Drinking Water Purification Systems Research Articles

Removal of arsenic from aqueous solution using magnetic biochar derived from Spirulina platensis

Arsenic contamination in surface waters and groundwater affects millions of people on a daily basis. Oxidation of As(III) to less toxic As(V) is a widely used strategy to enhance the removal of As from solution. This study developed and evaluated a Fe-modified biochar (FeSP600). Spirulina platensis (SP) is one of the most promising microalgae because of its physicochemical properties and potential applications. The high N content of SP may affect the physicochemical properties of the biochar, which could be used as an inherent N source for N doping biochar by carbonization. After Fe modification, the formed Fe species and N-containing components of SP were used to introduce pyridinic N, which can be coordinated with Fe to form Fe-N. We demonstrated that the formed Fe species (Fe0, Fe2+ and Fe3+) and the defective structures in FeSP600 could act as active sites for surface catalytic reactions. FeSP600 not only had magnetic properties but also could effectively remove As from an aqueous solution. These properties were attributed to the release of Fe2+ and the reactive oxygen species (ROSs) generated by the γ-Fe2O3 particles on the crystalline defect structure. As(III) and As(V) removal were affected by the initial pH values. The removal efficiencies for As(III) increased from 57.2 % to 94.9 % as the pH increased from 3 to 9, whereas that for As(V) decreased from 80.1 % to 46.8 %. The presence of coexisting ions either completely (PO43−) or partially (Cl−, CO32− and SO42−) inhibited As removal. The removal of As(V) depended on electrostatic interactions, but As(III) removal was a complex process, including both oxidation and surface adsorption, as the ROSs were able to oxidize As(III) to As(V). Our study demonstrates that FeSP600 has properties that are beneficial for the removal of As(III) and As(V) from aqueous environments. The findings of this study have potential for real-world application in treating As-contaminated water sources, particularly in improving drinking water purification systems in developing countries. More importantly, an assessment of the impact of FeSP600 usage on aquatic ecosystems is required to ensure the safe application of this technology. Therefore, developing methods for mass production of FeSP600 is essential for the commercialization of this technology, necessitating process engineering studies in this area.

Particle and DBP removal efficiency and toxicity evaluation of polypropylene cotton filters in household drinking water purification systems

PCF could efficiently remove iron particles and DBPs to reduce toxicity risks.

A cross-reactive plasmonic sensing array for drinking water assessment

The continuous monitoring of remote drinking water purification systems is a global challenge with direct consequences for human and environmental health. Nanoplasmonic sensors can monitor treatment systems and warn of failures.

Impact of UV-C Irradiation on Bacterial Disinfection in a Drinking Water Purification System.

The supply of microbiological risk-free water is essential to keep food safety and public hygiene. And removal, inactivation, and destruction of microorganisms in drinking water are key for ensuring safety in the food industry. Ultraviolet-C (UV-C) irradiation is an attractive method for efficient disinfection of water without generating toxicity and adversely affecting human health. In this study, the disinfection efficiencies of UV-C irradiation on Shigella flexneri (Gram negative) and Listeria monocytogenes (Gram positive) at various concentrations in drinking water were evaluated using a water purifier. Their morphological and physiological characteristics after UV-C irradiation were observed using fluorescence microscopy and flow cytometry combined with live/dead staining. UV-C irradiation (254 nm wavelength, irradiation dose: 40 mJ/cm2) at a water flow velocity of 3.4 L/min showed disinfection ability on both bacteria up to 108 CFU/4 L. And flow cytometric analysis showed different physiological shift between S. flexneri and L. monocytogenes after UV-C irradiation, but no significant shift of morphology in both bacteria. In addition, each bacterium revealed different characteristics with time-course observation after UV-C irradiation: L. monocytogenes dramatically changed its physiological feature and seemed to reach maximum damage at 4 h and then recovered, whereas S. flexneri seemed to gradually die over time. This study revealed that UV-C irradiation of water purifiers is effective in disinfecting microbial contaminants in drinking water and provides basic information on bacterial features/responses after UV-C irradiation.

Risk Control Efficiency of Polypropylene Cotton Filters in Household Drinking Water Purification System Considering Discoloration Control

Risk Control Efficiency of Polypropylene Cotton Filters in Household Drinking Water Purification System Considering Discoloration Control

On-site H2O2 electro-generation process combined with ultraviolet: A promising approach for odorous compounds purification in drinking water system

The on-site generation of hydrogen peroxide (H2O2) attracts much attention for advanced oxidation processes (AOPs) in water treatment. In this work, we reported a novel on-site H2O2 generation reactor combined with ultraviolet (UV) for taste and odor (T&O) compounds removal in drinking water purification systems. The reactor is equipped with a gas diffusion electrode (GDE) accompanied by a proton-conducting solid electrolyte. In this reactor, GDE is used to improve the oxygen transfer efficiency. The porous solid electrolyte is selected for the proton and electron conduction instead of an electrolyte solution, which is crucial for producing pure H2O2 solution. The production rate and concentration of H2O2 can be controlled through adjusting the applied current efficiency and the flow rate of deionized water in a solid chamber. Meanwhile, this system exhibits long-term stability during a continuous operation for 96 h. For the application of the system, the single-cell was assembled into cell stacks, which improved the H2O2 concentration from 780.9 to 2301.3 mg·L−1, along with the energy consumption reduced from 23.81 to 6.67 kWh·kg−1 under the applied current density of 30 mA·cm−2. To evaluate the water purification performance of this system, the oxidation degradation of 2,4,6-trichloroanisoles (TCA) was conducted using the on-site H2O2 generation process under both static and dynamic flow conditions combined with UV light. The degradation rate of TCA was >95% with its initial concentration of 1 μg·L−1 under the hydraulic retention time from 10 to 40 min−1 and H2O2 dosage from 10 to 100 mg·L−1. Meanwhile, almost no residual H2O2 was detected after the degradation process. This study proposed a promising device for drinking water purification.

Evaluation of a Household Drinking Water Purification System Performance in terms of Organic – Inorganic Water Pollution Indicators and Ecological – Health Risk Assessment Indices

In this study, the performance of one of the most popular household drinking water purification systems (WPS) of Turkey was evaluated. Tap and purified water samples were taken from İpsala District (Thrace Region). A total of 23 significant water quality assessment parameters including essential and toxic metals (pH, TDS, EC, turbidity, Cl, NO3, SO4, PO4, BOD, COD, B, Al, Cr, Mn, Ni, Cu, Zn, As, Sr, Mo, Sb, Ba, Pb) were measured in water samples and how much the WPS improves these parameters were determined. Also Water Quality Index (WQI), Heavy Metal Pollution Index (HPI), Heavy Metal Evaluation Index (HEI), Nutrient Pollution Index (NPI), Cancer Risk (CR), Hazard Quotient (HQ) and Hazard Index (HI) were applied to data in order to assess the qualities of tap and purified water in terms of multiple effects of toxicants and possible risks of human health. As a result of this research, it was determined that the investigated WPS significantly improved the drinking water quality and significantly reduced the scores of applied ecological and health risk assessment indicators.

Producing and storing self-sustaining drinking water from rainwater for emergency response on isolated island

Drinking water on isolated islands includes treated rainwater, water shipped from the mainland, and desalinated seawater. However, marine transportation and desalination plants are vulnerable to emergencies, such as extreme weather, making self-sustaining stand-by water for emergency response essential. Rainwater is ideal for producing the stand-by water, and rainwater harvesting is sustainable and clean, and prolonged biostability can be ensured by managing biological and chemical parameters. The present study applied a stand-by drinking water purification system (primarily including nanofiltration and low-dose chlorination) to explore the feasibility of producing and storing cleaner drinking water from rainwater and the following conclusions were drawn. First, treatment of rainwaters ensures biosafety for seven days, which is longer than that for untreated rainwater; the proportion of opportunistic pathogens decreased from 23.40–7.77% after nanofiltration, and it was proposed that the microbial community converges after advanced water treatment. Second, chemical qualities were improved. Local resource coral sand prevents pH in rainwater from decreasing below 6.5, and treated rainwater had lower disinfection by-product potential and higher disinfection efficiency, allowing periodical rainwater recycling. Third, harvesting rainwater was extremely cost-effective, with an operation cost of 1.5–2.5 RMB/m3. From biosafety, chemical safety, and economic cost perspectives, self-sustaining water from rainwater can contributes to the development of sustainable and cost-effective water supply systems on isolated islands. Mixing treated rainwater and desalinated seawater reasonably guarantees sufficiency and safety.

Adsorptive performance of activated carbon reused from household drinking water filter for hexavalent chromium-contaminated water

Powdered activated carbon blocks (PACBs) are waste products obtained from household drinking water purification systems. In this study, we demonstrate that they can be used as adsorbents for the cost-effective and environmentally benign removal of hexavalent chromium (Cr(VI)) from contaminated-water and rinse electroplating wastewater. To evaluate Cr(VI) sorption onto the PACB, studies on equilibrium, kinetics, and thermodynamics were performed using batch mode experiments. The experimental results indicated that Cr(VI) ions were efficiently adsorbed under acidic conditions (i.e., at initial pH below 3) and low initial Cr(VI) concentrations. The adsorptive behaviors of the PACB for Cr(VI) were well explained by the Langmuir isotherm, as well as pseudo-second-order kinetic models, suggesting that a Cr(VI) monolayer was adsorbed onto the PACB surface via chemisorption. The maximum adsorption capacity of Cr(VI) onto the PACB was determined to be 6.207 mg/g. The results of thermodynamic studies revealed that the adsorption process of Cr(VI) onto PACB was endothermic and non-spontaneous. Additionally, analysis of the PACB after Cr(VI) adsorption at an initial pH of 2 using scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) revealed that the interaction between the surface oxygenic functional groups on the PACB and Cr(VI) was primarily responsible for Cr(VI) sorption via surface complexation and electrostatic interactions. Based on the result of XPS analysis, the presence of trivalent chromium on the PACB surfaces indicated that some synergistic redox reactions involving Cr(VI) could have occurred during the sorption process. Although a commercially available powdered activated carbon outperformed the PACB adsorbent with respect to Cr(VI) removal from wastewater, complete Cr(VI) adsorption could be achieved using relatively large quantities of the PACB. These findings indicate that the PACB adsorbent could be used as a cheap and efficient material for the removal of Cr(VI) from wastewater.

Tapping Out: Influence of Organoleptic and Perceived Health Risks on Bottled Versus Municipal Tap Water Consumption Among Obese, Low Socioeconomic Status Pediatric Patients.

A variety of endocrine disrupting chemicals (EDCs), including some known to be obesogenic, can be found in household wastewater. Many are only partially treated by wastewater treatment and drinking water purification systems and can enter municipal drinking water supplies. We evaluated drinking water consumption habits in a cohort of obese pediatric patients to determine the percentage that might avoid exposure to EDCs from drinking municipal tap water. Obese (BMI ≥ 95th percentile) children presenting to an obesity clinic serving a largely poor and rural population were studied. Self-reported race/ethnicity, insurance status and details concerning type and volume of water consumed were obtained from their medical records. Most homes were supplied with municipal, rather than private well water (90.6% vs. 9.4%, respectively). A majority (76.4%) of patients with municipal water as their water supply only drank bottled water. "Taste" and "Health Concerns" were the most commonly endorsed reasons for eschewing tap water. Bottled water consumption among low socioeconomic status patients may reduce their risk for exposure to EDCs in municipal tap water. Further studies are needed to confirm the generalizability of this observation.

Characterization of the bacterial community composition in water of drinking water production and distribution systems in Flanders, Belgium.

The quality of drinking water is influenced by its chemical and microbial composition which in turn may be affected by the source water and the different processes applied in drinking water purification systems. In this study, we investigated the bacterial diversity in different water samples from the production and distribution chain of thirteen drinking water production and distribution systems from Flanders (Belgium) that use surface water or groundwater as source water. Water samples were collected over two seasons from the source water, the processed drinking water within the production facility and out of the tap in houses along its distribution network. 454‐pyrosequencing of 16S ribosomal RNA gene sequences revealed a total of 1,570 species‐level bacterial operational taxonomic units. Strong differences in community composition were found between processed drinking water samples originating from companies that use surface water and other that use groundwater as source water. Proteobacteria was the most abundant phylum in all samples. Yet, several phyla including Actinobacteria were significantly more abundant in surface water while Cyanobacteria were more abundant in surface water and processed water originating from surface water. Gallionella, Acinetobacter, and Pseudomonas were the three most abundant genera detected. Members of the Acinetobacter genus were even found at a relative read abundance of up to 47.5% in processed water samples, indicating a general occurrence of Acinetobacter in drinking water (systems).

Energy efficient drinking water purification system using TiO2 solar reactor with traditional methods

Waterborne diseases are a major health threat in India. The cost of various water purification systems is also high and need a considerable amount of fuel (wood, LPG etc.) or electrical energy to purify them. Keeping this and the rise in conventional energy prices in mind, we designed an experimental drinking water purification system that makes use of solar energy to purify the biological contaminants that are present in the drinking water. For this nano-Titanium Dioxide (TiO2) coated acrylic tubes are used. By attaching a number of such tubes in parallel connection, a reactor system is constructed. This reactor when exposed to sunlight, with the contaminated water passing through a photocatalytic activity takes place killing the micro-organisms present in the water. Along with this a slow sand filter, a cascaded aeration system and a charcoal filter is introduced to remove turbidity, harmful dissolved gases and heavy metals present in the water. The purification system is used to purify water for drinking purpose and is fixed on rooftops for exposure to sunlight. In this paper, purification of water in the solar reactor for different light intensities and water flow rate is studied. This experimental setup is easily installed in both rural and urban households.

Technological Innovation in the Area of Drinking Water for Treatment of Saline Water

The research paper reviews different types of desalination technologies for drinking water and the innovation in conventional drinking water purification systems for inland and sea water salinity. It also provides the updated status of salinity problem in India and attempts to document field experiences in tackling desalination problem for the benefit of the people with scientific approach.

A Simple and Semi-Empirical Model to Predict THMs Generation in Water Facilities Including pH Effects

Abstract This work presents a study focused on the development of a simple useful tool to predict the generation of trihalomethanes in drinking water purification systems, using two precursors and trichloromethane as model compounds through a simple chlorine decay model. This work proposed a semiempirical model without adjustable power parameters where fast and slow stages and the effect of pH were included. Despite that the model is not based in a complete kinetic scheme, using the proposed equations it is possible to predict the simultaneous evolution of chlorine and TCM with a set of linear kinetics parameters which characterize the system and will be obtained using simple routine laboratory measurements. The results show that both TCM formation and chlorine decay are strongly dependent on the chemical nature of the model precursor. Although resorcinol and phenol have different reactivity with chlorine and represent different functional groups which are present in natural compounds, the TCM generation appears to be properly described in both cases by the total chlorine consumption. Considering that during the potabilization processes the pH changes, the study of the effects of this variable is very important to achieve the minimization of THMs generation. The pH has a significant effect on the time evolution of chlorine-substituted hydroxybenzene intermediates and therefore on the TCM formation, since the properties of the reacting species are directly affected by the reaction medium for their participation in the different reaction paths. The study of the distribution and selectivity of the intermediate species allowed explaining the results obtained for the kinetics of formation of TCM. The results suggest that in order to understand the effect of pH, the nature of oxidation of HOCl and ClO‒, should be considered simultaneously with the electronegative nature of the precursor compounds. Finally, in terms of minimizing the generation of THM it is important to consider the potential impact of pH changes within the water treatment process and supply and the stages where chlorination may be carried out.

Evaluation of source water quality for selection of drinking water purification system

When renewing water purification facilities, it is important to select a suitable purification system that can accommodate the quality of the respective source water. The Japan Water Research Center has been collecting a large amount of water quality data from drinking-water utilities across Japan, categorising and analysing these data, and evaluating the suitability of water purification processes. Multivariate analyses such as hierarchical cluster analysis and principal component analysis were performed to investigate the relationships between the quality of source water used for water supply and various factors that affect the purification process. Based on these results, water sources throughout Japan were clearly categorised into four groups, and suitable water purification systems were identified for the different water quality groups. The results can serve as an important reference for water utilities during future facility renewal projects.

Problems of drinking water treatment along Ismailia Canal Province, Egypt

The present drinking water purification system in Egypt uses surface water as a raw water supply without a preliminary filtration process. On the other hand, chlorine gas is added as a disinfectant agent in two steps, pre- and post-chlorination. Due to these reasons most of water treatment plants suffer low filtering effectiveness and produce the trihalomethane (THM) species as a chlorination by-product. The Ismailia Canal represents the most distal downstream of the main Nile River. Thus its water contains all the proceeded pollutants discharged into the Nile. In addition, the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year. Moreover, the wide industrial zone along the upstream course of the canal enriches the canal water with high concentrations of heavy metals. The obtained results indicate that the canal gains up to 24.06x10(6) m3 of water from the surrounding shallow aquifer during the closing period of the High Dam gates, while during the rest of the year, the canal acts as an influent stream losing about 99.6x10(6) m3 of its water budget. The reduction of total organic carbon (TOC) and suspended particulate matters (SPMs) should be one of the central goals of any treatment plan to avoid the disinfectants by-products. The combination of sedimentation basins, gravel pre-filtration and slow sand filtration, and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC, SPM and heavy metals. Moreover, it reduces the use of disinfectants chemicals and lowers the treatment costs. However, this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application.