Thermally enhanced in situ bioremediation of groundwater contaminated with chlorinated solvents - A field test.

In situ bioremediation (ISB) using reductive dechlorination is a widely accepted but relatively slow approach compared to other technologies for the treatment of groundwater contaminated by chlorinated ethenes (CVOCs). Due to the known positive kinetic effect on microbial metabolism, thermal enhancement may be a viable means of accelerating ISB. We tested thermally enhanced ISB in aquifers situated in sandy saprolite and underlying fractured granite. The system comprised pumping, heating and subsequent injection of contaminated groundwater aiming at an aquifer temperature of 20-30°C. A fermentable substrate (whey) was injected in separate batches. The test was monitored using hydrochemical and molecular tools (qPCR and NGS). The addition of the substrate and increase in temperature resulted in a rapid increase in the abundance of reductive dechlorinators (e.g., Dehalococcoides mccartyi, Dehalobacter sp. and functional genes vcrA and bvcA) and a strong increase in CVOC degradation. On day 34, the CVOC concentrations decreased by 87% to 96% in groundwater from the wells most affected by the heating and substrate. On day 103, the CVOC concentrations were below the LOQ resulting in degradation half-lives of 5 to 6days. Neither an increase in biomarkers nor a distinct decrease in the CVOC concentrations was observed in a deep well affected by the heating but not by the substrate. NGS analysis detected Chloroflexi dechlorinating genera (Dehalogenimonas and GIF9 and MSBL5 clades) and other genera capable of anaerobic metabolic degradation of CVOCs. Of these, bacteria of the genera Acetobacterium, Desulfomonile, Geobacter, Sulfurospirillum, Methanosarcina and Methanobacterium were stimulated by the substrate and heating. In contrast, groundwater from the deep well (affected by heating only) hosted representatives of aerobic metabolic and aerobic cometabolic CVOC degraders. The test results document that heating of the treated aquifer significantly accelerated the treatment process but only in the case of an abundant substrate.

A new strategy to simultaneous microextraction of acidic and basic compounds.

The simultaneous extraction of acidic and basic pollutants from water samples is an interesting and debatable work in sample preparation techniques. A novel and efficient method named ion pair based surfactant assisted microextraction (IP-SAME) was applied for extraction and preconcentration of five selected acidic and basic aromatic species as model compounds in water samples, followed by high performance liquid chromatography-ultraviolet detection. A mixture including 1 mL of ultra-pure water (containing ionic surfactant as emulsifier agent) and 60 µL 1-octanol (as extraction solvent) was rapidly injected using a syringe into a 10.0 mL water sample which formed an emulsified solution. IP-SAME mechanism can be interpreted by two types of molecular mass transfer into the organic solvent (partitioning and ion pairing for non-ionized and ionized compounds, respectively) during emulsification process. The effective parameters on the extraction efficiency such as the extraction solvent type and its volume, type of the surfactant and its concentration, sample pH and ionic strength of the sample were optimized. Under the optimum conditions (60 µL of 1-octanol; 1.5 mmol L(-1) cethyltrimethyl ammonium bromide (CTAB) as emulsifier agent and sample pH 10.0), the preconcentration factors (PFs), detection limits and linear dynamic ranges (LDRs) were obtained in the range of 87-348, 0.07-0.6 µg L(-1) and 0.1-200 µg L(-1) respectively. All of natural water samples were successfully analyzed by the proposed method.

A comparative study among different photochemical oxidation processes to enhance the biodegradability of paper mill wastewater.

Advanced oxidation processes including UV, UV/H(2)O(2), Fenton reaction (Fe(II)/H(2)O(2)) and photo-Fenton process (Fe(II)/H(2)O(2)/UV) for the treatment of paper mill wastewater will be investigated. A comparison among these techniques is undertaken with respect to the decrease of chemical oxygen demand (COD) and total suspended solids (TSS) and the evolution of chloride ions. Optimum operating conditions for each process under study revealed the effect of the initial amounts of Fe(II) and hydrogen peroxide. Of the tested processes, photo-Fenton process was found to be the fastest one with respect to COD and TSS reduction of the wastewater within 45 min reaction time under low amounts of Fe(II) and hydrogen peroxide of 0.5 and 1.5mg/L, respectively, and amounted to 79.6% and 96.6% COD and TSS removal. The initial biodegradability of the organic matter present in the effluent, estimated as the BOD(5)/COD, was low 0.21. When the effluent was submitted to the different types of AOPs used in this study, the biodegradability increases significantly. Within 45 min of reaction time, the photo-Fenton process appears as the most efficient process in the enhancement of the biodegradability of the organic matter in the effluent and the BOD(5)/COD ratio increased from 0.21 to 0.7.

Catalytic ozonation-biological coupled processes for the treatment of industrial wastewater containing refractory chlorinated nitroaromatic compounds.

A treatability study of industrial wastewater containing chlorinated nitroaromatic compounds (CNACs) by a catalytic ozonation process (COP) with a modified Mn/Co ceramic catalyst and an aerobic sequencing batch reactor (SBR) was investigated. A preliminary attempt to treat the diluted wastewater with a single SBR resulted in ineffective removal of the color, ammonia, total organic carbon (TOC) and chemical oxygen demand (COD). Next, COP was applied as a pretreatment in order to obtain a bio-compatible wastewater for SBR treatment in a second step. The effectiveness of the COP pretreatment was assessed by evaluating wastewater biodegradability enhancement (the ratio of biology oxygen demand after 5 d (BOD(5)) to COD), as well as monitoring the evolution of TOC, carbon oxidation state (COS), average oxidation state (AOS), color, and major pollutant concentrations with reaction time. In the COP, the catalyst preserved its catalytic properties even after 70 reuse cycles, exhibiting good durability and stability. The performance of SBR to treat COP effluent was also examined. At an organic loading rate of 2.0 kg COD/(m(3)xd), with hydraulic retention time (HRT)=10 h and temperature (30+/-2) degrees C, the average removal efficiencies of NH(3)-N, COD, BOD(5), TOC, and color in a coupled COP/SBR process were about 80%, 95.8%, 93.8%, 97.6% and 99.3%, respectively, with average effluent concentrations of 10 mg/L, 128 mg/L, 27.5 mg/L, 25.0 mg/L, and 20 multiples, respectively, which were all consistent with the national standards for secondary discharge of industrial wastewater into a public sewerage system (GB 8978-1996). The results indicated that the coupling of COP with a biological process was proved to be a technically and economically effective method for treating industrial wastewater containing recalcitrant CNACs.

Source-zone characterization of a chlorinated-solvent contaminated Superfund site in Tucson, AZ.

An extensive site-characterization project was conducted at a large chlorinated-solvent contaminated Superfund site in Tucson, AZ. The project consisted of several components, including traditional site-characterization activities, tracer tests, laboratory experiments conducted with core material collected from the site, and mathematical modeling. The primary focus of the work presented herein is the analysis of induced-gradient contaminant elution tests conducted in a source zone at the site, investigation of the potential occurrence of immiscible liquid in the saturated zone, characterization of the relationship between mass flux reduction and mass removal, and evaluation of the impact of source-zone management on site remediation. The results of the present study, along with those of prior work, indicate that immiscible liquid is likely present in the saturated zone at the site source zones. Extensive tailing and rebound was observed for the contaminant-elution tests, indicating nonideal transport and mass-transfer behavior. The elution data were analyzed with a source-zone-scale mathematical model, and the results indicated that nonideal immiscible-liquid dissolution was the primary cause of the observed behavior. The time-continuous relationship between mass flux reduction and mass removal associated with the plume-scale pump-and-treat operation exhibited an initial large drop in mass flux with minimal mass removed, followed by a period of minimal mass flux reduction and a second period of large reduction. This behavior reflects the impact of both source-zone and aqueous-plume mass removal dynamics. Ultimately, a greater than 90% reduction in mass flux was achieved for a mass removal of approximately 50%. The influence of source-zone management on site remediation was evaluated by conducting two predictive simulations, one for which the source zones were controlled and one for which they were not. A plume-scale model was used to simulate the composite contaminant concentrations associated with groundwater extracted with the pump-and-treat system, which were compared to measured data. The information generated from this study was used to enhance the site conceptual model, help optimize operation of the pump-and-treat system, and evaluate the utility of source-zone remediation.

Enhanced coagulation of disinfection by-products precursors in Istanbul water supply.

During the chlorination of drinking water, chlorine reacts with natural organic matter (NOM) to produce disinfection by-products (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), which are believed to be harmful to human health. Enhanced coagulation is a DBPs precursor treatment technique with the objective of removing total organic carbon (TOC) to control DBPs formation in water. Scientifically, the removal of organic matter by coagulation depends on the TOC concentration, the chemical nature of the NOM, coagulant type, coagulant dosage, and coagulation pH. Currently, water treatment plants are practicing enhanced coagulation to further increase DBPs precursor removal. The focus of this study was to investigate enhanced coagulation of Terkos Lake Water (TLW) of Istanbul City. In this study, jar test experiments were conducted on TLW source to determine the effectiveness of enhanced coagulation for removal of DBPs surrogate parameters of total organic carbon (TOC), ultraviolet absorbance (UV(254)), and THM formation potential (THMFP). Jar tests results indicated that enhanced coagulation can increase the removal of DBPs precursors. To evaluate the coagulation performances, two different coagulants, aluminum and iron salts were used at different pH values to determine optimal coagulation conditions for surrogate parameters removal quantity.

Use of nanosized catalysts for transformation of chloro-organic pollutants.

A new method to transform anthropogenic, chloro-organic compounds (COC) by use of nanosized molecular catalysts immobilized in sol-gel matrixes is presented. COC represent a serious threat to soil and groundwater quality. Metalloporphyrinogens are nanometer sized molecules that are known to catalyze degradation of COC by reduction reactions. In the current study, metalloporphyrinogens were immobilized in sol--gel matrixes with pore throat diameters of nanometers. The catalytic activity of the matrix arrays for anaerobic reduction of tetrachloroethylene (PCE), trichloroethylene (TCE), and carbon tetrachloride (CT) was examined. Experiments were performed under conditions pertinent to groundwater systems, with titanium citrate and zero-valent iron as electron donors. All chloroorganic compounds were reduced in the presence of several sol-gel-metalloporphyrinogen hybrids (heterogeneous catalysts). For example, cobalt-5,10,15,20-(4-hydroxyphenyl)-21H,23H-porphine (TP(OH)P-Co) and cyanocobalamin (vitamin B12) reduced CT concentrations to less than 5% of their initial values in a matter of hours. Cyanocobalamin was found to reduce PCE to trace amounts in less than 48 h and TCE to less than 25% of its initial concentration in 144 h. The reactions were compared to their homogeneous (without sol-gel matrix) analogues. The reduction activity of COC for the homogeneous and heterogeneous systems ranged between similar reactivity in some cases to lower reduction rates for the heterogeneous system. These lower rates are, however, compensated by the ability to encapsulate and reuse the catalyst. Experiments with cyanocobalamin showed that the catalyst could be reused over at least 12 successive cycles of 24 h each.

Mass removal of chlorinated ethenes from rough-walled fractures using permanganate.

In situ chemical oxidation (ISCO) employing permanganate is an emerging technology that has been successful at enhancing mass removal from DNAPL source zones in unconsolidated media at the pilot-scale. The focus of this study was to evaluate the applicability of flushing a permanganate solution across two single vertical fractures in a laboratory environment to remove free phase DNAPL. The fracture experiments were designed to represent a portion of a larger fractured aquifer system impacted by a near-surface DNAPL spill over a shallow fractured rock aquifer. Each fracture was characterized by hydraulic and tracer tests, and the aperture field for one of the fractures was mapped using a co-ordinate measurement machine. Following DNAPL emplacement, a series of water and permanganate flushes were performed. To support observations from the fracture experiments, a set of batch experiments was conducted. The data from both fracture experiments showed that the post-oxidation effluent concentration was not impacted by the oxidant flush; however, changes in the aperture distribution, flow field, and flow rate were observed. These changes resulted in a significant decrease to the mass loading from the fractures, and were attributed to the build-up of oxidation by-products (manganese oxides and carbon dioxide) within the fracture which was corroborated by the batch experiment data and visual examination of the walls of one fracture. These results provide insight into the potential impact that a permanganate solution and oxidation by-products can have on the aperture distribution within a fracture and on DNAPL mass transfer rates. A permanganate flush or injection completed within a fractured rock aquifer may lead to the development of an insoluble product adjacent to the DNAPL which results in the reduction or complete elimination of advective regions near the DNAPL and reduces mass transfer rates. This outcome would have significant implications on the plume generating potential of the remaining DNAPL.

Cynthichlorine: a bioactive alkaloid from the tunicate Cynthia savignyi.

From ether extracts of the tunicate Cynthia savignyi, collected in Morocco, a new alkaloid-cynthichlorine-has been isolated. The structure of cynthichlorine has been characterized by extensive 2D-NMR data. Cynthichlorine possesses antifungal activity against two tomato pathogenic fungi: Botrytis cinerea and Verticillium albo atrum and antibacterial activity against Agrobacterium radiobacter, Escherichia coli and Pseudomonas aeruginosa and cytotoxicity against Artemia salina larvae.

Combined physical-chemical and biological treatment of poorly biodegradable industrial effluents.

Effluents from small and medium sized chemical plants may contain significant amounts of poorly biodegradable aromatic compounds, which could negatively affect water quality and public health. This is a key environmental issue, particularly in areas where effluents are discharged into drinking water sources. Unfortunately, conventional biological treatment may not be able to meet discharge standards, and combined systems should be implemented. In this context, this paper presents experimental results on the application of a combined sequential ozonation-activated carbon-biological system to treat effluents containing chlorinated aromatic contaminants from chlorine based pulp bleaching. The experimental system consisted of an ozone bubble column reactor (0.3 dm3), an activated carbon fixed bed reactor (0.2 dm3), and an aerobic bioreactor (20 dm3). Ozone was produced from pure O2 using a generator rated at 2 mmol O3 h(-1). The bleaching effluent was pretreated and fed into the aerated sequencing batch bioreactor containing preconditioned biological sludge (3-4 g VSS dm(-3)), and cultured for 24 h. Samples of raw and treated effluents were assayed for biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total organic carbon (TOC), total phenols, and adsorbable organic halogens (AOX), using standard techniques. The presence of potential genotoxic activity in untreated and treated samples was assessed using the Ames tests. Results show that biological treatment of raw samples could not remove mutagenic activity on its own. On the other hand, ozonation followed by activated carbon treatment and biological treatment successfully removed genotoxicity in all cases. Reductions in BOD, COD, TOC, AOX, and phenols by biological treatment increased when samples were pretreated with ozone/activated carbon.

Isolation of chlorinated fatty acid methyl esters derived from cell-culture medium and from fish lipids by using an aminopropyl solid-phase extraction column.

An aminopropyl-based solid-phase extraction technique was used for isolation of chlorinated fatty acids in lipids. A range of different chlorinated fatty acids was eluted in a small volume of solvent (4 ml) and the recoveries of the different species and isomers were quantitative. Only 1% of the vastly dominating unchlorinated fatty acid methyl esters were recovered in the fractions containing the chlorinated fatty acid methyl esters. This method makes it possible to isolate and detect > or = 1 microg of a chlorinated fatty acid methyl ester in 1 g of lipid.

Use of lysis and recycle to control excess sludge production in activated sludge treatment: bench scale study and effect of chlorinated organic compounds.

The most widely used treatment system in the pulp and paper industry--the activated sludge--produces high quantities of sludge which need proper disposal. In this paper a modified activated sludge process is presented. A synthetic wastewater, prepared to simulate the effluent of bleached and unbleached pulp and paper plant wastewater, was submitted to treatment in a bench scale aerobic reactor. The excess sludge was lysed in a mechanical mill--Kaddy mill--and totally recycled to the aeration tank. In the first phase the synthetic wastewater, without the chlorinated compounds, was fed to the reactor. In the second phase increasing dosages of the chlorinated compounds were used. Total recycle of excess sludge after disintegration did not produce adverse effects. During the first phase average COD removal efficiency was 65% for the control unit, which operated in a conventional way, and 63% for the treatment unit, which operated with total recycle. During the second phase the COD removal efficiency increased to 77% in the control unit and 75% in the treatment unit. Chlorinated organics removal was 85% in the treatment unit and 86% for the control unit. These differences are not significant.

Formation of disinfection by-products in chlorinated swimming pool water.

The formation of five volatile disinfection by-products (DBPs: chloroform, bromodichloromethane, chloral hydrate, dichloroacetonitrile, and 1,1,1-trichloropropanone) by the chlorination of the materials of human origin (MHOs: hair, lotion, saliva, skin, and urine) in a swimming pool model system was examined. Chlorination reactions took place with a sufficient supply of chlorine residuals (0.84 mg Cl2/l < total chlorine < 6.0 mg Cl2/l) in 300 ml glass bottles containing either ground water or surface water as a reaction medium at 30 degrees C and pH 7.0, for either 24 or 72 h. A longer reaction period of 72 h or a higher content of organic materials led to the increased formation of DBPs. Of the DBPs formed by the reaction, chloroform was a major compound found in both ground and surface waters. The formation of chloroform and bromodichloromethane per unit total organic carbon (TOC) concentration was suppressed when all types of MHOs were added to the surface water that already contained DBP precursors such as humic substances. However, the formation of dichloroacetonitrile was promoted, probably due to the increased degradation reactions of nitrogen-containing compounds such as urea and proteins of human origin. In conclusion, the materials of swimmers' origin including hair, lotion, saliva, skin, and urine add to the levels of DBPs in swimming pool water, and any mitigation measures such as periodic change of water are needed to protect swimmers from elevated exposures to these compounds.

Removal of chlorine dioxide disinfection by-products by ferrous salts.

Chlorine dioxide when used as an effective disinfectant forms undesirable disinfection by-products, i.e. chlorite and chlorate ions. The aim of this research was to study the removal of these ions by ferrous ions in the presence or absence of oxygen. The efficiency of Fe+2 for ClO2- and ClO3- removal was followed by a determination of their initial and final concentrations, pH and delta Fe+2 consumed/delta ClO2- removed ratios. The optimal weight ratio of delta Fe+2 consumed/delta ClO2- removed for complete ClO2 removal was found to be close to the theoretical calculated value of 3.31. It was proved that ferrous salts can reduce chlorite ions to harmless Cl- ions. This method can be recommended as a part of ClO2 disinfection to ensure safe drinking water, with no harm to water consumers and to the environment.