Kinetic Adsorption of Fluoride from an Aqueous Solution onto a Dolomite Sorbent

The adsorption of fluoride from an aqueous solution onto a dolomite sorbent was studied. The surface morphology of the dolomite sorbent was evaluated, and it was found to have an un-smooth porous structure. The point of zero charge (PZC), specific surface area, and average pore size of the dolomite were observed at pH 8.5, 1.17 m2/g, and 105.7 Å, respectively. The major mineral components of the dolomite sorbent were dolomite, calcite, and quartz. From a kinetic adsorption test, the dolomite sorbent required 12 hours of contact time to reach equilibrium with a fluoride adsorption capacity of 0.000581 mM/g, and the kinetic adsorption fitted well with a pseudo-second order kinetic reaction with a rate constant of 21.07 g/mM·min

Bacteriophage Removal Efficiency of In-line Coagulation with Ceramic Membrane Filtration

The main objectives of this study are to evaluate the removal efficiency of bacteriophage Qβ using in-line coagulation with ceramic membrane filtration at different coagulant dosages, ceramic membrane pore sizes and initial bacteriophage Qβ concentrations. Raw water was collected from the Ping River, Chiang Mai, Thailand, and spiked with bacteriophage Qβ to prepare an initial concentration of 8 x 106 PFU/ml. According to the resulted, it was found that the smaller pore sizes membrane yield higher bacteriophage Qβ log removal. However, the use of a ceramic membrane alone could not remove bacteriophage Qβ completely. In-line coagulation combined with ceramic membrane filtration was conducted. The optimal polyaluminum chloride (PACl) doses for the 1.0, 0.5 and 0.1 µm pore size membranes were 2.5, 2.0 and 1.5 mg-Al/L, respectively. Bacteriophage Qβ removal at the optimal PACl dose was more than 6.7 log in all cases. The results of effect of different initial bacteriophage Qβ concentration on the removal efficiency showed that in-line coagulation with ceramic membrane at all pore sizes can completely remove bacteriophage Qβ when the initial concentration was low (5 x 105 PFU/ml). However, the higher initial bacteriophage Qβ concentrations (4 x 106 and 8 x 107 PFU/ml) required a higher PACl dose to obtain effective bacteriophage Qβ removal

Effects of Activated Carbon and Cationic Exchange Resin Pretreatments on Groundwater Defluoridation by Reverse Osmosis Process

The objective of this research was to study the effects of a pretreatment using activated carbon and cationic exchange resin on groundwater defluoridation by a reverse osmosis membrane. Actual groundwater containing a high fluoride concentration was collected and examined. Experiments were operated under controlled conditions: a transmembrane pressure of 0.6 MPa and temperature of 25 °C. The reverse osmosis system with activated carbon and cationic exchange resin pretreatments had higher fluoride removal than the one without the pretreatments, 97% compared to 95%, respectively. Additionally, the reverse osmosis system with the pretreatments also produced a higher permeate flux, 1.1 × 10-5 compared 9.6 × 10-6 m3/m2•s without the pretreatment. When the reverse osmosis systems with and without pretreatments were fouled, they showed a decrease in fluoride rejection, as well as a permeate flux decline. After the fouled reverse osmosis membranes were chemically cleaned, the permeate flux recovery and the fluoride rejection of the osmosis system with the pretreatments improved. It could be concluded that the activated carbon and cationic exchange resin played an important role in improving the reverse osmosis system as they contributed to high fluoride rejection and high permeate flux.The objective of this research was to study the effects of a pretreatment using activated carbon and cationic exchange resin on groundwater defluoridation by a reverse osmosis membrane. Actual groundwater containing a high fluoride concentration was collected and examined. Experiments were operated under controlled conditions: a transmembrane pressure of 0.6 MPa and temperature of 25°C. The reverse osmosis system with activated carbon and cationic exchange resin pretreatments had higher fluoride removal than the one without the pretreatments, 97% compared to 95%, respectively. Additionally, the reverse osmosis system with the pretreatments also produced a higher permeate flux, 1.1 x 10-5 compared 9.6 x10-6 m3/m2·s without the pretreatment. When the reverse osmosis systems with and without pretreatments were fouled, they showed a decrease in fluoride rejection, as well as a permeate flux decline. After the fouled reverse osmosis membranes were chemically cleaned, the permeate flux recovery and the fluoride rejection of the osmosis system with the pretreatments improved.  It could be concluded that the activated carbon and cationic exchange resin played an important role in improving the reverse osmosis system as they contributed to high fluoride rejection and high permeate flux

Efficiencies of NF and RO Membranes on Pharmaceutical Removal and Membrane Fouling Effects

The efficiencies of nanofiltration (NF) and reverse osmosis (RO) membranes in removing carbamazepine (CBZ) and sulfamethoxazole (SMX) were studied. To do this, the NF and RO membranes NF-1 and RO-1 were used, and the isoelectric points of the NF-1 and RO-1 membranes were determined to be at approximate pH of 6.0. The NF-1 membrane’s CBZ rejections at solution pH values of 5.0, 6.0, and 7.0 were in a slight range of 92-93%. Additionally, SMX rejections by the NF-1 membrane at the same three solution pH values were 87%, 91%, and 94%, respectively. Meanwhile, the RO-1 membrane’s CBZ rejections at those solution pH values were also in a narrow range of 92-94%, and its SMX rejections were 94%, 97%, and 98%, respectively. Solution pH was found to have no effect on CBZ rejection but it did affect SMX rejection. Mixed pharmaceuticals showed insignificant change in rejections compared with those of single pharmaceutical. The effect of membrane fouling on SMX removal was observed. It was found that when the membranes were fouled by tannic acid (TA) in the presence and absence of calcium chloride (CaCl2), the membrane’s rejection of SMX was improved.The efficiencies of nanofiltration (NF) and reverse osmosis (RO) membranes in removing carbamazepine (CBZ) and sulfamethoxazole (SMX) were studied. To do this, the NF and RO membranes NF-1 and RO-1 were used, and the isoelectric points of the NF-1 and RO-1 membranes were determined to be at approximate pH of 6.0. The NF-1 membrane’s CBZ rejections at solution pH values of 5.0, 6.0, and 7.0 were in a slight range of 92 - 93%. Additionally, SMX rejections by the NF-1 membrane at the same three solution pH values were 87%, 91%, and 94%, respectively. Meanwhile, the RO-1 membrane’s CBZ rejections at those solution pH values were also in a narrow range of 92 - 94%, and its SMX rejections were 94%, 97%, and 98%, respectively. Solution pH was found to have no effect on CBZ rejection but it did affect SMX rejection. Mixed pharmaceuticals showed insignificant change in rejections compared with those of single pharmaceutical. The effect of membrane fouling on SMX removal was observed. It was found that when the membranes were fouled by tannic acid (TA) in the presence and absence of calcium chloride (CaCl2), the membrane’s rejection of SMX was improved

Reduction of DBP Precursors and Their THMFPs in Leachate Contaminated Groundwater by PAC Adsorption

This research investigated the reduction of dissolved organic matter (DOM) fractions and their trihalomethane formation potentials (THMFPs) by powder activated carbon (PAC) adsorption. Leachate contaminated groundwater around an inactive open-dumping landfill was selected as the raw water. The PAC adsorption reaction was proven to be the pseudo second order kinetic reaction and the Freundlich isotherm. The dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and THMFP removals were 55%, 57%, and 73%, respectively. The hydrophobic (HPO) fraction exhibited a higher THMFP compared to the hydrophilic (HPI) fraction. The results of DOM fractionation show that the use of PAC adsorption produced an efficient 87% reduction of the HPO fraction, which is characterized as having a high reactivity toward THMFP

Trihalomethanes in Water Supply System and Water Distribution Networks

The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO2-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September–November 2019) and dry (December 2019–February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R2 = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 µg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard

Effects of Activated Carbon and Cationic Exchange Resin Pretreatments on Groundwater Defluoridation by Reverse Osmosis Process

The objective of this research was to study the effects of a pretreatment using activated carbon and cationic exchange resin on groundwater defluoridation by a reverse osmosis membrane. Actual groundwater containing a high fluoride concentration was collected and examined. Experiments were operated under controlled conditions: a transmembrane pressure of 0.6 MPa and temperature of 25 °C. The reverse osmosis system with activated carbon and cationic exchange resin pretreatments had higher fluoride removal than the one without the pretreatments, 97% compared to 95%, respectively. Additionally, the reverse osmosis system with the pretreatments also produced a higher permeate flux, 1.1 × 10-5 compared 9.6 × 10-6 m3/m2•s without the pretreatment. When the reverse osmosis systems with and without pretreatments were fouled, they showed a decrease in fluoride rejection, as well as a permeate flux decline. After the fouled reverse osmosis membranes were chemically cleaned, the permeate flux recovery and the fluoride rejection of the osmosis system with the pretreatments improved. It could be concluded that the activated carbon and cationic exchange resin played an important role in improving the reverse osmosis system as they contributed to high fluoride rejection and high permeate flux.The objective of this research was to study the effects of a pretreatment using activated carbon and cationic exchange resin on groundwater defluoridation by a reverse osmosis membrane. Actual groundwater containing a high fluoride concentration was collected and examined. Experiments were operated under controlled conditions: a transmembrane pressure of 0.6 MPa and temperature of 25°C. The reverse osmosis system with activated carbon and cationic exchange resin pretreatments had higher fluoride removal than the one without the pretreatments, 97% compared to 95%, respectively. Additionally, the reverse osmosis system with the pretreatments also produced a higher permeate flux, 1.1 x 10-5 compared 9.6 x10-6 m3/m2·s without the pretreatment. When the reverse osmosis systems with and without pretreatments were fouled, they showed a decrease in fluoride rejection, as well as a permeate flux decline. After the fouled reverse osmosis membranes were chemically cleaned, the permeate flux recovery and the fluoride rejection of the osmosis system with the pretreatments improved.  It could be concluded that the activated carbon and cationic exchange resin played an important role in improving the reverse osmosis system as they contributed to high fluoride rejection and high permeate flux

Trihalomethanes in Water Supply System and Water Distribution Networks

The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO2-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September–November 2019) and dry (December 2019–February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R2 = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 μg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard (<1.0) of WHO’s Guideline Values (GVs)