Feed Water Samples Research Articles

Crown ether functionalized silver nanoparticles for colorimetric detection of alkali earth metals in real boiler feed water samples

Crown ether functionalized silver nanoparticles for colorimetric detection of alkali earth metals in real boiler feed water samples

Evaluation of the Anti-Fouling Effects of Micro-Nano Bubbles on the Performance of Reverse Osmosis Membrane

Colloidal fouling on a brackish water reverse osmosis (BWRO) membrane was simulated by a lab-scale plate-and-frame module in the presence and absence of air micro-nano bubbles (AMNBs). Synthetic feed water samples with the same physical and chemical properties, but various concentrations of colloidal silica (50, 100, 200, and 300 mg/L), were used for experiments. The results illustrate that colloidal fouling caused a severe decrease in permeate flux (24%–56%) and salt rejection (1.25% to 4.18%) in the absence of AMNBs. This reduction in membrane performance was attributed to the high hydraulic resistance and the cake-enhanced osmotic pressure (CEOP) of a fouled gel layer that were intensified with increase in the colloidal concentration. On the other hand, presence of AMNBs decreased the deposition rate of colloidal particles significantly and increased the porosity of fouling layer. Thus, an improvement in the membrane permeate flux (21%–40%) and salt rejection (1.2%–2.6%) were seen in the different concentrations of colloidal particles. The SEM images also confirmed the formation of loose fouling layers which were easily removed from the membrane surface by a clean-in-place (CIP) process. This research introduces AMNBs technology as an effective in-line method to control the adverse effects of colloidal fouling in reverse osmosis (RO) systems.

Wastewater recycling in Antarctica: Performance assessment of an advanced water treatment plant in removing trace organic chemicals

The Australian Antarctic Division (AAD) operates Australia's Davis Station in the Antarctic. In 2005, Davis Station's wastewater treatment plant failed and since then untreated, macerated effluent has been discharged to the ocean. The objectives of this study were to determine whether an advanced water treatment plant (AWTP) commissioned by the AAD and featuring a multi-barrier process involving ozonation, ceramic microfiltration, biologically activated carbon filtration, reverse osmosis, ultraviolet disinfection and chlorination was capable of producing potable water and a non-toxic brine concentrate that can be discharged with minimal environmental impact. The AWTP was tested using water from a municipal wastewater treatment plant in Tasmania, Australia. We used spot water and passive sampling combined with two multi-residue chromatographic-mass spectrometric methods and a range of recombinant receptor-reporter gene bioassays to screen trace organic chemicals (TrOCs), toxicity and receptor activity in the Feed water, in the environmental discharge (reject water), and product water from the AWTP for six months during 2014–15, and then again for three months in 2016. Across the two surveys we unambiguously detected 109 different TrOCs in the feed water, 39 chemicals in the reject water, and 34 chemicals in the product water. Sample toxicity and receptor activity in the feed water samples was almost totally removed in both testing periods, confirming that the vast majority of the receptor active TrOCs were removed by the treatment process. All the NDMA entering the AWTP in the feed and/or produced in the plant (typically < 50 ng/L), was retained into the reject water with no NDMA observed in the product water. In conclusion, the AWTP was working to design, and releases of TrOCs at the concentrations observed in this study would be unlikely cause adverse effects on populations of aquatic organisms in the receiving environment or users of the potable product water.

Multi-barrier approach for removing organic micropollutants using mobile water treatment systems

The diversity of organic micropollutants (OMPs) in aquatic environments has been increasing rapidly during the last decade. Therefore, it is important to monitor and attenuate emerging contaminants before they can negatively affect the aquatic environment. However, due to the diversity and complexity of OMPs, there are limitations to using a single method for treating a combination of these pollutants. To address this issue, a mobile water treatment system (MWTS) equipped with different treatment units was designed to remove OMPs under field conditions. The MWTS was configured with various modular units including coagulation, flocculation, dissolved air flotation, membrane filtration, ozone oxidation, granular activated carbon, and UV disinfection. Each treatment unit could be operated either individually or in different combinations to identify the optimal configuration of treatment units for the removal of OMPs. To investigate the effectiveness of the MWTS, twelve OMPs were selected and introduced simultaneously into the feed water samples collected from different rivers throughout Korea. The current study proved that the MTWS is an effective solution to treat OMPs and is a time saving treatment system. The combined effects of the different treatment units removed over 99% of the selected OMPs, regardless of their physicochemical properties. Moreover, since the system is mobile, on-site analyses can be conducted to identify the most effective treatment method and configuration for each OMP.

Water quality of small-scale desalination plants in southwest coastal Bangladesh

AbstractSouthwest coastal Bangladesh has an acute scarcity of safe drinking water. Both the government and non-government organizations are now promoting reverse osmosis based small scale desalination plants (SSDPs) to ensure safe drinking water. The aim of this study was to assess the physico-chemical and bacteriological quality of the desalination plants (DPs) installed in southwest coastal Bangladesh. Water samples were collected from the inlet and outlet of 10 DPs. The product water mostly complied with water quality standards. High levels of total dissolved solids (TDS) and electrical conductivity (EC) in feed water were reduced significantly after the treatment, although 10% and 20% of the product water samples respectively did not comply with the WHO drinking water standards for those parameters. Compliance of product water with the WHO and Bangladesh drinking water standards for chloride, bicarbonate and sodium were found in respectively 80%, 90% and 70% of the samples, although their concentrations in all the feed water samples were higher than both of the standards. About one-third of the DPs did not meet the drinking water standard for sodium, which may be an important health concern for the people consuming this water. Apart from one of the DPs, all of them complied with the standard for faecal coliform and Escherichia coli. Results suggest that proper maintenance of the SSDPs is necessary to ensure safe drinking water for the coastal population of southwest Bangladesh.

Reverse osmosis as one-step wastewater treatment: a case study on groundwater pollution

Abstract The present case study is focused on performance evaluation of a Reverse Osmosis (RO) membrane based pilot plant to treat the ground/surface drinking water sources polluted by flood, rivers and/or canals. The RO plant was designed, fabricated and then operated with polluted water. Two feed water samples having a TDS of 2.000 mg · L−1 and 10.000 mg · L−1 respectively, were taken and analyzed for physical, chemical and microbiological contaminants. The RO plant was run once through over a span of 100 hrs at an operating pressure of 15 bar. TDS rejections were found to be more than 94% while permeate flux was measured to be 25.82 L · m−2 · hr−1 to 40.55 L · m−2 · hr−1. Results show that RO plant has a potential to remove physical, chemical and microbiological contaminants like Total Coliform and E. Coli in one step.

Rapid, specific and quantitative polymerase chain reaction (PCR) detection of pathogenic protozoa Entamoeba histolytica for drinking water supply

In this study, a quantitative species-specific polymerase chain reaction (PCR) method to rapidly detect E. histolytica in water is developed. First, the specificity of E. histolytica PCR detection was verified by using species-specific primers of 16S-like rRNA genes to clearly differentiate it from the closely related amoebae species E. dispar and E. moshkovskii. The sensitivity of this method was subsequently determined using purified E. histolytica genomic DNA and culture cells as PCR reaction templates. Results indicated that conventional PCR visualized on 1% agarose gel was able to detect as low as 0.02 pg genomic DNA and 5 cells, while real-time PCR could detect 0.01 pg genomic DNA and 2 cells of E. histolytica. The protocols for E. histolytica PCR detection in real water samples were then optimized by spiking E. histolytica cells into tap water and reservoir raw water samples. A two-round centrifugation treatment to concentrate amoeba cells directly as a PCR template was the most effective way to detect E. histolytica in spiked tap water samples, while DNA extraction after concentrating amoeba cells was required for spiked reservoir raw water samples. The detection limit of 50 E. histolytica cells in 100 ml tap water was achieved in 2 h from sample collection to real-time PCR data readout. With these established protocols, 78 tap water samples, 11 reservoir raw water samples and 4 feed water samples from Singapore water supply systems were analyzed by both conventional PCR and real-time PCR methods. No E. histolytica cell was detected in tested samples.

Effect of gold nanoparticle as a novel nanocatalyst on luminol–hydrazine chemiluminescence system and its analytical application

In this work the catalytic role of unsupported gold nanoparticles on the luminol–hydrazine reaction is investigated. Gold nanoparticles catalyze the reaction of hydrazine and dissolved oxygen to generate hydrogen peroxide and also catalyze the oxidation of luminol by the produced hydrogen peroxide. The result is an intense chemiluminescence (CL) due to the excited 3-aminophthalate anion. In the absence of gold nanoparticles no detectable CL was observed by the reaction of luminol and hydrazine unless an external oxidant is present in the system. The size effect of gold nanoparticles on the CL intensity was investigated. The most intensive CL signals were obtained with 15-nm gold nanoparticles. UV–vis spectra and transmission electron microscopy studies were used to investigate the CL mechanism. The luminol and hydroxide ion concentration, gold nanoparticles size and flow rate were optimized. The proposed method was successfully applied to the determination of hydrazine in boiler feed water samples. Between 0.1 and 30 μM of hydrazine could be determined with a detection limit of 30 nM.

High level of recovery of fungi from water and dialysate in haemodialysis units

The counts of yeasts and filamentous fungi were investigated in the municipal water supplies of haemodialysis centres, in the treated water and the dialysate from all 85 haemodialysis units in Greece, in order to estimate their occurrence, their correlation with contamination indicator bacteria and other influencing factors. Filamentous fungi and yeasts were isolated from 69 (81.2%) and from three (3.5%) feed water samples, from 74 (87.1%) and seven (8.2%) treated water samples and from 66 (77.7%) and 11 (12.9%) dialysate samples respectively. Aspergillus spp and Penicillium spp were the most frequent moulds, while Candida spp were the prevailing yeasts. The occurrence of yeasts was significantly higher in dialysate than in tap water samples. Counts of filamentous fungi in all 255 samples were significantly correlated with the counts of total heterotrophic bacteria and enterococci, whereas the counts of yeasts were correlated with faecal coliforms, total heterotrophic bacteria, as well as enterococci, Pseudomonas spp and total coliforms, while no correlation was detected with the age of either haemodialysis units, the age of water treatment system, the number of artificial kidney machines or the components of the water purification system. High recovery of fungi from haemodialysis aqueous environments implies a potential risk for haemodialysis patients and indicates the need for continuous maintenance and monitoring.