Showing papers in "Journal of Water and Environment Technology in 2016"

Halogenated Polycyclic Aromatic Hydrocarbons in Soil and River Sediment from E-waste Recycling Sites in Vietnam

Abstract: We have determined halogenated polycyclic aromatic hydrocarbons (XPAHs) in 40 samples of surface soil (n = 32) and river sediment (n = 8) collected around the E-waste recycling area in Bui Dau, northern Vietnam. Thirty-one target compounds including 21 chlorinated PAHs (ClPAHs) and 10 brominated PAHs (BrPAHs) were quantified by gas chromatography-high resolution mass spectrometry (HRGC-HRMS). The highest concentrations of XPAHs in surface soils (3,960 pg/g dry wt) and river sediments (3,930 pg/g dry wt) were detected from samples near an open burning site and an E-waste recycling workshop. Composition ratios of BrPAHs to total XPAHs in this study were higher than those in fly ash of waste incinerators (12% and 29%), because E-waste in this study contained a large amount of brominated flame retardants (BFRs). These results suggested that XPAHs occurred in Ewaste recycling activities and they contaminated the surrounding soil and sediment. A large number of peaks of unidentified isomers of XPAHs, such as XnPhe/Ant (n = 1 − 4) were observed based on the isotope patterns of molecular ions [M, M+2, M+4] by HRGC-HRMS analyses. These unidentified isomers should be an important factor in the risk assessment for XPAHs.

Recent Developments in Electrochemical Technology for Water and Wastewater Treatments

Abstract: This paper presents the recent attention in scientific studies and development of electrochemical processes. Electrochemical technology has contributed significantly to the purification of water for better human health and aquatic life forms. In this study, we emphasize the developmental trends of electrochemical technologies, their applications, and recent developments in the context of water and wastewater treatments. Recent studies have made great advances in investigating and optimizing advanced electrochemical oxidation processes in treatment of various organic pollutants, reduction of halogenated contaminants, and disinfection of microorganisms. Besides, electrochemical oxidation processes have been combined with other treatment methods to enable their practical application. Excellent electro-catalytic treatment of contaminant and their by-products was achieved through the application of mixed metal oxides (PbO2, SnO2, Ti/RuO2, etc.), Pt, and boron-doped diamond (BDD) electrodes. Several studies have focused on selective removal of trace pollutants in a complex matrix. These studies have shown the possibility of removing target pollutants with relatively low energy consumption. It can be concluded that enhancement of treatment performance of the present technologies will contribute to a wider application of electrochemical processes in water and wastewater treatment.

Biological 1,4-dioxane wastewater treatment by immobilized Pseudonocardia sp. D17 on lower 1,4-dioxane concentration.

Abstract: Biological 1,4-dioxane removal performance using newly isolated Pseudonocardia sp. D17, which can utilize 1,4-dioxane as the sole carbon source, was evaluated. A low level of influent 1,4-dioxane, at 5–50 mg/L, was treated to meet the Japanese effluent standard of 0.5 mg/L. The gel entrapment technique was used for immobilization of Pseudonocardia sp. D17 so that it is not washed out from the bioreactor under a short hydraulic retention time. Consequently, an average effluent 1,4-dioxane concentration of 0.49 mg/L was achieved at a loading rate of 0.096 kg dioxane/(m3 · d) with an influent 1,4-dioxane concentration of 50 mg/L. The startup of the bioreactor was observed at 25°C within 2 weeks. Moreover, the effluent 1,4-dioxane concentration of 0.38 mg/L on an average was confirmed at a loading rate of 0.060 kg dioxane/(m3 · d), even though the operating temperature was 15°C. The temperature effect on 1,4-dioxane removal activity was characterized on the batch experiment. The maximum 1,4-dioxane removal activity was observed at 33.9°C. Moreover, 1,4-dioxane removal activity was observed even at 7.4°C, although that was decreased to 27% compared with that at 25°C. The activation energy for 1,4-dioxane removal by Pseudonocardia sp. D17, representing the temperature dependency, was calculated as 51.9 kJ/mol.

Chlorine Dose Determines Bacterial Community Structure of Subsequent Regrowth in Reclaimed Water

Abstract: Bacterial regrowth in reclaimed water, specifically observed when residual chlorine concentration declines along the distribution system, causes undesirable changes in water quality and hampers its acceptability. To study the impact of chlorination on regrowth and bacterial community structure, unchlorinated tertiary treated reclaimed water was collected and dosed with chlorine such that the initial doses were 1, 3, 5 mg-Cl2/L before being stored at ambient temperature under dark condition. Chlorine measurement, cell counts and bacterial community profiling were carried out at regular intervals for 21 days. Addition of chlorine caused rapid decline in intact cell concentration and no regrowth was observed until free chlorine decayed below detection limit (0.03 mg-Cl2/L). Upon regrowth, intact cell concentrations reached the initial level except in the case of 5 mg-Cl2/L where the intact cell concentration was lower by 1-log10. The dominant species that regrew under each condition were distinct, based on their capacity to withstand chlorine. The most chlorine-tolerant groups belonged to the order Sphingomonadales and Rhizobiales, which have been previously reported to initiate biofilms. This study demonstrates that chlorination selects specific bacterial groups which have the potential to regrow in the distribution network.

Prevalence of Protozoa and Indicator Bacteria in Wastewater Irrigation Sources in Kathmandu Valley, Nepal: Cases from Kirtipur, Bhaktapur, and Madhyapur Thimi Municipalities

Abstract: Wastewater irrigation using sewage and water from polluted sources is widespread in Kathmandu Valley, Nepal. Data on the prevalence of pathogens in irrigation sources are important for assessing the health risks for both farmers and consumers. In this study, 13 and 15 water samples were collected during the rainy (September 2014) and dry (April 2015) seasons, respectively, from irrigation sources [river water (n = 17), sewage (n = 5), pond water (n = 3), canal water (n = 1), and effluent of a wastewater treatment plant (WWTP; n = 2)] in Kathmandu Valley. Based on fluorescence microscopy, all the analyzed samples (n = 19) tested positive for Giardia, whereas 68% tested positive for Cryptosporidium. In addition, indicator bacteria (Escherichia coli and total coliforms) were detected in all samples (n = 28), with significantly higher concentrations during the dry season than during the rainy season (t-test, p < 0.05). Indicator bacteria and protozoan concentrations were abundant in sewage and river water samples and comparatively less in the remaining samples. Positive correlations between indicator bacteria and protozoa concentrations suggested that E. coli and total coliforms could be considered as rough indicators of protozoa contamination of wastewater irrigation sources.

Effects of pH and oxygen on phosphorus release from agricultural drainage ditch sediment in reclaimed land, Kasaoka Bay, Japan.

Abstract: Agricultural farms are considered to be non-point sources of phosphorus (P) loads to rivers and lakes. Sediment can act as a source or sink of P under different environmental conditions. Inorganic P is the major form, and is a very useful indicator to evaluate the potential release of P in sediment. This study aimed to evaluate the effects of pH and aerobic/anaerobic conditions on P release from sediment by the changes of P fractions before and after incubation. Sediment samples were collected from a drainage ditch of a livestock farm on reclaimed land in Kasaoka Bay, Japan. Experiments were conducted in a 200-mL glass serum bottle with 8 – 10 g fresh sediment and 100 mL of 0.02 M KCl solution, adjusted to pH 4, 7, or 10, and incubated under aerobic or anaerobic conditions. Phosphorus was released under both aerobic and anaerobic conditions until day 5. The amount of P released under anaerobic conditions increased continuously towards day 10 while that under aerobic conditions decreased after day 5 to the end of experiment (p < 0.05). Thus, sediment acted as a sink of P under aerobic conditions and as a source of P under anaerobic conditions. Sediment fractionations indicated that loosely sorbed P (loosely-P) and iron-bound P (Fe-P) fractions were the main sources of P released to the overlying water. The amount of P released from sediment at acidic pH was higher than that at neutral or alkaline pH under anaerobic conditions (p < 0.05). However, under aerobic conditions, the amount of P release was higher at alkaline pH than that at acidic or neutral pH (p < 0.05).

Application of Modified Tank Model to Simulate Groundwater Level Fluctuations in Kabul Basin, Afghanistan

Abstract: Groundwater management is a significant task to have sustainable groundwater sources in Afghanistan especially in Kabul Basin. In this study, the groundwater level fluctuation simulation and forecast by a traditional tank model, snow tank + traditional tank model (S + traditional tank), combined tank model and snow combined tank model (SC-tank model) were compared. The variables (precipitation, groundwater level, temperature and evaporation) were utilized to simulate and forecast groundwater level fluctuations at a representative observation well (CKB1-W) in Kabul Basin from 2005 to 2013. Shuffled Complex Evolution-University of Arizona (SCE-UA) algorithm was utilized to find the best parameter for the models. Accuracy of model estimation was evaluated by coefficient of determination, Nash-Sutcliffe efficiency (NSE) coefficient and root-mean-square error (RMSE). Consequently, the SC-tank model provided the most accurate result in simulation and forecast of groundwater level fluctuations at the representative observation well in Kabul Basin. The result indicated that the SCtank model constructed in this study could be applied for groundwater management in Kabul Basin, Afghanistan.

Inactivation Kinetics of Indicator Microorganisms during Solar Heat Treatment for Sanitizing Compost from Composting Toilet

Abstract: This study aimed to estimate the sanitization effectiveness of compost by solar heating. Compost produced from composting toilet was inoculated with Escherichia coli, Enterococcus faecalis and Ascaris eggs and subjected to solar heating. The heating was performed by direct exposure of compost to sun and in a solar box. From treated compost, the number of isolated bacteria was determined by plating method and the number of Ascaris eggs was determined by microscopy counting. The inactivation kinetics of microorganisms were modeled using nonlinear regression software tool. The result showed that the temperature regime produced by direct sunlight and solar box during heating were categorized as mesophilic (> 30°C) and pasteurization (> 70°C), respectively. The log reduction of microorganisms in heated compost by solar box was significantly higher than that of direct sunlight. The inactivation rate was slow in compost heated by the sun but fast in compost heated by solar box. Escherichia coli appears to be the most sensitive to destruction temperatures achieved by solar heating. The thermal decimal decay occurred rapidly in solar box while it was prolonged with the direct sunlight. The high and uniform temperature distribution obtained with solar box during heating proved to be an efficient option for safe use of compost.

Application of the Alkaline-Digestion-HPLC Method to the Rapid Determination of Polyhydroxyalkanoate in Activated Sludge

Abstract: A new method for analyzing polyhydroxyalkanoate (PHA) in activated sludge based on alkaline digestion followed by high-performance liquid chromatography (HPLC) was evaluated. The effects of the concentration of NaOH, reaction time, and reaction temperature were examined using activatedsludge samples containing PHA and commercially purchased PHA. To determine PHA concentrations, 0.5 mL 2 N NaOH was added to 1 mL activated-sludge mixed liquor, and the resulting mixture was heated at 105°C in a drying oven for 1 h to convert 3-hydroxybutyrate units into 2-butenoate and 3-hydroxyvalerate units into 2-pentenoate. The mixture was then acidified with 0.5 mL of 2 N H2SO4, and the solids were removed and subsequently analyzed by HPLC. The present method gave results consistent with those obtained by the conventional method of methanolysis followed by gas chromatography. The present method can facilitate investigations of PHA in activated sludge by reducing the time and labor required for analysis and by eliminating the use of organic solvents.

Ammonia Stripping from High Ammonia-Containing Wastewater by Downflow Hanging Sponge (DHS) Reactor

Abstract: Laboratory-scale experiment was conducted to evaluate ammonia removal from high ammoniacontaining wastewater by downflow hanging sponge (DHS) reactor used as ammonia stripping system. Synthetic deproteinized natural rubber wastewater was used for the experiment. The synthetic wastewater contains 0.2% (v/v) of ammonia and 0.1% (w/v) of urea with 10 − 11 of pH. Total volume of the DHS reactor was 5.6 L (1.7 m of height) including 1.4 L of sponge media. The experiment was conducted with 0.8 − 3.3 days of hydraulic retention time (HRT) and at ambient temperature. Based on the results of the experiment, the DHS reactor achieved 60.3% of ammonia removal with 3.3 days of HRT. In the DHS reactor, ammonia concentration and pH decreased from 1,620 to 650 mgN/L and from 10.4 to 8.1, respectively. The decrease of ammonia after 72 cm depth of the reactor was not observed. Furthermore, nitrate was confirmed in the DHS effluent corresponding approximately to 2 − 6% of removed ammonia. Therefore, it is indicated that ammonia stripping by DHS reactor can be applied as pre-treatment system for high ammonia-containing wastewater.

Distribution of Enterotoxin Gene-positive Clostridium perfringens Spores among Human and Livestock Samples and its Potential as a Human Fecal Source Tracking Indicator

Abstract: In this study, to evaluate whether Clostridium perfringens could be a useful fecal indicator in aquatic environments and could be employed as a potential source-tracking indicator, the distribution of C. perfringens spores and their toxin types in sewage and livestock fecal samples were analyzed. A total of 804 C. perfringens spore isolates (366 from human-related sewage and effluents, 128 from cattle, 129 from pigs, 72 from chicken, and 109 from abattoir wastewaters) were analyzed using multiplex polymerase chain reaction (PCR) to detect six C. perfringens toxin genes. On the basis of the presence of toxin genes, most of the isolates from both human sewage and livestock samples were determined as C. perfringens type A and they expressed cpa alone or cpa and C. perfringens enterotoxin (cpe) with or without cpb2. Moreover, cpe-positive C. perfringens was detected with frequencies of 29% and 32% in human sewage and effluents, respectively. However, only one isolate (from cattle feces) was cpe-positive among all the livestock samples tested. Thus, the distribution of cpe-positive C. perfringens should be considered an important source tracking indicator for human fecal pollution. Furthermore, we conclude that sewage effluents are a significant source of cpe-positive C. perfringens pollution.

Treatment of Saline Wastewater by Thermophilic Membrane Bioreactor

Abstract: The treatment of saline wastewater containing oil and organic matter of different biodegradability was examined for 35 days using a laboratory-scale membrane bioreactor (MBR) at a thermophilic condition (50°C). The performances were compared with those of a room-temperature reactor. The removal of COD was comparable for the two reactors. The half-life of mineral oil (C15 − C22 alkanes) was around 3 hours in the reactor. However, the operation at high temperature condition decreased the removal of dark brown (melanoidin) color from 58% to 44%. The fouling of the membrane was more severe for the thermophilic reactor. The room-temperature reactor maintained a volume flux of 0.22 m/day, while keeping the volume flux at the same level was difficult for the thermophilic reactor. It was suggested that lower flux operation of the membrane and worse effluent quality have to be considered, if high-temperature operation is required.

Characterizing Dissolved Organic Matter from Cattle Slurry in Kushiro River Water Using EEM-PARAFAC

Abstract: We applied excitation emission matrix-parallel factor analysis (EEM-PARAFAC) technique to ascertain the fluorophore group indicating fecal pollution from the complex nature of dissolved organic matter (DOM) in surface water of Kushiro River Basin. Covariation between relative concentrations of identified fluorophore groups and specific steroid profiles were analyzed to produce an alternate classical steroid indicator of fecal pollution by the identified fluorophore group. The fluorophore, showing fluorescent characteristics similar to those of the indole ring structure of tryptophan, was found from cattle slurry. The maximum fluorescence intensities (Fmax) of the fluorophore showed seasonal and spatial distribution similar to that of coprostanol (5β), which is known as indicator of fecal pollution. The fluorophore was widely detected in surface water of Kushiro River Basin collected from autumn through the following spring, after application of cattle slurry to pastureland. In this case, Fmax of the fluorophore showed good correlation with 5β, while during fall through spring, it is useful similar to 5β. Composition of 5β in fecal sterols is specific to the type of domestic animal. Correlation between 5β and Fmax of the fluorophore holds only in a basin that has the DOM sources of breeding beef and dairy cattle such as Kushiro River Basin.

Decomposition of Pesticides in Water through the Use of a Slurry-Type TiO2 Water Treatment Apparatus

Abstract: A newly developed slurry-type titanium dioxide (TiO2) photocatalyst has been applied to the decomposition of pesticides in water. This photocatalyst is composed of the TiO2 nanoparticles deposited on the surface of a zeolite. Kinetic studies were performed on the photocatalytic decomposition using atrazine as the model pesticide. Reaction rate constants of 0.123, 0.161, and 0.512 min−1 for the TiO2 concentrations in the TiO2/zeolite complex of 0.025, 0.050, and 0.250 g/L, respectively, were obtained using an ultraviolet light source of 1 mW/cm2 at a wavelength of 350 nm. This showed that as the concentration of the TiO2 particles increased, the reaction rate constant also increased. In the prototype apparatus study, the concentration of atrazine in the treated water was maintained at 10 μg/L. Bubbling oxygen in the photoreactor was found to facilitate the decomposition of pesticides, indicating that the diffusion of oxygen gas on the TiO2 surface is the rate-determining step in the overall reaction process. The electric energy per order (EEO) under high oxygen concentration was 0.159 kWh/m3/order, which is comparable to other treatment methods.

Phosphate Recovery from Synthetic Urine with Shell of Mizuhopecten yessoensis

Abstract: ABSTRTRACT Calcium phosphate can precipitate from phosphate in urine and calcium carbonate, which is the main component of Mizuhopecten yessoensis shells. Precipitation tests, analyses of SEM-EDS and XRD were carried out to study the formation of calcium phosphate from the shells and synthetic urine, to identify the products, and to investigate the effect of operation conditions on the form of the obtained products. Two precipitation processes were observed at low Ca/P and at high Ca/P ratios. The former involved an increase in pH and a decrease in concentrations of phosphate and calcium to form dicalcium phosphate dihydrate (DCPD), while the latter involved three steps: 1. a rapid increase in pH and a decrease in the concentrations of phosphate and calcium to form DCPD, 2. a decrease in pH and an increase in the phosphate concentration, causing to change the crystal structure into poorly crystallized apatite, and 3. an increase in pH. The observations of the particle surface by SEM-EDS and powder XRD analysis of precipitates were consistent with these phenomena. Elemental analysis of the cross section of particles showed that the reaction that formed calcium phosphate started from the particle surface and then progressed to inside the particles.