Dechlorination Research Articles

Chemical and isotopic evaluation of groundwater salinization processes in the Djebeniana coastal aquifer, Tunisia

This study aims at identifying the sources and fate of salinity in the Djebeniana basin (Tunisia) aquifers. Groundwater samples from the shallow Plio-Quaternary (PQ) phreatic aquifer and deep Miocene aquifer were analyzed for major/minor ions, trace elements, and stable isotopes of the water molecule (δ18OH2O - δ2HH2O), chlorine (δ37Cl) and bromide (δ81Br). Two clusters of samples with distinct chemical compositions were identified. Cluster I samples correspond to Na–Cl mineralized waters with δ37Cl from −0.3‰ to 0.16‰ and δ81Br from 0.21‰ to 0.39‰. Cluster II samples correspond to Ca–SO4 waters presenting a lower salinity than Cluster I, with δ37Cl from −0.3‰ to 0.09‰ and δ81Br from 0.28‰ to 0.54‰. When plotted in a δ2HH2O vs δ18OH2O graph, most of Cluster I groundwater samples tend to align on a mixing line with seawater whereas Cluster II samples appear to define a local evaporation line. The spatial distribution of samples associated with these clusters allows for evaluating the hydrogeochemical processes associated with groundwater salinization: 1) recent recharge from rainwater dissolving salts and entailing the downward migration of saltwater in the higher reaches of the groundwater flow system, 2) upward leakage of mineralized waters from the deep Miocene aquifer, 3) seawater intrusion in the lower reaches of the coastal aquifer, and 4) ion-exchange reactions prompted by seawater intrusion. A conceptual model of groundwater salinization is proposed as a tool for better managing groundwater resources in the Djebeniana basin.

Anthracite Releases Aromatic Carbons and Reacts with Chlorine to Form Disinfection Byproducts in Drinking Water Production.

Anthracite is globally used as a filter material for water purification. Herein, it was found that up to 15 disinfection byproducts (DBPs) were formed in the chlorination of anthracite-filtered pure water, while the levels of DBPs were below the detection limit in the chlorination of zeolite-, quartz sand-, and porcelain sandstone-filtered pure water. In new-anthracite-filtered water, the levels of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ammonia nitrogen (NH3-N) ranged from 266.3 to 305.4 μg/L, 37 to 61 μg/L, and 8.6 to 17.1 μg/L, respectively. In aged anthracite (collected from a filter at a DWTP after one year of operation) filtered water, the levels of the above substances ranged from 475.1 to 597.5 μg/L, 62.1 to 125.6 μg/L, and 14 to 28.9 μg/L, respectively. Anthracite would release dissolved substances into filtered water, and aged anthracite releases more substances than new anthracite. The released organics were partly (around 5%) composed by the μg/L level of toxic and carcinogenic aromatic carbons including pyridine, paraxylene, benzene, naphthalene, and phenanthrene, while over 95% of the released organics could not be identified. Organic carbon may be torn off from the carbon skeleton structure of anthracite due to hydrodynamic force in the water filtration process.

Sulfidated microscale zero-valent iron/reduced graphene oxide composite (S-mZVI/rGO) for enhanced degradation of trichloroethylene: The role of hydrogen spillover

Atomic hydrogen (H*) has long been thought to play an important role in the dechlorination of trichloroethylene (TCE) by carbon-supported zero-valent iron (ZVI), which offers an alternative pathway for TCE dechlorination. Herein, we demonstrate that the reductive dechlorination of TCE by sulfidated microscale ZVI (S-mZVI) can be further enhanced by promoting the formation of H* through the introduction of reduced graphene oxide (rGO). The completely degradation of 10 mg/L TCE can be achieved by S-mZVI/rGO within 24 h, which was 3.3 times faster than that of S-mZVI. The change in the distribution of TCE degradation products over time suggests that the introduction of rGO leads to a change in the dechlorination pathway. The percentage of ethane in the final products of TCE degradation by S-mZVI/rGO was 34.3 %, while that of S-mZVI was only 21.9 %. The electrochemical tests confirmed the occurrence of hydrogen spillover in the S-mZVI/rGO composite, which promoted the reductive dechlorination of TCE by H*. Although the S-mZVI/rGO composite had stronger hydrogen evolution propensity than S-mZVI, the S-mZVI/rGO composite still exhibited higher electron utilization efficiency than S-mZVI thanks to the increased utilization of hydrogen.

Catalytic activation of formic acid using Pd nanocluster decorated graphitic carbon nitride for diclofenac reductive hydrodechlorination

Halogenated pharmaceuticals exhibit high toxicity if released to natural environment, and dehalogenation is a key process for their degradation. In this study, a reductive and directional dehalogenation technique, heterogenous formic acid (HCOOH) catalytic activation system, was proposed for diclofenac (DCF) dechlorination and detoxification. A functional material of Pd nanocluster decorated graphitic carbon nitride (Pd/g-C3N4) was developed for HCOOH activation. Although the optimized material (Pd1/g-C3N4) showed lower HCOOH decomposition rate (k1 = 0.287 ± 0.017 min−1) than the pristine Pd particles (k1 = 0.401 ± 0.031 min−1), it processed higher DCF degradation efficiency (97.9% within 30 min) than Pd particles. The enhancement mechanism was revealed by both experiments and theoretical calculations. Firstly, the six-fold cavities of g-C3N4 acted as anchor sites, which offered strong coordination environment for Pd nanoclusters. Secondly, the strong coordination environment of Pd led to upshifted d-band center of Pd 4d with enhanced bonding state, and then promoted HCOOH adsorption on Pd/g-C3N4, thus facilitating HCOOH decomposition through formate pathway rather than carboxyl pathway. Thirdly, Pd/g-C3N4 ensured HCOOH selectively decomposed as dehydrogenation reaction, which generated more H* (adsorbed H on Pd) than the dehydration reaction. The H* was proved to be the dominant reductive species for DCF hydrodechlorination. Moreover, the toxicities of DCF dechlorination products were greatly reduced.

Global Three-Dimensional Emission Inventory for Launch Vehicles from 2009 to 2018

Launch vehicles enable Earth observation, terrestrial navigation, communication, and space exploration. In doing so, they emit chemicals including carbon dioxide, water vapor, chlorine, alumina, black carbon, and other species that contribute to climate change and ozone depletion. With commercial launches increasing and new engines being developed, the impact of rocket launches must be reassessed. This work introduces a global three-dimensional inventory of stoichiometric emissions from rocket launches between 2009 and 2018. We calculate fuel burned and emissions as functions of altitude using publicly available data and a physics-based trajectory model. We estimate that 140 kt of carbon dioxide were emitted in total, and that 79 kt of water vapor, 5 kt of chlorine, and 8 kt of alumina were emitted above the tropopause between 2009 and 2018. All those emissions were produced in the Northern Hemisphere, of which 65% were from Russian and American launches. The number of launches and emissions of carbon dioxide are increasing over time, whereas water vapor and chlorine emissions have decreased since 2009 with the retirement of the space shuttle. Our results constitute the first global, spatially resolved inventory of launch emissions; and they are a critical step toward fully understanding the environmental effects of launch vehicles.

Complete pentachlorophenol biodegradation in a dual-working electrode bioelectrochemical system: Performance and functional microorganism identification

Bioelectrochemical system (BES) can effectively promote the reductive dechlorination of chlorophenols (CPs). However, the complete degradation of CPs with sequential dechlorination and mineralization processes has rarely achieved from the BES. Here, a dual-working electrode BES was constructed and applied for the complete degradation of pentachlorophenol (PCP). Combined with DNA-stable isotope probing (DNA-SIP), the biofilms attached on the anodic and cathodic electrode in the BES were analyzed to explore the dechlorinating and mineralizing microorganisms. Results showed that PCP removal efficiency in the dual-working BES (84% for 21 days) was 4.1 and 4.7 times higher than those of conventional BESs with a single anodic or cathodic working electrode, respectively. Based on DNA-SIP and high-throughput sequencing analysis, the cathodic working electrode harbored the potential dechlorinators (Comamonas, Pseudomonas, Methylobacillus, and Dechlorosoma), and the anodic working enriched the potential intermediate mineralizing bacteria (Comamonas, Stenotrophomonas, and Geobacter), indicating that PCP could be completely degraded under the synergetic effect of these functional microorganisms. Besides, the potential autotrophic functional bacteria that might be involved in the PCP dechlorination were also identified by SIP labeled with 13C-NaHCO3. Our results proved that the dual-working BES could accelerate the complete degradation of PCP and enrich separately the functional microbial consortium for the PCP dechlorination and mineralization, which has broad potential for bioelectrochemical techniques in the treatment of wastewater contaminated with CPs or other halogenated organic compounds.

Recent advances and trends of trichloroethylene biodegradation: A critical review.

Trichloroethylene (TCE) is a ubiquitous chlorinated aliphatic hydrocarbon (CAH) in the environment, which is a Group 1 carcinogen with negative impacts on human health and ecosystems. Based on a series of recent advances, the environmental behavior and biodegradation process on TCE biodegradation need to be reviewed systematically. Four main biodegradation processes leading to TCE biodegradation by isolated bacteria and mixed cultures are anaerobic reductive dechlorination, anaerobic cometabolic reductive dichlorination, aerobic co-metabolism, and aerobic direct oxidation. More attention has been paid to the aerobic co-metabolism of TCE. Laboratory and field studies have demonstrated that bacterial isolates or mixed cultures containing Dehalococcoides or Dehalogenimonas can catalyze reductive dechlorination of TCE to ethene. The mechanisms, pathways, and enzymes of TCE biodegradation were reviewed, and the factors affecting the biodegradation process were discussed. Besides, the research progress on material-mediated enhanced biodegradation technologies of TCE through the combination of zero-valent iron (ZVI) or biochar with microorganisms was introduced. Furthermore, we reviewed the current research on TCE biodegradation in field applications, and finally provided the development prospects of TCE biodegradation based on the existing challenges. We hope that this review will provide guidance and specific recommendations for future studies on CAHs biodegradation in laboratory and field applications.

Characterization and chlorine reactivity of particulate matter released by bathers in indoor swimming pools

Disinfecting swimming pool water is essential for preventing waterborne diseases. An unforeseen consequence of treating water with disinfectants is the formation of disinfection by-products (DPBs) that can cause harmful effects to health through the interactions between the added disinfectant and organic matter in the water. The present work focuses on the chlorine reactivity with particles released by bathers. Such particles are collected in the filter backwash water of swimming pools and this study intends to distinguish DPBs generated from dissolved chemicals from those formed by particulate matter. Therefore, filtered and unfiltered backwash waters were collected from several swimming pools, analysed physicochemically and chemically, and then chlorinated as is (79 mgL−1) and as diluted suspensions (36.2 and 11.9 mgL−1) at varying concentrations of chlorine (1.2 mg and 24 mgCl2L−1). Utilizing a DPD colorimetric technique and GC-ECD, respectively, the kinetics of chlorine consumption and DPBs production have been investigated. Up to 25.7 μgL−1 of chloroform was produced within 96 h at 1.2 mgCl2L−1, followed by haloacetic acids (HAAs) and haloacetonitriles (HANs). Within 96 h, the concentration of trichloroacetic acid reached a maximum of 231.8 μgL−1 at a chlorine concentration of 231.8 μgL−1. The formations of 0.13 μmol THMs, 0.31 μmol HAAs, and 0.04 μmol HANs per mg of dissolved organic carbon (DOC) were finally determined by correlating the organic content of particles with the nature of the DBPs generated. Comparing the quantities of DBPs generated in filtered and unfiltered samples helps us conclude that ∼50% of DBPs formed during the chlorination of swimming pool water are derived from particles brought by bathers.

Effect of Water Treatment on the Chemical Composition of Drinking Water: A Case of Lovozero, Murmansk Region, Russia

The surface waters in Russia’s Murmansk Region used for public water supply are exposed to the negative impact of dust particles carried from the storage facilities for mining waste. For example, lanthanides and other rare metals enter the surface waters in Lovozero District from the tailings storage facilities (TSFs) of the Lovozero Concentrator, which requires thorough water treatment of drinking water. Using the monitoring data of the natural water of the Virma River and of the tap water in the residential community of Lovozero, Murmansk Region, and with the help of physical and chemical modeling (in the software suite Selector), we examined the effect of reagents used in water treatment on water chemistry. It was shown that the use of aluminum polyoxydichloride coagulant can lead to an increase in the concentration of aluminum and chlorine in water, a change in pH and Eh values. The use of liquid chlorine leads to a decrease in pH values and a change in the concentration of HCO3−, which entails a change in the forms of migration of calcium and lanthanides in solution. The composition of the precipitated phases changed, which indicates a change in the water chemistry, demonstrating that the applied water treatment technology adopted in Lovozero fails to improve water quality. It was shown that replacing liquid chlorine (a hazardous reagent) with NaOCl optimized the water treatment process, eliminating the need to stabilize the pH by adding sodium. Physical and chemical modeling was found to be useful for studying and optimizing water treatment processes.

Определение содержания йода, йодидов и йодатов в пищевых продуктах

Currently iodine deficiency diseases are one of the most important medical and social problems. In this regard, the purpose of the study is to determine the content of iodine, iodides, iodates in iodized salt, drinking and mineral water, seaweed, to determine the stability of the iodine content in salt. For the qualitative determination of iodides and iodates ions in salts and molecular iodine in seaweed, an iodine starch reaction has been carried out. The presence of iodide ions in iodized water has been determined by reaction with silver nitrate and chlorine water, the iodine released has been extracted with chloroform. Quantitative determination of iodine in salt has been carried out by the titrimetric method, in water – by colorimetric method, in seaweed – by gravimetric method with subsequent titration. The study has found that iodized salt contains iodine in the form of potassium iodate, in an amount of 18.65 μg / g of elemental iodine, kelp contains molecular iodine in the amount of 8.12 μg / g of elemental iodine, and iodized water contains potassium iodide in the amount of 0.327 μg / ml of elemental iodine. The study has proved that over time, the amount of iodine in the salt iodized with potassium iodate decreases after a month by 5.6 times. In order to comply with the daily rate of iodine intake, it is necessary to include in your diet about 9.7 g of iodized salt, which exceeds the daily norm of its consumption in 5 g. In this regard, it is recommended to use iodized salt (not more than 5 g) or iodized water (0.7 L of water) or kelp (18.47 g) as a prevention of iodine deficiency.

1193. Disinfection of the Sink Drains to Reduce a Source of Serratia marcescens During Infection Outbreaks in a Neonatal Intensive Care Unit

Abstract Background Sink drains are known reservoirs of pathogens and have been associated with multiple nosocomial outbreaks. In this study, the distribution of Serratia marcescens was investigated within the sink environment of a NICU and in colonized or infected newborns. The effect of different types of drain disinfection on bacterial concentration and on the detection of Serratia marcescens in sink drains was also investigated. Methods Sink drains from a NICU were sampled: 20 drains sampled for 6 weeks in the first year and 28 drains sampled for 5 months in the second year. S. marcescens isolated from positive patients were collected. A high-throughput short sequence typing (HiSST) method was developed to identify S. marcescens and compare strains and environmental DNA from sink drains with 56 clinical strains from 5 nosocomial outbreaks. Five interventions were tested: self-disinfecting drains, hot water disinfection, chlorine disinfection, steam disinfection and hot tap water flushing. Bacterial concentration of samples was measured in culture and flow cytometry and the HiSST method was used to identify S. marcescens. Results During the first and second sampling campaigns, 40% and 60% of sink drain samples were positive for S. marcescens with a moderate genotype diversity (1 to 11 different STs). The genotype profile of the 56 clinical strains was heterogeneous (26 STs). Four distinct STs were retrieved in 8 sinks after detection in patients whereas 1 ST was detected in a sink before detection in patient. Some environmental and clinical strains were found in drains for up to a year after the first sampling campaign. Each tested drain intervention reduced culturable bacteria (4-8 log) and viable bacteria (2-3 log), except for chlorine. The self-disinfecting drains, hot water and steam disinfection were able to remove temporarily S. marcescens from the drains. Conclusion The high genotypic diversity of the clinical strains suggests diffuse sources of S. marcescens within the NICU likely to cause nosocomial infection outbreaks. The self-disinfecting drains, hot water and steam disinfection seem to be the best methods to reduce bacterial concentration in drains and eliminate S. marcescens in the short term, thus limiting the risk of pathogens spread from the sink environment to patients. Disclosures All Authors: No reported disclosures.

Effect of polyhydroxyalkanoates on the microbial reductive dechlorination of polychlorinated biphenyls and competing anaerobic respirations in a marine microbial culture

The effect of polyhydroxyalkanoates (PHAs) with different composition on the reductive dechlorination activity of a polychlorinated biphenyls (PCBs) dechlorinating marine microbial community and on the activity of sulfate-reducing (SRB) and methanogenic bacteria (MB), were investigated in marine sediment microcosms and compared with the main monomer, 3-hydroxybutyric acid (3HB). Despite PHAs were fermented more slowly than 3HB, all electron donors stimulated constantly sulfate-reduction, methanogenesis and, only transiently, PCB reductive dechlorination. No relevant differences were observed with different compositions of PHAs. According to electron balances, the majority of the supplied electrons (50 %) were consumed by SRB and to less extent by MB (9–31 %), while a small percentage (0.01 %) was delivered to OHRB. In the studied conditions PHAs were confirmed as potential slow‑hydrogen releasing compounds in marine environment but their fermentation rate was sufficiently high to mainly stimulate the competitors of organohalide respring bacteria for electron donors.

Electrochemical Reduction of Halogenated Alkanes and Alkenes Using Activated Carbon-Based Cathodes.

Granular activated carbon (GAC) is used to sorb a broad range of halogenated contaminant classes, but spent GAC disposal is costly. Taking advantage of GAC's conductivity, this study evaluated the conversion of the GAC to cathodes for electrochemical reductive dehalogenation of 15 halogenated alkanes and alkenes exhibiting a diversity of structures (type of halogen, number of halogens, functional groups) and including contaminants of practical importance (e.g., trichloroethylene). Alkane degradation rates increased with the number of halogens and in the order: chlorine < bromine < iodine. Quantitative structure-activity relationships (QSARs) correlating experimental first-order degradation rate constants for alkanes with molecular descriptors associated with an outer-sphere one-electron transfer calculated using density functional theory indicated that correlations with molecular descriptors improved in the order: aqueous phase reduction potentials (E0,aq) < energy of the substrate's lowest unoccupied molecular orbital (ELUMO) < Marcus theory activation free energies (ΔG‡) ∼ gas-phase standard reduction free energies (ΔG0,gas). Chlorinated alkene degradation rates increased with decreasing number of chlorines, and QSAR correlations were opposite those of alkanes, indicating a different reaction mechanism. Degradation timescales ranged from 1 min to 3 h with halides as predominant products. These results suggest that the electrochemical reduction of halogenated alkanes and alkenes can be used to regenerate spent GAC.

Uncertainty analysis of water quality in water distribution system

Abstract Water quality simulation is affected by uncertain parameters such as pipe roughness coefficients, chlorine bulk decay coefficients, and chlorine wall decay coefficients, which are usually considered to be fuzzy variables. The minimum and maximum nodal chlorine concentrations and water ages at each α-cut level were obtained by the genetic algorithm (GA) based on EPANET hydraulic and water quality simulation toolkit. The fuzziness of nodal chlorine concentrations and water ages were measured using the fuzziness measure (FM) proposed in this paper. The method was applied to four networks to analyze the fuzziness of nodal chlorine concentrations and water ages. The results indicated that the distribution of nodal chlorine concentrations does not follow typical trapezoid distribution, while the distribution of nodal water ages follows typical trapezoid distribution. In addition, the chlorine concentration and water ages of nodes farther from the source are affected by uncertain parameters to a greater extent. The greater demands of nodes lead to less effects of uncertain parameters on chlorine concentration, and greater effects of uncertain parameters on water ages. This study would help in analyzing the fuzziness of hydraulic and water quality simulation results in WDS under uncertain conditions.

A novel application of a geotechnical soil stabilization technology for improved delivery of remedial amendments

AbstractAccelerating the remediation of contaminants that have diffused into low‐permeability (low‐k) geologic units such as silts and clays is a key need for the groundwater remediation industry. Injection‐based remedial technologies are often ineffective because the injected amendments are more likely to influence transmissive media (sands and sandy silts) and generally do not penetrate low‐k units. While some emerging technologies are now being tested, they are often expensive or have other technical limitations (e.g., installation depth and rate of amendment emplacement). To address the problem of treating contaminants in low‐k media, a geotechnical technology called the “Grout Bomber” (Keller North America) was repurposed for an environmental application to emplace ~800 vertical “reaction columns” containing zero valent iron (ZVI), sand, and neat vegetable oil for the treatment of chlorinated volatile organic compounds (CVOCs) in lean clays and sandy clays. The reaction columns were closely‐spaced (2–3 ft apart) to greatly accelerate the back diffusion of CVOCs from the low‐k media to the reaction columns where contact with ZVI and vegetable oil promotes abiotic and biotic reductive dechlorination of CVOCs, respectively. Overall, 35 tons of ZVI were emplaced into the 5200 cubic yard (yd3) (~4000 m3) source zone during the project. Key benefits of this technology include rapid installation (average of 107 reaction columns per day), ease of remediation amendment mixing, consistent amendment dosing, and relatively low unit installation costs ($71 per cubic yard of treatment zone). It should be emphasized that this application of the Grout Bomber relies on diffusion of contaminants into the reaction columns from the surrounding low‐k media—a process that occurs slowly over years to decades. A planning‐level model showed that installation of closely spaced vertical reaction columns in a TCE‐laden clay unit reduced the time to achieve maximum contaminant levels from greater than 500 years to approximately 26 years. Groundwater monitoring confirmed the establishment of a concentration gradient between the reaction columns which promotes diffusion of CVOCs toward the reaction columns. The presence of dissolved acetylene and gaseous “higher coupling” products (&gt;C3) provide further evidence of ongoing abiotic reductive dechlorination within the reaction columns.

Optimisation of chlorinedisinfection in drinkingwater supply network

Abstract Chlorination is one of the most commonly used procedures for drinking waterdisinfection. The research aimed to soptimise the subsequent disinfection ofdrinking water with chlorine in the water supply network in the city Velenje,taking into account the applicable legislation. The gradual reduction of chlorinedosage was implemented with simultaneous monitoring of selected physico-chemical and microbiological parameters of drinking water. During the two-month period, 418 samples were taken at 22 previously defined differentsampling spots. Free chlorine values were reduced from the initial 0,18 mg/L tothe final 0,08 mg/L at the outlet, while values at some remote sampling sitesreached only 0,01 mg/L of free chlorine. Microbiological analyses of samplesshowed that the drinking water met the limit values in the regulations, despitethe low values of free chlorine. Based on the results, a modified chlorination ofdrinking water was introduced in the tested supply area, and the introduction ofa similar regime in other supply areas is being actively considered. In this way,we reduce the consumption of disinfectants and ensure the supply of qualityand healthy drinking water to consumers.

Degradation characteristics of 2,4,6-trichlorophenol by the anaerobic consortium XH-1

Organic pollutant 2,4,6-trichlorophenol (2,4,6-TCP) is commonly found in anaerobic environments such as sediments and groundwater aquifers. To investigate the ability of the anaerobic consortium XH-1 to degrade 2,4,6-TCP, we established anaerobic incubations using 2,4,6-TCP as the substrate and inoculated the incubations with XH-1. Additional subcultures were established by amending with intermediate product 4-chlorophenol (4-CP) or phenol as the substrate. The transformation products of 2,4,6-TCP were analyzed and determined using high-performance liquid chromatography (HPLC). Microbial community structure and key microbial groups involved in the degradation of 2,4,6-TCP were analyzed based on 16S rRNA gene high-throughput sequencing. The results showed that the initial 122 μmol·L-1 2,4,6-TCP was completely transformed after a 80-day incubation at a rate of 0.15 μmol·d-1. 2,4-dichlorophenol (2,4-DCP), 4-CP and phenol were identified as the intermediate products. All intermediate products generated from 2,4,6-TCP transformation were completely degraded after being incubated for 325 days. The main microbial groups responsible for the reductive dechlorination of 2,4,6-TCP might be the organohalide respiring Dehalobacter and Dehalococcoides. The subsequent reductive dechlorination of 4-CP to phenol was likely driven by Dehalococcoides. The cooperation between the organohalide respiring bacteria, Syntrophorhabdus and methanogens (e.g. Methanosaeta and Methanofolis) was responsible for the complete degradation of 2,4,6-TCP.

A Nested-PCR assay for detection of Cryptosporidium spp. in cattle in Sulawesi Island, Indonesia

Cryptosporidium spp. is a protozoan parasite that cause cryptosporidiosis, a gastroenteric disease in wide range of animals and humans. Cryptosporidiosis affects significant economic loss in livestock production due to poor management practices, leading to faecal contamination. The parasite can be transmitted by ingestion of oocysts which have high survival ability in various type of environment and resistant to water chlorination treatment. In this study, we aimed to investigate the presence of Cryptosporidium spp. in various faecal samples of cattle (n=24, aged 1-2 years old) obtained from several farms in Sulawesi. Following faecal DNA extraction, we performed a nested-PCR assay using validated-Cryptosporidium 18S ribosomal RNA (18S rRNA) primers, resulting a size of amplified DNA approximately 770 bps. A total four samples (16.7%) were regarded as positive for Cryptosporidium spp., including samples obtained from farms in South Sulawesi (n=2), Central Sulawesi (n=1) and Gorontalo (n=1). This result confirms the risk of cryptosporidiosis not only among cattle in Sulawesi but also potential transfer of this parasite to humans especially from contaminated water and food. Therefore, early detection of the spread of oocysts is also crucial for monitoring animal health including cattle as production animals, human health, and environment.

Integrated anaerobic-aerobic biodegradation of mixed chlorinated solvents by electrolysis coupled with groundwater circulation in a simulated aquifer.

Chlorinated solvents are widespread subsurface contaminants that are often present as complex mixtures. Complete biodegradation of mixed chlorinated solvents remains challenging because the optimal redox conditions for biodegradation of different chlorinated solvents differ significantly. In this study, anaerobic and aerobic conditions were integrated by electrolysis coupled with groundwater circulation for biodegradation of a mixture of chloroform (CF, 8.25mg/L), 1,2-dichloroethane (DCA, 7.01mg/L), and trichloroethylene (TCE, 4.56mg/L). A two-dimensional tank was filled with field sandy and silty-clayed sediments to simulate aquifer conditions, a pair of electrodes was installed between an injection well and abstraction well, and groundwater circulation transported cathodic H2 and anodic O2 to produce multiple redox conditions. Microbial community analysis demonstrated that the system constructed a habitat suitable for the co-existence of aerobic and anaerobic microbes. After 50days of treatment, 93.1%, 100%, and 87.3% of CF, 1,2-DCA, and TCE were removed without observed intermediates, respectively. Combined with compound specific isotope analysis, the degradation of 1,2-DCA and CF was mainly attributed to aerobic oxidation and reductive dechlorination, respectively, and TCE was removed by both aerobic and anaerobic biodegradation. Our findings provide a new and efficient strategy for in situ bioremediation of groundwater contaminated by mixed chlorinated solvents.

Influence of microplastics on microbial anaerobic detoxification of chlorophenols

Microplastics (MPs) can absorb halogenated organic compounds and transport them into marine anaerobic zones. Microbial reductive dehalogenation is a major process that naturally attenuates organohalide pollutants in anaerobic environments. Here, we aimed to determine the mechanisms through which MPs affect the microbe-mediated marine halogen cycle by incubating 2,4,6-trichlorophenol (TCP) dechlorinating cultures with various types of MPs. We found that TCP was dechlorinated to 4-chlorophenol in biotic control and polypropylene (PP) cultures, but essentially terminated at 2,4-dichlorophenol in polyethylene (PE) and polyethylene terephthalate (PET) cultures after incubation for 20 days. Oxygen-containing functional groups such as peroxide and aldehyde were enriched on PE and PET after incubation and corresponded to elevated levels of intracellular reactive oxygen species (ROS) in the microorganisms. Adding PE or PET to the cultures exerted limited effects on hydrogenase and ATPase activities, but delayed the expression of the gene encoding reductive dehalogenase (RDase). Considering the limited changes in the microbial composition of the enriched cultures, these findings suggested that microbial dechlorination is probably affected by MPs through the ROS-induced inhibition of RDase synthesis and/or activity. Overall, our findings showed that extensive MP pollution is unfavorable to environmental xenobiotic detoxification.