Potable Water Treatment Research Articles

Integrated modelling and management of manganese for a conventional potable water treatment plant

A reliable simulation of the manganese cycle in water supply system is essential for timely and effective manganese treatment strategies. A data-driven model estimating manganese levels in the treated water was developed through a threshold-based approach using raw water and supernatant return manganese levels. This data-driven model and a three-dimensional manganese cycle model for the source reservoir were integrated to simulate the overall manganese variations from the lake to the treated water. A decision support system based on the developed data-driven model was established to allow operators to react to situations that could result in elevated levels of manganese in the treated water. Scenario analyses were completed to examine the manganese variations in the reservoir, raw water and treated water due to different precipitations and wind conditions and to allow the identification of optimal strategies for manganese management from the reservoir to the water supply system.

Effects of coagulation-sedimentation-filtration pretreatment on micropollutant abatement by the electro-peroxone process

The electro-peroxone (EP) process has been considered an attractive alternative to conventional ozonation for micropollutant abatement in water treatment. However, how to integrate the EP process into the water treatment trains in water utilities has yet to be investigated. This study compared micropollutant abatement during the EP treatment of potable source water with and without pretreatment of biological oxidation, flocculation, sedimentation, and filtration. Results show that this pretreatment train removed 39% of dissolved organic carbon (DOC) and 28% of the UV254 absorbance of the raw water, leading to higher ozone (O3) stability in the treated water. By electrochemically generating hydrogen peroxide to accelerate O3 decomposition to hydroxyl radicals (•OH), the EP process considerably shortened the time required for ozone depletion and micropollutant abatement during the treatment of both the raw and pretreated water to ∼1 min, compared to ∼3 and 7.5 min during conventional ozonation of the raw and treated water, respectively. For the same specific ozone dose of 1 mg O3 mg−1 DOC (corresponding to 4.3 and 2.8 mg O3 L−1 for the raw and treated water, respectively), the abatement efficiencies of micropollutants with moderate and low ozone reactivity were increased by ∼10–15%, while the energy consumption for micropollutant abatement was decreased by ∼24–56% during the EP treatment of the treated water than the raw water. These results indicate that partial removal of DOC and ammonia from the raw water by the pretreatment train has a beneficial effect on enhancing micropollutant abatement and reducing energy consumption of the EP process. Therefore, it is more cost-effective to integrate the EP process after the pretreatment train in water utilities for micropollutant abatement.

Remote-sensing-based algorithms for water quality monitoring in Olushandja Dam, north-central Namibia

AbstractFrequent and continuous water quality monitoring of Olushandja Dam in Namibia is needed to inform timely decision making. This study was carried out from November 2014 to June 2015 with Landsat 8 reflectance values and field measured water quality data that were used to develop regression-analysis-based retrieval algorithms. Water quality parameters considered included turbidity, total suspended solids (TSS), nitrates, ammonia, total nitrogen (TN), total phosphorus (TP) and total algae counts. Results show that turbidity levels exceeded the recommended limits for raw water for potable water treatment while TN and TP values are within acceptable values. Turbidity, TN, and TP and total algae count showed a medium to strong positive linear relationship between Landsat predicted and measured water quality data while TSS showed a weak linear relationship. The regression coefficients between predicted and measured values were: turbidity (R2 = 0.767); TN (R2 = 0.798,); TP (R2 = 0.907); TSS (R2 = 0.284,) and total algae count (R2 = 0.851). Prediction algorithms are generally the best fit to derive water quality parameters. Remote sensing is recommended for frequent and continuous monitoring of Olushandja Dam as it has the ability to provide rapid information on the spatio-temporal variability of surface water quality.

High methylmercury uptake by green algae in Lake Titicaca: Potential implications for remediation

Anthropogenic pressure in the high altitude lakes such as Titicaca and Uru (Bolivia) may favor the production of methylmercury (MeHg) known to accumulate in trophic chains. Periphyton associated with emerged aquatic plants (totoras) from the lake shores accumulates and demethylates MeHg providing a potential cost-effective water treatment technique. In this laboratory study, we measured the MeHg uptake kinetics of a consortium of green algae isolated from Lake Titicaca totora's periphyton. The most abundant algal consortium, composed of Oedogonium spp., Chlorella spp., Scenedesmus spp., was exposed to rising MeHg concentrations (from 5 to 200 ng·L−1) to assess their maximum potential capacity for MeHg accumulation. Various algal biomass concentrations were tested to choose the optimal one. Results provided a net MeHg uptake rate by this algal consortium of 2.38 amol ng−1·h−1·nM−1 (the total uptake was 2863 ng MeHg·g−1) for an initial concentration of 200 ng MeHg·L−1 with an algal biomass concentration of 0.02 g·L−1. This initial MeHg concentration is 1000 times higher than the one measured in the eutrophic Cohana Bay of Lake Titicaca, which shows the high accumulation potential of these green algae. Our data suggest that periphyton has a high potential for the treatment of Hg contaminated waters in constructing wetlands in the Andean Altiplano.

Waterworks Sludge: An Underrated Material for Beneficial Reuse in Water and Environmental Engineering

Waterworks sludge refers to the inevitable suspended and dissolved solids produced during the water purification process when producing tap water where Al-salt and/or Fe-salt are used as coagulant worldwide. Waterworks sludge is dewatered and the resultant cakes have been treated as “waste” for landfill as their major final disposal solution for a long time in practice. As waterworks sludge is the residual of potable water treatment process, it is not harmful and without toxic elements such as heavy metals in most cases in comparison to sewage sludges for instance. Actually, waterworks sludge is an underrated material with huge potential for beneficial reuse as raw material in water and environmental engineering. However, little was significantly progressed on this topic until the last two decades. Research and development (R&D) with special interest and focus on waterworks sludge reuse was conducted in our group in the last 15 years and this paper reports and discusses the main work and its novel application profile. Overall, it is believed that the R&D of waterworks sludge is useful and will help to develop national strategy of the entire waterworks sludge management, allowing its transformation from a “waste” into value-added products, and thus contribute to sustainable development.

Recent Achievements in Polymer Bio-Based Flocculants for Water Treatment.

Polymer flocculants are used to promote solid–liquid separation processes in potable water and wastewater treatment. Recently, bio-based flocculants have received a lot of attention due to their superior advantages over conventional synthetic polymers or inorganic agents. Among natural polymers, polysaccharides show many benefits such as biodegradability, non-toxicity, ability to undergo different chemical modifications, and wide accessibility from renewable sources. The following article provides an overview of bio-based flocculants and their potential application in water treatment, which may be an indication to look for safer alternatives compared to synthetic polymers. Based on the recent literature, a new approach in searching for biopolymer flocculants sources, flocculation mechanisms, test methods, and factors affecting this process are presented. Particular attention is paid to flocculants based on starch, cellulose, chitosan, and their derivatives because they are low-cost and ecological materials, accepted in industrial practice. New trends in water treatment technology, including biosynthetic polymers, nanobioflocculants, and stimulant-responsive flocculants are also considered.

The influence of certain ecological parameters on a potable water treatment plant in El-Dakahleyia Province.

The influence of certain ecological parameters on a potable water treatment plant in El-Dakahleyia Province.

Electrodialytic Processes: Market Overview, Membrane Phenomena, Recent Developments and Sustainable Strategies.

In the context of preserving and improving human health, electrodialytic processes are very promising perspectives. Indeed, they allow the treatment of water, preservation of food products, production of bioactive compounds, extraction of organic acids, and recovery of energy from natural and wastewaters without major environmental impact. Hence, the aim of the present review is to give a global portrait of the most recent developments in electrodialytic membrane phenomena and their uses in sustainable strategies. It has appeared that new knowledge on pulsed electric fields, electroconvective vortices, overlimiting conditions and reversal modes as well as recent demonstrations of their applications are currently boosting the interest for electrodialytic processes. However, the hurdles are still high when dealing with scale-ups and real-life conditions. Furthermore, looking at the recent research trends, potable water and wastewater treatment as well as the production of value-added bioactive products in a circular economy will probably be the main applications to be developed and improved. All these processes, taking into account their principles and specificities, can be used for specific eco-efficient applications. However, to prove the sustainability of such process strategies, more life cycle assessments will be necessary to convince people of the merits of coupling these technologies.

Evaluation of Toxicity and Bioremediation of Contaminated Drinking Water Sources in Delta State, Nigeria

Drinking water samples were collected from boreholes in six locations in Ughelli and environs in Delta State of Nigeria and were treated by filtration through a substrate colonized with mycelium of Pleurotus tuber-regium. Water samples were analysed for pH, heavy metal concentration and microbiological content before and after filtration. Results obtained showed that the pH of unfiltered water samples were acidic (5.0 – 5.8) and below the WHO and SON permissible limits for drinking water. The same trend was followed by the concentrations of heavy metals such as lead, iron, zinc and chromium. Water samples from all six locations also had high total bacterial and coliform counts. Filtration through the mycelium colonized substrate showed adjustment of pH to a range within the WHO permissible limits. Reduction in heavy metal concentration ranged from 45.0 – 100%. Total bacterial count of mycofiltered water samples was impressively reduced by 77.3 – 100% and coliform count was not detected. The results obtained in this study makes mycofiltration a potential cost-effective and efficient technique for the treatment of potable water for domestic use.

Highly efficient removal of selenite by electrolysis-assisted nano-zerovalent iron (nZVI): Implication for corrosion and reduction

In present work, an efficient purification of selenite-contaminated water using electrolysis-assisted nano zerovalent iron (E-nZVI), which achieved a removal capacity of 15.83 mg Se(IV)/g nZVI and exceeded the none-assisted nZVI system by 135% was tested. Although Se(IV) removal dramatically increased with applied voltages over 2.0 V in E-nZVI system, the kinetics indicate that higher applied voltage (~4.0 V or more) and lower resistance could not result in apparent promotion on the reaction rate constant. Furthermore, the results from separate anode-cathode tests and surface-sensitive quantitative characterization reveal the synergistic effects of nZVI and cathodic reduction on elemental selenium precipitation, and nZVI corrosion aggravated by electrochemical oxidization improved removal performance in the anode chamber. In conclusion, the electrolysis-assisted nZVI showed good removal efficiency of Se(IV) and is a potential water treatment method for removing reducible contaminants.

Operating parameters optimization of combined UF/NF dual-membrane process for brackish water treatment and its application performance in municipal drinking water treatment plant

As an important water resource, brackish water has been extensively utilized in the industry. However, there are few cases of municipal potable water treatment plants that use low chloride content brackish water as the source. In this paper, the brackish water treatment efficiency of ultrafiltration (UF)/nanofiltration (NF) dual-membrane process was evaluated in a municipal potable water treatment plant, combining with a pilot optimization experiment. Results showed that UF guaranteed the inlet water quality of NF and NF could efficiently reject organics and salts, with a chloride removal over 95 %. Pilot experiment showed that the UF membrane flux decreased only 12 % after continuously 30-days operation under the optimized UF operation conditions, effectively extending the chemical cleaning interval. Response surface method was adopted in the NF removal efficiency and energy consumption optimization. With the increase of feed water conductivity, the influences of pressure and recovery on the removal efficiency were strengthened, and the removal efficiency could be regulated over a wider range. When the conductivity was less than 3500 μS/cm, NF could perform high treatment efficiency under the operation pressure of 0.65−0.85 MPa and recovery of 55–70 % . Besides, as feed conductivity increased, it was necessary to increase the pressure and reduce the recovery within this range to maintain efficient operation. This paper will provide a guidance for the UF/NF dual-membrane process design and operational optimization.

Solar energy in the operation of the municipal aqueduct of González department of Cesar

The Cesar´s Department has presented historically problems in terms of availability energy, which has hindered the implementation and continuity of some projects. One of the alternatives solutions focuses on the use of solar energy in this area, considering that the highest daily average brightness values are in the Caribbean region and the Orinoquia. For this reason, the Municipality of González, in the Cesar Department, promoted the construction of the first aqueduct in Colombia that operates only with hydraulic and solar energy, which ensures continuity in the drinking water service, and the contribution with the reduction of CO2 emissions at the atmosphere , In order to minimized the use of fuel for this operation. In support of the above investigation, the object of the present project has two main ideas; the first one is estimate the radiation potential in the municipality of González and the second one is establish the dimensions of the photovoltaic solar system to take advantage of this kind of energy. The mathematical model selected, is an empirical one proposed by Bristow-Campbell, based on the availability of information, and the match presented in previous studies , in which was analized secondary information, coming from the Aguas Claras Airport weather station, and the information available on the POWER page, that is a set of solar and meteorological data from NASA’s researchs for renewable energy. For the evaluation of the photovoltaic solar system, it was used a methodology based on the radiation potential available in the area, the energy requirement in the operation of the drinking water treatment plant, the administrative and laboratory facilities of the municipal aqueduct and the measure that were used of the generation, accumulation and investment regulator subsystem. It was conclude that the radiation potential for the Municipality of González, is estimated in a range between (4.5 and 6) KWH/m2/day, and that value is enough to meet th average, as well as the measurement proposed, have the capacity to supply electricity in the operation of the potable water treatment plant, the administrative and laboratory facilities of the aqueduct.

Seeded growth core-shell (Ag–Au–Pd) ternary nanostructure at room temperature for potential water treatment

Seed-mediated growth is a promising technique for preparation of multi-metallic nanostructures, in which reduction of metal ions takes a place over the surface of another one. Herein, a seed growth mechanism was investigated for synthesis of core-shell Ag–Au–Pd ternary nanostructures through a facile method at room temperature. Ascorbic acid and sodium alginate were used as nano-generator and stabilizing agent, respectively. Spherical shaped monocular Ag nanostructure with size of 13.6 nm grew to 24.4 nm of Ag–Au binary and to 58.8 nm of Ag–Au–Pd ternary core-shell nanostructures. The crystalline shape of nanostructures was approved by X-Ray diffraction analyses. While, FT-IR data approved the redox mechanism for synthesis the as-required nanostructures. The catalytic reactivity of the prepared nanostructures in reductive degradation of methylene blue dye was studied. The results approved the role of Pd in perfection of catalytic degradation of the as-tested dye. The rate constant of dye degradation was considerably enlarged from 62.1 × 10−3 m−1 for Ag monocular nanostructures to 403.3 × 10−3 m−1 for Ag–Pd binary and to 852.4 × 10−3 m−1 for Ag–Au–Pd ternary core-shell nanostructures. The obtained results offer an energy saving method to fabricate core-shell catalytically active ternary nanostructures with promising applicability in water treatment.

Coupling Laccase production from Trametes pubescence with heavy metal removal for Economic Waste Water Treatment

The objective of this work is to evaluate simultaneously the impact of nickel and lead on the fungus Trametes pubescence growth and laccase production, and their removal efficiency by T. pubescence. Here laccase activity and production were investigated in both in vitro and in vivo fungal growth conditions at the presence of either Pb or Ni, with the results showing inhibitory effects of Pb and Ni on T. pubescence growth and laccase activity. In particular, T. pubescence was seen to be able to withstand 1000 mg L−1 of Pb and Ni, while the fungus was capable of removing 99 % of Pb and 8.6 % of Ni, respectively. Most importantly, it was found that although only live cells will secrete laccase, both live and dead fungal biomass can accumulate heavy metals in the aqueous solutions. The laccase production can thus be coupled with heavy metal removal for potential waste water treatment.

ANALYSIS OF TECHNICAL SOLUTIONS FOR SHIP POTABLE WATER SYSTEMS

The article provides an overview and analysis of all main types of potable water systems currently used on inland and mixed navigation vessels: without potable water treatment; with elements of potable water disinfection and conditioning; with complete purification and disinfection of potable water. The operation principles of potable water systems of all types and designs are considered in detail, all the advantages and disadvantages of these systems are noted. Special attention is paid to stations for preparing potable water by using UV lamps, which essentially differ in the technological process from most of the stations used, and provide guaranteed high-quality disinfection of potable water, which allows to choose the most promising station type and outline a plan for further work on creating new and improving existing stations.

Numerical simulation and field test of double-storey sedimentation tank in potable water treatment

A method combining CFD and field test is applied to study the influence of geometric parameters of double-storey sedimentation tank on hydraulic characteristics. The results show that the flow field of the sedimentation tank is close to the clear water sedimentation tank and the effect of particles on water flow is relatively small. Longer width, longer length, upper and lower stories with comparable depths, and longer sumps are beneficial for reducing the particle concentration at the outlet. The velocity of the bottom is small and the velocity of the upper storey is large. The floc particles in the front section are larger and the sedimentation speed is larger, and the flocs in the rear section are opposite.

Quantification of biodegradable natural organic matter (NOM) fractions and its impact on bacterial regrowth in a South African Water Treatment Plant

Natural organic matter (NOM) contributes to bacterial regrowth during potable water treatment and supply. Most conventional water treatment plants insufficiently remove the biodegradable dissolved organic (BDOC) NOM fraction. The presence of labile BDOC in water creates conducive conditions for bacterial regrowth. To reduce NOM and the bacterial regrowth potential (BRP) in water, the study aimed at establishing which of the NOM polarity fractions are biodegradable and if the BRP (enumerated according to the heterotrophic plate count [HPC]) method) can be correlated to biodegradability. Specific ultraviolet absorbance (SUVA) was used to characterise source and treated water NOM fractions (i.e. hydrophilic [Hpi], transphilic [Tpi] and hydrophobic [Hpo]) obtained through the modified polarity rapid assessment method (m-PRAM). The source and treated water SUVA values of the Hpi and Hpo were on average, 3.88 L/mg.m and 2.04 L/mg.m, respectively. The Hpi and Tpi fractions on the source and treated were the most biodegradable fractions, with mean BDOC values ranging between 29.22%, and 35.75 %. The high BDOC of the Tpi and Hpi NOM substantially contributed to BRP by up to 121.4 × 103-197.4 × 103 CFU/mL, respectively. The strong correlation (R2 > 0.96) between BRP and BDOC allows for the effective management of water treatment and supply processes, particularly for microbial control.

A new backwash strategy for reducing the cost of an immersed ultrafiltration system by restricting cake layer breakage

Abstract Ultrafiltration (UF) is increasingly used for potable water treatment, but membrane fouling necessitates the application of periodical backwash, which increases running cost. A new backwash strategy, in which air scouring was only applied with sludge water discharging, was proposed to improve backwash performance in a water plant using UF. Four gravity-driven UF systems were simultaneously run at increasing air scouring intervals (3–24hours) and sludge water discharging intervals (12–24hours). The membrane fluxes were monitored to assess membrane fouling and the mix solution turbidity was also monitored to investigate deposition of particles. The results indicated that membrane fouling was not aggravated by the extension of air scouring and sludge water discharging intervals. Water backwash on its own induced a shift of particle deposition from the membrane surface to the bottom of the membrane tank due to limited cake layer breakage, enabling the extension of sludge water discharging intervals. For the gravity-driven system investigated, the running cost, including energy, water and chemical demand, was reduced by 16.67% as the air scouring and sludge water discharging intervals increased from 3hours to 24hours and from 12hours to 24hours, respectively.

Concentrations and Loads of Dissolved and Particulate Organic Carbon in Urban Stormwater Runoff

Urban landscapes are significant contributors of organic carbon (OC) in receiving waters, where elevated levels of OC limit the light availability, increase the transport of pollutants, and result in high costs of potable water treatment. Our objective in this study was to investigate the concentrations, fractions (dissolved and particulate), and loads of OC in a residential catchment (3.89 ha drainage area) located in Florida, United States. The outlet of the stormwater pipe draining the residential catchment was instrumented with an automated sampler, a flowmeter, and a rain gauge. The rainfall and runoff samples collected over 25 storm events during the 2016 wet season (June to September) were analyzed for dissolved organic carbon (DOC) and total organic carbon (TOC), with particulate OC (POC) calculated as the difference between TOC and DOC. Mean concentration of DOC was 2.3 ± 1.7 mg L−1 and POC was 0.3 ± 0.3 mg L−1 in the rainfall, whereas DOC was 10.5 ± 6.20 mg L−1 and POC was 2.00 ± 4.05 mg L−1 in the stormwater runoff. Concentrations of DOC were higher during the rising limb of the hydrograph in 15 out of 25 storm events, suggesting flushing of DOC, with an increase in the amount of runoff, from the landscape sources in the residential catchment. The estimated total export of OC during the 2016 wet season was 66.0 kg ha−1, of which DOC was 56.9 kg ha−1 (86.2% of TOC), and POC was 9.1 kg ha−1 (13.8% of TOC). High concentrations and loads of OC, especially DOC, in the stormwater runoff imply that residential catchments in urban watersheds are hot-spots of DOC influx to water bodies. Reducing DOC transport in the urban landscapes is complex and require identifying the origin of DOC and then using site-specific targeted approaches to mitigate DOC loss.

Nanocellulose water treatment membranes and filters: a review

AbstractThis review covers the use of nanocelluloses in water treatment applications with particular focus on membranes and filters made either entirely from (nano)cellulose or in composite approaches. Nanocelluloses are among the emerging materials of this century, having found an abundance of potential applications in the fields of composites, medicine, functional additives or water treatment. Water treatment applications in particular have received significant academic and commercial attention, with a large variety of approaches developed in order to address arguably one of the largest problems that humanity is confronted with in the 21st century: clean water. In this regard, treatment of both potable water and wastewater is of high importance. The reason for the viability of nanocelluloses as base material relies upon their high specific surface area and abundance of OH groups that already exhibit certain attraction toward pollutants carrying ionic structures or dyes and also can be easily modified to significantly increase the affinity of nanocelluloses toward these pollutants. Nanocelluloses in their various forms (cellulose nanocrystals, cellulose nanofibrils, bacterial cellulose) have been applied in water treatment, with membranes and filters (size exclusion, e.g. for nanoparticle filtration, or affinity membranes) as well as adsorbents (e.g. heavy metal ions, dyes, nitrates) being the most studied. © 2020 The Author. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.