Surface Water Treatment Plant Research Articles

Comparative Analysis of Natural and Artificial Coagulants

Abstract: Turbidity is the measure of relative clarity of a liquid. It is an optical characteristic of water and is a measurement of the amount of light that is scattered by material in the water when a lightis shined through the water sample. The higher the intensity of scattered light, the higher the turbidity Turbidity in the water creates both aesthetic and health issues. Surface water treatment plants remove particles because they can cause objectionable appearances, tastes, and odour and can interfere with disinfection. A wide range of natural coagulants, such as moringa seeds, banana peel, jatropha curcas, cassava peel starch, watermelon, pawpaw, beans, nirmali seeds, papaya seeds, organic dry hibiscus and okra have been studied previously. Natural coagulants in powder forms are usually added directly to wastewater. The most commonly used inorganic chemical coagulants in water treatment. Aluminium sulfate Al2(SO4)3 is the most commonly used chemical for coagulation in wastewater treatment. Additional commonly used coagulants include sodium aluminate NaAIO₂, ferric sulphate Fe2(SO4)3 and ferric chloride FeCl3.

New California Surface Water Treatment Plant Reduces Groundwater Reliance

New California Surface Water Treatment Plant Reduces Groundwater Reliance

Floodproofing at New Braunfels Utilities

Key TakeawaysA Texas utility planning to double its surface water treatment plant (SWTP) capacity weighed the most cost‐effective path to achieving flood resilience for its critical assets.Adopting an asset‐by‐asset approach, the utility applied wet and dry floodproofing techniques to the proposed assets depending on resilience needs and priorities.Highlights of the SWTP project's success included bringing a flood‐resilience mindset to the proceedings, centering safety goals, and discussing permitting from the outset.

Exploring source water mixing strategies to reduce chemical consumption and environmental footprint in surface water treatment

Abstract Common methods for treating surface waters involve chemical flocculation, for which a significant factor contributing to the total cost and climate impact is the consumption of chemicals, chiefly coagulants and pH-adjusting chemicals. The amount of chemicals required for treating surface waters and achieving suitable flocculation pH depends greatly on the alkalinity of the source water. This study investigates the viability of mixing two surface waters with different chemical properties with the aim of reducing the amount of chemicals used during chemical flocculation. Bench-scale experiments were carried out, and the results were compared with full-scale operations at a surface water treatment plant (WTP). The WTP uses ferric chloride as a coagulant, which effectively removes natural organic matter, but consumes large amounts of hydroxide to manage pH before and after flocculation. As an alternative process, this study tested the use of aluminum sulfate, polyaluminum chloride and ferric chloride at varying dosages in combination with different source water mixtures to achieve suitable flocculation pH. The results showed that pH-adjusting chemicals could be omitted by adding a small amount of high alkalinity surface water to the primary source water, thereby reducing costs and climate impact substantially.

Impacts of Comorbidity and Mental Shock on Organic Micropollutants in Surface Water During and After the First Wave of COVID-19 Pandemic in Wuhan (2019–2021), China

The first pandemic wave of coronavirus disease 2019 (COVID-19) induced a considerable increase in several antivirals and antibiotics in surface water. The common symptoms of COVID-19 are viral and bacterial infections, while comorbidities (e.g., hypertension and diabetes) and mental shock (e.g., insomnia and anxiety) are nonnegligible. Nevertheless, little is known about the long-term impacts of comorbidities and mental shock on organic micropollutants (OMPs) in surface waters. Herein, we monitored 114 OMPs in surface water and wastewater treatment plants (WWTPs) in Wuhan, China, between 2019 and 2021. The pandemic-induced OMP pollution in surface water was confirmed by significant increases in 26 OMP concentrations. Significant increases in four antihypertensives and one diabetic drug suggest that the treatment of comorbidities may induce OMP pollution. Notably, cotinine (a metabolite of nicotine) increased 155 times to 187 ng·L−1, which might be associated with increased smoking. Additionally, the increases in zolpidem and sulpiride might be the result of worsened insomnia and depression. Hence, it is reasonable to note that mental-health protecting drugs/behavior also contributed to OMP pollution. Among the observed OMPs, telmisartan, lopinavir, and ritonavir were associated with significantly higher ecological risks because of their limited WWTP-removal rate and high ecotoxicity. This study provides new insights into the effects of comorbidities and mental shock on OMPs in surface water during a pandemic and highlights the need to monitor the fate of related pharmaceuticals in the aquatic environment and to improve their removal efficiencies in WWTPs.

Disinfection as a stabilization method for backwash water reuse

The necessity to limit water use and for using recirculating economy leads to much attention being devoted to the reuse of backwash from filter flushing in water treatment plants. Pre-treatment of backwash water, especially the elimination of harmful substances and microorganisms, is necessary for its reuse. This paper presents an evaluation of the possibility of achieving water backwash biostability from surface and infiltration water treatment plants by subjecting it to chlorination or irradiation with UV light. The results of this study have shown that it is necessary to use large chlorine and radiation doses, irrespective of the type of treated water. At the same time, the optimal disinfection process parameters were determined, which ensured an elimination of pathogenic microorganisms, and limiting the number of other microorganisms. Both analyzed disinfection methods allow for the recirculation of backwash water into the beginning of the water treatment process, yet physical disinfection requires larger investments and operating costs. The increased cost in treating backwash water with UV as compared to chlorine is small, yet it eliminates the problem of the creation of disinfection by-products, whose concentration were significant, but did not exceed the values allowed for drinking water. The disinfection of backwash water from treating surface and infiltration water allowed for a reduction in sourced water in the amount of about 4% of treated water volume.

Examination of the Efficiency of Fabric Filter Media in Two-Stage Crossflow Pre-Filtration of Turbid Surface Water Using the Davies Flow Equation

Clogging of rapid sand filters during heavy rainfall causes surface water treatment plants to stop their operations until the river water turbidity decreases to a level that the rapid sand filter is capable of filtering. As clogging of rapid sand filters is impediment in surface water treatment, two-stage crossflow pre-filtration with fabric filter media (linen, crepe-backed satin, burlap, and cotton) was considered in a previous study by Davis and Ekwue (2020) as a possible solution. Pre-filtration with linen fabric filter medium was found to be the most efficient at retaining particles. The present paper incorporated properties of various fabrics previously measured and identified by Davis and Ekwue (2020) with the aim of identifying ideal fabric properties that were effective in removing particles from turbid water. Mechanisms of filtration (surface straining, depth filtration and cake filtration) depicted by each selected fabric during two-stage crossflow pre-filtration were identified and compared to the operation of standard filter media (absorbent, adsorbent, biological and woven). The Davies equation was used to calculate the flow of water through single layer and four layers of fabric filter media. Results indicate that no one specific fabric property could be used to proclaim a fabric as the ideal filter media, but rather all properties of the various fabric contribute to their performance during filtration.Linen fabric was once again determined as the fabric type most efficacious at retaining particles during two-stage crossflow pre-filtration of turbid river water and is therefore recommended.

Appraisal of treated drinking water quality from arsenic removal units in West Bengal, India: Approach on safety, efficiency, sustainability, future health risk and socioeconomics

The present study depicts the true failed scenario of the arsenic (As) removal units (ARU) in West Bengal by evaluating their treated water quality. Annual As removal efficiency of the 12 studied ARUs range between 35.2% and 82.6%. A comprehensive physico-chemical parameters and trace elements analysis find almost 25% and 16.7% of treated drinking water samples with poor water quality index (WQI) and high heavy metal evaluation index (HEI), respectively. The pond-based water treatment plant maintains the production of continuous As-safe water with a range between 60.2% and 66.7% due to its high Fe/As ratio. It’s a discontent concluding the treated drinking water of the groundwater based-ARUs were observed with sufficient As mediated cancer risk (3 ×10−3). The non-cancer risk (HQ) of As is safe for the surface water treatment plant (0.38), whereas it is threatening for the groundwater based-ARUs (7.44). However, the drinking water samples are safe in view of HQ from the other trace elements like Hg, Al, Cd, Cr, Pb, F- and NO3-. Small scale ARU could be a feasible mitigation strategy in reducing the As menace in the long run if the plants are maintained correctly. Nevertheless, surface treated water is the most sustainable solution as withdrawal of groundwater for drinking purpose is not a viable practice.

Taxonomic diversity and biomass of the invertebrate fauna of nine drinking water treatment plants and their non-chlorinated distribution systems

Invertebrates such as Asellus aquaticus, halacarid mites, copepods and cladocerans are known to regularly occur in drinking water distribution systems (DWDS). An eight-year study investigated the biomass and taxonomic composition of invertebrates in the finished water of nine Dutch drinking water treatment plants (using surface water, ground water or dune-infiltrated water) and their non-chlorinated distribution systems. The main aims of the study were to examine the source waters’ influence on invertebrate biomass and composition in the distribution networks and to describe invertebrate ecology in relation to the habitat of filters and the DWDS.Invertebrate biomass of the finished drinking waters of the surface water treatment plants was significantly higher than in the finished waters of the other treatment plants. This difference was due to the higher nutrient levels of the source water. The main part of the biomass in the finished water of the treatment plants consisted of rotifers, harpacticoid copepods, copepod larvae, cladocerans and oligochaetes, which are small-sized, euryoecious and tolerate broad environmental conditions. Most of them reproduce asexually.Most species found in the DWDS are known to be detritivores, but all are benthic and euryoecious organisms, many of which have a cosmopolitan distribution. The euryoeciousness of these freshwater species was also shown by their occurrence in brackish waters and ground or hyporheic waters and the ability of many eurythermic species to overwinter in the DWDS habitat. These species are preadapted to the oligotrophic environment of the DWDS and can develop stable populations there. Most species can reproduce asexually and the sexually reproducing invertebrates (Asellus aquaticus, cyclopoids and probably also halacarids) have obviously overcome the potential problem of finding a mating partner. This study also showed a significant correlation of DOC in the drinking water with the invertebrate biomass. A. aquaticus was the dominant biomass component in six out of nine locations and was highly correlated with the Aeromonas counts in the DWDS. Thus, invertebrate monitoring in DWDS is an important additional parameter in understanding biological stability conditions in non-chlorinated DWDS.

Improved Cadmium Removal Induced by Interaction of Nanoscale Zero-Valent Iron and Microplastics Debris

Nanoscale zero-valent iron (nZVI) is one of the most prevalently used engineered nanomaterials for heavy metals removal. Microplastics (MPs) have been detected extensively in the environment, such as soil, surface water, groundwater, and water treatment plant. PVC MPs and Cd coexist in a variety of environment, and Cd compounds are often used as stabilizers in PVC production, which increases the likelihood of their coexistence. In this work, the influence of aged PVC MPs on Cd2+ removal with nZVI was evaluated. Spent nZVI after reaction with Cd2+ with and without MPs was characterized with scanning transmission electron microscopy (STEM), energy-dispersive spectroscopy (EDS), scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FTIR), and Brunauer-Emmett-Teller (BET). The results showed that when MPs coexisted, the removal rate of Cd2+ with nZVI increased by up to 73.4%. Spent nZVI has more extensive oxidation, and has looser structure and higher specific surface area in a mixed contamination solution with trace MPs, resulting in high removal efficiency of Cd2+. Interaction between PVC MPs and nZVI shows positive promotion toward removal of Cd2+ with nZVI; thus, nZVI may have great potential for remediation of Cd in the water environment rich in PVC MPs.

Integrating trapezoidal fuzzy best–worst method and single-valued neutrosophic fuzzy MARCOS for efficiency analysis of surface water treatment plants

Integrating trapezoidal fuzzy best–worst method and single-valued neutrosophic fuzzy MARCOS for efficiency analysis of surface water treatment plants

Feasibility and Environmental Impact of NOM Reduction by Microfiltration at a Finnish Surface Water Treatment Plant

Low-pressure membranes (including microfiltration and ultrafiltration) for natural organic matter removal in drinking water treatment have gained increasing interest in the Nordic countries. Microfiltration can produce stable water quality and requires less space than conventional treatment. Hollow fibre microfiltration coupled with chemical coagulation was tested at a Finnish surface water treatment plant to study its feasibility and environmental impact compared to clarification, rapid sand filtration and ozonation. Microfiltration improved both physical and chemical water quality, while natural organic matter removal was similar to that of conventional treatment. Membrane treatment would increase operational costs by 2.5–3.5 euro cents per m3. Most of the costs derive from chemicals used in membrane cleaning. Membrane treatment is an energy-intensive process, but energy production in the Nordic countries has a low emission factor. Greenhouse gas emissions from operating microfiltration are estimated at 16 g CO2-eq./m3 of permeate. Lowering chemical consumption and using renewable energy in production could decrease total emissions.

Efficiency of a gravity-driven membrane in a water treatment plant

Abstract Membrane filtration technology is widely applied in conventional surface water treatment plants because of its low power load and high filtration accuracy. This study follows the transition from a power-driven to a gravity-driven siphon-submerged ultrafiltration membrane system in a drinking water treatment plant in Shandong Province, China. The proportion of space membrane areas in the tank was further developed, by increasing the membrane areas of a single tank to 1.6 times that before the transformation, and the design production capacity of a single tank is increased from 10,000 m3/d before the transformation to 16,700 m3/d. The recovery rate of a single tank was also increased from 96.28 to 97.77%. The energy consumption per ton of water decreased from 0.06 to 0.017 MJ. The annual carbon emissions reduction reached 197.13 tons per tank. In terms of the water quality, the algae removal rate from surface water by the ultrafiltration membrane reached 100%. Further, the removal rates of 2 μm particles, turbidity, and chlorophyll were above 99%. Our results suggest that gravity-driven siphon-submerged ultrafiltration promotes environmental protection, energy conservation, and emissions reduction. This technology introduces a new development direction for membrane filtering in drinking water treatment plants.

Reusing sludge from surface water treatment plant for hexavalent chromium adsorption in aqueous solution

Contaminants in plating wastewater are hard to remove, especially hexavalent chromium ions. This waste stream contains a large amount of Cr6+, a highly toxic metal, potential to cause cancer. To reduce this pollution, sludge from a supply water treatment plant (DWTS) has been used to make adsorbent. This sludge was denaturized by thermal method. After that, a plating synthetic waste stream contained Cr6+ was treated by a batch adsorption model with adsorbent made from DWTS. pH, amount of adsorbent, and treatment time were investigated to determine the suitable treatment conditions. The study was also evaluated the suitability of two adsorption models Langmuir and Freundlich. Results showed that, under the conditions of pH = 6.0, the adsorbent content of 25.0 g/l, after 90.0 minutes, Cr6+ content remained 0.14 mg/l, close to QCVN 40:2011/BTNMT, column B. The parameters of the Langmuir and Freundlich adsorption equations are: qmax = 12.578 mg/g; Kads = 0.747 l/mg; n = 0.338; kf = 5.138. The Freundlich isothermal model is better fitted to the chromium adsorption process than Langmuir isothermal model.

A Risk-Based Framework to Evaluate Infrastructure Investment Options for a Water Supply System

Increasing water demand due to socio-economic development often requires structure-level interventions, e.g., infrastructure expansion of water supply systems to bridge the gap between demand and water supply. Evaluating different expansion options is critical to making informed decisions. This study focuses on evaluating infrastructure investment options from the reliability perspectives of a water supply system. The evaluation framework is comprised of probabilistic demand projections, stochastic streamflow generation, a mixed-integer programming, and system performance evaluation. Different “industry understood” performance metrics, e.g., annual reliability, maximum delivery capacity, the probability of unsuccessful status, and the magnitude of potential water shortage, can be employed to evaluate the performance of water supply systems. This framework has been applied to Tampa Bay Water, a regional supply agency on the west coast of Florida, United States. The probabilistic demand projections for the future (2021–2040) consider socio-economic projections and climate conditions based on the statistics of historical observations. The Latin Hypercube Sampling algorithm is used to capture the bivariate distribution of supply and demand. This mixed-integer programming is a daily system optimization that minimizes operational cost and considers operational constraints and preferences, e.g., water withdrawal permits, facility production capacity, and water production preferences. Current infrastructure capacity and operational conditions are defined as the baseline scenario. Two additional planning scenarios of expanding the treatment capacity of a surface water treatment plant by 75,708 m3/day [20 million gallons per day (mgd)] and 113,562 m3/day (30 mgd) in the year 2028 are investigated. Results reveal that annual reliability would increase with the expansion of surface water treatment plant capacity. The spatio-temporal supply and demand variability determines that the firm yield from the surface water treatment is less than its expanded production capacity. Except for low demand realizations in the future, the duration and magnitude of potential water shortage could be reduced in both scenarios with engineering intervention. Although this framework is demonstrated for a regional water utility in Florida, it can be applied to other water supply systems around the world.

Application of Novel MCDM for Location Selection of Surface Water Treatment Plant

Surface water treatment plants (SWTPs) are responsible for supplying treated water to urban or rural consumers to satisfy the demand of the proximal population for drinking water. One important reason why an SWTP may fail is the poor selection of its location. This article proposes an automated framework for decision making which was developed empirically to identify a location objectively and cognitively, with consideration of all relevant indicators, selected in relation to their role in ensuring the optimality of SWTP performance. Thus, a new multicriteria decision making method was developed to identify the most common and significant indicators and to develop an index that would capture the feasibility of a given location for the installation of an SWTP. In addition to this method, another novel predictive model was developed, based on a polynomial neural network architecture and bagged modeling, to automate the process of the feasibility assessment of the location. These two models were developed and utilized for the first time for the automatic assessment of location feasibility for an SWTP installation. The prototype application of the two new models concerned a few test locations of a peri-urban metro city, located in northeast India, where the results obtained from the model seconded the real scenario for the test locations. The results encourage further application of this process.

Antibiotics in sewage treatment plants, receiving water bodies and groundwater of Chennai city and the suburb, South India: Occurrence, removal efficiencies, and risk assessment

The presence of antibiotics in the aqueous environment can alter the water microbiome, inducing antimicrobial resistance genes. Hence, the occurrence of 18 antibiotics belonging to sulfonamides, fluoroquinolones, tetracyclines, phenicols, and macrolides classes were investigated in surface water, groundwater, and sewage treatment plants in Chennai city and the suburbs. Fluoroquinolones had the maximum detection frequency in both influent and effluent samples of urban and suburban STPs, with ofloxacin and ciprofloxacin showing the highest influent concentrations. Erythromycin was the predominant antibiotic in surface water samples with an average concentration of 194.4 ng/L. All the detected antibiotic concentrations were higher in the Buckingham Canal compared to those in Adyar and Cooum rivers, possibly due to direct sewer outfalls in the canal. In groundwater samples, ciprofloxacin showed the highest levels with an average of 20.48 ng/L and the concentrations were comparable to those of surface water. The average sulfamethazine concentration in groundwater (5.2 ng/L) was found to be slightly higher than that of the surface water and much higher than the STP influent concentrations. High levels of ciprofloxacin and sulfamethazine in groundwater may be because of their high solubility and wide use. Moreover, erythromycin was completely removed after treatment in urban STPs; FQs showed relatively lesser removal efficiency (2.4–54%) in urban STPs and (8–44%) in suburban STP. Tetracyclines and phenicols were not detected in any of the samples. Ciprofloxacin and azithromycin in surface water pose a high risk in terms of estimated antibiotic resistance. This study revealed that the measured surface water concentration of antibiotics were 500 times higher for some compounds than the predicted calculated concentrations from STP effluents. Therefore, we suspect the direct sewage outlets or open drains might play an important role in contaminating surface water bodies in Chennai city.

Monitoring Mixture Effects of Neurotoxicants in Surface Water and Wastewater Treatment Plant Effluents with Neurite Outgrowth Inhibition in SH-SY5Y Cells.

Cell-based assays covering environmentally relevant modes of action are widely used for water quality monitoring. However, no high-throughput assays are available for testing developmental neurotoxicity of water samples. We implemented an assay that quantifies neurite outgrowth, which is one of the neurodevelopmental key events, and cell viability in human neuroblastoma SH-SY5Y cells using imaging techniques. We used this assay for testing of extracts of surface water collected in agricultural areas during rain events and effluents from wastewater treatment plants (WWTPs), where more than 200 chemicals had been quantified. Forty-one chemicals were tested individually that were suspected to contribute to the mixture effects among the detected chemicals in environmental samples. Sample sensitivity distributions indicated higher neurotoxicity for surface water samples than for effluents, and the endpoint of neurite outgrowth inhibition was six times more sensitive than cytotoxicity in the surface water samples and only three times more sensitive in the effluent samples. Eight environmental pollutants showed high specificity, and those ranged from pharmaceuticals (mebendazole and verapamil) to pesticides (methiocarb and clomazone), biocides (1,2-benzisothiazolin-3-one), and industrial chemicals (N-methyl-2-pyrrolidone, 7-diethylamino-4-methylcoumarin, and 2-(4-morpholinyl)benzothiazole). Although neurotoxic effects were newly detected for some of our test chemicals, less than 1% of the measured effects were explained by the detected and toxicologically characterized chemicals. The neurotoxicity assay was benchmarked against other bioassays: activations of the aryl hydrocarbon receptor and the peroxisome proliferator-activated receptor were similar in sensitivity, highly sensitive and did not differ much between the two water types, with surface water having slightly higher effects than the WWTP effluent. Oxidative stress response mirrored neurotoxicity quite well but was caused by different chemicals in the two water types. Overall, the new cell-based neurotoxicity assay is a valuable complement to the existing battery of effect-based monitoring tools.

Lab-In-Syringe automation of deep eutectic solvent-based direct immersion single drop microextraction coupled online to high-performance liquid chromatography for the determination of fluoroquinolones

Lab-In-Syringe direct immersion single drop microextraction is proposed as an automated sample pretreatment methodology and coupled online to HPLC with fluorescence detection for the determination of fluoroquinolones in environmental waters. For the first time, a drop of a natural deep eutectic solvent (NADES), synthesized from hexanoic acid and thymol, has been used as an extractant in automated single-drop microextraction. The extraction procedure was carried out within the 5 mL void of an automatic syringe pump. A 9-position head valve served the aspiration of all required solutions, air, waste disposal, and hyphenation with the HPLC instrument. Sample mixing during extraction was done by a magnetic stirring bar placed inside the syringe. Only 60 μL of NADES were required omitting toxic classical solvents and improving the greenness of the proposed methodology. By direct injection, linear working ranges between 0.1 and 5 μg L−1 were achieved for all fluoroquinolones. The limit of quantification values and enrichment factors ranged from 20 ng L−1 to 30 ng L−1 and 35 to 45, respectively. Accuracies obtained from the analysis of spiked surface water and wastewater treatment plant effluent analysis at two concentration levels (0.5 and 4 μg L−1) ranged from 84.6% to 119.7%, with RSD values typically <3%.

Analysis of solid waste discharged from water treatment plant as a fluoride-absorbing functional material

Solid waste from a surface water treatment plant (WTP sludge) was used as a fluoride adsorbent material for the treatment of water from underground sources by applying the concept of circular flow of materials. The sludge can be used as an alternative economic mineral resource and can be employed in drinking water collection, treatment, and distribution services. Physical and chemical characterization of the WTP sludge was performed via the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential thermal and thermogravimetric analysis (DTA/TGA), and particle size analysis. The structural characterization indicated that the dominant phases of WTP sludge were quartz, kaolinite, and illite. Chemical analysis demonstrated that the distributions of elements such as aluminum, iron, and silicon in the WTP sludge were identical to those in a clayey residue. Thermal analysis revealed a mass loss of approximately 30% in the sample. The WTP sludge exhibited a fluoride removal ability of approximately 28% as determined by adsorption assays. The Langmuir and Freundlich models were both adequate for representing the removal, particularly the Langmuir model. The pseudo-second-order kinetic model represented the results well, with R2 = 0.9986 and an experimental adsorption capacity (qe) of 0.206 mg/g. The experimental design was based on three factors (pH, initial fluorine concentration, and initial ion concentration) and showed (95% confidence, α = 0.05) that the interaction between the three factors was significant in the response variable. However, these individual parameters were not statistically significant. This study demonstrates the potential of WTP sludge as a groundwater fluoride adsorbent.