Conventional Water Treatment Plants Research Articles

Modelling the predictive analysis of turbidity removal efficiency in the in-line coagulation and flocculation process

Coagulation and flocculation processes are commonly used in conventional water treatment plants to remove suspended solids from water. However, these methods often suffer from drawbacks such as high chemical consumption, sludge generation, and the need for huge areas, leading to high construction costs. To address these limitations, this study investigated the performance of in-line coagulation and flocculation processes as an alternative to conventional methods. The objectives were to determine the efficiency of in-line coagulation and flocculation, understand the underlying mechanisms, establish optimal operating conditions and design criteria, and to develop theoretical models for predicting turbidity removal efficiency in the in-line coagulation-flocculation process. Experiments were conducted using a continuous setup consisting of a static mixer and a 35-m helically coiled hydraulic tube flocculator.Various operating parameters, including water flow rate (100 – 800 L/hr), initial turbidity (20 – 200 NTU), and coagulant types (aluminum sulfate, poly aluminum chloride, aluminum chlorohydrate, and ferric chloride), were examined. The results demonstrated that aluminum sulfate was the appropriate coagulant for the water characteristics studied, and the in-line coagulation and flocculation processes achieved turbidity removal efficiencies of approximately 91 % under all operating conditions, with a notable 97 % removal efficiency achieved at a liquid flow rate of 600 L/hr, with a Gt value of 21,715 and an overflow rate of 2 m/hr. A prediction model of turbidity removal efficiency was developed, showing good agreement between experimental and predicted removal efficiency model, with an average deviation of about 20 %. This model can aid in determining optimal operating conditions and serve as a hybrid process in future water treatment systems, potentially applicable to other separation processes as well.

Pre-oxidation and coagulation-flocculation as a pretreatment to UF-RO applied for surface water treatment and arsenic removal

In this paper, the effects of applying pre-oxidation, coagulation, and flocculation (C/F) as pretreatment of an ultrafiltration (UF) - reverse osmosis (RO) system treating water containing arsenic were assessed. For this, the performance of a pilot scale – with a maximum treatment capacity of 2.25 m3/h - UF-RO system with and without pretreatment was evaluated. The membranes were able to generate high-quality permeates, even when the feed presented a remarkable increase in color (>2100 uH) and turbidity (>300 NTU) due to the beginning of the rainy season. UF was not efficient for arsenic removal, so RO was essential to guarantee safe water, generating permeates with concentrations below 0.5 μg/L of arsenic. The effective removal of iron and manganese, among other ions, was verified using membranes. Given the high quality of the permeates, blend formulation strategies were carried out, mixing filtered water from the conventional water treatment plant and RO permeate (Strategy I) and mixing filtered water, UF permeate, and RO permeate (strategy II). Strategy II was viable for arsenic concentrations in filtered water of 13 and 15 μg/L. Pretreatment was important in maintaining a higher membrane permeability and ensured a more stable performance in the face of variations in feed quality, which may be seasonal in some places, as in the present case, where feed quality is significantly altered by the rainy season. Overall, although UF and RO membranes are effective processes for treating surface water containing arsenic, the results suggested that pretreatment, which is already part of the treatment of several water treatment plants, guarantees more robustness to the treatment concerning a higher and more stable membrane permeability, directly impacting operational expenses with membranes operation.

Enhancing nanoplastics removal by metal ion-catalyzed ozonation

Nanoplastics (NPs), characterized by sizes < 1 µm, are not completely removed in conventional drinking water treatment plants affecting human health. Catalytic ozonation appears as a promising alternative due to its ability to oxidize emerging pollutants by generating hydroxyl radicals with higher removal rate and mineralization than single ozonation. In this work, catalytic ozonation was investigated for the removal of polystyrene nanoplastics (PSNPs) by employing transition metal ion catalysts, Fe3+, Co2+, Ni2+, and Zn2+. The single ozonation of PSNPs, in the absence of catalyst, led to low turbidity reduction (33 %) and low mineralization rate (16 %) even after 2 h reaction time. Nevertheless, the rapid size reduction of PSNPs by >99 % in less than 5 min of ozonation (TOD: 30 mg L−1) was confirmed. This fact could imply a new issue under the ozone disinfection conditions by the formation of smaller-size particles. However, in the presence of Co2+ (1 mM), the highest PSNPs ozonation performance was achieved, decreasing the turbidity up to 65 % and achieving 70 % of mineralization in the same ozonation time. The scavenger experiments with methanol confirmed that direct ozonation and catalyst role were responsible for PSNPs degradation, with the generation of •OH being the most dominant catalytic mechanism. Therefore, although single ozonation at disinfection doses reduced the particle size of PSNPs, the catalytic process demonstrated greater efficacy in the total removal of PSNPs. These results highlight the need to further investigate ozonation of NPs intermediates, and the synergic improvements of catalytic ozonation for their mineralization.

Occurrence, efficiency of treatment processes, source apportionment and human health risk assessment of pharmaceuticals and xenoestrogen compounds in tap water from some Ghanaian communities

The occurrence of pharmaceuticals and xenoestrogen compounds (PXCs) in drinking water presents a dire human health risk challenge. The problem stems from the high anthropogenic pollution load on source water and the inefficiencies of the conventional water treatment plants in treating PXCs. This study assessed the PXCs levels and the consequential health risks of exposure to tap water from selected Ghanaian communities as well as that of raw water samples from the respective treatment plants. Thus the PXCs treatment efficiency of two drinking water treatment plants in the metropolises studied was also assessed. The study also conducted source apportionment of the PXCs in the tap water. Twenty six (26) tap and raw water samples from communities in the Cape Coast and Sekondi-Takoradi metropolises were extracted using SPE cartridges and analysed for PXCs using Ultra-fast-HPLC-UV instrument. Elevated levels of PXCs up to 24.79 and 22.02 μg/L were respectively recorded in raw and tap water samples from the metropolises. Consequently, elevated non-cancer health risk (HI > 1) to residential adults were found for tap water samples from Cape Coast metropolis and also for some samples from Sekondi-Takoradi metropolis. Again, elevated cumulative oral cancer risks >10−5 and dermal cancer risk up to 4 × 10−5 were recorded. The source apportionment revealed three significant sources of PXCs in tap water samples studied. The results revealed the inefficiency of the treatment plants in removing PXCs from the raw water during treatments. The situation thus requires urgent attention to ameliorate it, safeguarding public health. It is recommended that the conventional water treatment process employed be augmented with advanced treatment technologies to improve their efficacy in PXCs treatment.

Determination of oxidation rate constant for nodularin‐r, saxitoxin, dc‐saxitoxin, and neo‐saxitoxin with conventional water treatment plant oxidants and advanced oxidation processes

AbstractThe effectiveness of chemical oxidation depends on the type of cyanotoxins present in the water and varies with the water quality parameters. This study investigated four cyanotoxins to understand their reactions with conventional drinking water treatment plant oxidants and with advanced oxidation. Kinetic rate constants between saxitoxin, and two variants (dcSTX and neoSTX), and nodularin‐R with chlorine, monochloramine, permanganate, ozone, and hydroxyl radicals (UV‐H2O2) were developed under different pH and temperature conditions. Nodularin‐R kinetic rate constants were comparable to peer‐reviewed microcystin‐LR rate constants with reaction rates in the order of OH radicals &gt; ozone &gt;&gt; chlorine &gt; permanganate &gt;&gt; monochloramine. The speciation of saxitoxins with pH had a dominant effect on their reaction rates with the listed oxidants. Chlorine was the only oxidant effective for saxitoxins removal. The reaction rates of saxitoxins with OH radicals varied slightly with pH but were around two orders of magnitude less than microcystin‐LR's.

Downflow sponge biofilm reactors for polluted raw water treatment: Performance optimisation, kinetics, and microbial community

Water outages caused by elevated ammonium (NH4+-N) levels are a prevalent problem faced by conventional raw water treatment plants in developing countries. A treatment solution requires a short hydraulic retention time (HRT) to overcome nitrification rate limitation in oligotrophic conditions. In this study, the performance of polluted raw water treatment using a green downflow sponge biofilm (DSB) technology was evaluated. We operated two DSB reactors, DSB-1 and DSB-2 under different NH4+-N concentration ranges (DSB-1: 3.2–5.0 mg L−1; DSB-2: 1.7–2.6 mg L−1) over 360 days and monitored their performance under short HRT (60 min, 30 min, 20 min, and 15 min). The experimental results revealed vertical segregation of organic removal in the upper reactor depths and nitrification in the lower depths. Under the shortest HRT of 15 min, both DSB reactors achieved stable NH4+-N and chemical oxygen demand removal (≥95%) and produced minimal effluent nitrite (NO2−-N). DSB system could facilitate complete NH4+-N oxidation to nitrate (NO3−-N) without external aeration energy requirement. The 16S rRNA sequencing data revealed that nitrifying bacteria Nitrosomonas and Nitrospira in the reactor were stratified. Putative comammox bacteria with high ammonia affinity was successfully enriched in DSB-2 operating at a lower NH4+-N loading rate, which is advantageous in oligotrophic treatment. This study suggests that a high hydraulic rate DSB system with efficient ammonia removal could incorporate ammonia treatment capability into polluted raw water treatment process and ensure safe water supply in many developing countries.

Integrating reverse osmosis to a conventional river water treatment plant as a strategy to produce drinking water after mining dam rupture events: a case study

ABSTRACT Incidents of mining dam failure have compromised the water quality, threatening the water supply. Different strategies are sought to restore the impacted area and to guarantee the water supply. One example is water treatment plants that treat high-polluted waters within the required limits for their multiple usages. The current study assesses the integration of reverse osmosis (RO) to a river water treatment plant (RWTP) installed in Brumadinho (Minas Gerais, Brazil) to treat the water from the Ferro-Carvão stream impacted by the B1 dam rupture in 2019. The RWTP started eleven months after the mining dam rupture and is equipped with eight coagulation-flocculation tanks followed by eight pressurised filters. A pilot RO plant was installed to polish the water treated by the RWTP. Water samples were collected at different points of the water treatment plant and were characterised by their physical, chemical, and biological parameters (160 in total). The results were compared with the historical data (1997–2022) to reveal the alterations in the water quality after the rupture event. The compliance with both parameters was only achieved after the RO treatment, which acted as an additional barrier to 30 contaminants. The water quality indexes (WQI) suggested that the raw surface water, even eleven months after the incident, was unfit for consumption (WQI: 133.9) whereas the reverse osmosis permeate was ranked as excellent in the rating grid (WQI: 23.7).

Synergy between heterogeneous catalysis and homogeneous radical reactions for pharmaceutical waste destruction: Perspective

Enormous quantities of pharmaceuticals are consumed by humans leading to a growing and continuous release of harmful components into the environment. Existing conventional water treatment plants are designed mainly for eliminating biodegradable organics and nutrients and cannot degrade pharmaceuticals and personal care products efficiently enough due to their chemical stability. Advanced oxidation processes using radicals generated from ozone can be efficiently combined with heterogeneous catalysis for treatment of wastewater containing pharmaceuticals and personal care products. From the technology viewpoint, elimination of pharmaceuticals from water by heterogeneously catalyzed ozonation should done in a continuous fixed bed reactor. The structured catalysts can be prepared by additive manufacturing using 3D-direct printing of supports/catalysts allowing a high degree of freedom in both the composition and design of the final catalytic material for a fixed bed heterogeneous-homogeneous reaction. Structured materials can exhibit non-periodic structure, such as for example semi-ordered structures, inspired by nature. For periodic and semi-periodic structures, heat and mass transfer should be investigated using computational fluid dynamics and flow imaging methods, guiding further design of novel architectures and subsequently allowing in combination with the materials development efficient control of activity and selectivity. The innovative catalytic reactor engineering should include experimental and numerical investigation of the stage wise injection of the oxidation agent, variation of the reactor cross-section size, changing the distance between the catalyst beds and introduction of the recycle loops.

Impact of harmful algal bloom severity on bacterial communities in a full-scale biological filtration system for drinking water treatment

The occurrence of harmful algal blooms (HABs) in freshwater environments has been expanded worldwide with growing frequency and severity. HABs can pose a threat to public water supplies, raising concerns about safety of treated water. Many studies have provided valuable information about the impacts of HABs and management strategies on the early-stage treatment processes (e.g., pre-oxidation and coagulation/flocculation) in conventional drinking water treatment plants (DWTPs). However, the potential effect of HAB-impacted water in the granular media filtration has not been well studied. Biologically-active filters (BAFs), which are used in drinking water treatment and rely largely on bacterial community interactions, have not been examined during HABs in full-scale DWTPs. In this study, we assessed the bacterial community structure of BAFs, functional profiles, assembly processes, and bio-interactions in the community during both severe and mild HABs. Our findings indicate that bacterial diversity in BAFs significantly decreases during severe HABs due to the predominance of bloom-associated bacteria (e.g., Spingopyxis, Porphyrobacter, and Sphingomonas). The excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC) confirmed that filter influent affected by the severe HAB contained a higher portion of protein-like substances than filter influent samples during a mild bloom. In addition, BAF community functions showed increases in metabolisms associated with intracellular algal organic matter (AOM), such as lipids and amino acids, during severe HABs. Further ecological process and network analyses revealed that severe HAB, accompanied by the abundance of bloom-associated taxa and increased nutrient availability, led to not only strong stochastic processes in the assembly process, but also a bacterial community with lower complexity in BAFs. Overall, this study provides deeper insights into BAF bacterial community structure, function, and assembly in response to HABs.

Study on Conventional Drinking Water Treatment for Removing Emerging Contaminants: A Literature Review

Emerging contaminants (ECs) are substances that can be synthetic or natural, or even microorganisms that are usually not monitored in the environment and could be harmful to the environment and human health. These chemicals can include pharmaceuticals, such as ibuprofen and acetaminophen, and industrial chemicals, e.g., perfluorooctanoic acid (PFOA). Common conventional drinking water treatment plants (CDWTP) are not designed to remove emerging contaminants, so these compounds can enter the water system and affect the drinking water treatment process. This study aims to focus on the performance of CDWTP in removing ibuprofen, acetaminophen, and PFOA parameters, as well as determine suitable water treatment units to eliminate these parameters from the system. An extensive literature review was conducted and further analysed using descriptive and qualitative analysis to understand the unit performance in removing emerging contaminants, followed by the simple simulation to determine the types of advanced drinking water treatment facilities that perform better in eliminating ECs. The results show that CDWTP could reduce ibuprofen concentration in water with 40%, 20%, and 36% efficiency through coagulation-flocculation, sand filtration, and disinfection, respectively. Acetaminophen removal is up to 67%, 51%, and 66.45% during coagulation-flocculation, sand filtration, and disinfection, respectively. However, PFOA removal is only up to 5%, 7%, and 2% during coagulation-flocculation, sand filtration, and disinfection, respectively. Membrane treatment technology with reverse osmosis could remove ibuprofen, acetaminophen, and PFOA compounds more effectively with removal efficiencies of 99.99%, 96%, and 100%, respectively.

Formation of chlorinated disinfection by-products and fate of their precursors in individual processes of a conventional water treatment plant assessed using high-resolution mass spectrometry

Formation of chlorinated disinfection by-products and fate of their precursors in individual processes of a conventional water treatment plant assessed using high-resolution mass spectrometry

Assessment of a Francis Micro Hydro Turbine Performance Installed in a Wastewater Treatment Plant

The purpose of this research work was to examine the hydroelectric potential of wastewater treatment plants by harnessing the kinetic and/or potential energy of treated wastewater for electricity generation. Such a concept encapsulates the essence of renewable energy and resonates with international sustainable development mandates and climate change adaptation strategies. The primary objective was to analyze the performance parameters of the Francis turbine, a key component of this energy generation system. An experimental analysis encompassed model tests on the Francis turbine, simulating varied flow conditions using the GUNT turbine. Additionally, historical data from the Toruń Wastewater Treatment Plant (WWTP) 2018 annual wastewater discharge were employed to validate the findings and shed light on real-world applications. The tested efficiency of the Francis turbine peaked at 64.76%, notably below the literature-reported 80%. The turbine system’s overall efficiency was approximately 53%, juxtaposed against the theoretical value of 66.35%. With respect to the Toruń WWTP data, the turbine’s power output was highest at 24.82 kW during maximum wastewater flow, resulting in a power production of 150.29 MWh per year. The observed turbine efficiencies were consistent with the previously documented range of 30% to 96%. The turbine displayed optimal outputs during heightened flow rates and maximized production at more frequent, lower flow rates throughout the year. Implementing such turbines in wastewater treatment plants not only aligns with global renewable energy goals but also boasts lower construction costs and environmental impacts, primarily due to the utilization of existing infrastructure. Furthermore, wastewater flow consistency counters the seasonal variability seen in conventional water treatment plants. These findings pave the way for more energy-efficient design recommendations for turbines within wastewater treatment and hydropower plants.

Human health risk assessment of Triclosan in water: spatial analysis of a drinking water system.

Triclosan (TCS) has been increased in the water during the COVID-19 pandemic because it cannot remove by conventional water treatment. In addition, it can accumulate in the human body over time through long-term exposure. Therefore, the occurrence of TCS in the water treatment plant (WTP) and tap water, and its human health risk assessment through tap water ingestion, dermal absorption, and inhalation routes in Isfahan, Iran, were investigated. Moreover, spatial regression methods were used for the prediction of water quality parameters, TCS concentration, and total hazard quotient (HQ). The average TCS concentration in the influent and effluent of WTP and tap water was 1.6, 1.4, and 0.4 μg/L, respectively. Conventional WTP has low efficiency in the removal of TCS (12.6%) from water. The average values of total HQ for males were 7.79×10-5, 4.97×10-4, and 4.97×10-5 and for females were 3.31×10-5, 2.11×10-4, and 2.11×10-5 based on RfDEPA, RfDMDH, and RfDRodricks, respectively that were in the low-risk levels (HQ<1). Furthermore, TCS concentration in tap water and the ingestion rate of drinking water had the highest effect on the risk of TCS exposure from tap water. The non-carcinogenic health risk of TCS in water was low. The results of this study may be useful for promoting WTP processes to remove emerging pollutants.

Fate of Cryptosporidium and Giardia through conventional and compact drinking water treatment plants

Over the past three decades, a notable rise in the occurrence of enteric protozoan pathogens, especially Giardia and Cryptosporidium spp., in drinking water sources has been observed. This rise could be attributed not only to an actual increase in water contamination but also to improvements in detection methods. These waterborne pathogens have played a pivotal role in disease outbreaks and the overall escalation of disease rates in both developed and developing nations worldwide. Consequently, the control of waterborne diseases has become a vital component of public health policies and a primary objective of drinking water treatment plants (DWTPs). Limited studies applied real-time PCR (qPCR) and/or immunofluorescence assay (IFA) for monitoring Giardia and Cryptosporidium spp., particularly in developing countries like Egypt. Water samples from two conventional drinking water treatment plants and two compact units (CUs) were analyzed using both IFA and qPCR methods to detect Giardia and Cryptosporidium. Using qPCR and IFA, the conventional DWTPs showed complete removal of Giardia and Cryptosporidium, whereas Mansheyat Alqanater and Niklah CUs achieved only partial removal. Specifically, Cryptosporidium gene copies removal rates were 33.33% and 60% for Mansheyat Alqanater and Niklah CUs, respectively. Niklah CU also removed 50% of Giardia gene copies, but no Giardia gene copies were removed by Mansheyat Alqanater CU. Using IFA, both Mansheyat Alqanater and Niklah CUs showed a similar removal rate of 50% for Giardia cysts. Additionally, Niklah CU achieved a 50% removal of Cryptosporidium oocysts, whereas Mansheyat Alqanater CU did not show any removal of Cryptosporidium oocysts. Conventional DWTPs were more effective than CUs in removing enteric protozoa. The contamination of drinking water by enteric pathogenic protozoa remains a significant issue globally, leading to increased disease rates. Infectious disease surveillance in drinking water is an important epidemiological tool to monitor the health of a population.

Tailoring the pore architecture and crystalline structure of UiO-66 for the selective adsorption of anionic species in aqueous media

Micropollutants such as organic dyes and pharmaceuticals have received much attention in recent years due to their harmful effects on humans and wildlife, high stability against natural degradation, and difficult removal in conventional water treatment plants. In this work, we have optimized the adsorption of organic pollutants on UiO-66 metal–organic frameworks by changing some synthesis parameters, which allowed the tuning of their crystal structure and pore architecture. Samples with an extended microporous structure and specific surface areas over 1300 m2.g−1 were prepared by a solvothermal approach, which favored the access of the pollutant molecules to active adsorption sites. The specific surface areas measured in this study are among the highest ever reported for UiO-66. In batch adsorption tests conducted using aqueous solutions containing low initial concentrations (20 mg.L-1) of acid orange (AO7), ibuprofen (IBU), and methylene blue (MB), the materials tested in this study exhibited preferential adsorption of the anionic species AO7 (192 mg.g−1) and IBU (173 mg.g−1), resulting in AO7/MB and IBU/MB selectivities of 9.6 and 8.7, respectively. The primary adsorption mechanism is most likely a combination of electrostatic and Lewis acid-base interactions involving Zr-(-SO3−) for AO7 and Zr-(–CO2−) for IBU. Subsequent tests with moderately higher concentrations of AO7 (50 mg.L–1) showed even higher adsorption capacities, exceeding 340 mg.g−1. These results demonstrate that the optimized UiO-66 structure prepared in this study exhibits high-performance adsorption capabilities for the removal of anionic pollutants from aqueous media, thereby expanding the knowledge on the use of Zr-based MOFs for water remediation.

Upgrading of conventional water treatment plant by nanofiltration for enhanced organic matter removal

Natural organic matter (NOM) is responsible for a variety of problems in water, including taste, odor, and color. If NOM is present in treated water, it can also promote microbial growth in water distribution systems. Another problem related with NOM is that it combines with chemicals such as chlorine in water resulting in the formation of disinfection by-products (DBPs). With the DBP regulations becoming more stringent, several advanced treatment methods started to be applied to enhance NOM removal. Pilot-scale advanced treatment tests employing tight nanofiltration (T-NF) membrane with high ion rejection capacity and loose nanofiltration (L-NF) membrane with low ion rejection capacity were conducted in this study in order to remove total organic carbon (TOC) having an average concentration of 2 mg/L at the sand filter effluent of a full-scale drinking water treatment plant and to avoid DBP production. The cost of incorporating membrane processes into the treatment process scheme was also determined during the study, in addition to the experimental studies. At constant 6 bar, the average fluxes for the T-NF and L-NF were determined to be 12.7 and 7.6 L /m2 h, respectively. L-NF had a TOC removal efficiency of 96.0%, which is quite similar to the removal efficiency achieved by T-NF (96.3%). Heavy metals, anions, and cations removal efficiency in T-NF membranes were greater than in L-NF, as expected. The removal efficiencies of Cl-, and Fe on T-NF membrane were determined to be 90.3 ± 2.2% and 69.6 ± 5.6, respectively, which are much greater than those achieved in L-NF membrane The total cost of 400,000 m3/d L-NF membrane system upgrade is calculated as 28,901,262 $/y including capital and operation and maintenance (O&M) costs, while in T-NF is calculated as 28,074,282 $/y. The total cost of NF upgrading is estimated to be around 0.191–0.198 $/m3, which is nearly 50% of the cost of the conventional treatment plant. When upgrading a conventional treatment system with this type of membrane system, additional expenses are typically incurred, resulting in a higher total cost; however, the resultant water quality is significantly improved.

A case study of comparative techno-economic and life cycle assessment of tap water versus household reverse osmosis-based drinking water systems in a North Indian city

Abstract Household reverse osmosis (RO)-based water purifiers have gained popularity in India due to concerns about the quality of tap water. However, the widespread adoption of these systems has significant impacts on water pricing and the environment. The objective of this study was to assess the techno-economic performance and life cycle assessment (LCA) of household RO-based water purifiers in Srinagar city of North India. Our results demonstrate that household ROs reduce the concentration of important dietary minerals such as fluoride and magnesium in drinking water by 50%. In addition, the average total water cost from a household RO is three to four times more than what is being paid for tap water. Two different scenarios were compared in LCA. The first scenario was safe drinking water from a conventional drinking water treatment plant (scenario 1), while the second scenario was water from a household RO system (scenario 2). The results showed that the environmental impacts of abiotic depletion, acidification of water bodies, eutrophication, global warming and ozone depletion in scenario 2 were higher than in scenario 1. The findings infer that water utilities should encourage citizens to rely on conventional tap water as a cheaper and environmentally friendly option compared to household ROs.

Assessment of Microplastics Contamination in River Water, Bottled Water, Sachet Water and Branded Table Salt Samples in Kaduna Metropolis, Nigeria

Microplastics (MPs) &lt; 5 mm-sized are regarded as global environmental contaminants. This study analyzes MP concentrations in the Kaduna River (raw water), treated water from two conventional water treatment plants, brands of bottled water, and food-grade salts available in Kaduna Metropolis, Nigeria using standard methods. Data obtained show that levels of MPs ranged from 25 to 36 particles L-1 in treated water, and to 153 particles L-1 in raw water. While samples of bottled water contained 1.4 to 3.7 particles L-1 and samples of table salt contained 0.13 to 0.27 particles g-1. Water and salt samples contained five different types of polymers, including polyethylene, polypropylene, polyester, polyvinyl chloride and polyethylene terephthalate. Additionally, MPs were divided into three groups based on their physical characteristics. In both raw and treated water, fragments were clearly more prevalent; in samples of bottled water and table salt, fragments and fibers predominated. Microplastics in bottled water pose a medium pollution risk, according to pollution risk indices. The estimated daily intake was generally minimal, indicating little harm from daily consumption, but it also demonstrates that children have a larger intake of microplastics than adults. Leaching from the packing material was identified as the MPs' primary source. This study fills the knowledge gap in the area of emerging microplastic pollution of water sources, drinking water, and food-grade salt.

Performance of Conventional Drinking Water Treatment Plants in Removing Microplastics in East Java, Indonesia

Performance of Conventional Drinking Water Treatment Plants in Removing Microplastics in East Java, Indonesia

Recent Advances in 1,4-Dioxane Removal Technologies for Water and Wastewater Treatment

1,4-Dioxane is a contaminant of emerging concern and a probable human carcinogen that has been widely detected in aqueous environments. However, the removal of 1,4-dioxane by conventional water and wastewater treatment plants had proven to be ineffective due to its unique physicochemical properties. The development of innovative technologies for both in-situ and ex-situ treatment of 1,4-dioxane to meet increasingly strict standards is in urgent need. This review summarizes the current available physicochemical and biological treatment technologies for the removal of 1,4-dioxane from both water and wastewater and the strategies that may potentially fulfill the stringent 1,4-dioxane standard were discussed. Advanced oxidation processes (AOPs), such as ultraviolet radiation coupled with H2O2 (8–10 mg L−1), had shown efficient 1,4-dioxane destruction and had already been applied for both water and wastewater treatment processes. On the other hand, more than 30 pure microbial strains and microbial communities that can metabolically or metabolically degrade 1,4-dioxane were reported. Biodegradation has been proven to be a feasible and cost-effective approach for 1,4-dioxane remediation. Suspended growth bioreactor, immobilized cell bioreactor, and biofiltration systems were the most commonly used biological approaches to remove 1,4-dioxane from contaminated water. Though 1,4-dioxane easily desorbs after the adsorption by materials such as granular activated carbon (GAC) and zeolite, temporary 1,4-dioxane removal by adsorption followed by 1,4-dioxane biodegradation in the bioaugmented adsorption media may be a feasible strategy treating 1,4-dioxane contaminated water. Overall, the treatment chain that combines physical-chemical processes and biodegradation has a great potential for synergistic removal of 1,4-dioxane at lower operating costs.