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The effectiveness of different treatment processes on assimilable organic carbon (AOC) removal and bacterial diversity variations was evaluated in a water treatment plant. The van der Kooij technique was applied for AOC analysis and responses of bacterial communities were characterized by the metagenomics assay. Results show that the AOC concentrations were about 93, 148, 43, 51, 37, and 38 μg acetate-C/L in effluents of raw water basin, preozonation, rapid sand filtration (RSF), ozonation, biofiltration [biological activated carbon (BAC) filtration], and chlorination (clear water), respectively. Increased AOC concentrations were observed after preozonation, ozonation, and chlorination units due to the production of biodegradable organic matters after the oxidation processes. Results indicate that the oxidation processes were the main causes of AOC formation, which resulted in significant increases in AOC concentrations (18-59% increment). The AOC removal efficiencies were 47, 28, and 60% in the RSF, biofiltration, and the whole system, respectively. RSF and biofiltration were responsible for the AOC treatment and both processes played key roles in AOC removal. Thus, both RSF and biofiltration processes would contribute to AOC treatment after oxidation. Sediments from the raw water basin and filter samples from RSF and BAC units were collected and analyzed for bacterial communities. Results from scanning electron microscope analysis indicate that bacterial colonization was observed in filter materials. This indicates that the surfaces of the filter materials were beneficial to bacterial growth and AOC removal via the adsorption and biodegradation mechanisms. Next generation sequencing analyses demonstrate that water treatment processes resulted in the changes of bacterial diversity and community profiles in filters of RSF and BAC. According to the findings of bacterial composition and interactions, the dominant bacterial phyla were Proteobacteria (41% in RSF and 56% in BAC) followed by Planctomycetes and Acidobacteria in RSF and BAC systems, which might affect the AOC biodegradation efficiency. Results would be useful in developing AOC treatment and management processes in water treatment plants.

Emulsified polycolloid substrate (EPS) was developed and applied in situ to form a biobarrier for the containment and enhanced bioremediation of a petroleum-hydrocarbon plume. EPS had a negative zeta potential (−35.7 mv), which promoted its even distribution after injection. Batch and column experiments were performed to evaluate the effectiveness of EPS on toluene containment and biodegradation. The EPS-to-water partition coefficient for toluene (target compound) was 943. Thus, toluene had a significant sorption affinity to EPS, which caused reduced toluene concentration in water phase in the EPS/water system. Groundwater containing toluene (18 mg/L) was pumped into the three-column system at a flow rate of 0.28 mL/min, while EPS was injected into the second column to form a biobarrier. A significant reduction of toluene concentration to 0.1 mg/L was observed immediately after EPS injection. This indicates that EPS could effectively contain toluene plume and prevent its further migration to farther downgradient zone. Approximately 99% of toluene was removed after 296 PVs of operation via sorption, natural attenuation, and EPS-enhanced biodegradation. Increase in total organic carbon and bacteria were also observed after EPS supplement. Supplement of EPS resulted in a growth of petroleum-hydrocarbon degrading bacteria, which enhanced the toluene biodegradation.

Utilization of bacterial volatilization can be problematic to remediate mercury (Hg)-contaminated soils because most of the Hg in soils is bound to soil particles. The objective of this study was to develop a two-stage system (chemical extraction followed by microbial reduction) for Hg-contaminated soil remediation. The tasks were to (1) select the extraction reagents for Hg extraction, (2) assess the effects of extraction reagents on the growth of Hg-reducing bacterial strains, and (3) evaluate the effectiveness of Ca2+ and Mg2+ addition on merA gene (Hg reductase) induction. Bacterial inhibition was observed with the addition of 0.1 M ethylenediaminetetraacetic acid or citric acid. Up to 65% of Hg was biotransformed (Hg concentration = 69 mg/kg) from the soils after a 24 h extraction using 0.5 M ammonium thiosulfate. Ca2+ and Mg2+ were selected because they have the same electric charge as Hg and the studied groundwater contained high concentrations of Ca2+ and Mg2+. Results showed that the addition of 200 mg/L Ca2+ or 650 mg/L Mg2+ could reach effective merA induction. In the two-stage experiment, 120 mg/kg Hg-contaminated soils were extracted with 2 rounds of extraction processes for 10 h using 0.5 M ammonium thiosulfate. Approximately 77% of Hg was extracted from the soils after the first-step extraction process. Up to 81% of Hg2+ was transformed from the washing solution via the biotransformation processes with Enterobacter cloacae addition and Ca2+ and Mg2+ supplementation. The two-stage remedial system has the potential to be developed into a practical technology to remediate Hg-contaminated sites.

The Love River and Ho-Jin River, two major urban rivers in Kaohsiung City, Taiwan, are moderately to heavily polluted because different types of improperly treated wastewaters are discharged into the rivers. In this study, sediment and river water samples were collected from two rivers to investigate the river water quality and accumulation of polycyclic aromatic hydrocarbons (PAHs) in sediments. The spatial distribution, composition, and source appointment of PAHs of the sediments were examined. The impacts of PAHs on ecological system were assessed using toxic equivalence quotient (TEQ) of potentially carcinogenic PAHs (TEQcarc) and sediment quality guidelines. The average PAHs concentrations ranged from 2161 ng/g in Love River sediment to 160 ng/g in Ho-Jin River sediment. This could be due to the fact that Love River Basin had much higher population density and pyrolytic activities. High-ring PAHs (4-6 rings) contributed to 59-90% of the total PAHs concentrations. Benzo(a)pyrene (BaP) had the highest toxic equivalence quotient (up to 188 ng TEQ/g). Moreover, the downstream sediments contained higher TEQ of total TPHs than midstream and upstream sediment samples. The PAHs were adsorbed onto the fine particles with high organic content. Results from diagnostic ratio analyses indicate that the PAHs in two urban river sediments might originate from oil/coal combustion, traffic-related emissions, and waste combustion (pyrogenic activities). Future pollution prevention and management should target the various industries, incinerators, and transportation emission in this region to reduce the PAHs pollution.

Phytoremediation is an environmentally friendly green rehabilitation technology that is often incorporated with an application to improve phytohormones required for the growth of agricultural plants with the expectation to improve the effectiveness of plant rehabilitation. This study adopts phytoremediation, a green remediation technology, for the sake of restoring soil fertility and ensuring environmental sustainability, and adds ethylenediaminedisuccinic acid (EDDS) and the plant growth regulator (GA3) to examine the overall efficiency of phytoremediation. The experiments using pots in this study finds that environmentally sustainable phytoremediation achieves the greatest efficacy regarding the remediation of soil polluted by copper, zinc and nickel. The best combination of operational factors is the addition of the EDDS and GA3. The environment where the EDDS is added shows a poorer performance in the remediation of the heavy metal lead. In addition, the PCR(Polymerase chain reaction)-DGGE analysis results of bacterial flora change show that the combination “heavy metal + EDDS + GA3” brings about the richest bacterial flora, indicating that the addition of EDDS and GA3 can stimulate microbial growth, thereby achieving richer bacterial flora.

The goal of this study was to establish a modeling tool for river water quality with a direct linkage to the water quality index (WQI5) calculation and the river water quality model, the Water Quality Analysis Simulation Program (WASP), for pollutant transport modeling. The integrated WASP and WQI5 tool was field-tested to assess pollutant loadings and their impacts on river environment. Suspended solid (SS) and electric conductivity (EC) correlation equations and the WQI5 calculation tool were included in the water quality model and direct WQI5 calculation. The SS concentration, which was influenced by river flows, had crucial effects on river water quality and WQI5 values. EC value was controlled by dissolution of soil minerals, which was affected by the watershed drainage area and surface runoff. The integrated system could establish a direct correlation for river water quality, river flow, and WQI5.

Intrinsic bioremediation (IB) is the major mechanism causing the containment of petroleum hydrocarbons in groundwater. The effectiveness and mechanisms of IB on the contaminant removal were evaluated in this study. Groundwater was analyzed for the efficiency of IB, dominant bacteria, bacterial diversity, and biodegradation rates. Concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl tert-butyl ether (MTBE) dropped from 6.5 and 0.14 mg/L in source area to 67 and 19 µg/L at the 145 m downgradient area. The biodegradation capacities for BTEX (50.9 mg/L) and MTBE (58.5 mg/L) were higher than the BTEX (6.5 mg/L) and MTBE (0.14 mg/L) concentrations within the plume. The bacterial diversities were assessed by 16S rRNA-based denatured gradient gel electrophoresis and nucleotide sequence analyses. More than 21 petroleum–hydrocarbon biodegrading bacterial species were detected in groundwater indicating that contaminants could be biodegraded by natural-occurring bacteria. The calculated MTBE and BTEX first-order decay rates were 5.7 × 10−4 and 1.3 × 10−3 per day, respectively. The high decay rates indicate that IB mechanisms played important roles in contaminant removal. The observed evidences of IB processes in highly contaminated areas included: (1) decreased electron acceptors, (2) production of degradation byproducts, (3) increased microbial populations and alkalinity, and (4) decreased electron donors and pH.

Petroleum hydrocarbons are commonly found pollutants in groundwater at industrial and gas station sites. Enhanced bioremediation is a cost-effective approach to cleanup petroleum hydrocarbon-polluted groundwater. The applicability of using sulfate-reducing biobarrier on the containment and control of petroleum-hydrocarbon plumes were assessed by batch and column studies. The innovative in situ biobarrier contained sulfate-releasing materials (SRMs) for a long-term sulfate release to enhance anaerobic petroleum hydrocarbons biodegradation with sulfate reduction mechanisms. SRMs were developed by blending rice husk powder (or starch) (used as permeability increment materials), magnesium sulfate (used as a source of sulfate), and polylactic acid (PLA) (used as a binder) together using a kneader. The mixed components were smelted to form pasty liquid at 190 °C, and it was transferred to a cylinder container to form SRMs. A column study was used to investigate the effectiveness of developed SRMs on the treatment of a methyl tert-butyl ether (MTBE) and toluene contaminated groundwater. The optimal sulfate release rate was achieved when the mass ratio of sulfate/starch/PLA was 0.5/0.5/2 [sulfate release rate (mg.d−1.g−1) = −0.009 × release period (d) + 3.4 (mg). Approximately 70% of MTBE and 92% of toluene could be remediated via sulfate reduction processes because the released sulfate from SRMs were served as electron acceptors, which promoted the growth of sulfate reducers. The next generation sequencing data suggest that bacterial strains with sulfate reduction and petroleum hydrocarbon biodegradation functions were detected after SRM supplement. Evidences of sulfate reduction of toluene and MTBE included (1) increased concentrations of sulfate and sulfide, (2) decreased concentrations of toluene and MTBE, (3) production of tert-butyl alcohol (degradation byproduct of MTBE), and (4) increased sulfate-reducing and petroleum-hydrocarbon bacteria. The biobarrier system containing the SRMs can be developed into a pragmatic technology for in situ remediation of petroleum-hydrocarbon plumes.

A two-stage system for octachlorinated dibenzo-p-dioxin (OCDD)-contaminated soil remediation was developed. Soil washing using emulsified oil (EO) was applied in the first stage for OCDD extraction followed by the second stage of bioremediation using P. mendocina NSYSU for remaining OCDD biodegradation. The major tasks included (1) determination of optimal soil washing conditions for OCDD extraction by EO, (2) evaluation of feasibility of OCDD biodegradation by P. mendocina NSYSU under aerobic cometabolic conditions using EO as the primary substrate, and (3) assessment of the effectiveness of OCDD removal using the two-stage system. During the soil washing stage, EO with two different oil-to-water ratios (1:50 and 1:200) and pore volumes were tested with initial soil OCDD concentration of 21,000 µg/kg. Results indicate that EO could effectively improve the solubility and desorption of OCDD in soils. Up to 74% of OCDD removal could be obtained after washing with 60 PVs of EO and dilution factor of 50. After the soil washing process, enriched P. mendocina NSYSU solution was added into the reactor to enhance the aerobic biodegradation of remaining OCDD in soils. P. mendocina NSYSU could use adsorbed EO globules as substrates and caused significant OCDD degradation via the aerobic cometabolic mechanism. Approximately 82% of the remaining OCDD could be removed after 50 days of operation, and P. mendocina NSYSU played important roles in OCDD biodegradation. Up to 87% of OCDD was removed through the EO washing and biodegradation process. The two-stage system is a potential technology to remediate dioxin-contaminated soils.

Tetrachloroethene (PCE) is one of the commonly found toxic chemicals in chlorinated-solvent contaminated groundwater. The objective of this study was to evaluate the effectiveness of enhanced bioremediation of PCE-contaminated groundwater with the supplement of nanoscale zero-valent iron (nZVI) contained long-lasting emulsified colloidal substrate (LECS) at a PCE-contaminated site. Approximately 50 L of LECS solution was pressured-injected into a remediation well (RW) and groundwater samples were collected from RW, two downgradient monitor wells (MWs), a control well, and a background well periodically for analyses. Injected LECS caused a rapid increase of the total organic carbon (TOC) concentration (up to 874 mg/L), and the increased TOC resulted in the transformation of the oxidation-reduction potential from aerobic to anaerobic stage. The pH was maintained in neutral due to the release of hydroxide ion after the oxidation of nZVI. Biodegradative reductive dechlorination of PCE was significantly enhanced, and PCE dropped from 0.5 to 0.01 mg/L after 130 days of operation. PCE dechlorination byproducts were also observed in downgradient MWs. Real-time polymerase chain reaction (PCR) results show that the populations of Dehalococcoides spp. (DHC) and Desulfitobacterium spp. (DSB) increased from 2 × 10 3 to 1.2 × 10 7 and from 1 × 10 3 to 7.4 × 10 6 cell/L after 60 days of operation in RW, respectively. DHC population was mainly composed of DHC in Victoria and Pinellas subgroups. Results demonstrate that supplement of LECS in PCE-polluted groundwater can effectively contain the PCE plume and accelerate the PCE dechlorinating rate under anaerobic conditions.

To enhance the reductive dechlorination of 1,2-dichloroethane (DCA) in groundwater, substrate injection may be required. However, substrate biodegradation causes groundwater acidification and sulfide production, which inhibits the bacteria responsible for DCA dechlorination and results in an odor problem. In the microcosm study, the effectiveness of the addition of ferrous sulfate (FS), desulfurization slag (DS), and nanoscale zero-valent iron (nZVI) on acidification and sulfide control was studied during reductive dechlorination of DCA, and the emulsified substrate (ES) was used as the substrate. Up to 94% of the sulfide was removed with FS and DS addition (0.25 wt%) (initial DCA concentration = 13.5 mg/L). FS and DS amendments resulted in the formation of a metal sulfide, which reduced the hydrogen sulfide concentration as well as the subsequent odor problem. Approximately 96% of the DCA was degraded under reductive dechlorination with nZVI or DS addition using ES as the substrate. In microcosms with nZVI or DS addition, the sulfide concentration was reduced to less than 15 μg/L. Acidification can be controlled via hydroxide ions production after nZVI oxidation and reaction of free CaO (released from DS) with water, which enhanced DCA dechlorination. The quantitative polymerase chain reaction results confirmed that the microcosms with nZVI added had the highest Dehalococcoides population (up to 2.5 × 10(8) gene copies/g soil) due to effective acidification control. The α-elimination mechanism was the main abiotic process, and reductive dechlorination dominated by Dehalococcides was the biotic mechanism that resulted in DCA removal. More than 22 bacterial species were detected, and dechlorinating bacteria existed in soils under alkaline and acidic conditions.

The objectives of this pilot-scale study were to evaluate the effectiveness of trichloroethylene (TCE)-contaminated groundwater in situ remediation by intrinsic and enhanced bioremediation mechanisms. Under enhanced bioremediation processes, leaked fuel oil served as the primary substrate to activate the reductive dechlorination of TCE. Real-time polymerase chain reaction (PCR) was performed to evaluate the variation in TCE-dechlorinating bacteria (Dehalococcoides spp.). Within the fuel oil plume, the natural attenuation of total petroleum hydrocarbon (TPH) and enhanced bioremediation of TCE was observed, and the evidence was as follows: (1) decreased TPH and TCE concentrations along the groundwater flow path; (2) depletion of the electron acceptor [dissolved oxygen (DO), nitrate, and sulfate)] concentrations; (3) production of dissolved ferrous iron, sulfide, methane, and CO2; (4) production of TCE degradation byproducts; (5) increased alkalinity and microbial populations; (6) decreased pH and oxidation–reduction potential and (7) increased Dehalococcoides. The results from PCR, denaturing gradient gel electrophoresis, and nucleotide sequence analysis revealed that 32 bacterial species that might be related to TPH and TCE degradation had been verified within the TPH plume. The results indicate that natural attenuation mechanisms could effectively contain the TPH plume and cause TPH removal. Although dechlorination of TCE was observed after the fuel oil spill, the dechlorination rate was not sufficient for TCE plume control due to the limited biodegradable primary substrates released from the fuel oil. An alternative primary substrate supplement was necessary to increase the substrate concentrations to obtain a higher TCE dechlorination rate. The results indicate that Dehalococcoides spp., which was one of the dominant bacteria in the groundwater at the site, can be used as a biomarker to evaluate the efficacy of TCE dechlorination.

In this study, the modified γ-poly-glutamic acid (m-PGA) was developed for continuous substrate supplement and pH control to bioremediate trichloroethene (TCE)-contaminated groundwater. The m-PGA was prepared by mixing γ-PGA and a stabilizer (a more sticky carbon source) [carboxymethyl cellulose, gelatin, starch, or emulsified colloidal substrate (ES)] together, which was used as a source of slow-release carbon substrate. Microcosm experiments were conducted to determine the feasibility of m-PGA for a long-term substrate releasing to enhance anaerobic TCE dechlorination. The globule diameter, viscosity, stability, adsorption and retardation effect, and zeta potential of γ-PGA mixtures were assessed. The mixture of γ-PGA and ES (volume ratio of 1:0.25) (m-PGA) had the most stable, biodegradable, long-lasting, TCE adsorption, and dispersive characteristics with a negative zeta potential (−132 mv) and uniform droplet. Up to 99% of TCE removal was achieved in microcosms with m-PGA supplement. M-PGA addition could result in an immediate TCE removal via physical adsorption and subsequent dechlorination mechanisms. In the pilot-scale study, 20 L of m-PGA was injected into an injection well to enhance TCE dechlorination. After 55 days of m-PGA injection, about 96% of TCE could be dechlorinated without byproduct accumulation. Increased ammonia concentrations were observed in microcosm and pilot-scale studies via the hydrolysis of amine from m-PGA, which could neutralize acidified groundwater. Results from the next generation sequencing indicate that strains with functions of reductive dechlorination, carbon biodegradation, B12 synthesis, and hydrogen production were detected after m-PGA injection.

The effectiveness of using gamma poly-glutamic acid (γ-PGA) as the primary carbon and nitrogen sources to bioremediate trichloroethene (TCE)-contaminated groundwater was studied in this pilot-scale study. γ-PGA (40 L) solution was injected into the aquifer via the injection well (IW) for substrate supplement. Groundwater samples were collected from monitor wells and IW and analyzed for TCE and its byproducts, geochemical indicators, dechlorinating bacteria, and microbial diversity periodically. Injected γ-PGA resulted in an increase in total organic carbon (TOC) (up to 9820 mg/L in IW), and the TOC biodegradation caused the formation of anaerobic conditions. Increased ammonia concentration (because of amine release from γ-PGA) resulted in the neutral condition in groundwater, which benefited the growth of Dehalococcoides. The negative zeta potential and micro-scale diameter of γ-PGA allowed its globule to distribute evenly within soil pores. Up to 93% of TCE removal was observed (TCE dropped from 0.14 to 0.01 mg/L) after 59 days of γ-PGA injection, and TCE dechlorination byproducts were also biodegraded subsequently. Next generation sequence (NGS) analyses were applied to determine the dominant bacterial communities. γ-PGA supplement developed reductive dechlorinating conditions and caused variations in microbial diversity and dominant bacterial species. The dominant four groups of bacterial communities including dechlorinating bacteria, vinyl chloride degrading bacteria, hydrogen producing bacteria, and carbon biodegrading bacteria.

Perchlorate (ClO4−) is a highly oxidizing and water soluble chemical. In this study, a hybrid electrodialysis reversal and reverse osmosis process (EDR + RO) was designed to remediate and reclaim perchlorate-contaminated groundwater. The EDR tests were conducted using a laboratory-scale equipment with seven pairs of ion-selective membranes and a total membrane area of 352 cm2. Up to 95% of perchlorate could be removed in 2.5 h of operation with a voltage of 40 V. The effluent perchlorate concentration dropped to below 0.02 mg/L after the two-stage treatment (EDR followed by RO). Bimetallic nanoparticles Fe0/Al0 (nZVI-coated nZV aluminum) were applied to reduce perchlorate via chemical reduction. Approximately 30.8% of perchlorate could be removed by Fe0/Al0 reduction. Strong acidic functional group (SO3H) on the EDR cation exchange membrane was electrolyzed, which resulted in the accumulation of sulfur content on the ion-exchange membrane. Results from the 3-D excitation-emission fluorescence matrix (EEFM) analyses show that the most proportion of organic matters in groundwater were type II and type IV that are aromatic protein (AP) and soluble microbial by-product-like (SMP) chemicals. The system could electrolyze perchlorate and generate hydrochloric acid (HCl), which could inhibit the hydroxide production and minimize the fouling on the RO membrane.

The groundwater at an abandoned industrial site located in Southern Taiwan has been polluted by mercury (Hg), which endangers human health and ecosystems. The objectives of this study were ...

This study determined the influence of emerging industries development on molybdenum (Mo) groundwater contamination. A total of 537 groundwater samples were collected for Mo determination, including 295 samples from potentially contaminated areas of 3 industrial parks in Taiwan and 242 samples from non-potentially contaminated areas during 2008-2014. Most of the high Mo samples are located downstream from a thin film transistor-liquid crystal display (TFT-LCD) panel factory. Mean groundwater Mo concentrations from potentially contaminated areas (0.0058 mg/L) were significantly higher (p

The novelty of this study is to rapidly reduce hazardous lead leachates from solid waste using microwave digestion treatment, which is an energy-saving and low greenhouse gas emission technology. The article presents the reduction of toxic characteristic leaching procedure-extractable lead concentration in the municipal solid waste incineration fly ash by the microwave digestion treatment in HNO3/H2SO4 combination, and focuses on the effects of treatment time and temperature. The results obtained from this study indicated a significant reduction efficiency of toxic characteristic leaching procedure-extractable lead concentration and showed sufficient reduction in leaching levels to render the treated fly ash safe in lead compound leaching characteristics. The reduction efficiency of toxic characteristic leaching procedure-extractable lead concentration can reach 98% in 15 minutes of treatment time. This is equivalent to the original toxic characteristic leaching procedure-extractable lead concentration of 46.2 mg L−1 in raw fly ash being reduced down to less than 1.0 mg L−1. Based on the experimental data obtained in this study, a useful correlation between reduction efficiency and treatment conditions is proposed. For engineering applications, the necessary minimum treatment time is solved using a graphic illustration method, by which the minimum treatment time (tmin) is obtained if the desired reduction efficiency (η) and treatment temperature (T) are known. The effects of treatment time and temperature are discussed. Some problems caused by the microwave digestion treatment method are also delineated in this article.

Summary The Ju-Liao Stream is one of the most contaminated streams in Kaohsiung City, Taiwan. A constructed wetland (CW) system was built in 2010 for polluted stream water purification and ecosystem improvement. An aerated gravel-packed contact bed (CB) system was built in 2011 and part of the stream water was treated by the CB before discharging to the CW. The influent rates of the CW and CB were approximately 5570 and 900 m3/d, respectively. The CW contained one free-water surface basin planted with emergent wetland plants, followed by the plug-flow channel-shaped free-water surface basin planted with emergent and floating wetland plants. The mean measured hydraulic loading rate (HLR), hydraulic retention time (HRT), water depth, and total volume of wetland system were 1.7 m/d, 0.68 d, 0.7 m, and 4400 m3, respectively. The aeration zone of the CB system had a dimension of 24 m (L) × 8 m (W) × 3 m (H), which was filled with gravels (average diameter = 5 cm) with a porosity of 0.4, and the aeration rate was 7.8 m3/min. Results show that the CB system was able to remove 69% of suspended solid (SS), 86% of biochemical oxygen demand (BOD), and 58% of total nitrogen (TN). Up to 82% of BOD and 27% of TN could be removed in the CW system. Removal efficiency of SS was affected by the growth of chlorophyll a in the CW system due to the growth of algae. The observed first-order decay rates (k) for BOD and TN in CB were 9.3 and 4.2 1/d, and the k values for BOD and TN removal in CW were 2.5 and 0.45 1/d. The high pollutant removal efficiencies in the CB system indicate that the system could enhance the organic and nutrient removal through the biological processes effectively. Sediments contained high total organic matter (1.9–4.5%), sediment total nitrogen (6.4–10.1 g/kg), sediment total phosphorus (0.59–0.94 g/kg), and sediment oxygen demand (0.9–4.1 g O2/m2 d). The organic and nutrient-abundant sediments resulted in reduced conditions (oxidation–reduction potential measurements

A long-lasting emulsified colloidal substrate (LECS) was developed for continuous carbon and nanoscale zero-valent iron (nZVI) release to remediate trichloroethylene (TCE)-contaminated groundwater under reductive dechlorinating conditions. The developed LECS contained nZVI, vegetable oil, surfactants (Simple Green™ and lecithin), molasses, lactate, and minerals. An emulsification study was performed to evaluate the globule droplet size and stability of LECS. The results show that a stable oil-in-water emulsion with uniformly small droplets (0.7 μm) was produced, which could continuously release the primary substrates. The emulsified solution could serve as the dispensing agent, and nZVI particles (with diameter 100–200 nm) were distributed in the emulsion evenly without aggregation. Microcosm results showed that the LECS caused a rapid increase in the total organic carbon concentration (up to 488 mg/L), and reductive dechlorination of TCE was significantly enhanced. Up to 99% of TCE (with initial concentration of 7.4 mg/L) was removed after 130 days of operation. Acidification was prevented by the production of hydroxide ion by the oxidation of nZVI. The formation of iron sulfide reduced the odor from produced hydrogen sulfide. Microbial analyses reveal that dechlorinating bacteria existed in soils, which might contribute to TCE dechlorination.

The 2016 International Conference on Civil, Architecture and Environmental Engineering (ICCAE 2016), November 4-6, 2016, Taipei, Taiwan, is organized by China University of Technology and Taiwan Society of Construction Engineers, aimed to bring together professors, researchers, scholars and industrial pioneers from all over the world. ICCAE 2016 is the premier forum for the presentation and exchange of experience, progress and research results in the field of theoretical and industrial experience. The conference consists of contributions promoting the exchange of ideas between researchers and educators all over the world.