pumped through the columns at concentrations of 5, 50 and 200 mg/l. These media were also assessed for their abilities to attenuate Cr and Cd from a contaminated soil. The order of Cr removal was: ZVI > OMx > OM > HA. The ZVI treatment maintained a removal rate of > 95% throughout the study. All treatments used for Cd removal had a removal rate of 98% across all treatments. The ZVI was the only treatment capable of retaining any of the mobile soil Cr and Cd from the contaminated soil. / Department of Natural Resources and Environmental Management

The capacity and efficiency of melter slag (provided by New Zealand Steel) to remove heavy metals and suspended solids from stormwater samples are studied in this thesis. A series of batch tests were carried out to investigate the adsorption-desorption mechanism of the slag to remove heavy metals (Cd2+, Zn2+ and Cu2+) from working solutions. The results showed that all the tested metallic ions could be removed by mixing the melter slag with the working solutions. Adsorption and ion exchange are the dominant mechanisms in this process. The adsorption capacity follows the descending order of Cu2+ > Zn2+ = Cd2+. Varied binding energy of different metallic ions to the slag resulted in competitive adsorption between ions.A variety of substances: inorganic salts (KCl, NaCl, KNO3 and sea water), organic acids (citric and tartaric) and inorganic acids (nitric and carbonic), were tested as desorbing agents to recover the used slag. Citric acid in sea water was found to be the best in terms of desorption efficiency and cost-effectiveness.The column tests were carried out to simulate the filtration bed in laboratory conditions. Stormwater samples were collected from residential and commercial areas in Auckland. The synthetic stormwater samples were prepared from clay and metallic ion solution. Both samples were used as feeding solutions in the tests. The removal efficiencies of suspended solids and metallic ions (Zn2+, Cd2+ and Cu2+) vary depending on different operation conditions. They are in inverse proportion to the grain size of the melter slag and the influent flow rate. The higher removal efficiency of Zn2+ than that of suspended solids infers that metallic ions are removed by both precipitation and adsorption.

M.Ing. (Civil Engineering) / Natural organic matter (NOM) is a complex mixture of organic compounds resulting from the decay of plants and animals. When not properly removed, NOM reacts with disinfectants to form disinfection by-products, of which some are known to be carcinogenic. Regulations have become more and more stringent about the maximum level of NOM in drinking water. Different water treatment processes can be applied to remove NOM. However, because each process targets specific fractions of NOM, this results in the existence of recalcitrant NOM fractions that are not removed, for each treatment process. The main objective of the study was thus to investigate NOM removal by using three advanced water treatment processes alone and in combination. The processes used were enhanced coagulation, granular activated carbon adsorption and ion exchange resin processes. Strong and weak base ion exchange resins were used. Although NOM removal methods have been investigated intensively, little attention is given to a so-called “multi-barrier” approach of NOM removal through enhanced coagulation, granular activated carbon adsorption and ion exchange resin that could be applied in practice. In order to take the seasonal and geographical variability of NOM into account, water samples were collected at eight geographical areas over five to seven seasons from 2010 to 2013. Results showed that different treatment processes remove different NOM fractions with different efficiency. Results also confirmed that EC performs better than the adsorptive treatment processes. But the literature shows that NOM removal by EC is difficult for water with high alkalinity and low SUVA values, which is common with SA waters. The adsorptive processes used for NOM removal revealed that they are not viable options, because even low percentage of NOM removal would require high adsorbent dosages, which removes this approach as a practical option.

Ph.D. (Chemistry) / Phosphorus in the form of phosphate needs to be removed from the aqueous environment as it is primarily responsible for eutrophication of water bodies. In an attempt to limit the discharged of phosphorus into the aqueous environment, the phosphate discharge limits for wastewater treatment plants have been decreased. These limits are not easily or economically met by current phosphorus removal technologies. In addition phosphorus is a non-renewable resource. To ensure the ongoing quality of water bodies and security of food production it is vital that phosphate in water be removed and recovered. In order to address these issues, novel hybrid metal oxide ion exchange resins based on Fe(III), Cu(II), Mn(IV and Ti(IV) oxides have been prepared and their phosphate adsorption characteristics determined.

Granular activated carbon (GAC) pretreatment was evaluated for the removal of trihalomethane (THM) precursors from a surface water supply, the Occoquan Reservoir, in northern Virginia. The carbon contactors were operated in the upflow mode at flow rates of 2, 4, and 6 gpm which provided empty bed contact times (EBCT) of 26, 13, and 6.6 minutes, respectively. Reservoir raw water quality data was collected to determine what relationship existed between these measurements and the trihalomethane formation potential (THMFP) of the reservoir water. The results indicated that THM precursors, as measured by total organic carbon (TOC) and THMFP, could be removed from an untreated surface water supply by GAC contact. The degree to which THM precursors were removed was directly related to EBCT, the most effective being 26 minutes (2 gpm). GAC contact appeared to be selective for the removal of those precursors responsible for instantaneous THM concentrations i.e., those produced within a thirty minute chlorine-contact period. Those precursors responsible for THM concentrations produced after thirty minutes and for up to seven days thereafter (herein designated THMFP) appeared to be associated either with particulate matter in the raw water or with larger molecular weight organic substances which were not well adsorbed by the carbon. There were no discernible direct correlations between THMFP and the turbidity, color, TOC, chlorophyll-a concentration and algal populations in the raw water. Runoff from a rainstorm late in the period of study resulted in increases in raw water color, turbidity, and TOC concentrations, but it was impossible to determine which of these factors was responsible for the increased raw water THMFP that occurred at the same time. / Master of Science

Excess fluoride (F-) in drinking water poses a health threat to millions of people around the world. In the present work, activated alumina (AA) has been used as an adsorbent. Data obtained from batch experiments were fitted to the (i) pseudo-first order, (ii) pseudo-second order, and (iii) Langmuir kinetic model. Model (ii) performed better than model (i), and fitted the data well. However, the rate constant for adsorption ka had to be varied as a function of the initial concentration of F- in the liquid phase c0. A more satisfactory approach is provided by Langmuir model, which fitted the data reasonably even though ka was independent of c0. Shreyas (2008) developed a model for the batch adsorption of F- onto porous pellets of AA. Some errors were detected in his computer program were corrected. The parameters of the model were estimated by fitting predictions to data. The parameter values suggest that the adsorption process is likely to be diffusion limited. Column experiments were conducted as follows. The pellets were soaked in deionized water for a time ts before they were loaded into columns. A feed solution having a fluoride concentration cf = 3 mg/L was fed to column and the concentration of F- in the exit stream ce was measured at regular intervals. Breakthrough was deemed to have occurred when ce exceeded the permissible limit (= 1 mg/L). Constant values of the bed height H, and the empty bed contact time tc were used in the experiments. The volume of treated water V, scaled by the volume of the bed Vb, varied strongly with the soaking time ts, with a maximum at ts = 24 h. To understand the possible reasons for this behaviour, XRD, FESEM, and FTIR were used to characterize the surface of AA. Though the concentrations of the surface hydroxyl groups may influence the adsorption of F-, FTIR studies show there is no direct correlation between V/Vb and the concentrations of these groups. The FESEM and XRD studies indicate that fresh AA consists mainly of boehmite, which gradually converted to gibbsite during soaking. For fixed values of H and tc, the dimensionless volume of treated water V/Vb was a maximum at D = 45 mm. This behaviour may be caused by wall effects for small values of D and by occurrence of quasi-static regions near the wall for large values of D. The cost of treated of water was Rs. 0.42/L. It decreased slightly to Rs. 0.37/L after one regeneration cycle, but increased to Rs. 0.41/L after two cycles. The volume of treated water after two regeneration cycles was 595 L/kg. The concentration of Al3+ ions ca in the treated water increased and exceeded the permissible limit of 0.2 mg/L as the number of regeneration cycles increased. The concentration of F- in regeneration effluent cre was in the range 32-70 mg/L. The effluent was subjected to solar distillation, leading to a distillate whose fluoride concentration F- was in the range 9-12 mg/L. The distillate can be discharged into the public sewers, as the permissible limit is 15 mg/L.