Conventional Drinking Water Treatment Plants Research Articles

Identification of microplastics in conventional drinking water treatment plants in Tehran, Iran.

The online version contains supplementary material available at 10.1007/s40201-021-00737-3.

Visible-Light Enhanced Catalytic Wet Peroxide Oxidation of Natural Organic Matter in the Presence of Al/Fe-Pillared Clay

An Al/Fe-pillared clay catalyst (Al/Fe-PILC) prepared from low cost technical-grade reagents has been investigated in the photocatalytic Wet Peroxide Oxidation (photo-CWPO) of dissolved Natural Organic Matter (NOM) under circumneutral pH. The successful pillaring of the layered clay material was confirmed by X-ray diffraction (XRD), N2 adsorption at −196 °C, cation exchange capacity (CEC) and simultaneous thermal analysis (TGA/DSC). High levels of mineralization of the dissolved organic carbon and color removal of a synthetic NOM surrogate solution were achieved even under natural lab’s lighting and ambient temperature and pressure, whereas the absence of radiation (in dark) was found to strongly affect the performance of the degradation. The photo-CWPO of NOM activated by the Al/Fe-PILC clay catalyst under visible light irradiation (LED lamp, 450 and 550 nm peaks) displayed a DOC mineralization of 72% and color removal of 73% in just 210 min of irradiation at neutral pH, whereas both responses decayed under ultraviolet lightning (λ: 365 nm) to 41% and 58%, respectively. This behavior is ascribed to formation of triplet states of natural organic matter (3NOM*) by absorption of visible light, which seems to synergistically improve the rate-determining step of the heterogeneous Fenton process, namely reduction of Fe3+ into Fe2+ on the surface of the clay catalyst. Interestingly, experiments performed at neutral and pH 3.0 showed very similar efficiencies under visible light irradiation; these findings may really facilitate the application of the photo-CWPO process to assist conventional drinking water treatment plants in the removal of NOM before the typical disinfection by chlorine to produce safer drinking water.

The Price of Really Clean Water: Combining Nanofiltration with Granular Activated Carbon and Anion Exchange Resins for the Removal of Per- And Polyfluoralkyl Substances (PFASs) in Drinking Water Production

The removal of per- and polyfluoroalkyl substances (PFASs) presents a challenge for drinking water providers. Guidelines for PFAS concentrations in final drinking water are regularly updated to ever-decreasing values, and conventional drinking water treatment plants are not designed to remove PFASs. Currently, the most frequently used removal technique, adsorption to granular activated carbon (GAC), is often considered challenging. High-pressure membranes, such as nanofiltration (NF), have been shown to remove PFASs efficiently. However, the creation of a waste stream comprised of at least 10% of the feedwater volume is recognized as a major drawback of this technique. In this study, a NF pilot plant was operated at a drinking water treatment plant in the city of Uppsala, Sweden, for six months. NF removed up to >98% of PFASs and fulfilled other water quality targets, such as the removal of uranium-238, dissolved organic carbon (DOC), and mineral hardness from the raw water. The concentrate from the pilot plant was treated with two different GAC materials and two different anion exchange (AIX) resins in column tests, where the superior performance of AIX over GAC was observed in terms of PFAS removal. PFAS adsorption curves for GAC were found to superimpose each other for the two water types if normalized to the specific throughput of DOC. The application of the freely available PHREEQC model revealed improvement possibilities in terms of resin properties. A cost analysis using the column test results compared GAC filtration to the combination of NF with adsorption materials. Treatment costs were found to be largely dependent on the PFAS drinking water treatment goals and concentrate discharge requirements, which highlight the economic consequences of prevailing guidelines for drinking water and discharge to the environment. The results of this study provide both the scientific community as well as drinking water providers with important insights into the application of NF for PFAS removal during drinking water treatment as well as that mechanistic and economic aspects of NF treatment and the management of the resulting concentrate.

Comparative removal efficiencies of natural organic matter by conventional drinking water treatment plants in Zimbabwe and South Africa.

Natural organic matter (NOM) influences the quality and treatability of drinking water; therefore, its removal is paramount. A few studies exist on NOM removal in developing countries, and comparative studies are even fewer globally. This study compared the removal efficiencies for bulk NOM and biodegradable organic carbon (BDOC) fractions of drinking water treatment plants in Zimbabwe (Z) and South Africa (S). NOM removal efficiency at the coagulation stage of plant Z and plant S was 11% and 13%, respectively. The fluorescence index (FI) for the raw water feeding plant Z (1.66) indicated a mixture of both microbial and terrestrially derived NOM, whereas for plant S the FI (4.08) showed terrestrially derived NOM. Based on the log-transformed absorbance at the disinfection stage, plant S had a 58% greater opportunity to produce disinfection by-products than plant Z. The BDOC results for plant Z showed humic fractions were the major substrates for bacterial assimilation, whereas the heterotrophic bacteria in plant S were not particularly selective toward DOC fractions. Overall, the plants had comparable NOM removal performances. PRACTITIONER POINTS: NOM removal efficiency at the coagulation stage of plant Z and plant S was 11% and 13%, respectively. Plant Z had a mixture of both microbial and terrestrially derived NOM, whereas plant S had terrestrially derived NOM. Plant S had a 58% greater opportunity to produce disinfection by-products than plant Z. Humic fractions were the major substrates for bacterial assimilation for plant Z, whereas the heterotrophic bacteria in plant S were not selective towards DOC fractions.

Seasonal occurrence and removal of organophosphate esters in conventional and advanced drinking water treatment plants

In this study, the fate of organophosphate esters (OPEs) in conventional and advanced drinking water treatment plants (DWTPs) was investigated in field scale. In addition, the risk of OPEs by drinking water was assessed. The average total OPE concentrations in raw and treated water were lower in the rainy season (94.3 and 57.1 ng/L, respectively) than dry season (163 and 84.2 ng/L, respectively). Advanced DWTPs showed better removal efficiencies of major OPEs rather than those in conventional DWTPs. The average removal rates for two chlorinated OPEs, including tris(2-chloroethyl)phosphate (TCEP) and tris(1-chloro-2-propyl)phosphate (TCIPP), were negative (TCEP: −87%, TCIPP: −41%) for a conventional DWTP but positive (TCEP: 46%, TCIPP: 49%) for advanced DWTPs using granular activated carbon filtration. The average removal rates for advanced DWTPs were statistically higher for the alkyl/aryl OPEs, tri-n-butyl phosphate (TNBP: 67%) and tris(2-butoxyethyl) phosphate (TBOEP: 63%), than those for the conventional DWTPs (TNBP: 21%, TBOEP: 25%). The hazardous quotient (HQ) of major OPEs were lower for advanced DWTPs and water irrigated from upstream sties/reservoir compared to that of conventional DWTPs and water irrigated from downstream sites. We believe that this is the first comparison of OPE removal efficiencies achieved in conventional and advanced DWTPs.

Formation and Fate of Carbonyls in Potable Water Reuse Systems.

Low molecular weight, uncharged compounds have been the subject of considerable study at advanced treatment plants employed for potable water reuse. However, previously identified compounds only account for a small fraction of the total dissolved organic carbon remaining after reverse osmosis treatment. Uncharged carbonyl compounds (e.g., aldehydes and ketones) formed during oxidation have rarely been monitored in potable water reuse systems. To determine the relative importance of these compounds to final product water quality, samples were collected from six potable water reuse facilities and one conventional drinking water treatment plant. Saturated carbonyl compounds (e.g., formaldehyde, acetone) and α,β-unsaturated aldehydes (e.g., acrolein, crotonaldehyde) were quantified with a sensitive new analytical method. Relatively high concentrations of carbonyls (i.e., above 7 μM) were observed after ozonation of wastewater effluent. Biological filtration reduced concentrations of carbonyls by over 90%. Rejection of the carbonyls during reverse osmosis was correlated with molecular weight, with concentrations decreasing by 33% to 58%. Transformation of carbonyls resulted in decreases in concentration of 10% to 90% during advanced oxidation, with observed decreases consistent with rate constants for reactions of the compounds with hydroxyl radicals. Overall, carbonyl compounds accounted for 19% to 38% of the dissolved organic carbon in reverse osmosis-treated water.

Simultaneous control of algal micropollutants based on ball-milled powdered activated carbon in combination with permanganate oxidation and coagulation

This study reports application of KMnO4 pre-oxidation and engineered powdered activated carbon (PAC) adsorption to simultaneously control geosmin, 2-methylisoborneol (2-MIB), and microcystin-LR (MC-LR) in conventional drinking water treatment plants (DWTPs). Pulverization of commercial wood-based PAC (1 mm ZrO2 ball, 12 h) reduced the median size to ~6 μm and resulted in overall enhanced kinetics for adsorption of the algal micropollutants. A series of parametric experiments were performed to estimate minimal contact for KMnO4 (1 mg L−1, 10 minutes) and PAC (20 mg L−1, 40 minutes) prior to coagulation, with the aim to meet guidelines (0.02, 0.02, and 1 μg L−1 for geosmin, 2-MIB, and MC-LR, respectively) at specific influent concentrations (0.1, 0.1, and 100 μg L−1) in surface water matrix. Ball-milling of parent PAC with a low oxygen content (~2.5 w/w%) could avoid interferences from/to the KMnO4 pre-oxidation and subsequent coagulation. Pilot-scale experiments confirmed the compatibility of the combined KMnO4 and PAC at existing DWTPs.

Occurrence and risk assessment of pharmaceutically active compounds in water supply systems in Brazil

The presence of pharmaceutically active compounds (PhACs) in water supply systems has been generating great concern about their effects on the environment and human health. Twenty-eight PhACs were monitored during one year in four Brazilian water sources, aiming to understand the factors that influence their occurrence and removal in conventional drinking water treatment plants (DWTPs) and to assess the environmental and human health risks. Trace levels of PhACs were detected in surface and drinking water in all assessed water sources. Effects of seasonality and socioeconomic aspects were observed in PhACs occurrence, like their higher concentrations during winter and in locales with higher values of gross domestic product per capita and human development index. Betamethasone, prednisone, and fluconazole were the most commonly detected PhACs, and also presented the highest concentrations. However, they were not related to toxicological risks. Nonetheless, all surface waters were subject to toxicological risk owing to at least one PhAC. PhACs related to the highest toxicological risks were loratadine, atorvastatin, norfloxacin, caffeine, and ranitidine, however, all these PhACs presented low quantification frequency. DWTPs capacity to remove PhACs was only partial, so treated water was still contaminated with these compounds. Furthermore, atorvastatin presented a margin of exposure below 100, indicating possible risk for public health. Thus, additional advanced treatment steps should be considered to improve PhACs removal during drinking water treatment.

Identification of emerging contaminants and their transformation products in a moving bed biofilm reactor (MBBR)-based drinking water treatment plant around River Yamuna in India.

The prevalence of emerging contaminants of concern in water regimes is very common these days. High anthropogenic intervention is leading to occurrence of various types of microcontaminants of concern in drinking water systems. Their removal using conventional form of treatment systems employed in water treatment plants is not widely researched upon. Their fate in the conventional as well as advanced water treatment system needs to be focused upon for efficient and safe water disposal. Some compounds may leave the system unchanged or some might transform into much more toxic byproduct. Moreover, understanding level of occurrence of these emerging contaminants in source water bodies is also quintessential for assessing their fate in treatment plant itself as well as in the final treated water. Here in this study, the occurrence and removal of various classes of emerging contaminants were investigated in a moving bed biofilm reactor (MBBR)-based advanced drinking water treatment plant (ADWTP) alongside one conventional drinking water treatment plant, both of which use River Yamuna as the source of water. Non-target analysis utilizing high-performance liquid chromatography combined with time of flight (HPLC-QToF) identified more than 300 compounds. Pharmaceuticals accounted for a major fraction (58%) of the identified compounds, followed by plasticizers and insecticides. Nine parent compound and their transformation products were additionally identified using solid-phase extraction followed by analysis using gas chromatography mass spectrometry and HPLC-QToF. The degradation pathway of the parent compounds in MBBR-based ADWTP was also analyzed in depth. The efficiency of each unit process of MBBR-based drinking water treatment plant was studied in terms of removal of few emerging contaminants. Pharmaceutical compound like diclofenac supposedly was persistent, even, toward the end of the treatment train. Semi-quantitative analysis revealed ineffective removal of pyridine, hydrochlorothiazide, and diethyl phthalate in the outlet of ADWTP. ADWTP was able to remove a few emerging contaminants, but a few were recalcitrant. Likewise, it was established that although some parent compounds were degraded, much more toxic transformation products were formed and were prevalent at the end of the treatment.

An Investigation of a Conventional Water Treatment Plant in Reducing Dissolved Organic Matter and Trihalomethane Formation Potential from a Tropical River Water Source

The characteristics and composition of dissolved organic matter (DOM) and trihalomethane (THM) generation during water treatment are important for producing safe drinking water. However, little information is available on this topic within the context of Indonesia. This study aimed to investigate the efficiency of a conventional drinking water treatment plant (WTP) in removing DOM and chloroform forming potential (CHCl3FP), and evaluate surrogate parameters for CHCl3FP. Samples were taken during the rainy season and the dry season from raw water, after secondary treatment and after the rapid sand filter. DOM was characterized based on the A254, A355, SUVA, dissolved organic carbon (DOC), and fluorescence DOM (FDOM) parameters. The composition of the DOM was identified using the peak picking method. Overall, from raw to finished water, the WTP performed better in the rainy season with 55.96% reduction of DOC and 63.45% reduction of A355 as compared to the dry season with 53.27% reduction of DOC and 24.18% reduction of A355.The overall removal of humic and tryptophan compounds during the rainy season was 33.33% and 37.50%, respectively. In the dry season, humic compounds were reduced by 18.80%, while tryptophan increased threefold. A355 can serve as a surrogate parameter for CHCl3FP in raw water and water after secondary treatment, containing more humic-like compounds than tryptophan-like compounds.

Occurrence of pesticides in surface water, pesticides removal efficiency in drinking water treatment plant and potential health risk to consumers in Tengi River Basin, Malaysia

Agricultural activities have been arising along with the use of pesticides. The use of pesticides can impact not only on vector or other pest but also able to harm human health. Pesticide may leach from the irrigation of plant into the groundwater and in surface water. These waters could be sources of drinking water in a pesticides polluted area. This study aims to determine the occurrence pesticides in surface water and pesticides removal efficiency in a conventional drinking water treatment plant (DWTP) and the potential health risk to consumers. The study was conducted in Tanjung Karang, Selangor, Malaysia. Thirty river water samples and eighteen water samples from DWTP were collected. The water samples were extracted using solid phase extraction (SPE) before injected to the ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Five hundreds and ten respondents were interviewed using questionnaires to obtain information for health risk assessments. The results showed that propiconazole had the highest mean concentration (4493.1 ng/L) while pymetrozine had the lowest mean concentration (1.3 ng/L) in river water samples. The pesticides removal efficiencies in the conventional DWTP were 77% (imidacloprid), 86% (propiconazole and buprofezin), 88% (tebuconazole) and 100% (pymetrozine, tricyclazole, chlorantraniliprole, azoxystrobin and trifloxystrobin), respectively. The hazard quotients (HQs) and hazard index (HI) for all target pesticides were <1, indicating there was no significant chronic non-carcinogenic health risk due to consumption of the drinking water. Conventional DWTP was not able to completely remove four pesticide; thus, advanced treatment systems need to be considered to safeguard the health of the community in future.

EVALUATION OF THE REMOVAL EFFICIENCY OF TOTAL ORGANIC CARBON IN ŞANLIURFA DRINKING WATER TREATMENT PLANTAL EFFICIENCY OF TOTAL ORGANIC CARBON IN ŞANLIURFA DRINKING WATER TREATMENT PLANT

5.8 billion cubic meters of water is drawn from the water resources in Turkey for drinking and potable water network, according to the Turkey Statistical Institute's 2016 Municipal Water Statistics results. 92.9% of this water by conventional treatment methods, 6.1% by advanced treatment techniques and 1% by physical treatment methods is treated. Conventional drinking water treatment plants generally include oxidation, pretreatment, chemical treatment (coagulation-flocculation-sludge), filtration and disinfection units. The same treatment units are used in Sanliurfa drinking water treatment plant which is the subject of the present study. Total Organic Carbon (TOC) is one of the water quality determination methods such as BOD and COD. It refers to organic substances dissolved or suspended in water. With this study; the treatment efficiency of Sanliurfa drinking water treatment plant was evaluated according to TOC parameter. The TOC removal efficiency performance evaluation of treatment plant was made by comparing experimental data for January-May period. According to this; average efficiency was determined as 28.51%. As a result, this performance value is concluded to be an average treatment efficiency for such conventional drinking water treatment plants.

Formation and interdependence of disinfection byproducts during chlorination of natural organic matter in a conventional drinking water treatment plant.

It is crucial to explore the source, formation process and interdependence of disinfection byproducts (DBPs) to reduce their risk on public health. In this investigation, a source water was chlorinated to evaluate the initial formation rates and the maximum yields of trichloromethane (TCM), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA) based on a hyperbola model. The results showed that TCM achieved the highest initial formation rate and maximum theoretical concentration compared with DCAA and TCAA. The TCM yield can be used to forecast the yields of DCAA and TCAA throughout the whole reaction process, and the yields of chloral hydrate (CH), dichloroacetonitrile (DCAN) and 1,1,1-trichloropropanone (1,1,1-TCP) within the initial reaction stage. Besides, the raw water, settled water and filtered water collected from a drinking water treatment plant were divided into five fractions, respectively, by ultrafiltration membranes to evaluate their DBP formation after chlorination. Compared with the medium molecular weight species, high and low molecular weight organic matters exhibited relatively high specific regulated and unregulated DBP yields (expressed as μg/mg C), respectively. Humic acid-like compositions predominantly contributed to regulated DBP yields, while soluble microbial by-product-like compounds preferentially generated DCAN. The correlation study revealed that the TCM could also serve as an indicator for the measured DBPs from chlorination of sample fractions with different molecular weight. Finally, it was found that the theoretical cytotoxicity was enhanced during chlorination of filtered water compared with chlorination of settled water.

Contributions of volatilization, photolysis, and biodegradation to N‑nitrosodimethylamine removal in conventional drinking water treatment plants

N‑nitrosodimethylamine (NDMA) was detected in the source water of some Chinese drinking water treatment plants (DWTPs), which decreased in concentration along the treatment train. Volatilization, photolysis, and/or biodegradation were suspected of being capable of attenuating NDMA. In this study, the contribution of these mechanisms to NDMA removal was investigated by a field study in a conventional DWTP with aerated bio-pretreatment, as well as in laboratory-based experiments. The effluent of each unit process (i.e., aerated bio-pretreatment tank, horizontal sedimentation tank, sand filter) of this DWTP was sampled in the winter and summer, and the concentration of NDMA, its formation potential, and other water quality parameters were measured. NDMA removal by volatilization and biodegradation was simulated in batch experiments, and that by photolysis was calculated with parameters reported in the literature. The sampling results indicated that the aerated biofilm reactor of this DWTP removed 48% of the NDMA in August and 22% in December. According to modeling results, it could be well explained by photolysis (NDMA removal of 51% in summer and 25% in winter) and biotreatment (NDMA removal of 0.2–12% in summer and 0.1–6.1% in winter), with little contribution from aeration (NDMA removal of 0.8%). The sampling results indicated that the sedimentation tank removed 19% of NDMA in August and 9.2% in December. According to modeling results, it could be well explained by photolysis (NDMA removal of 16% in August and 9.4% in December), but little by volatilization. Thus, photolysis was shown to be the most important process for NDMA removal in this DWTP. Further investigation is needed to better understand NDMA removal during biotreatment.

An investigation of changes in water quality throughout the drinking water production/distribution chain using toxicological and fluorescence analyses

Changes in water quality from source water to finished water and tap water at two conventional drinking water treatment plants (DWTPs) were monitored. Beside the routine water quality testing, Caenorhabditis elegans-based toxicity assays and the fluorescence excitation–emission matrices technique were also applied. Both DWTPs supplied drinking water that met government standards. Under current test conditions, both the investigated finished water and tap water samples exhibited stronger lethal, genotoxic and reprotoxic potential than the relative source water sample, and the tap water sample was more lethal but tended to be less genotoxic than the corresponding finished water sample. Meanwhile, the nearly complete removal of tryptophan-like substances and newly generated tyrosine-like substances were observed after the treatment of drinking water, and humic-like substances were identified in the tap water. Based on these findings, toxic pollutants, including genotoxic/reproductive toxicants, are produced in the drinking water treatment and/or distribution processes. Moreover, further studies are needed to clarify the potentially important roles of tyrosine-like and humic-like substances in mediating drinking water toxicity and to identify the potential sources of these contaminants. Additionally, tryptophan-like fluorescence may be adopted as a useful parameter to monitor the treatment performance of DWTPs. Our observations provided insights into the importance of utilizing biotoxicity assays and fluorescence spectroscopy as tools to complement the routine evaluation of drinking water.

Evaluation of conventional drinking water treatment plant efficiency according to water quality index and health risk assessment

The objective of this research is to investigate the effluent water quality of a treatment plant in Turkey fed from surface and groundwater, according to water quality index (WOI) and health risk assessment (HRA). In order to achieve this goal, the quality of the influent and effluent water of the treatment plant was monitored monthly from January 2017 to January 2019. Water quality parameter results were compared with the Turkish drinking water standards and the World Health Organization (WHO), revealing that all parameters were within approved limits. Principal component analysis (PCA) was applied to determine the water quality parameter impacts in the overall quality of water and the most attractive parameters were trace elements, heavy metals, NH3-N, NO3, and TKN. To evaluate water quality and the impacts on human health, WQI and HRA, including hazard quotient (HQ) and hazard index (HI), were used. The WQI values were calculated by taking into account PCA results. WQI results demonstrated that the influent and effluent of water treatment plant values have a small number of WQI ranking that expressed the water category was "excellent" for drinking purpose. Finally, metal contamination in influent and effluent waters was assessed and the associated health risks to rural populations were estimated for different age groups, children and adults in the service area of the treatment plant. The health risk assessment with similar to WQI results, the acute, sub-chronic, and chronic risks of trace elements was "negligible" level, i.e., to a level affecting 1 person in 1,000,000 inhabitants.

Optimizing the performance of conventional water treatment system using quantitative microbial risk assessment, Tehran, Iran

The performance of conventional drinking water treatment plants (WTPs) can be improved using quantitative microbial risk assessment (QMRA). A QMRA study on Cryptosporidium using actual pathogen density was conducted to examine the performance of Jalaliyeh WTP in Tehran, Iran. The infection risk and the burden of disease attributed to the parasite presence in finished water were estimated incorporating physical and chemical log reduction values (LRVs), using stochastic modeling and disinfection profiling. The risk and burden of disease were compared with health-based targets, i.e. one case of infection per 10,000 people or 10−6 DALYs per person per year. The parasite's LRVs were 2.31 and 0.034 log provided by physico-chemical treatment and disinfection processes, respectively. The mean of estimated risk (111 cases per 104 people per year) and the burden of disease (11.7 DALYs per 106 people per year) both exceeded the targets. To control the excess risk, three QMRA-based disinfection scenarios were examined including: (1) employing chlorine dioxide (ClO2) instead of chlorine (2) ozonation with a concentration of 0.75 mg/L (Ct = 22.5 min mg/L) and (3) UV irradiation with a dose of 10 mJ/cm2. The LRV of parasite may be increased to 3.0, 5.1 and 4.9 log by employing ClO2, ozonation and UV irradiation, respectively. The use of ozone or UV as alternative disinfectants, could enhance the disinfection efficacy and provide sufficient additional treatment against the excess risk of parasite. QMRA could make it easier applying appropriate improvement to conventional WTPs in order to increase the system performance in terms of health-based measures.

Occurrence, removal and seasonal variation of pharmaceuticals in Brasilian drinking water treatment plants

The presence of pharmaceuticals in aquatic environments has become a major issue of concern for scientific community, since there is a lack of information about risks and impacts to the environment and public health. In the context of Brazil, many cities do not have Wastewater Treatment Plants (WWTPs) and domestic sewage is dumped directly into the water bodies, aggravating the problem. Thus, the present study aimed to evaluate the presence of 28 prescribed pharmaceuticals from different therapeutic classes in six full-scale Drinking Water Treatment Plants (DWTPs) in Minas Gerais state. Samples were collected in twelve field campaigns from August 2016 to August 2017 and water quality were monitored. Analytical methodology was based on solid phase extraction (C18 cartridge) followed by High Performance Liquid Chromatography (Prominence DGU/20A3 – Shimadzu) coupled to Mass Spectrometry (micrOTOF-QII – Bruker). Considering the 28 pharmaceuticals analyzed, 18 were detected in the surface water source at concentrations ranging from Method Quantification Limit (MQL) to 11,960 ng/L. In drinking water, the concentration of the 11 pharmaceuticals detected ranged from <MQL to 6323 ng/L. Betamethasone, Fluconazole, Atorvastatin and Prednisone were the most detected pharmaceuticals. The drinking water monitoring showed a decrease in the concentration of all detected pharmaceuticals, indicating some removal of these compounds by the water treatment processes. The removal efficiency assessed shows a great variation among different compounds, DWTPs and over the year, ranging from an average of 32% ± 6% (Prednisone –DWTP3) to 100% ± 0% for some pharmaceuticals. The highest total concentrations and the maximum concentration values for the most frequently detected pharmaceuticals were related to the winter due, presumably, to lower dilution and temperature.Trace levels of pharmaceuticals were detected in surface and drinking water in Brazil and conventional DWTPs were not able to remove the pharmaceuticals completely.

Application of double filtration with activated carbon for the removal of phenols in drinking water treatment processes

Abstract The primary source of the discharge of phenols into the environment is industrial activity, such as the production of pharmaceuticals, plastics, and pesticides, being the majority discharged into surface water sources, reaching concentrations around 0.001 to 0.400 mg/L. These compounds are considered a priority contaminant due to their toxicity to aquatic life and effects on human health. The presence of phenols even at low concentrations generates flavour and odour in drinking water. Due to the molecular stability and solubility of phenols in water, their removal by conventional water treatment methods is inefficient. However, adsorption with granular activated carbon (GAC), after conventional filtration with sand and anthracite, is an efficient technique for the reduction of organic compounds such as phenols. This paper studied the effect of applying double filtration to the reduction of phenols present in the filtered water of a conventional drinking water treatment plant, using two types of GAC (vegetable and mineral) and three GAC:Sand configurations (100:00; 00:100; 50:50). The configurations with GAC showed an efficient reduction of turbidity, organic matter indicator variables (UV254 absorbance and total organic carbon) and phenols, the mineral GAC being the most efficient GAC.

Photocatalysis with easily recoverable linear engineered TiO2 nanomaterials to prevent the formation of disinfection byproducts in drinking water

Two photocatalytic linear engineered TiO2 nanomaterials (LENs) were synthesized and evaluated against commercial standard P25 TiO2 nanoparticles in terms of their effects on common parameters used to measure and characterize natural organic matter (NOM) and disinfection byproduct (DBP) precursors in drinking water. DBPs, some of which have been linked to cancer and other negative human health outcomes, are regulated in most jurisdictions in North America and Europe as well as parts of Asia, Africa, and South America, and the removal of DBP precursors is a central goal of conventional drinking water treatment plants. All three of the nanomaterials evaluated in this study were capable of degrading NOM, including DBP precursors, when irradiated with UVA LED light. The materials differed in terms of crystal phase, surface morphology, and available surface area. These differences impacted the predominant NOM removal processes occurring in each case and consequently the overall treatment efficacy of the two materials in two different water sources. One of the LENs evaluated in this study, designated NB 700, reduced the DBP formation potential of one of the water sources by 90% and was readily removed from the water via filtration. Irrespective of the nanomaterial employed, DBP precursor degradation was faster in the water source with higher NOM and lower alkalinity and hardness. The electrical energy per order (EEO) required to degrade DOC and THM precursors in one of the water sources was comparable to reported values for the degradation of these compounds with UV/H2O2, another advanced oxidation process.