Drinking Water Treatment Technologies Research Articles

Application of Ozone-BAC process in advanced treatment of drinking water and sewage

With the increasing pollution of water sources and the improvement of Drinking Water Regulations, the conventional treatment technology can no longer meet the needs of the people. It is increasingly necessary to adopt advanced drinking water treatment technologies. Ozone-BAC process (O3-BAC) is a new type of process to treat slightly-polluted source water efficiently, catalysts and oxidants preparation of which are simple and efficient. It can remove turbidity, odor and color from the water, to improve the effect of flocculation as well as the taste; it can also remove hard-to-degrade and soluble organics; can achieve the indicators of circulating water, with good application prospects. This article analyzes the operation status of ozone-BAC process in water treatment process, proposes the problems of the technology in water treatment process and discusses its future development.

Pilot-scale iron electrocoagulation treatment for natural organic matter removal

ABSTRACTThe efficacy of electrocoagulation at a pilot-scale as an alternative drinking water treatment technology to conventional coagulation is explored. A novel reactor was integrated into a pilot plant at the surface water supply of a small, remote community. Using iron anodes, the effect of metal loading (ML), current density and inter-electrode gap on the reduction of natural organic matter (NOM) was studied. Dissolved organics were characterized by large fractions of low molecular weight (<750 Da) hydrophilic carbon structures with lower charge density. A greater reduction in UV254 was yielded compared to dissolved organic carbon, indicating better removal of larger molecular weight fractions of NOM. As ML dosages increased from 27.8 to 60.8 mg/L, specific ultraviolet absorbance decreased from 1.92 ± 0.14 to 1.60 ± 0.10 L/m•mg respectively, from an initial raw water value of 2.21 L/m•mg. No clear trend was observed for the effect of current density and inter-electrode gap for NOM, however ML was the primary variable dictating the process’ effectiveness. Energy requirements were observed to vary greatly and were highly dependent on ML, current density and inter-electrode gap; variables that all effect the operating potential and resistance. In general, conditions that yielded the greatest reduction of NOM, a 1 mm gap and 4-cell configuration, had energy requirements between 0.480 and 0.602 kWh/m3 of water treated.

Synthesis, Characterization of Nanosized ZnCr2O4 and Its Photocatalytic Performance in the Degradation of Humic Acid from Drinking Water

Zinc chromite (ZnCr2O4) has been synthesized by the thermolysis of a new Zn(II)-Cr(III) oxalate coordination compound, namely [Cr2Zn(C2O4)4(OH2)6]·4H2O. The coordination compound has been characterized by chemical analysis, infrared spectroscopy (IR), and thermal analysis. The zinc chromite obtained after a heating treatment of the coordination compound at 450 °C for 1 h has been investigated by XRD, FE-SEM, TEM/HR-TEM coupled with selected area electron diffraction (SAED) measurements. The photocatalytic performance of nanosized zinc chromite was assessed for the degradation and mineralization of humic acid (HA) from a drinking water source, envisaging the development of the advanced oxidation process for drinking water treatment technology. A mineralization efficiency of 60% was achieved after 180 min of 50 mg L−1 HA photocatalysis using zinc chromite under UV irradiation, in comparison with 7% efficiency reached by photolysis.

KONDISI KUALITAS AIR SUMUR PENDUDUK DI WILAYAH GENANGAN SEMBURAN LUMPUR SIDOARJO

Sidoardjo mudflow has been occuring since 2006. This disaster is the first incident in Indonesia which has such a broad impact, like the settlements, fields, roads and other buildings submerged, resulting in enormous losses. Besides damaging the existing infrastructure in the area, the mud flow is also causing environmental damage, particularly contamination of ground water community. To find out how much the impact of the mud flow to the water quality community, carried out observations and surveys of well water quality conditions of the communities around the location of the mud puddles. In this paper provided an alternative drinking water treatment technology can be applied in this area. Keywords: Lapindo mud, environmental degradation, pollution of well water quality, alternative water treatment technologies

Chlorination and ozonation reduce microcystin content and tumour promoting activity of complex cyanobacterial extract

&lt;p&gt;Despite intensive research and management efforts in the past decades, cyanobacterial blooms and their toxins, such as microcystins (MC), continue to represent a major ecological and health problem in fresh waters throughout the world. Our objective was to compare the efficacy of two commonly used drinking water treatment technologies, chlorination and ozonation, in removing MCs and in reducing tumour promotion-related effects of cyanobacteria&lt;em&gt;,&lt;/em&gt; such as inhibition of gap junctional intercellular communication (GJIC) and activation of mitogen activated protein kinases (MAPKs) in a pluripotent rat liver epithelial cell line (WB-F344). This combined chemical and bioassay approach demonstrated that ozone effectively removed all MCs from an extract of globally important bloom-forming cyanobacterium, &lt;em&gt;Microcystis&lt;/em&gt; sp. Ozone also significantly reduced the overall tumour promotional potency of the cyanobacterial extract, as indicated by a substantial reduction in the ability of the extract to inhibit GJIC and activate extracellular receptor kinase 1/2 (ERK1/2). Although comparable reduction of total organic carbon was achieved by ozone and chlorine treatment, chlorination was much less effective in removing MCs and reducing the effects on GJIC. Chlorination had a biphasic effect with reduction of extract-induced activation of ERK1/2 at lower doses of chlorine; at high doses of chlorine, however, the by-products of chlorination actually induced the activation of ERK1/2. The extracts induced p38 activation and chlorination was not effective in reversing this effect, while ozone did reverse this effect, but not as much as the activation of ERK1/2. Thus, ozone was effective in reducing the toxicity of cyanobacterial extracts while chlorination was not only lacking efficacy but at high doses further produced by-products that were equally as toxic as the untreated samples. Our study points to advances of ozonation approach and brings evidences supporting the need of effect-based monitoring implementation.&lt;/p&gt;

Adsorption of arsenic from drinking water using natural orange waste: kinetics and fluidized bed column studies

The biosorption potential of orange waste (OW) was investigated using synthetic solutions of arsenic and contaminated drinking water under different parameters, e.g. biosorbent dose, initial concentrations of solution, contact time, and pH in a batch system. The optimum conditions were identified as a contact time of 30 minutes, pH 6, biosorbent dose of 1 g L−1, and initial arsenic concentration of 250 ppb. A fluidized bed column was used to study the removal of arsenic in the column. The results showed that biosorption of arsenic gave promising results in batch and continuous system, lowering the arsenic concentration down to WHO standards (10 ppb) for drinking water. The Fourier transform infrared spectra indicated that hydroxyl and carboxyl groups were major active sites for biosorption, while the results of scanning electron microscopy showed obvious changes in surface morphology of OW after the biosorption process. With 90% removal efficiency, results indicated that OW is a cost-effective and eco-friendly biosorbent and comparable to current drinking water treatment technologies. Further research is needed to get the optimum conditions for pilot-scale testing of the biosorption process by OW as well as evaluation of treated water for food quality parameters in order to commercialize the process.

Potential Effectiveness of Point-of-Use Filtration to Address Risks to Drinking Water in the United States.

Numerous contemporary incidents demonstrate that conventional control strategies for municipal tap water have limited ability to mitigate exposures to chemicals whose sources are within distribution systems, such as lead, and chemicals that are not removed by standard treatment technologies, such as perfluorooctanoic acid (PFOA)/perfluorooctanesulfonic acid (PFOS). In these situations, point-of-use (POU) controls may be effective in mitigating exposures and managing health risks of chemicals in drinking water, but their potential utility has not been extensively examined. As an initial effort to fill this information gap, we conducted a critical review and analysis of the existing literature and data on the effectiveness of POU drinking water treatment technologies for reducing chemical contaminants commonly found in tap water in the United States. We found that many types of water treatment devices available to consumers in the United States have undergone laboratory testing and often certification for removal of chemical contaminants in tap water, but in most cases their efficacy in actual use has yet to be well characterized. In addition, the few studies of POU devices while “in use” focus on traditional contaminants regulated under the Safe Drinking Water Act, but do not generally consider nontraditional contaminants of concern, such as certain novel human carcinogens, industrial chemicals, pesticides, pharmaceuticals, personal care products, and flame retardants. Nevertheless, the limited information available at present suggests that POU devices can be highly effective when used prophylactically and when deployed in response to contamination incidents. Based on these findings, we identify future areas of research for assessing the ability of POU filters to reduce health-related chemical contaminants distributed through public water systems and private wells.

Accuracy, precision, usability, and cost of portable silver test methods for ceramic filter factories.

Locally manufactured ceramic water filters are one effective household drinking water treatment technology. During manufacturing, silver nanoparticles or silver nitrate are applied to prevent microbiological growth within the filter and increase bacterial removal efficacy. Currently, there is no recommendation for manufacturers to test silver concentrations of application solutions or filtered water. We identified six commercially available silver test strips, kits, and meters, and evaluated them by: (1) measuring in quintuplicate six samples from 100 to 1,000 mg/L (application range) and six samples from 0.0 to 1.0 mg/L (effluent range) of silver nanoparticles and silver nitrate to determine accuracy and precision; (2) conducting volunteer testing to assess ease-of-use; and (3) comparing costs. We found no method accurately detected silver nanoparticles, and accuracy ranged from 4 to 91% measurement error for silver nitrate samples. Most methods were precise, but only one method could test both application and effluent concentration ranges of silver nitrate. Volunteers considered test strip methods easiest. The cost for 100 tests ranged from 36 to 1,600 USD. We found no currently available method accurately and precisely measured both silver types at reasonable cost and ease-of-use, thus these methods are not recommended to manufacturers. We recommend development of field-appropriate methods that accurately and precisely measure silver nanoparticle and silver nitrate concentrations.

Titanium dioxide-modified activated carbon for advanced drinking water treatment

Abstract This study reported a new anatase TiO2-modified granular activated carbon (GAC-TiO2) synthesized by microwave-assisted hydrothermal method. The composite was characterized morpho-structurally by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra and Brunauer–Emmett–Teller (BET) measurement. GAC-TiO2 composite was used for the removal of humic acids (HA) rom water by the photocatalysis under UV irradiation in comparison with the sorption process. Kinetics results correlated with Zeta potential results allowed elucidating some mechanistic aspects. GAC-TiO2 composite revealed high photoactivity for HA degradation and mineralization. A self-cleaning activity of the composite proved in this study makes it very remarkable in developing next generation of filtering system avoiding its fouling in the drinking water treatment technology.

Water microbial quality during drinking water treatment technology and distribution provided by two Romanian companies

Under European Economic Area Agreement, Romania and Norway have developed a project for monitoring the quality of raw and potable water (from production technology until distribution) supplied by two Romanian water companies. In the present study was investigated the microbiological quality of water, which was compared with organic matter loads. Resulting free chlorine and trihalomethane compounds after disinfection processes were also analysed. The raw water collected from Danube hydrographical basin showed significant pollution with potential pathogenic microorganisms with faecal origin such as Salmonella sp., Escherichia coli, Enterobacter sp., Klebsiella pneumoniae, Proteus mirabilis, Citrobacter braakii, Providencia stuartii, and Enterococcus sp. Also other bacteria such as Pseudomonas aeruginosa, Acinetobacter, total number of bacteria at 22 and 37 °C were detected, being related to high water oxidability. The microbial load was reduced considerably after the disinfection process. However, the total number of bacteria at 22 or 37 °C was constantly higher than the imposed limit and Clostridium perfringens was identified occasionally. The tap water presented a sporadic microbial loading with Enterococcus sp., Pseudomonas aeruginosa and E. coli and constantly with total number of bacteria due to an improper water distribution network.

The removal of natural organic matter with LiCl–TiO2-doped PVDF membranes by integration of ultrafiltration with photocatalysis

Ultrafiltration has become one of the best alternatives replacing conventional drinking water treatment technologies because of increasing stringent regulations for drinking water quality. However, membrane fouling is an important factor which restricts its widespread application. In this study, the modified polyvinylidene fluoride (PVDF) membranes were prepared by adding different amounts of LiCl and TiO2 particles. The performances of PVDF–LiCl membranes and PVDF–LiCl–TiO2 membranes were investigated by discussing the rejection of natural organic matter (NOM) and flux decline in both dead-end and cross-flow filtration experiments. The effect of photocatalytic degradation on TiO2-doped PVDF membranes was also evaluated. Results from both this study and the previous one with the membrane prepared by adding organic addition agent PEG and TiO2 photocatalyst indicated that appropriate TiO2-doped modification on PVDF membrane could be an effective way for better NOM rejection and reduction of membrane fouling at the same time. TiO2-doped PVDF membrane also shows good self-cleaning ability. The fouled membrane can be cleaned with irradiation and the foulants' photocatalytic degradation is most effective in the first 30min.

The performance of quaternized magnetic microspheres on control of disinfection by-products and toxicity in drinking water

Abstract The aim of this study was to evaluate the performance of quaternized magnetic microspheres (NDMP) on control of disinfection by-products (DBPs) and toxicity in drinking water. High concentrations of dissolved organic carbon (6.7 mg/L) and bromide (185 μg/L) were present in the raw water. The NDMP showed good performance on removing dissolved organic matter, bromide and dissolved organic nitrogen. In the present study, we investigated the formation potential (FP) of DBPs as well as the human hepatoma cells cytotoxicity and genotoxicity before and after resin treatment. The results showed that the FP of trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) were greatly reduced by the NDMP treatment with maximum removal efficiency of 73%, 56% and 81%, respectively. Additionally, the NDMP resin greatly reduced the cytotoxicity and genotoxicity of the raw water during subsequent chlorination. With increasing bromide levels, the FP of THMs, HAAs and HANs were increased by 31%, 36% and 27%, respectively. On the contrary, the FP of THMs, HAAs and HANs were reduced by 85%, 77% and 69% when the ammonia concentration reached to 10.5 mg/L. The addition of bromide increased the toxicity after chlorination due to the formation of more toxic brominated DBPs. NDMP can efficiently control the DBPs formation and toxicity in treated water, which provide us a new kind of advanced drinking water treatment technology in the future.

Removal of the cyanotoxin anatoxin-a by drinking water treatment processes: a review.

Anatoxin-a (ANTX-a) is a potent alkaloid neurotoxin, produced by several species of cyanobacteria and detected throughout the world. The presence of cyanotoxins, including ANTX-a, in drinking water sources is a potential risk to public health. This article presents a thorough examination of the cumulative body of research on the use of drinking water treatment technologies for extracellular ANTX-a removal, focusing on providing an analysis of the specific operating parameters required for effective treatment and on compiling a series of best-practice recommendations for owners and operators of systems impacted by this cyanotoxin. Of the oxidants used in drinking water treatment, chlorine-based processes (chlorine, chloramines and chlorine dioxide) have been shown to be ineffective for ANTX-a treatment, while ozone, advanced oxidation processes and permanganate can be successful. High-pressure membrane filtration (nanofiltration and reverse osmosis) is likely effective, while adsorption and biofiltration may be effective but further investigation into the implementation of these processes is necessary. Given the lack of full-scale verification, a multiple-barrier approach is recommended, employing a combination of chemical and non-chemical processes.

Study on full-scale H2O2/O3–UBAC process for removing organic matters in drinking water treatment

Ozone–biological activated carbon process (O3–BAC) is an advanced drinking water treatment technology that has been widely used. The combined process of O3/H2O2-upflow BAC filter (UBAC)—sand filter has been adopted by a drinking water treatment plant. The paper summarizes the effect of advanced oxidation process (O3 and O3/H2O2) on the overall combined process in two seasons. The influence of different O3/H2O2dosages on the effluent water quality is investigated and the effectiveness of the combined process is analyzed. The results indicate that O3 can effectively decompose organic matters in water and increase the biodegradability of dissolved organic carbon. The organic matters removal rate of combined process increases as ozone dosage increases. Biodegradable dissolved organic carbon (BDOC) after ozonation increases by 30, 93, and 101% with increasing ozone dosages from 1.0, 1.5 to 2.0 mg/L. The removal rates of BDOC by the combined process reached 39, 45, and 73%, respectively. H2O2/O3 does not give better effect than O3 alone. Turbidity removal rate by sand filtration remains stable, which is above 87%. Higher temperature is favorable to microbial degradation by UBAC and sand filter.

Drinking water treatment technologies in Europe: state of the art – challenges – research needs

Eureau is the European Federation of National Associations of Water and Wastewater Services. At the request of Eureau Commission 1, dealing with drinking water, a survey was produced focusing on raw drinking water sources and drinking water treatment technologies applied in Europe. Raw water sources concerned groundwater, surface water, surface water with artificial recharge and river bank filtration. Treatment schemes concerned no treatment, conventional treatment, advanced treatment and conventional plus advanced treatment. The response covered 73% of the population to which drinking water is supplied by the utilities joint in Eureau. Groundwater and surface water are the major raw water sources (>90%). In total, 59% of the drinking water supply concerns not-treated drinking water or drinking water treated with only conventional technologies, while 12% of the drinking water is not disinfected. Challenges for the European drinking water sector are the contamination of raw water sources with emerging substances, absence of disinfection and the potential formation of disinfection by-products. These challenges entail research needs such as the development of quantitative structure activity relationships (QSARs) to better understand and predict the removal rates of treatment technologies for emerging contaminants, the introduction of Water Safety Plans to safeguard the hygienic quality of drinking water, and the optimization of disinfection processes and strategies.

An evaluation of virus removal mechanisms by ultrafiltration membranes using MS2 and φX174 bacteriophage

Low pressure membranes are a widely used drinking water treatment technology to reject particles and microbiological contaminants. A commercial UF membrane was used to investigate the removal of two virus surrogates (MS2 and φX174 bacteriophage) of similar size but with different surface characteristics. MS2 was better removed than φX174 regardless of its smaller size. φX174 removal was found to decrease significantly as the feed solution pH increased from 6.5 to 9.4. Using mathematical modeling, size exclusion was confirmed to be the main removal mechanism for both bacteriophage. These values were then compared with experimental results and virus characteristics to evaluate the contribution of other removal mechanisms. The additional removal for MS2 above baseline size exclusion was likely a result of electrostatic repulsion. For φX174, adsorption was shown to increase rejection at pH 6.5, but at pH 9.4 removal was due solely to size exclusion. The higher isolectric point of φX174, along with its complex capsid structure, are believed to be responsible for the different removal patterns between the two phage types.

Electrochemical study of the stability of ferrates(VI) in low temperature molten hydroxide

Abstract During last decades interest in ferrates(VI) has increased significantly. On one hand they serve as strong, non-toxic oxidants without harmful by-products and, on the other hand, as an efficient coagulant in both drinking and waste water treatment technology. In this work we focused on the electrochemical preparation of ferrate (VI) salts in eutectic low temperature molten sodium hydroxide - water mixture using pure iron anodes. Some information on the stability and kinetics of decomposition of sodium ferrate(VI) prepared by molten-system electrolysis is discussed. An assumption that electrochemically prepared ferrate(VI) in molten hydroxide media are stable enough to be used especially in the field of waste water treatment was confirmed by our observation.

Pretreatment Process of Nanofiltration for Silting Density Index Reduction in Drinking Water Treatment System

Calcium ions, magnesium ions, and silicate were the main reasons for the high silting density index (SDI) of natural waters. Therefore, they posed serious membrane fouling problems in the nanofiltration (NF) system, which restricted the wide application of this excellent drinking water treatment technology. In this study, the sand filtration and the micro-flocculation/sand filtration hybrid process were investigated as the pretreatment process of NF for SDI reduction. Compared with the sand filtration, the hybrid process of micro-flocculation/sand filtration was more effective for SDI reduction. When polyaluminium chloride (PAC) was used as the flocculant at a dose of 10 mg/L and the filtration rate of the sand filter was controlled at 10 m/h, the SDI value in the effluent of the pretreatment process maintained below 3. As a result, the subsequent NF system stably ran for one year. 68% CODMn was removal by NF. The membrane fouling during the operation was quite slight as the transmembrane pressure (TMP) increased by 17% after one-year use. Chemical cleaning with sodium tripolyphosphate (2%) and sodium dodecyl benzene sulfonate (0.25%) at 6 months interval could effectively recover the flux loss of the NF membrane.

Comparative Assessment of the Environmental Sustainability of Existing and Emerging Perchlorate Treatment Technologies for Drinking Water

Environmental impacts of conventional and emerging perchlorate drinking water treatment technologies were assessed using life cycle assessment (LCA). Comparison of two ion exchange (IX) technologies (i.e., nonselective IX with periodic regeneration using brines and perchlorate-selective IX without regeneration) at an existing plant shows that brine is the dominant contributor for nonselective IX, which shows higher impact than perchlorate-selective IX. Resource consumption during the operational phase comprises >80% of the total impacts. Having identified consumables as the driving force behind environmental impacts, the relative environmental sustainability of IX, biological treatment, and catalytic reduction technologies are compared more generally using consumable inputs. The analysis indicates that the environmental impacts of heterotrophic biological treatment are 2-5 times more sensitive to influent conditions (i.e., nitrate/oxygen concentration) and are 3-14 times higher compared to IX. However, autotrophic biological treatment is most environmentally beneficial among all. Catalytic treatment using carbon-supported Re-Pd has a higher (ca. 4600 times) impact than others, but is within 0.9-30 times the impact of IX with a newly developed ligand-complexed Re-Pd catalyst formulation. This suggests catalytic reduction can be competitive with increased activity. Our assessment shows that while IX is an environmentally competitive, emerging technologies also show great promise from an environmental sustainability perspective.

Cost scenarios for small drinking water treatment technologies

ABSTRACT The objective of this paper is to present statistical models of costs based on new data obtained from manufacturers of a menu of treatment technologies suitable for small water systems. This analysis would be of interest to water management engineers and planners. We classify these technologies into six classes, depending on the contaminants removed. Our statistical results show that average costs (including capital, operating and maintenance) of production of these technologies depend on the flow rate as well as the number of contaminants removed. The larger the flow rate the lower the cost per volume treated and the more contaminants are removed, the higher the cost, for any given flow rate. One of our major finding is that for surface waters except those with high color and turbidity, UV-based treatment technologies can be cost effective. However, for any particular system, water engineers would take site-specific features into account to determine what technology is most appropriate.