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Trichloroethylene (TCE) was once a widely applied industrial solvent, but is now an infamous contaminant in groundwater. Although anaerobic reductive dechlorination is considered a greener remediation approach, the accumulation of toxic intermediates, such as vinyl chloride (VC), and a longer remediation period are highly concerning. Biostimulation and bioaugmentation have been developed to solve these problems. The former method may not be effective, and the latter may introduce foreign genes. Here, we propose a new approach by applying environmental stresses to reshape the indigenous microbiome. In this study, by using the Taguchi method, the effects of heating, pH, salinity, and desiccation were systematically examined. The optimum conditions were defined as 50 °C, pH 9, 3.50% salinity (w/v), and 21% volumetric water content (θ

The agricultural lands in most Asian countries have been contaminated by pesticides for decades, especially γ-hexachlorocyclohexane (lindane) and dichlorodiphenyltrichloroethane (DDT). For most sites, the concentrations are in the parts per million level favoring bioremediation. However, due to high hydrophobicity, they are hard to be biodegraded in soils. In situ phase inversion emulsification and biological reductive dechlorination (ISPIE/BiRD) is proposed as an effective approach for the removal of lindane and DDT in soil. Three tests were conducted, i.e., a batch test, a column test, and a sandbox test. In the batch test, the Taguchi method was applied to define optimum environmental parameters, such as pH, water content, emulsion concentration, and soil organic matter level. A column test was performed using a real agricultural soil to define the removal efficiency of a single operation of ISPIE on lindane and DDT. A sandbox was employed to test if the remaining emulsion can assist in the biodegradation of lindane and DDT in a real agricultural soil. Next-generation sequencing (NGS) was performed to profile the microbial community for the best groups in the batch test and the sandbox test. The batch test results showed that water content and emulsion concentration are critical controlling factors, and the removal of lindane and DDT was 99.7% and 88.9%, respectively. A single operation of ISPIE removed 52.9% and 31.5% of DDT and lindane, respectively, and the difference is probably due to the log KOW. The best parameter combination was employed in the sandbox test and the best removal rates of DDT and lindane on the 28th day were 78.0 ± 1.2% and 99.7 ± 0.5%, respectively. NGS data results showed that agriculture soil has more abundant and diverse microorganisms than the acclimated sediment culture. NGS analysis showed two cohesive groups were competing against each other in the batch test and complex interactions existed in the sandbox test. These results suggest that ISPIE/BiRD is a highly viable remediation option for rice paddy farming lands contaminated by highly hydrophobic contaminants. ISPIE followed by BiRD can be finished in a 42-day period and is highly suitable for implementation during an annual break of paddy field farming. Some potential strong degraders and complex interactions require more research in the future.

Sediment contamination in Taiwan is a critical environmental problem because it threatens human health through food chains and the local ecosystem as well. Er-Ren River (ERR) in southern Taiwan is one of the most polluted and its sediments have been severely contaminated by hydrophobic organic compounds (HOCs). Among all HOCs, polychlorinated biphenyls (PCBs) have been detected at high levels while hexachlorobenzene (HCB) has been most frequently detected. Due to their higher Kow values and lower biodegradability, they can be biomagnified through trophic levels and consequently pose high risks to humans and the ecosystem. This field study is to demonstrate an effective remediation technology on sediments contaminated by Aroclor 1254 and HCB by coupling in situ phase-inversion emulsification and biological reductive dechlorination (ISPIE/BiRD). By using real contaminated sediment with weathered and freshly-added contaminants, a single ISPIE operation can remove about 62% and 60% of weathered Aroclor 1254 and HCB, respectively. For weathered HCB and Aroclor 1254, the total removal could reach as high as 98% in 70 days. Metagenomic results showed that heat selection during ISPIE significantly changed the diversity and species evenness of the microbial community and that the Dehalococcoides were not positively correlated with the PCB removals. Instead, heat-tolerant archaea, Methanosaeta spp., may play much more important roles in the subsequent biological dechlorination. These results strongly support that ISPIE/BiRD is highly feasible on a full-scale field remediation and that this new microbial consortium could be a highly effective tool for bioremediation of HOC-contaminated sediments.

Trichloroethylene (TCE) was a widely used industrial solvent but is now regarded as a notorious groundwater contaminant. Both physicochemical and biological methods have been applied to remediate groundwater contaminated by TCE. For medium to low level of TCE contamination, bioremediation could be more cost-effective. However, bioremediation approaches suffer from slow degradation rates and accumulation of vinyl chloride (VC). In addition, bioaugmentation is often highly encouraged but may introduce foreign genes and increase the pace of microbial evolution. In this study, a microbiome reengineering strategy by heat selection is applied to solve these problems. Out of eight heat-treated mixed cultures, two showed a much-improved TCE degradation rate, more than 70 times higher than the untreated. The biodegradation half-life (t1/2) of TCE was 0.0627 d or shorter. No VC was detected by a gas chromatography equipped with flame ionization detector (GC-FID) and only a minimal amount by a GC-mass spectrometer (GC-MS). Ethene achieved a fairly good mass balance. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and next-generation sequencing (NGS) results showed that the heating process did not kill most bacteria, but Dehalococcoides were either not present or very scarce. Acetoanaerobium and Methanosarcina could be the most important species in this reductive dechlorination process. Kinetic study results showed that the maximum specific TCE degradation rate was approximately 1,271 nmole/min/mg cell protein, which are two orders of magnitude higher than that of the mixed cultures reported in literature. These results suggest that apart from biostimulation and bioaugmentation, microbiome reengineering could be a promising approach for rapid bioremediation of TCE-contaminated aquifers.

Trichloroethene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA) are notorious pollutants in groundwater. The biodegradation of them yields more toxic vinyl chloride (VC) and 1,1-dichloroethene (1,1-DCE). Although their biodegradation is highly feasible in the lab, field remediation still faces huge challenges. One challenge of them is the lack of good microbial indicators and consequently, monitoring famous species can cause the prediction of project time span and related expenses to fail. Here, in this study, we offer a solution by integrating predominance, correlation, and principal component analysis on the testing results of the biodegradation of VC and 1,1-DCE under seven different nutrient-amendment conditions. The inoculum was from a contaminated site with accumulated 1,1-DCE and VC. Next-generation sequencing (NGS) was applied to 15 microbial communities. Traditional analysis relying predominance on NGS data may be misleading due to the variation of copy number per cell for different microorganisms. By considering predominance, correlation between copy number and removal efficiency, and PCA loading factors of the principle component analysis, bacteria of the Ruminococcaceae family, Syntrophomonas sp., Pseudomonas stutzuri, Candidatus Methanoregula, and Methanospirillum sp. could be microbial indicators for removing 1,1-DCE and VC in biodegradation. The results suggested a variety of combinations of bacteria and archaeal species can effectively remove 1,1-DCE but less so for VC. The influence of archaeal species in the natural environment on bioremediation of chlorinated solvents cannot be neglected.

Polybrominated diphenyl ethers (PBDEs) are flame retardants and regarded as emerging contaminants and persistent organic pollutants (POPs). Due to high lipophilicity and low biodegradability, they tend to accumulate in sediments. Decabrominated diphenyl ether (BDE-209) is the most predominant congener among 209 PBDE congeners in river sediments, accounting for more than 90 % of total PBDEs in most samples. This study is to explore the feasibility of an integrated remedial approach, direct removal by emulsion recovery and subsequent biological reductive debromination. A double emulsion (water in oil in water) was formulated and used in direct recovery of BDE-209 in sediment samples. After this recovery operation, the residual oil left in sediments was used as an electron donor for anaerobic microbial reductive debromination. In order to improve the robustness of this direct recovery method, a variety of operational parameters and environmental variables were tested, such as mixing speed, mixing time, initial concentrations of BDE-209, salinity contents of sediment, and fractions of humic acids. A biodegradation experiment with different humic acid contents and with or without residual emulsion was conducted to compare the biodegradation rates under different conditions. All samples were extracted by using accelerated solvent extraction and detected by a gas chromatography with an electron capture detector. In this study, we used an emulsion to recover BDE-209 in simulated sediment samples with different salinity and humic acid contents. BDE-209 was recovered as much as 96.10 % in a single recovery operation under a condition similar to the real situation of Er-Ren River in Taiwan. The biodegradation of unrecovered BDE-209 was assessed under anaerobic conditions with residual emulsion as an electron donor. The average half-life is 11.7 ± 1.9 days with residual emulsion, which is about 40 % shorter than that of those without emulsion and much shorter than those reported in literature. Real sediment samples were also tested and the result indicated that this method is highly feasible. Emulsion-enhanced recovery and biodegradation could be a highly feasible way to remove BDE-209 in river sediments. This method is not sensitive to the initial concentration of BDE-209 but sensitive to the salinity and humic acid concentration in sediments.

The environmental persistence of hazardous organochlorine pesticides (OCPs) such as lindane has resulted in a need for the development of reliable remediation technology for the removal of OCPs. Green tea extract/Fe2+ under alkaline conditions is a potential green chemistry technology proven to be effective in reducing lindane. This study investigated the feasibility of directly using green tea leaves (GT-leaf) or cold-brew tea solution (GT-sol) with Fe2+ additives at (bi)carbonate buffered pH 10 to treat lindane in the aqueous phase. The polyphenol was gradually released in the GT-leaf system and reached a similar concentration as that in the GT-sol system (∼800 mg L−1 at pH 6.5). Based on the analytical results of lindane degradation byproducts, it was recognized that the reductive mechanism acts as a major pathway and alkaline hydrolysis is a minor pathway. However, physical adsorption rapidly removes lindane from the GT-leaf system. A comprehensive evaluation of lindane degradation, chlorobenzene formation, degradation kinetics, and chloride liberation were conducted for the alkaline GT-sol/Fe2+ system. The nonlinear simulations of the models developed showed good fits, with R2 > 0.96. This study highlights the potential for GT-sol/Fe2+ systems to remediate OCPs contamination.

River sediment contamination is a critical environmental problem. Concentrations of certain hydrophobic organic compounds (HOCs) in sediments in Taiwan are ranked at the top in the world. In this study, we proposed a novel in situ phase-inversion emulsification and biological reductive dechlorination (ISPIE/BiRD) method that integrates (1) heating contaminated sediments by hot water-in-oil emulsion to increase the contact between hydrophobic organic contaminants (HOCs), to accelerate the mass transfer between two phases, and to select heat-tolerant hydrogen-producing bacteria, (2) ISPIE forming oil-in-water emulsion to enhance recovery of HOCs by pushing cool water and nutrient buffer through the sediment column, and (3) subsequent BiRD using residual emulsion in sediment. Aroclor 1254 and hexachlorobenzene (HCB) were selected due to significantly higher human health and ecological risks in sediments. Batch biological dechlorination tests were conducted using an L 9(34 ) orthogonal table according to the Taguchi method . The results showed that significant controlling factors for biological dechlorination were temperature and emulsion concentration. A single operation of ISPIE can achieve the removal of Aroclor 1254 and HCB at as high as 58.2% and 56.5%, respectively. Column study on BiRD further removed about 30% of the residual Aroclor 1254 and HCB at the upper and middle sections of the sediment cores in 35 days. These results supported that ISPIE/BiRD is feasible for HOC-contaminated sediments remediation.

Algal toxin is a unique type of toxin generated with harmful algal blooms in water bodies. This phenomenon is worsened by eutrophication caused by excessive discharge of nutrients into surface water bodies. Since algal toxins are hard to remove after they enter the water treatment processes, an efficient method is required to inhibit the growth of algal cells, to settle the cells at the bottom of the water body and to removes the toxin from the water. We report an efficient way to prepare a novel nanohybrid material, i.e., magnetic nanosilicate platelet (MNSP), and its effects on the removal of microcystin toxins as well as the cells of Microcystis aeruginosa. MNSP was fabricated by a special treatment of a clay mineral, montmorillonite, and then its surface was decorated with magnetite nanoparticles by in situ synthesis. The nanohybrid can efficiently inhibit the growth of M. aeruginosa-a typical species that can generate one of the most notorious algal toxins, i.e., microcystins. Algal cells can be settled with minimal 500 ppm MNSP, and the turbidity can be reduced by more than 67%. The removal of microcystin-LR (MC-LR) was as high as 99.39% at an concentration of 100 ppm, while the pristine nanosilicate platelet could only remove 36.84% at the same dosage.

Drinking water safety has been threatened by increasing harmful algal blooms (HABs) in water sources. HABs are closely associated with eutrophication in freshwater lakes, e.g. Lake Tai in China, and marine environments as well, e.g. Baltic Sea in Europe. Among all HABs, Microcystis aeruginosa attracted much attention due to its easy proliferation and potent toxins, microcystins. Most of the current control technologies can result in immediate release of microcystins which are hard to remove by drinking water treatment processes. Here we propose to simultaneously remove M. aeruginosa and its toxin, microcystin-LR (MC-LR), using nanosilicate platelet (NSP) derived from natural clay mineral. In this study, NSP showed strong selective growth inhibition and good settling enhancing effects on M. aeruginosa and highly efficient removal of MC-LR. NSP can inhibit the growth of M. aeruginosa (initial cell concentration at 3.00×10(6)cellmL(-1)) with a LC50 at 0.28ppm after 12h exposure. At the dosage of 100ppm, NSP can enhance settling of suspended M. aeruginosa. Bacterial growth inhibition tests showed NSP had very mild growth inhibition effects on Escherichia coli at high dosage but promoted the growth of Pseudomonas aeruginosa and Bacillus halodurans. For MC-LR removal, at an initial concentration of 100μgL(-1), NSP achieved higher than 99% removal. Thus, the results suggest that NSP could be an excellent candidate for controlling M. aeruginosa-related HABs in water bodies.

Algal toxin is a unique type of toxin generated with harmful algal blooms in water bodies. This phenomenon is worsened by eutrophication caused by excessive discharge of nutrients into surface water bodies. Since algal toxins are hard to remove after they enter the water treatment processes, an efficient method is required to inhibit the growth of algal cells, to settle the cells at the bottom of the water body and to removes the toxin from the water. We report an efficient way to prepare a novel nanohybrid material, i.e., magnetic nanosilicate platelet (MNSP), and its effects on the removal of microcystin toxins as well as the cells of Microcystis aeruginosa. MNSP was fabricated by a special treatment of a clay mineral, montmorillonite, and then its surface was decorated with magnetite nanoparticles by in situ synthesis. The nanohybrid can efficiently inhibit the growth of M. aeruginosa-a typical species that can generate one of the most notorious algal toxins, i.e., microcystins. Algal cells can be settled with minimal 500 ppm MNSP, and the turbidity can be reduced by more than 67%. The removal of microcystin-LR (MC-LR) was as high as 99.39% at an concentration of 100 ppm, while the pristine nanosilicate platelet could only remove 36.84% at the same dosage.

Mycobacterium immunogenum and Pseudomonas aeruginosa currently present one of the highest health concerns in metalworking processes. The former is a Gram positive bacterium strongly associated with hypersensitivity pneumonitis outbreaks and the latter is a Gram negative famous for its opportunistic pathogenesis and frequent isolation from in-service metalworking fluids (MWFs). Thus far, biocide addition is the only microbial control measure in MWFs, but it often fails on preventing mycobacteria proliferation. This study aimed to formulate an inherently bacteria-resistant MWF with industrial grade chemicals. Using a phase inversion temperature method, we created a low-cost mineral oil nanoemulsion (MONE) which has extraordinarily high bactericidal activity against M. immunogenum and P. aeruginosa and has the smallest oil droplet size ever reported in the literature. A short-term biocidal test showed that a 5% dilution of MONE (5% MONE) exhibited high emulsion stability and strong bactericidal effects. The first-order biocidal rate constants of 5% MONE are higher than 72% of the 32 different test combinations of commercially available MWFs amended with two industrial biocides, KATHON™ LXE and Preventol® CMK-NA. A further longer term test on an aged 5% MONE showed it achieved 100% elimination of all tested bacteria either in pure cultures or a mixed culture up to 28 days. The biocidal kinetics of MONE seemed to follow a new equation, ln(N/N0) = −k0’(exp(n’C))t, much better than the currently most widely accepted Chick–Watson law equation. Among the reported antimicrobial nanomaterials and industrial biocides, this nanoemulsion formulation may offer a low-cost solution in sustainable utilization of mineral oil in MWF applications and a new research perspective on biodeterioration prevention of MWFs.

A key component in any investigation of cause-effect relationships between point source pollution, such as an incinerator, and human health is the availability of measurements and/or accurate models of exposure at the same scale or geography as the health data. Geostatistics allows one to simulate the spatial distribution of pollutant concentrations over various spatial supports while incorporating both field data and predictions of deterministic dispersion models. This methodology was used in a companion paper to identify the census blocks that have a high probability of exceeding a given level of dioxin TEQ (Toxic Equivalents) around an incinerator in Midland, Michigan. This geostatistical model, along with population data, provided guidance for the collection of 51 new soil data, which permits the verification of the geostatistical predictions, and calibration of the model. Each new soil measurement was compared to the set of 100 TEQ values simulated at the closest grid node. The correlation between the measured concentration and the averaged simulated value is moderate (0.44), and the actual concentrations are clearly overestimated in the vicinity of the plant property line. Nevertheless, probability intervals computed from simulated TEQ values provide an accurate model of uncertainty: the proportion of observations that fall within these intervals exceeds what is expected from the model. Simulation-based probability intervals are also narrower than the intervals derived from the global histogram of the data, which demonstrates the greater precision of the geostatistical approach. Lognormal ordinary kriging provided fairly similar estimation results for the small and well-sampled area used in this validation study, however, the model of uncertainty was not always accurate. The regression analysis and geostatistical simulation were then conducted using the combined set of 53 original and 51 new soil samples, leading to an updated model for the spatial distribution of TEQ in Midland, MI.

The accurate detection and enumeration of mycobacteria in metalworking fluids (MWFs) is imperative from an environmental protection and occupational health perspective. We report here on a comparis...

The accurate detection and enumeration of Mycobacterium immunogenum in metalworking fluids (MWFs) is imperative from an occupational health and industrial fluids management perspective. We report here a comparison of immunomagnetic separation (IMS) coupled to flow-cytometric enumeration, with traditional centrifugation techniques for mycobacteria in a semisynthetic MWF. This immunolabeling involves the coating of laboratory-synthesized nanometer-scale magnetic particles with protein A, to conjugate a primary antibody (Ab), specific to Mycobacterium spp. By using magnetic separation and flow-cytometric quantification, this approach enabled much higher recovery efficiency and fluorescent light intensities in comparison to the widely applied centrifugation technique. This IMS technique increased the cell recovery efficiency by one order of magnitude, and improved the fluorescence intensity of the secondary Ab conjugate by 2-fold, as compared with traditional techniques. By employing nanometer-scale magnetic particles, IMS was found to be compatible with flow cytometry (FCM), thereby increasing cell detection and enumeration speed by up to two orders of magnitude over microscopic techniques. Moreover, the use of primary Ab conjugated magnetic nanoparticles showed better correlation between epifluorescent microscopy counts and FCM analysis than that achieved using traditional centrifugation techniques. The results strongly support the applicability of the flow-cytometric IMS for microbial detection in complex matrices.

Mycobacteria are relevant target microorganisms in metalworking fluids (MWFs), owing to their recent recovery from industrial systems and their potential implication in respiratory illness. Whereas a number of detection technologies are available to monitor microbial contamination in MWF, no methods have been developed for the detection of mycobacteria in these matrices. We report here a novel method for detecting Mycobacterium parafortuitum in a semi-synthetic MWF with nonspecific nucleic acid dyes using flow cytometry (FCM). Following disaggregation of bacteria through (probe) sonication, the emulsion was destabilized using isopropanol (IPA) to minimize the nonspecific binding of the fluorescent dye to MWF components. The quantitative results show good correlation with direct counts using epifluorescent microscopy (EFM) within the range of 2.31×104 to 2.31×10 7 cells ml −1 . The time required to complete FCM and EFM enumeration was 10 and 300 s sample −1 , respectively. These results lend support to the applicability of FCM, a multiparametric data acquisition technique, for microbial detection in these complex fluids.

Arsenic (As) contamination in groundwater is a great environmental health concern and is often the result of contact between groundwater and arsenic-containing rocks or sediments and from variation of pH and redox potentials in the subsurface. In the past decade, magnetite nanoparticles (MNPs) have been shown to have high adsorption activity towards As. Alerted by the reported cytotoxicity of 5&ndash, 12 nm MNP, we studied the adsorption behavior of 1.15 nm MNP and a MNP composite (MNPC), MNPs interlinked by silane coupling agents. With an initial concentration of As at 25 mg L&minus, 1, MNPs exhibited high adsorption capacity for As(V) and As (III), 206.9 mg&middot, g&minus, 1 and 168.6 mg&middot, 1 under anaerobic conditions, respectively, and 109.9 mg&middot, 1 and 108.6 mg&middot, 1 under aerobic conditions, respectively. Under aerobic conditions, MNPC achieved even higher adsorption capacity than MNP, 165.1 mg&middot, 1 on As(V) and 157.9 mg&middot, 1 on As(III). For As(V) at 50 mg L&minus, 1, MNPC achieved an adsorption capacity as high as 341.8 mg&middot, 1, the highest in the literature. A kinetic study indicated that this adsorption reaction can reach equilibrium within 15 min and the rate constant of As(V) is about 1.9 times higher than that of As(III). These results suggested that MNPC can serve as a highly effective adsorbent for fast removal of As.

As part of the University of Michigan Dioxin Exposure Study, soil samples were collected from 766 residential properties near the Tittabawassee River between Midland and Saginaw; near the Dow Chemical Facility in Midland; and, for comparison, in the other areas of Midland and Saginaw Counties and in Jackson and Calhoun Counties, all located in the state of Michigan, USA. A total of 2,081 soil samples were analyzed for 17 polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). In order to better understand the distribution and sources of the PCDD/F congeners in the study area, hierarchical cluster analysis (HCA) was used to statistically group samples with similar congener patterns. The analysis yielded a total of 13 clusters, including: 3 clusters among the soils impacted by contamination present in the Tittabawassee River sediments, a cluster comprised mainly of samples collected within the depositional area of the Dow incinerator complex, a small cluster of samples with elevated 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD), and several clusters exhibiting background patterns. The clusters related to the Tittabawassee River floodplain contamination all contained elevated PCDF levels and were differentiated from one another primarily by their relative concentrations of higher-chlorinated PCDDs, a difference likely related to both extent and timing of impacts from Tittabawassee sediments. The background clusters appear to be related to combustion processes and are differentiated, in part, by their relative fractions of TCDD. Thus, HCA was useful for identifying congener profile characteristics in both contaminated and background soil samples. Environ. Toxicol. Chem. 2010;29:64-72. # 2009 SETAC Keywords—Polychlorinated dibenzo-p-dioxins Polychlorinated dibenzofurans Cluster analysis Multivariate statistics Tittabawassee River

The University of Michigan dioxin exposure study was undertaken to address concerns that the industrial discharge of dioxin-like compounds in the Midland, MI area had resulted in contamination of soils in the Tittabawassee River floodplain and downwind of the incinerator. The study was designed in a rigorously statistical manner comprising soil measurements of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) from 766 residential properties, selected probabilistically, in the Midland area and in Jackson and Calhoun Counties (Michigan) as a background comparison. A statistical comparison determined that the geometric mean toxic equivalent (TEQ) levels in samples from the target populations were statistically significantly above background. In addition, the probabilities of being above the 75th and 95th percentiles of background were also greater. Congener contributions to the TEQ were dominated by 2,3,4,7,8-PeCDF and 2,3,7,8-TCDF in the floodplain and by 2,3,7,8-TCDD in the incinerator plume. However, PCB 126 was the top congener contributing to the background TEQ. On the basis of statistical inference to the total population, it was estimated that about 36% of the properties in the floodplain and incinerator plume have at least one soil sample over the Michigan Department of Environmental Quality's soil direct contact criterion of 90 pg/g TEQ.