Disinfection by-products

Aims: The aim of this study was to evaluate the effectiveness of microwave irradiation sterilization on Molloplast –B soft denture liner. Materials and Methods: Sixty specimens of Molloplast –B soft denture liner were fabricated in a standardize procedure and autoclaved. The total 60 specimens were divided into 4 groups. Each group has 15 specimens inculated with Brain Heart Infusion Broth (BHI) media containing one of the tested microorganisms (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeroginosa and Candida albicans). Then the 15 specimens in each group was further divided into 3 subgroups: group C (positive control); 5 none irradiated specimens, group D (dry microwave treatment); 5 specimens placed in a dry beaker and microwave irradiated at 540W for 6 minutes, group W (wet microwave treatment; 5 specimens immersed in distalled water and irradiated in the same manner as group D. After incubation of all specimens for 24 hours at 37°C, the specimens were got vortex and then the replicated  specimens (100μL) of suspensions were plated on 4 selective media appropriate for each organism. All plates were incubated at 37°C for 48 hours. After incubation, colonies were counted. Further 7 days incubation for microwaved specimens was done to verify the effectiveness of dry and wet microwave sterilization. Results: Significant reduction in cfu/ml of all microorganisms was observed at 48 hours. No growth of C.  albicans was recorded at 48 hours and after 7 days incubation. Conclusions: Microwave irradiation at 540W for 6 min in dry and wet conditions was proved to be effective in the disinfection of soft lining material specimens contaminated with Staph. aureus, Ps.  aeruginosa and B.  subtilis. Wet treatment was more effective than dry one. Dry and wet microwave treatment sterilized specimens contaminated with C.  albicans.

Access to clean drinking water remains a challenge in many developing countries, emphasizing the critical need
for affordable, scalable and sustainable water treatment technologies. This study employs an electrochemical
flow cell incorporating a 3D-printed biomimetic flow field for efficient in situ electrochlorination, avoiding water
recirculation or external chloride dosing. The impact of varied ionic compositions of groundwater on electrochlorination
efficiency is examined using synthetic groundwater samples, reflecting diverse hydrogeological
conditions within a region in a developing country. Employing a Multilevel Factorial Design (MFD), the study
highlights the significant influence of water ionic composition, flow rate, and applied current on free chlorine
production. The results affirm the capability of the reactor to generate free chlorine species in a range of
0.32–6.13 mg⋅L􀀀 1. The specific energy consumptions oscillate between 0.49 and 19.67 Wh⋅mg􀀀 1 for chloride
concentration in the samples ranging from 24 to 146 mg⋅L􀀀 1. This confirms the potential of the suggested
electrochemical cell design for broad use in the studied region, and possibly in similar settings worldwide.

Aims: The representativeness of European standards phase 2, step 1 regarding bactericidal and yeasticidal activities was used for the comparison of two marketed antiseptic solutions, one containing chlorhexidine digluconate (0.5%) and the other combining chlorhexidine digluconate (0.25%), benzalkonium chloride (0.025%) and benzylic alcohol (4%). Methods: The bactericidal activity of the antiseptic solutions used pure or diluted was assessed according to the European standards NF EN 13727 and NF EN 13624 for the bactericidal and yeasticidal activity respectively. The contact time was 1 min at 20˚C. Interfering substances used correspond to soiling conditions i.e. bovine serum albumin and sheep erythrocytes. A reduction of colony-forming units by ≥5 log10 was deemed to meet the requirements to conclude bactericidal activity and ≥4 log10 for yeasticidal activity. Results: Regarding all the mandatory strains, both solutions are bactericidal and yeasticidal even after a 40% dilution and even under "dirty" conditions. Conclusions: The present study demonstrated the efficient bactericidal and yeasticidal activity of aqueous solutions containing chlorhexidine digluconate either alone at a concentration of 0.5% (w/v) or at a concentration of 0.25% (w/v) when combined with benzalkonium chloride at 0.025% (w/v) and benzylic alcohol 4%. These results have to be considered regarding the respective formulations and potent allergy risks.

The present study was conducted to identify and examine locally available natural coagulant (Sorghum bicolor [NC]) and its blended form with chemical coagulant (alum) to treat turbid water. Blended form of NC was prepared by mixing different proportions of NC and alum. NC, alum and blended coagulant (NC B) were compared with each other to check maximum turbidity removal efficiencies. At optimum doses and pH, turbidity removal efficiencies by alum, NC and NC B were 97.9%, 93.2% and 98.96%, respectively. Also statistical analysis was performed for validation of results. Further, NC was characterized by Fourier transformed infrared test that confirmed the presence of protein-specific functional groups (medium, small and broad 1° and 2° amines, medium aliphatic amines and small saturated aliphatic groups) responsible for coagulation activity. Floc sizes were also observed through micro-photographic analyses of NC, alum and NC B were found out to be 19, 39 and 45 µm, respectively. In water treatment, NC B proved to be the best coagulant for turbidity removal and the coagulation mechanism observed was charge neutralization in it.

Disinfectants are used to maintain the bioburden of any facility under limits and making them free from any external or internal pathogenic intervention.The cleanroom area of any pharmaceutical facility comprises of different surface, these surfaces are easier to disinfect and so the cleaning and disinfection programs complement each other. The Disinfection efficacy and validation studies are carried in consistent with the United State Pharmacopeia <1072> Disinfectants and Antiseptics protocol. This study was aimed to generate data to provide a high degree of assurance that the disinfection program will consistently yield results that meet pre-determined specification by using different types of Imagard brand disinfectant. The recommended concentration of all the disinfectant at precise time i.e., 10 minutes showed excellent log reduction against the standard test organisms. The results proved that Disinfectant Imagard HD, Imagard IG PRO 401, Imagard IL 15, Imagard AS 10, Imag...

Metals in the drinking water distribution system (DWDS) play an important role on the fate of disinfection byproducts (DBPs). They can increase the formation of DBPs through several mechanisms, such as enhancing the proportion of reactive halogen species (RHS), catalysing the reaction between natural organic matter (NOM) and RHS through complexation, or by increasing the conversion of NOM into DBP precursors. This review comprehensively summarizes these complex processes, focusing on the most important metals (copper, iron, manganese) in DWDS and their impact on various DBPs. It organizes the dispersed 'metals-DBPs' experimental results into an easily accessible content structure and presents their underlying common or unique mechanisms. Furthermore, the practically valuable application directions of these research findings were analysed, including the toxicity changes of DBPs in DWDS under the influence of metals and the potential enhancement of generalization in DBP model research by the introduction of metals. Overall, this review revealed that the metal environment within DWDS is a crucial factor influencing DBP levels in tap water.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Wodociągi i kanalizacja W odociągi i kanalizacja/ Water supply and sewage systems Ocena jakości wód podziemnych pod kątem zawartości substancji organicznych na ujęciach wody w Środzie Wielkopolskiej Assessment of groundwater quality in terms of organic matter content at water intakes in Środa Wielkopolska IZABELA ZIMOCH, ALEKSANDRA GÓRSKA, ŁUKASZ WEBER

The study assessed the levels of trihalomethanes in drinking water from Ahmadu Bello University treatment plant between 2008 and 2010. Two hundred and fifty two (252) samples of processed drinking water at various stages of treatment and distribution were taken in duplicates. In accordance with the United States Environmental Protection Agency (USEPA) Method 551.1, samples were taken using ammonium chloride as de-chlorinating agent and methyl tert-butyl ether (MTBE) as solvent extractant during samples’ analyses. Concentrations of the four regulated trihalomethanes (trichloromethane – CHCl3, tribromomethane – CHBr3, tribromochloroomethane and bromodichloromethane) were analysed using Agilent gas chromatograph (GC) model 19091-413 with Chemstation software. From the study, only tribromomethane was detected immediately after chlorination while trichloromethane and bromodichloromethane were detected at storage in the booster station. Peak values of these analytes were also obtained at ...

A laboratory study was undertaken to evaluate the effectiveness of marble dust as a soil stabilizer. The study revealed that the geotecnical parameters of forest soils are improved substantially by the addition of marble dust. Significant PI reductions occurred with MD treatment, particulary for high PI soils. Results showed that plasticity was reduced by 15 to 30% and strength increased by 25 to 50 %. The highest strength were achieved at 8 % marble dust after 28 days .Increases in the unconfined compressive strength (UCS) of soil occured with the addition of marble dust (MD). Also we found that the deflection has been reduced at 11%, CBR and the strength layer coefficient are increased 50 and 30% respectively.

The presence of CECs in aquatic systems has raised significant concern since they are potentially harmful to the environment and human health. Eliminating CECs has led to the development of alternatives to treat wastewater, such as advanced oxidation processes (AOPs). The ultraviolet-mediated activation of monochloramine (UV/NH 2 Cl) is a novel and relatively unexplored AOPs for treating pollutants in wastewater systems. This process involves the production of amino radicals (• NH 2) and chlorine radicals (Cl •) from the UV irradiation of NH 2 Cl. Studies have demonstrated its effectiveness in mitigating various CECs, exhibiting advantages, such as the potential to control the amount of toxic disinfection byproducts (TDBPs) formed, low costs of reagents, and low energy consumption. However, the strong influence of operating parameters in the degradation efficiency and existence of NH 2 Cl, the lack of studies of its use in real matrices and techno-economic assessments, low selectivity, and prolonged treatment periods must be overcome to make this technology more competitive with more mature AOPs. This review article revisits the state-of-the-art of the UV/NH 2 Cl technology to eliminate pharmaceutical and personal care products (PPCPs), micropollutants from the food industry, pesticides, and industrial products in aqueous media. The reactions involved in the production of radicals and the influence of operating parameters are covered to understand the formation of TDBPs and the main challenges and limitations of the UV/NH 2 Cl to degrade CECs. This review article generates critical knowledge about the UV/NH 2 Cl process, expanding the horizon for a better application of this technology in treating water contaminated with CECs.

The PCFH is an alternative technology to conventional disinfection methods used to control the microbial quality of water. To verify its effectiveness, it is necessary to generate new information related to inactivation kinetics of MS2 coliphage by PCFH. Therefore, in this research we studied the mathematical modeling of the virus inactivation by PCFH-Al/Fe-PILC in presence of a synthetic pattern of natural organic matter. The inactivation constant was subjected to two approximations, finding out that the experimental data were adjusted to the pseudo-first order Chick-Watson model with constant inactivation rate. With the PCFH technology it was possible to obtain the maximum inactivation constant $k=0.1648\, min^{-1}$ in the catalytic tests MS2-3 and MS2-7, kinetics indicates that a rapid inactivation occurs in the first minutes of the reaction, followed by a slow inactivation in the rest of the reaction time. This research suggests the potential of PCFH to improve the quality of dr...

Plasma discharge is a novel disinfection and effectual inactivation approach to treat microorganisms in aqueous systems. Inactivation of Gram-negative Escherichia coli (E. coli) by generating high-frequency, high-voltage, oxygen (O 2) injected and hydrogen peroxide (H 2 O 2) added discharge in water was achieved. The effect of H 2 O 2 dose and oxygen injection rate on electrical characteristics of discharge and E. coli disinfection has been reported. Microbial log reduction dependent on H 2 O 2 addition with O 2 injection was observed. The time variation of the inactivation efficiency quantified by the log reduction of the initial E. coli population on the basis of optical density measurement was reported. The analysis of emission spectrum recorded after discharge occurrence illustrated the formation of oxidant species (OH • , H, and O). Interestingly, the results demonstrated that O 2 injected and H 2 O 2 added, underwater plasma discharge had fabulous impact on the E. coli sterilization. The oxygen injection notably reduced the voltage needed for generating breakdown in flowing water and escalated the power of discharge pulses. No impact of hydrogen peroxide addition on breakdown voltage was observed. A significant role of oxidant species in bacterial inactivation also has been identified. Furthermore the E. coli survivability in plasma treated water with oxygen injection and hydrogen peroxide addition drastically reduced to zero. The time course study also showed that the retardant effect on E. coli colony multiplication in plasma treated water was favorable, observed after long time. High-frequency underwater plasma discharge based biological applications is technically relevant and would act as baseline data for the development of novel antibacterial processing strategies.

The present study aims to reduce Trihalomethane (THMs) level, residual aluminum and control filter run time in EL-Nobarya drinking water treatment plant via the application of enhanced coagulation technique. The effectiveness of the treatment process was evaluated in terms of the removal of natural organic matter (NOM), and the decrease in THM levels in the period from January to August 2020. First, the optimal coagulant dose (60-70 mg/L) for NOM removal was determined on bench scale and then applied on the plant. The results showed that NOM and THM concentrations were reduced by 28-44% and 25-35%, respectively. The residual aluminum varied from 0.1-0.13 mg/L compared to 0.18-0.26 mg/L using conventional treatment. In addition, the filter run time increased from 12 hours to 24 hours saving about 250 m3 of washing water for each filter. Enhanced coagulation was adopted as a controlling strategy for THM in EL-Nobarya plant and EL-Beheira water&drainage company (BWADC). Further control of chlorine dose and point of injection was needed for more reduction in THM.

Project-level research strategies at the U.S. Environmental Protection Agency regarding chemical mixtures are impacted by administrative priorities, public interests, expert opinions, scientific advances, regulatory needs, and legislative actions, influencing the setting of priorities and goals. Perhaps, the most significant influence on conducting chemical mixtures research is the passage of laws requiring the EPA to investigate the potential toxicity of various mixtures, specifically the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, the Food Quality Protection Act of 1996, and the Safe Drinking Water Act Amendments of 1996. Scarce resources are allocated to broadly defined issues for consideration by teams of scientists, who design and implement specific projects. Because resources are limited, projects may have several goals, e.g., filling specific data gaps to support a regulation and, simultaneously, producing data to evaluate a risk assessment method. Research areas of emphasis are shaped by risk assessment needs, data gap uncertainties, and experimental design considerations. This paper discusses factors shaping EPA research strategies for chemical mixtures and presents an example of efficient research planning to investigate potential toxicity from exposure to drinking water disinfection by-products.

Electrocoagulation (EC) is an electrochemical method in water treatment. Nowadays, electrochemical disinfections have created great interest in water treatment as an alternative for conventional disinfection. In this study, the effects of electrochemical inactivation with monopolar electrodes on Escherichia coli and Clostridium perfringens bacteria removal from potable water by the EC process were investigated. In addition, the effects of initial pH, reaction time, current density, as well as inter-electrode distance and conductivity on abatement of selected bacteria along with operating costs have been studied. The structure and surface morphology of the alum nanocrystallites were investigated by X-ray fluorescence, N 2 adsorption-desorption, transmission electron microscopy, powder X-ray diffraction, and field emission-scanning electron microscopy. The experiments were performed in a batch reactor. According to the results, the optimum condition for removal efficiency of 100% E. coli and C. perfringens with an 0.6 USD/m 3 operation cost for the treated aqueous solution were as follows: reaction time = 25 min, initial pH = 7, inter-electrode distance = 2 cm, current density = 33.3 A/m 2 , electrical conductivity = 0.75 mS/cm, and initial bacteria count = 10 4 CFU/mL. Findings indicated that increasing pH from 7 to 9 can significantly decrease the removal efficiency for E. coli and C. perfringens from 100% to 74% and 71%, respectively. Increasing reaction time and current density decreased both strains significantly. Inter electrode distance had an intangible effect on strains abatement. Field Emission-Scanning Electron Microscopy analysis revealed morphological variations and the mechanism through which the killing and trapping of the bacteria by alum nanocrystallites occur. The present method is able to reduce the E. coli and C. perfringens count in potable water, which meets the drinking water standards according to WHO guidelines.

To address the urgent need for safe potable water in South Africa's rural areas, sustainable systems for water disinfection at the village-scale of operation are required. In this thesis, the development of a small-scale water chlorination system that runs on salt and solar panels is described. The system combines a membrane-based hypochlorite generator, or "membrane electrolyser", with an automated hypochlorite dosing system. The system was designed to (i) coordinate hypochlorite production and dosing automatically in a flow-through system, and (ii) fit inline with low pressure pipelines from overhead storage tanks or raised water sources. Low cost materials were used for construction, and water-powered mechanisms were devised to control both brine supply to the electrolyser and regulation of water flow. The capacity of the system was based on the maximum daily output of the electrolyser at ~20 g of sodium hypochlorite. This was sufficient chlorinate up to 10 kL of water per day using less than 80 g of salt and less than 0.1 kW.h of electricity. The cost of the system was estimated at ~R10 000 and therefore potentially affordable for communities up to 100 people, e.g. small farms and villages. Testing of the system was carried out at a farm site in Worcester (Western Cape) using remote monitoring of current levels in the electrolyser. Operation of the system over a two month test period, dosing at ~4 mg/L, produced consistent chlorination measured as (FAC). Community participation in maintenance of the brine supply was managed and chlorinated water was made available to the community after a brief social survey was conducted. Community awareness of chlorination was minimal. No significant history of diarrhoea was reported. However, the community regularly boiled their tap water in response to turbidity increase in summer. The system was affected by turbidity increase in the local water, which caused a drop in electrolyser current and chlorine production due to particle blockage of the membrane in the electrolyser. However, turbidity at acceptable levels for chlorination was found to have no detrimental effect on the system's performance. The system showed promise for rural implementation providing low turbidity was maintained. Therefore, groundwater sites, and surface waters with appropriate clarification systems are recommended for the system's installation. Further testing of the system will be required to establish its long term viability in the hands of a rural community. v DECLARATION "I declare that Development and Testing of a Small-scale Electro-chlorination System for Rural Water Supplies is my own work and that all the sources I have used or quoted have been indicated and acknowledged as complete references."

Electrochlorination is an efficient and cost-effective treatment technique to provide safe drinking water in remote locations. Commercial electrochlorinators normally rely on the replenishment of salts to generate the disinfectant. In this work, a novel undivided electrochemical flow cell with affordable electrode materials (graphite and stainless steel) is proposed, simulating the chlorides naturally present in groundwater sources (25−250 mg• L −1). The biomimetic 3D-printed flow field allows to generate chlorine in a single pass with residence times lower than 1 min. Parameters controlling the electrochlorination are evaluated through a definitive screening design and include applied current, flow rate, and concentration of ions, such as chloride, sulfate, bicarbonate, and calcium. The main factors influencing free chlorine are chloride concentration, applied current, and water inlet flow rate. These significant parameters are further studied and optimized in a Box− Behnken design, obtaining free chlorine concentrations higher than 0.5 mg•L −1 in all evaluated chloride concentrations, with a maximum of 3.70 mg•L −1 for the most favorable conditions. The optimal conditions for achieving the minimum specific energy consumption (SEC) while maximizing chlorine production were identified at a chloride concentration of 250 mg•L −1 , operating with a flow rate of 400 mL•h −1 and applying a current of 35.5 mA. This setup resulted in the lowest observed SEC of 0.59 Wh•mg FC −1. The favorable results for electrochlorination in this type of cell open up the possibility for scale-up, allowing processing at higher drinking water flow rates.

In this paper, we describe a numerical model to simulate the evolution in time of the hydrodynamics of water storage tanks, with particular emphasis on the time evolution of chlorine concentration. The mathematical model contains several ingredients particularly designed for this problem, namely, a boundary condition to model falling jets on free surfaces, an arbitrary Lagrangian-Eulerian formulation to account for the motion of the free surface because of demand and supply of water, and a coupling of the hydrodynamics with a convection-diffusion-reaction equation modeling the time evolution of chlorine. From the numerical point of view, the equations resulting from the mathematical model are approximated using a finite element formulation, with linear continuous interpolations on tetrahedra for all the unknowns. To make it possible, and also to be able to deal with convection-dominated flows, a stabilized formulation is used. In order to capture the sharp gradients present in the chlorine concentration, particularly near the injection zone, a discontinuity capturing technique is employed.

Chloramination and chlorination contribute to the formation of N-nitrosodimethylamine and trihalomethanes, respectively, both of which are defined as disinfection by-products. To be able to select the most appropriate water treatment scheme, it is important to comparatively evaluate the formation of both of these disinfection by-products during the application of different disinfection methods. In this study, chlorination, chloramination and stepwise chloramination methods have been applied to surface water samples that have been spiked with known N-nitrosodimethylamine precursors. Experimental results showed that ranitidine can be an effective N-nitrosodimethylamine precursor in distilled water, when chloraminated with high concentrations (140 mg/L) for a long time (10 days), resulting in approximately 450 ng/L of N-nitrosodimethylamine. However, neither dimethylamine nor ranitidine leads to significant trihalomethanes or N-nitrosodimethylamine formation in lake water when chloramination is conducted with low concentration (2 mg/L) for 2 h. These results suggest that N-nitrosodimethylamine concentration measured in the effluent of the drinking water treatment plant may underestimate the N-nitrosodimethylamine concentration that will reach the consumers since chloramination reactions will continue in the distribution system. On the other hand, when only N-nitrosodimethylamine formation potential is used, it will overestimate the N-nitrosodimethylamine that might form in the distribution system due to high disinfectant concentration, high contact time and adjusted pH values used in the N-nitrosodimethylamine formation potential test.

Objective: Wastewater based epidemiology studies are a complementary approach used to measure and monitor the presence and prevalence of infectious diseases when clinical testing capacity is limited. It can also help with the detection of coronaviruses in wastewater and how they spread in the society. In the COVID-19 pandemic, SARS-Coronavirus-2 (SARS-CoV-2) is excreted with the feces of infected people and mixed with wastewater. Most people infected with viruses that infect enterically spread their feces and virus into their sewage systems both for the days or weeks before and after symptoms begin to appear. Through the detection of Covid-19 in wastewater, the number of asymptomatic people who do not represent any indication related to diseases but are carriers can be determined, and the total number of people infected in that society can be estimated. Therefore, an early warning system can be created, and it will be possible to take the necessary precautions before the second or third wave occurs.

The mechanisms and by-product formation of electrochemical oxidation (EO) for As(III) oxidation in drinking water treatment using groundwater was investigated. Experiments were carried out using a flowthrough system, with an RuO 2 /IrO 2 MMO Ti anode electrode, fed with synthetic and natural groundwater containing As(III) concentrations in a range of around 75 and 2 µg/L, respectively. Oxidation was dependent on charge dosage (CD) [C/L] and current density [A/m 2 ], with the latter showing plateau behaviour for increasing intensity. As(III) concentrations of <0.3 µg/L were obtained, indicating oxidation of 99.9 % of influent As(III). Achieving this required a higher charge dosage for the natural groundwater (>40 C/L) compared to the oxidation in the synthetic water matrix (20 C/L), indicating reaction with natural organic matter or other compounds. As(III) oxidation in groundwater required an energy consumption of 0.09 and 0.21 kWh/m 3 , for current densities of 20 and 60 A/m 2 , respectively. At EO settings relevant for As(III) oxidation, in the 30-100 C/L CD range, the formation of anodic by-products, as trihalomethanes (THMs) (0.11-0.75 µg/L) and bromate (<0.2 µg/L) was investigated. Interestingly, concentrations of the formed by-products did not exceed strictest regulatory standards of 1 µg/L, applicable to Dutch tap water. This study showed the promising perspective of EO as electrochemical advanced oxidation process (eAOP) in drinking water treatment as alternative for the conventional use of strong oxidizing chemicals.

The current conventional disinfection for municipal water relies primarily on chlorine disinfection alone, in spite of its high running cost and its production of disinfection by-products. Ultrasonic disinfection is a physical technology widely accepted and continuously appraised as an alternative to conventional techniques for water disinfection. The efficiency of using the ultrasonic disinfection technique was evaluated and compared to the conventional chlorination technique using HOCl. Hybrid treatment was also investigated via the combination of both types of treatment. A laboratory-scale unit was constructed to carry out disinfection experiments using synthetic water (feed solution) prepared with a known concentration of Escherichia coli. The results showed that all the tested treatment methods are capable, to some degree, of inactivating E. coli in water. However, the best treatment option was achieved when coupling ultrasonic and HOCl for disinfection. This kind of treatment significantly reduces the concentration of bacteria higher than using each treatment alone. Thus, the ultrasonic technique is a better option for disinfection enhancement when combined with HOCl, in terms of inactivation of E. coli bacteria in municipal water.

This review paper deals with the formation of disinfection by-products (DBPs). Water basin remains a wonderful chemical reactor that allows the occurrence of intricate secondary disinfection chemical reactions, forming several hundreds of DBPs at the same time with microorganisms killing. The kinetics of DBPs formation is tightly dependent on water physicochemical characteristics such as temperature, hydrophobic/hydrophilic fractions in natural organic matter (NOM), pH, and pretreatment. Reducing DBPs levels in drinking water is not a relevant measure as the newly-developed analytical techniques and the health-related research reveal that the tolerable DBPs' levels must be further decreased and would be detected at ng L-1 instead of μg L-1 scale. Furthermore, because of the fact that man is being exposed to DBPs concentrations in drinking water in his lifetime, there will be a cumulative effect of these toxic chemical products even at their more reduced concentrations. Hence, the removal of these chemical products is sought for and is considered a real challenge and the main objective of water treatment technology for mankind survival.

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 265122. This publication reflects only the author's views and the European Union is not liable for any use that may be made of the information contained therein.

In drinking water sources, seasonal algal blooms have augmented greatly during the last decades following the elevated temperature and nutrient loading in surface water because of agricultural and surface runoff. More than 95% of algal cells may be retained via coagulation/flocculation techniques. Nevertheless, algal organic matter (AOM) stays not eliminated well throughout coagulation, therefore it provokes many working dares in potable water treatment. This work aims to discuss the performance of coagulation on AOM reduction. The main pathway of algae and AOM reduction stays charge neutralization (CN) at an optimum pH of about 6.0. More research has to follow the reduction of low-molecular weight AOM, reluctant to coagulate, with additional treatment methods to diminish its negative influence on water safety. As dissolved microcystins (MCs) are efficaciously eliminated via CN, enhanced coagulation (EC) would be more suitable for their elimination. On the other hand, some precautions must be followed to guarantee that the acid injection has not a secondary impact in the form of algaecide treatment to avert the dissolved MCs concentration augmentation. Consequently, both algae and dissolved MCs may be efficiently removed by EC when appropriate rapid mixing and acid/coagulant dosage are guaranteed.

Chlorine has been and is still widely used chemical to disinfect wastewater. Trihalomethanes (THMs) and other disinfection byproducts (DBPs) are formed when chlorine reacts with organic acids (commonly refers to humic acids). Recent years, DBPs and THMs have been regulated by the agencies that enforced POTWs to find solutions to minimize THMs and DBPs. One common solution is to use alternative disinfection technologies such as UV disinfection, ozonation, etc. However, often time, such implementations are not feasible due to budgetary and time constraints. This paper summarizes a series of bench and full-scale testing findings to minimize THMs formation (specifically dibromo-chloromethane) while adequately disinfecting wastewater to meet the antispated coliform limits. Full-scale demonstrations have showed that chloramination is simple, effective and economic solution to meet the coliform requirements and minimize disinfection by products and THM formation. The findings of this study are directly applicable to other wastewater facilities dealing with the similar problems.

This works is focused on testing a novel MMO-Ti/RuO2IrO2 electrode to reduce the dangerousness of hospital urines polluted with antibiotics. To do this, this electrode was used as anode in electro-Fenton (EF) and photoelectro-Fenton (PhEF) processes, and results were compared with those obtained using boron doped diamond (BDD) as anode, as well as those obtained by a conventional Fenton oxidation. The performance of treatment processes was evaluated in terms of antibiotic removal, toxicity (using standardized method with Vibrio fisheri) and antibiotic resistance of treated urine (using Enterococcus Faecalis as target bacterium). Results demonstrate that Penicillin G degrades in the following sequence: Fenton < EF < PhEF. The best results were found for the MMO-PhEF, capable of removing 100% of the antibiotic, reducing toxicity by 96%, and reaching complete removal of the antibiotic activity. Tests were also carried out with BDD for the sake of comparison and results point out the higher convenience of the new electrode in terms of a more adequate use of energy because the effluents generated can be further degraded in urban wastewater treatment plant. Because of that, MMO-RuO2-IrO2 emerges as a promising cost-effective material for the pre-treatment of hospital urine.

This work focuses on the importance of choosing a suitable electrochemical cell to remove antibiotics from urines. For this purpose, we investigate the use of two electrochemical cells for electrolysis and photo-electrolysis of urine polluted with a mixture of Penicillin G, Meropenem, and Chloramphenicol. The two reactors studied were a conventional flow pass electrochemical cell (E-cell) and a microfluidic flow-through reactor (MF-Reactor). Both reactors are equipped with a mixed metal oxide anode (MMO-RuO2IrO2) produced by hybrid heating using microwaves. The MMO coating was deposited on a Ti plate for the E-cell (2-D electrode) and on a Ti foam for the MF-Reactor (3-D electrode). Results demonstrate that the MF-Reactor stands out to reduce two important factors in electrochemical oxidation, the ohmic resistance associated with the microfluidic concept and the mass transfer limitations associated with the flow-through configuration. Moreover, it allows operating at a lower effective current density because of its larger active anodic surface area. Photo-electrolysis results in faster removal of all antibiotics studied in the MF-Reactor and E-cell, compared to the single electrolysis, thereby highlighting the significance of UV light-mediated electrochemical oxidation processes. This work highlights that despite the large number of papers focused on the selection of suitable electrodes for the electrochemical treatment of different types of wastes, the choice of the electrochemical cell can be even more important than the selection of those electrode materials, and it demonstrates that even using the same coating as the anode, highly different outcomes can be reached.

This paper reports the method and mechanism for improving the strength of marl and desert sand utilizing electric arc furnace dust (EAFD), an industrial by-product, in lieu of cement or lime. EAFD was used in conjunction with a small quantity (2%) of cement. The mechanical properties and durability characteristics of marl and sand mixed with 2% cement plus 5-, 10-, 20- or 30%-EAFD, by weight of the soil, were evaluated. The soil-cement-EAFD mixtures were used to determine their unconfined compressive strength (UCS), soaked California Bearing Ratio (CBR) and durability. The risk of leaching of toxic heavy metals, such as lead and cadmium, from the stabilized soils to the groundwater was also investigated. The mechanisms of stabilization of the selected soils due to the use of EAFD along with a small quantity of cement are also elucidated. The usage of 20 to 30% EAFD with 2% cement was noted to considerably improve the mechanical properties and durability of both marl and sand.

Water must be made safe to drink, and an important step in ensuring water safety is disinfection. Disinfectants are added to water to kill disease-causing microorganisms. Ground water sources can be disinfected by "The Water Treatment Rule," which requires public water systems for disinfection. Chlorination, ozone, ultraviolet light, and chloramines are primary methods for disinfection. However, potassium permanganate, photocatalytic disinfection, nanofiltration, and chlorine dioxide can also be used. Organic material is naturally present in water. Certain forms of chlorine can react with these organic materials and result in the formation of harmful by-products; the U.S. Environmental Protection Agency has anticipated maximum levels for these contaminants.

In this study, we aimed to use ferrate as an all-in-one alternative for the removal of chlorine-consumed compositions such as organic, color, turbidity, iron, and manganese in river water for water supply purposes. Ferrate (FeO42-) was simultaneously employed as coagulant and oxidant for purification of Saigon River water in order to reduce the formation of disinfection by-products in the produced tap water. The Jartest was conducted using both ferrate for raw river water and poly-aluminum chloride (PAC) for chlorinated water to determine the optimum concentration of chemicals and pH values as well as comparing the effectiveness of ferrate and traditional coagulation with pre-chlorination technology for surface water purification. Results showed that ferrate could be used to remove organic compounds with high efficiency of 86.2% at pH 5 - 6 and ferrate concentration of 16 mgFe/L. Moreover, the removal efficiency for turbidity, color, and iron were at least 90%, indicating that ferra...

Disinfectants, especially air disinfectants, are necessary to prevent the potential spread of pathogens (bacteria and viruses) in the pandemic era and minimize the spread of pathogens. Some of the commercial disinfectant products that are often used generally contain chlorine dioxide (ClO2) gas. This study tested the effectiveness of two different commercial disinfectants, a liquid stick disinfectant and a powder disinfection card, to carry out the disinfection of pathogenic bacteria in the environment. These two disinfectants were used as a medium for releasing chlorine dioxide gas which has a much stronger bactericidal effect. In the form of liquid stick, ClO2 is more effective in the disinfection process rather than in the form of powder. The effectiveness of the liquid disinfectant in inhibiting the growth of pathogenic bacteria is influenced by the temperature and the area of the open space covered. Considering that the release from both disinfectants used is very small (0.002 ...

Electrodisinfection of wastewater has been investigated extensively in the past, although a consensus over the use of direct current (DC) or alternating current (AC) as the most efficient electricity source has not been reached to date. The research presented herein compares the use of DC and AC in electrodisinfection of municipal wastewater aiming to provide conclusive evidence on the benefits of using one type of current over the other. During the experimental phase, a bench-scale electrodisinfection reactor equipped with iridiu m o xidecoated titanium electrodes was operated continuously, and E.coli inactivation, free and total chlorine generation were measured. The results observed indicate that, under the experimental conditions, DC represents a more efficient and economical alternative to electrodisinfection than AC.

This paper describes a laboratory study comparing three coagulants (alum, ferric chloride, and ferric sulfate) to determine which coagulant would not only remove NOM but DBP precursors as well. Experiments were conducted to compare the effectiveness of three coagulants in removing DBPs precursors from raw water samples. The results show that the removal of total organic carbon (TOC) which is mean NOM here, was dependent on the coagulant type and was enhanced with increasing coagulant dose, but ferric chloride, and ferric sulfate have no further considerable effect in case of increasing to high levels. For all the treated samples coagulation with ferric chloride proved to be more effective than alum and ferric sulfate at similar doses and the mean values of treatment efficiencies were 30%, 37%, and 45% by ferric sulfate, alum, and ferric chloride respectively. The range of TOC removal rates obtained using ferric sulfate (18-48%), (14-50%) for alum, and (21-59%) for ferric chloride. F...

The flow of a jet stream entering a cross flow main stream is modelled along with introducing the related App. The turbulent flow details are computed and validated against similar computational and experimental results. For example, dimensionless streamwise and cross-streamwise velocity components, dimensionless turbulent kinetic energy, and dissipation are shown in colour-expression figures, along with streamlines near the jet entrance to the main stream flow. The results agree with those from the existing references. We used a custom designed structured mesh for all models. Also, for democratization of the model applications a COMSOL® model-based App is built and introduced a .

A mathematical model of turbulent density-driven flows is presented and is solved numerically. A form of the k-E turbulence model is used to characterize the turbulent transport, and both this non-linear model and a sediment transport equation are coupled with the mean-flow fluid motion equations. A partitioned, Newton-Raphson-based solution scheme is used to effect a solution. The model is applied to the study offlow through a circular secondary sedimentation basin.

Graphite electrodes incorporated with multi-metal oxides (Pt, Pd, Ru, Cu, Ni and Co) were prepared by electrodeless deposition technique using NaBH 4 as the reductant. The electrodes so prepared were characterized with SEM, EDS, XRD, and XPS. Electrochlorination was carried out using Escherichia coli (E. coli) as the model microorganism. Results showed that the metal oxides significantly improved the efficiency of chlorine generation. The rate constant of chlorine generation increased in the order: PteNieCo/G > RueNieCo/G > NieCo/G > PdeNieCo/G > CueNieCo/G > graphite (G). Pt-, Ni-, and Cooxides were formed on the PteNieCo/G electrode surface, which contributed to the generation of high chlorine concentration at high current efficiency and low energy consumption. Cyclic votammetry (CV) analysis of the PteNieCo/G electrode showed that the chlorine evolution potential was lower than the oxygen evolution potential. The PteNieCo/G electrode had a high chlorine evolution potential due to the presence of Co(II) and Co(III) on the electrode surface and the unique morphology that brought about active surface sites. An E. coli killing efficiency of 5.2-log could be achieved over a contact time of around 10 min on the PteNieCo/G electrode in the presence of NaCl at a dilute concentration of 0.01 M NaCl and a constant current density of 10 mA cm À2 .

The antimicrobial activity of three commonly used disinfectant brands D, R and P against Escherichia coli, Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa were investigated. Their efficacies were determined using the In-use test and capacity test (Kelsey-Sykes) at different dilutions of the test disinfectants while their potency were tested under clean and dirty conditions using the Kelsey-Sykes standard test. The results of the study show that as the concentration reduced the susceptibility rates of the test organisms were also reduced. The potency of the disinfectants showed that they were all effective, with D being the most potent Original Research Article

This study investigated how chlorine inactivates and damages Escherichia coli cells. E. coli that had transformed to express enhanced green fluorescent protein (EGFP) at the cytoplasm was treated with chlorine. Damage to the cell membrane and cell wall was analyzed by measuring the fluorescence intensity of the leaked EGFP, then accounting for the fluorescence deterioration. At pH 7, E. coli was lethally damaged after treatment with chlorine, but significant leakage of EGFP was not observed. In contrast, significant leakage of EGFP was observed at pH 9, even though E. coli was not as inactivated as it was at pH 7. Flow cytometry was used to confirm the fluorescence intensity of the remaining EGFP inside the cells. No significant fluorescence loss was observed in the cells at pH 7. However, at pH 9, the fluorescence intensity in the cells decreased, indicating leakage of EGFP. These results suggest that hypochlorous acid inactivates E. coli without damaging its cell membrane and cell...

TRILITY has developed a production cloud data management solution, KOIOS DatalytiX to provide hybrid machine learning applications and deterministic modelling tools to its operations, asset management, and engineering teams. Two optimiser applications for chemical coagulant prediction and filtration performance were deployed in the Riverland, South Australia at 10 conventional water treatment plants in 2018, to full production in 2019. One year later the impacts on the optimisation behaviour of operations teams, process performance and trihalomethane (THM) reduction outcomes are discussed.

Whilst wood tars and resins were used as remedies and preservatives since Prehistoric times (Ambrose 2018), creosote truly entered European sensory culture during the nineteenth-century as an industrial preservative and medical disinfectant. In Europe, the generic term 'creosote' mostly refers to two distinct products, often confused with each other: wood-tar creosote and coal-tar creosote. The former is a light-coloured oily substance produced by heating certain types of timber (usually beech, birch, or coniferous woods) at high-temperatures. The latter is a dark thick oily liquid extracted from coal-tar. Both share some medicinal and chemical properties (antiseptic, caustic, antifungal, to cite a few) as well as comparable tarry and phenolic olfactory profiles. Wood-tar creosote was discovered by Karl Von Reichenbach in 1832 by working on pyroligneous acid and beech tar. First known under the name ‘carbolic acid’, coal-tar creosote on the other hand was discovered in 1834 by Rungé, and was soon renamed ‘coal-tar creosote’ after chemists highlighted its similar properties with its wood based counterpart (Schorlemmer 1885). Both creosotes were subsequently used in a variety of contexts requiring thorough disinfection, like factories, surgical rooms, or dental offices, but also in the treatment of several respiratory illnesses, such as pneumonia and tuberculosis. Despite most accounts describing creosote's pungent smell as particularly unpleasant, its association with hygienic and medical practices turned its tarry scent into a signifier of health and hygiene, feeding into the idea that treatments must smell bad to be effective, and contributing to the perception that physical pain and sensory distress are necessary experiences of proper care.

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The transportation of exotic species in ballast tanks is one of the most important global environmental problems facing the shipping industry. Electrochemical techniques offer one of the most viable solutions for ballast water problems. This work reports laboratory experiments conducted by Istanbul Technical University (ITU) for the best and optimal electrochemical cell design for EU Project BaWaPla (Contract 031529), in which a new hybrid ballast water treatment system has been developed. The capability of an electrochemical system to effectively eliminate these organisms depends on various internal and external parameters. Five different electrochemical cells were assessed for the BaWaPla system. The variable parameters of the cell design were the geometry and dimensions of the electrodes. In additional to cell design, the effects of Ca 2+ and Mg 2+ concentrations, along with ammonia, were also investigated as external parameters for system capability. The results show that the enlargement of electrode surfaces result in increased chlorine concentrations in the disinfectant. On the other hand, suitable electrode and coating materials are essential for "reverse polarity" operation in order to avoid scaling of Ca 2+ and Mg 2+ ions on electrodes and clogging the membrane. Ammonia, if present in ballast water, has a negative effect on disinfection quality. Experiments show that presence of 7.8 mg/L ammonia in electrolyte may cause up to 73% loss of free available chlorine and 38% loss of total available chlorine concentrations. Measures should be considered, both in the design stage and during the disinfection process, to reduce the negative effect of ammonia.

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Disinfection by-products (DBPs) are a class of chemicals that are formed when disinfectants react with organic compounds of drinking water [1]. Some of the DBPs may be carcinogenic and some are suspected of causing health effects. They are undesirable chemical compounds that are created as a result of water disinfection and oxidation. According to Krasner et al., DBPs are classified into four major classes: trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs) and halocetones (HKs) [2]. So, a special class of DBPs are THMs, which in addition to carbon, they also contain chlorine and bromine. THMs were discovered in 1974 by Rook (Netherlands) and Bellar (USA). They first identified chloroform (CHCl 3), which is the main THMs in drinking water and are in trace concentration (µg/L). After that date, many other DBPs were identified in chlorinated drinking water, eg. brominated THMs, haloacetic acids, halocetones etc. More than 500 DBPs have been identified in tap waters and since 1980 they have raised great concern due to the fact that they cause side effects in human health, cancer and reproductive disorders [3]. Interest in studying organic substances in drinking water began in 1974 with the detection of haloforms or trihalomethanes by Rook J. during the quality control of water treatment at the Berenplaat, Netherlands [4]. THMs as synthetic organic compounds are created by replacement of three hydrogen

Antibiotic resistance has been considered a major human health threat that may endanger the success of medicine. Recent studies have unveiled worldwide asymmetries of antibiotic resistance occurrence, being factors as diverse as climate, socioeconomic, or antibiotic use possible drivers of such asymmetric distribution. In Europe, where clinical antibiotic resistance is surveyed for more than 20 years, the European Centre for Disease Prevention and Control (ECDC) consistently describes an increasing gradient from North-to-South and from West-to-East. This observation motivated the current perspective paper aiming to qualitatively compare two countries located at the extreme latitude of Europe and also at distant longitude-Poland in the Central-East region and Portugal in the SouthWest. Both countries have been among those with the highest prevalence of antibiotic resistance in clinical settings, although as it is discussed, climate, socioeconomic factors, and antibiotic use are different. In general, in Poland higher antibiotic consumption and resistance prevalence is observed, mainly at the community level, when compared to Portugal. However, in Portugal, treated wastewater may hold identical or slightly higher resistance loads. Based on these observations, it is discussed how different factors may influence the abundance of antibiotics, antibiotic resistant bacteria, and genes in wastewater before and after treatment.