Low Chlorine Concentrations Research Articles

Evaluating the impact of residual low chlorine concentration on phytoplankton communities by flow cytometry

Chlorination is widely used to prevent biological fouling in power station cooling water systems. It may impact non-target organisms both within the cooling system and after discharge (primary and secondary entrainment). However, there is a lack of data on the impacts of the low chlorine concentrations that occur in the discharged plume on marine phytoplankton community structure and function.We examine the impacts on natural phytoplankton communities of single and multiple exposures to chlorination at concentrations between 0.02 and 0.1 mg/L total residual oxidants (TRO). Low-level chlorination causes limited changes in diversity and has no impact on total biomass. However, changes in size structure and functional diversity quantified using flow cytometry do show a reduction in smaller cells, particularly eukaryote picophytoplankton.These impacts are not detectable using chlorophyll a concentration alone, so flow cytometry provides important additional information over more standard ecotoxicological methods.The effects are likely to be localised in the vicinity of the discharges (mixing zone) where the environmental quality standard (EQS) of 10 μg/L for chlorine is exceeded, but impacts on coastal food webs and biogeochemical cycles should be further evaluated.

Simultaneous treatment with tap water-based neutral electrolyzed water and citric acid for inactivating foodborne pathogens on stainless steel and their synergistic bactericidal mechanisms

Electrolyzed water has many potential applications, the primary one being the eliminating microorganisms in the food industry. However, this application is limited by high chlorine levels. Tap water-based neutral electrolyzed water (TNEW) has the advantage of relatively low chlorine concentration (1.7–4.6 mg/L), but its sterilization effect is limited. In this study, TNEW was combined with citric acid (CA) solution, resulting in strong synergistic inactivation effect on Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on stainless steel surfaces. Simultaneous treatment of stainless steel with TNEW [available chlorine concentration (ACC) of 4.97 mg/L] and 0.1% CA for 15 min resulted in 4.78-, 4.26-, and >5.69 log CFU/cm2 surface reduction in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, which was a synergistic cell count reductions of 3.25, 2.83, and >3.84 log units, respectively. Fluorescence and RT-qPCR analyses identified synergistic production of intracellular reactive oxygen species (ROS), damage to the cell membrane resulting from lipid peroxidation, and DNA damage as the major factors contributing to the synergistic lethal effect. The results of this study suggest that the TNEW–CA combination treatment can be applied as a potential substitute for conventional electrolyzed water treatment for food contact surface disinfection.

The combined leaching of copper, gold and uranium in chloride solutions. I. Chalcopyrite

In a study (Part II) aimed at the simultaneous heap leaching of copper (predominantly chalcopyrite), gold and uranium from an ore, it was found that this could be achieved using chlorate as the oxidant in chloride solutions. As a result, a more detailed study has been made using electrochemical and batch leach tests on pure chalcopyrite electrodes under typical heap leach conditions.The use of chlorate at moderately low concentrations has shown that enhanced rates of dissolution of chalcopyrite can be maintained over periods up to 4 days at ambient temperatures in acidic chloride solutions. The rate of dissolution is enhanced at higher acid concentrations. The rate in the presence of chlorate does not appear to depend on the iron(III) (and presumably the copper(II)) concentration.The observed rates are significantly greater than those predicted for oxidative dissolution from the electrochemistry and the mixed potential model. An alternative non-oxidative mechanism has been revisited to account for this difference.A preliminary measurement has been made of the kinetics of the oxidation of hydrogen sufide and iron(III) by low concentrations of chlorine produced by reaction of chlorate with chloride ions. These reactions are rapid, and theory shows that they would support the proposed non-oxidative mechanism.

Formation, speciation, and temporal variability of DBPs in drinking water distribution systems in the context of ASR operations and extended storage periods

As climate change induces changes in water quality and available water quantity of drinking water supply sources, the final product water quality changes in terms of trace organics including disinfection byproducts (DBPs) formed during water treatment. In this study, the seasonal variability and speciation of DBPs across nine sample sites within a drinking water distribution system serving ∼400k people over a one-year period was investigated considering the governing parameters of water quality and treatment/transport/storage of finished water. The system considered treats surface water from a river and practices aquifer storage and recovery to address seasons water availability changes. Eighty-eight (88) sample sets were collected and held for 6-months in the laboratory to simulate extended storage scenarios associated with ASR operations, and each was analyzed at 9 different timesteps for concentration and speciation of chlorinated DBPs. Samples from groundwater influenced sites exhibited significantly lower total organic carbon (TOC) compared to other sites from the river source, and also were observed to have the lowest DBP formation. Three sites exceeded the Maximum Contaminant Level (MCL) for four total trihalomethanes (THM4) within 30–60 days of storage. Chloroform was the predominant THM4 species, even in groundwater-influenced locations, whereas di- and tri-chloroacetic acid (DCA and TCA) were the most prevalent haloacetic acids (HAA5). Extended water age at one site, coupled with low initial chlorine concentrations exhibited higher initial THM4 concentrations and flat DBP formation curves. The study results provide new insights into DBP occurrence and fate in drinking water distribution systems which consider water storage such as in ASR.

Selectivity Study of Anodic Seawater Electrolysis Catalysts Using the Rotating Ring-Disc Electrode Method

Water electrolysis generating green hydrogen will play a vital role in achieving the net-zero 2050 goal; however, freshwater electrolysis will further strain an already strained supply of clean freshwater.1 If seawater electrolysis can be scaled successfully, it would provide an important source of green hydrogen. Current research on untreated, direct seawater electrolysis is limited, and only recently have studies emerged analyzing catalyst performance at near-neutral pH.2 At industrially-relevant current densities, the formation of corrosive hypochlorite must be considered as a secondary reaction.3 Hypochlorite forms through the chloride oxidation reaction (ClOR), which competes with the oxygen evolution reaction (OER) in seawater electrolysis.2 In this work, we discuss the limitations of the current methods for determining anodic catalyst selectivity between OER and ClOR. The short lifetime of hypochlorite can cause faradaic efficiency measurement methods such as titration or oxygen gas capture to become unreliable, as these tests require that the hypochlorite remain stable. Using a rotating ring-disc electrode (RRDE), we measure the selectivity of common OER catalysts in-situ (Figure 1a). Real-time hypochlorite sensing overcomes the challenge of measuring catalyst selectivity posed by the short lifetime of hypochlorite. Remarkably, a PtRu catalyst outperformed more common OER catalysts with the best in OER selectivity and low overpotential, a novel development in the field of near-neutral water electrolysis. We also determine that elevated heat and low chlorine concentration are conducive to improved OER selectivity on an IrO2 catalyst (Figure 1b). We hope this work will set the standard in catalyst benchmarking for seawater electrolysis catalysts and could lead to the development of catalysts for efficient, scalable, and sustainable hydrogen production from seawater. H. Jin et al., Sci Adv, 9, eadi7755 (2023) https://www.science.org/doi/10.1126/sciadv.adi7755.F. Dionigi, T. Reier, Z. Pawolek, M. Gliech, and P. Strasser, ChemSusChem, 9, 962–972 (2016) https://onlinelibrary.wiley.com/doi/full/10.1002/cssc.201501581.J. Guo et al., Nature Energy 2023, 1–9 (2023) https://www.nature.com/articles/s41560-023-01195-x. Figure 1. a) LSV profiles of common OER catalysts (solid line) and the corresponding faradaic efficiency (dashed line) for the OER, measured using the ring current of the rotating ring-disc electrode. Catalysts were tested in 0.5 M NaCl and buffered with KHCO3 to pH 8.5. b) A ternary plot depicting the effect of varying Cl concentrations and temperatures on the selectivity of an IrO2 catalyst at pH 8.5. Figure 1

Influence of Lateral Length and Residual Chlorine Concentration on Soil Nitrogen and Soil Enzyme Activities under Drip Irrigation with Secondary Sewage Effluent

Chlorination has been demonstrated to be an effective method for the prevention and reduction in emitter biological blockage in drip irrigation systems. The injected chlorine dose is generally determined by chlorine concentration at the terminal of the laterals which may lead to a high concentration of residual chlorine at the front of the system and bring detrimental impact to the soil environment and growth of crops, especially in large irrigation units with long laterals. A two-season experiment was undertaken to determine the effects of chlorine disinfection and lateral length on soil NO3-N, enzyme activities, and maize yield under wastewater drip irrigation. The experiments were constructed with lateral lengths ranging from 20 to 80 m and injection chlorine concentrations at the end of laterals ranging from 2 to 6 mg L−1. Lateral length had a major impact on enzyme activities in the partial growth stage, although the effects of lateral length and chlorine concentration on soil nitrogen content and maize yield were negligible. Enzyme activity and soil nitrogen concentration decreased throughout the lateral length as a result of chlorination. A higher detrimental impact on soil characteristics and maize yield is probably going to result from a high concentration of chlorine and a long lateral length mode. The maize yield peaked at L80 with a concentration of 2 mg L−1 chlorine, while it peaked at L40 with 6 mg L−1 chlorine concentration. A chlorination scheme with long lateral length and low chlorine concentration is recommended in consideration of maize yield and minimizing potential negative effects on the soil environment.

Application of Slightly Acidic Electrolyzed Water as a Potential Sanitizer in the Food Industry

The food industry has extensively explored postharvest microbial control, seeking viable technologies to ensure food safety. Although numerous chlorine-based commercial sanitizers serve this purpose, many are plagued by constraints such as instability and diminished disinfectant efficacy. These issues arise from exposure to organic matter in wash water, light, or air. As an innovative and promising alternative, slightly acidic electrolyzed water (SAEW) has emerged, captivating attention for its robust sterilization potential and eco-friendliness in agricultural and food sectors. SAEW generated via electrolysis of a diluted hydrochloric acid (HCl) solution with concentrations ranging from 2 to 6% or aqueous solution of sodium chloride (NaCl) in a nonmembrane electrolytic chamber is reported to possess equivalent antimicrobial properties as strong acidic electrolyzed water (StAEW). In contrast to traditional chlorine sanitizers, SAEW leaves less chlorine residue on sanitized foods such fresh-cut fruit and vegetables, meat, poultry, and aquatic products due to its low available chlorine concentration (ACC). Its near neutral pH of 5 to 6.5 not only renders it environmentally benign but also mitigates the production of chlorine gas, a contrast to low pH conditions seen in StAEW generation. The bactericidal effect of SAEW against various strains of foodborne pathogens is widely believed and accepted to be due to the combined action of high oxidation-reduction-potential (ORP) reactions and undissociated hypochlorite/hypochlorous acid (HOCl). Consequently, a burgeoning interest surrounds the potential of SAEW for sanitation in the food industry, offering an alternative to address shortcomings in sodium hypochlorite solutions and even StAEW. It has been hypothesized from a number of studies that SAEW treatment can increase the quality and nutritional value of harvested fruits, which in turn may enhance their ability to be stored. Therefore, SAEW is not only a promising sanitizer in the food industry but also has the potential to be an efficient strategy for encouraging the accumulation of bioactive chemicals in plants, especially if it is used extensively. This review encapsulates the latest insights concerning SAEW, encompassing its antimicrobial effectiveness, sanitization mechanism, advantages vis-à-vis other sanitizers, and plausible applications across the food industry.

Optimization of Breakpoint Chlorination Technologies for Drinking Water Treatment: a Hungarian Case Study

Ammonium ion is one of the major pollutants found in drinking water sources in Hungary, especially in deep aquifers. under oxidative conditions, ammonium can transform into nitrite ions in the water system, posing potential health risks. In Hungary mostly biological process or breakpoint chlorination are used to eliminate ammonium ion from raw water during the drinking water treatment process. When breakpoint chlorination is applied, harmful by-products are formed. Trihalomethanes concentrations have long been regulated in Hungary, therefore during the design and optimization of the breakpoint technologies trihalomethane concentrations have been considered. However, haloacetic acids (HAA5) and chlorate ion have been recently regulated in accordance with EU Directive 2020/2184. Chlorate is a by-product that appears in treated water when sodium hypochlorite is used in breakpoint chlorination.Experiments were carried out at four Hungarian case study areas to determine the optimal strategy for breakpoint chlorination: applying higher chlorine dosages with lower contact times, or lower chlorine dosages with higher contact times. The investigations concluded that the preferable dosing strategy is to use lower chlorine concentrations and longer contact times. This approach reduces chemical demand (cost-effective) and has a neutral effect on THMs formation. it can be concluded that when the raw water contains ammonium ion concentrations above 0.5 mg/l, the use of sodium hypochlorite may raise concerns due to elevated chlorate ion levels in the treated water, particularly during summer. Further research is required to expand the optimization strategy, considering not only ammonium and trihalomethane concentrations but also chlorate concentrations.

Chlorine disinfection modifies the microbiome, resistome and mobilome of hospital wastewater – A nanopore long-read metagenomic approach

The aim of the present study was to analyze changes in the microbiome, resistome, and mobilome of hospital wastewater (HWW) induced by disinfection with chlorine compounds. Changes in bacterial communities and specific antibiotic resistance genes (ARGs) in HWW were determined with the use of a nanopore long-read metagenomic approach. The main hosts of ARGs in HWW were identified, and the mobility of resistance mechanisms was analyzed. Special attention was paid to the prevalence of critical-priority pathogens in the HWW microbiome, which pose the greatest threat to human health. The results of this study indicate that chlorine disinfection of HWW can induce significant changes in the structure of the total bacterial population and antibiotic resistant bacteria (ARB) communities, and that it can modify the resistome and mobilome of HWW. Disinfection favored the selection of ARGs, decreased their prevalence in HWW, while increasing their diversity. The mobility of the HWW resistome increased after disinfection. Disinfection led to the emergence of new drug resistance mechanisms in previously sensitive bacterial taxa. In conclusion, this study demonstrated that HWW disinfected with low (sublethal) concentrations of free chlorine significantly contributes to the mobility and transfer of drug resistance mechanisms (including critical mechanisms) between bacteria (including pathogens).

Size-Dependent Chlorinated Nitrogen-Doped Carbon Nanotubes: Their Use as Electrochemical Detectors for Catechol and Resorcinol

In this study, various-sized nitrogen-doped carbon nanotubes (NCNTs) were fabricated by varying the concentration of chlorine in the feed. The diameter of the NCNTs was found to influence the sensing ability of the nanomaterials when coated onto the glassy carbon electrode (GCE) and used for the detection of catechol (CC) and resorcinol (RS). Larger diameter NCNTs (denoted NCNTs (2 : 1)) were produced when a low concentration of chlorine was added into the acetonitrile feed, whereas smaller diameter NCNTs (denoted NCNTs (1 : 2)) were produced when a large concentration of chlorine was added. This investigation revealed that the addition of controllable amounts of chlorine during the fabrication of NCNTs led to the creation of nanostructures with different properties. The greatest current response which was evidenced by an enhanced anodic peak of CC and RS was obtained when GCE was coated with NCNTs (2 : 1), and this was attributed to their large diameter and high graphitic nature which facilitated electron transfer as evidenced by scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analysis. A linear response was obtained when varying the concentration of both CC and RS, with the limits of detection of about 0.059 μM (CC) and 0.034 μM (RS) (3S/M) obtained.

Fabrication of low-loss III-V Bragg-reflection waveguides for parametric down-conversion

Entangled photon pairs are an important resource for many types of quantum protocols. Semiconductor Bragg-reflection waveguides are a promising photon-pair source due to mature fabrication, integrability, large transparency window in the telecom wavelength range, integration capabilities for electro-optical devices as well as a high second-order nonlinear coefficient. To increase performance, we improved the fabrication of Bragg-reflection waveguides by employing fixed-beam-moving-stage optical lithography, low-pressure, and low chlorine concentration etching, and resist reflow. The reduction in sidewall roughness yields a low optical loss coefficient for telecom wavelength light of αreflow = 0.08 (6) mm−1. Owing to the decreased losses, we achieved a photon-pair production rate of 8800 (300) (mW · s · mm)−1, which is 15-fold higher than in previous samples.

Evolution of reactive species and their contribution to the removal of ketamine and amine-containing pharmaceuticals during the sunlight/chlorine process

Sunlight-induced photoirradiation of chlorine (sunlight/chlorine) can be observed in outdoor swimming pools and open-channel disinfection units for wastewater treatment. In this study, the degradation of ketamine, an environmentally persistent pharmaceutical, under sunlight irradiation in the presence of a low concentration of chlorine (1 mg/L as Cl2) was investigated to elucidate the evolution of reactive species and their contribution to ketamine removal. •OH dominates the initial stage of sunlight/chlorine; however, after chlorine depletion, reactions still progress with an observed rate constant (kobs = 7.6 ± 0.50 × 10−3 min−1) an order of magnitude higher than photolysis alone (kobs = 2.9 ± 0.15 × 10−4 min−1). When chlorine is depleted, O3 becomes the major reactant that degrades ketamine. High O3 yields were found in both sunlight/HOCl (12.5 ± 0.5% at pH 5) and sunlight/ClO− (10 ± 1% at pH 10) systems. At sub-µM levels, O3 resulted in substantial removal of ketamine, and even faster rates were observed in the presence of sunlight. A kinetic model was also established, and evaluate time-dependent concentration levels during sunlight/chlorine. The model simulation showed that the cumulative O3 concentration could reach 0.91 μM, and O3 contributed 31% ketamine removal during the sunlight/chlorine process. Primary and secondary amine functional groups were demonstrated to be the reaction sites of O3; other pharmaceuticals, such as atenolol and metoprolol, underwent similar phenomena. In addition, the experimental and model results further indicated that sunlight/ClO2− or ClO2 also participates in the degradation of ketamine with a minor role; trace amounts (below nM level) of ClO2− and ClO2 were estimated by the simulation.

Significance and Challenges of Poultry Litter and Cattle Manure as Sustainable Fuels: A Review

Growing animal production results in a significant amount of waste, composed of manure, bedding, feed, feathers, etc., whose safe and cost-effective disposal becomes a troublesome challenge. The literature review points out that the higher heating value (HHV) of animal-origin waste reaches 19 MJ/kg (dry basis), which positions it as a promising renewable energy source. Various paths of energy recovery were investigated in the literature, but the thermal processes, particularly combustion and co-combustion, were indicated as the most effective from both technical and environmental points of view. The presented study reviews the fuel characteristics, possible combustion-related challenges, and ash disposal routes of the most popular animal-origin waste: poultry litter and cow (cattle) manure with a slight sight on piggery (swine) manure. When considering animal-origin feedstock as fuel, usually only animal species is given (poultry, cattle, etc.). However, according to the analyzed literature data, this is not sufficient information. Several more factors crucially influence the fuel and ash properties of animal waste and the most vital are: the housing system, type of bedding, and farming style. Animal litter is considered a “difficult” fuel, nevertheless, it does not always cause combustion-related problems. Some analyzed feedstock feature low chlorine concentrations and high ash melting temperatures, which makes them combustion-friendly.

Concentrations and spatial distribution of chlorine in the pedosphere in China: Based on the China Geochemical Baselines Project

The China Geochemical Baselines (CGB) project obtained harmonious geochemical baseline data covering all of China and provided reliable data for 76 elements, including chlorine, from 3382 top (0–25 cm) and 3380 deep (>100 cm) sediment or alluvial soil samples. Chlorine concentrations were determined by X-ray fluorescence spectrometry under strict quality control. The median chlorine concentration values, which were considered geochemical baseline values, in the top and deep samples were 78 μg/g and 72 μg/g, with mean values of 1609 μg/g and 1176 μg/g, respectively. Chlorine concentrations ranged as 8–372,643 μg/g and 9–210,374 μg/g in the top and deep samples, respectively. Generally, salt-forming parent material provides a reliable source of chlorine in the pedosphere, and the geochemical behavior of chlorine determines its ability to migrate in different media. Soils with low chlorine concentrations are distributed in southwest and southern China. This is mainly due to the subtropical, temperate monsoon climate with precipitation of >800 mm throughout the year, a dense network of rivers, and abundant surface runoff. Soils with high chlorine concentrations are distributed in northwestern and northern China and coastal areas. The chlorine concentrations are affected by various factors, including the sedimentary region, landscape, arid climate, low precipitation, high evaporation, surface runoff, groundwater, and salt lake distribution. Previous studies on chlorine have primarily focused on saline areas. Thus, this is the first study to estimate the concentration and spatial distribution of chlorine in the Chinese Mainland. This study provides basic geochemical data for salt mineral development, regional climate, environmental monitoring, and efficient land use in both saline and non-saline areas.

Assessment of water, sanitation, and hygiene services in district health care facilities in rural area of Mekong Delta, Vietnam.

Access to sufficient water, sanitation, and hygiene (WASH) services is a crucial requirement for patients during therapy and general well-being in the hospital. However, in low- and middle-income countries, these services are often inadequate, resulting in increased morbidity and mortality of patients. This study aimed at assessing the current situation of WASH services in six District Health Care Facilities (DHCFs) in rural areas of the Mekong Delta provinces, Vietnam. The results showed that these services were available with inappropriate quality, which did not compromise the stakeholders' needs. The revealed WASH infrastructures have raised concerns about the prolonged hospital stays for patients and push nosocomial infections to a high level. The safety of the water supply was doubted as the high E. coli (> 60%) and total coliform incidence (86%) was observed with very low residual chlorine concentration (< 0.1mg/L) in water quality assessment. Moreover, water supply contained a high concentration of iron (up to 15.55mg/L) in groundwater in one DHCF. Technical assessment tool analysis proved that the improper management and lack of knowledge by human resources were the primary roots of the observed status WASH services. Improvement of the perceptions of WASH should be done for the hospital staff with collaboration and support from the government to prevent incidents in the future.

Mechanism of Biofilm Formation on Installation Materials and Its Impact on the Quality of Tap Water

In the conducted study, an attempt was made to verify and evaluate the impact of the biofilm formed on the surfaces of the installation material on the quality and sanitary safety of tap water reaching the consumer. For biofilm studies, fractal analysis and quantitative bacteriological analysis were used. The quality of tap water flowing through the experimental installation (semi-technical scale) was determined using physicochemical and microbiological parameters. The quantitative analysis of the biofilm showed that an increase in the number of microorganisms was observed in the initial phase of biofilm formation (reached 1.4 × 104 CFU/mL/cm2 on day 14). During this period, there was a chaotic build-up of bacterial cells, as evidenced by an increase in the roughness of the profile lines. Unstable elevations of the biofilm formed in this way could be easily detached from the structure of the material, which resulted in deterioration of the bacteriological quality of the water leaving the installation. The obtained results indicate that the biofilm completely and permanently covered the surface of the tested material after 25 days of testing (the surface roughness described by the fractal dimension decreased). Moreover, the favorable temperature (22.6 °C) and the recorded decrease in the content of inorganic nitrogen (by 15%), phosphorus (by 14%), and dissolved oxygen (by 15%) confirm the activity of microorganisms. The favorable environmental conditions in the installation (the presence of nutrients, low chlorine concentration, and high temperature) contributed to the secondary development of microorganisms, including pathogenic organisms in the tested waters.

Performance Assessment for Increasing Connection Rates of Private Water Supply Operators in Cambodia

Private water supply operators (PWSOs) play an important role in extending piped water services in small cities in Cambodia. However, the connection rates to PWSOs are highly varied. Therefore, this study aimed to find the reasons for the low connection rates of PWSOs and to propose ways to increase the connection rates. The three PWSOs selected for this study supply water continuously, with sufficiently high pressure and good water quality except for the low concentration of residual chlorine, while the per capita supply volume varies significantly. Households with alternative water sources, namely rainwater and well water, consume less piped water than those without alternative water sources. Scattered service areas far away from water treatment plants had coverage rates that were lower than in compact service areas. The present connection costs and water tariffs are higher than those that non-connected households are willing to pay, though they pay high costs for bottled water. Due to the high variation in household income, connection fees and water tariffs are a financial burden for low-income households. Because the operating rates of the PWSOs are 21–47%, it is advised that PWSOs reduce their connection fees and water tariffs to obtain more connected households in their service areas.

Induced Circulation by Plunging and Submerged Jets in Circular Water Storage Tanks Using CFD

Water circulation in storage tanks significantly impacts water quality in distribution networks since old water tends to have low residual chlorine concentrations that are insufficient to neutralize microbial regeneration. Their large capacity and long residence times result in uneven mixing, which can accelerate the disinfectant decay and the formation of potentially carcinogenic disinfection by-products. The phenomenon is strongly related to the tank inflow conditions, since there are no active mixing devices. This paper presents a comprehensive analysis of the flow dynamics in circular storage tanks using a three-dimensional computational fluid dynamics model. The main motivation is that the inflow—which mixing processes rely on—strongly influences the circulations. The numerical analysis provided includes a thorough investigation of interest in understanding flow dynamics for two inflow configurations: (i) the plunging jet modelling and comparison with published experimental data and (ii) the submerged jet as an improvement measurement for these storage tanks.

Perspectives in solid recovered fuel production in Bolivia: Analysis of characteristics and potential benefits

Solid recovered fuels (SRF) can provide another treatment option to the solid waste management (SWM) sector. However, in developing countries, to date, this system approach has not found considerable application. In Bolivia, SRF is not deemed within the national regulation and the final disposal in open dumping areas is still a reality. This research article provides the first attempt in evaluating the SRF characteristics and its potentialities in Bolivia, taking La Paz as a case study. Laboratory analysis of the rejects produced after selective collection and sorting has been conducted, focusing on non-hazardous and non-recyclable waste fractions. The international standards related to EN 15359:2011 for the classification of the SRF were employed, assessing the most feasible mix of materials to provide the highest classification of SRF in terms of low calorific value (LCV), chlorine, and mercury concentration. Results reported that the SRF made of 80% plastics (85% PE and 15% PP) and 20% cellulosic (blend 2), as well as 30% plastics (50% PP and 50% PE) and 70% cellulosic (blend 1), can be considered an alternative fuel in Bolivia. On balance, it has been estimated that the use of non-recyclable plastics and cardboard from municipal solid waste can provide, on average, about 0.9–2.7 billion MJ of energy for cement kilns, solving about 1.4–5.3% of the SWM issues and covering about 8–23.4% of the energy demand for cement production in Bolivia. These results are novel for the scientific literature for estimating the potentialities of SRF in Latin America.

Determination of Stable Chlorine Isotopes by Isotopic Preparative Chromatography (IPC) with Positive–Thermal Ionization Mass Spectrometry (P-TIMS)

A novel approach to chlorine isotope analysis is presented to overcome many drawbacks of existing methods. Contemporary methods often require several laborious off-line procedures prior to instrumental determination; interfering ions (SO4 2- and NO3 -) in real samples are difficult to completely remove, especially when the concentrations of those ions are equal to that of the Cl- ion. This study was aimed to develop an automatic sample preparation method with chromatographic purity for determination of chlorine isotopes using isotopic preparative chromatography (IPC), which was a modified ion chromatograph and a fraction collector. An AS19 chromatographic column was employed to separate chlorine from interference ions using an eluent, flow rate, and suppressor current of 30 mM NaOH, 1 mL/min, and 70 mA, respectively. After the original solutions introduced into the IPC, eluted pure chlorine in the form of HCl was collected in an automated procedure from the outlet of the detector for 6 to 10 mins. The recoveries of chlorine were more than 95% with the relative standard deviation (RSD) of the separation less than 1.8%. After transforming the HCl into CsCl with a resin and concentration in a super-clean laboratory, the samples were sent to the thermal ionization mass spectrometer. The present method was validated by certified reference materials and real samples. The precision of 37Cl/35Cl ratio value was generally below 0.20 ‰. This method provides a potential approach for the analysis of samples with low chlorine concentrations.