Wetland technology for the treatment of HCH-contaminated water - Case study at Hajek site

Hexachlorocyclohexanes (HCH) isomers and their transformation products, such as chlorobenzenes (ClB), generate severe and persistent environmental problems at many sites worldwide. The Wetland technology employing oxidation-reduction, biosorption, biodegradation and phytoremediation methods can sufficiently treat HCH-contaminated water. The treatment process is inherently natural and requires no supplementary chemicals or energy. The prototype with a capacity of 3 L/s was installed at Hajek quarry spoil heap (CZ), to optimize the technology on a full scale. The system is fed by drainage water with an average concentration of HCH 129 μg/L, ClB 640 μg/L and chlorophenols (ClPh) of 16 μg/L. The system was tested in two years of operation, regularly monitored for HCH, ClB and ClPh, and maintained to improve its efficiency. The assessment was not only for environmental effects but also for socio and economic indicators. During the operation, the removal efficiency of HCH ranged from 53.5 % to 96.9 % (83.9 % on average) depending on the flow rate. Removal efficiency was not uniform for individual HCH isomers but exhibited the trend: α = γ = δ > β = ε. The improved water quality was reflected in a biodiversity increase expressed by a number of phytobenthos (diatoms) species, a common biomarker of aquatic environment quality. The Wetland outranked the conventional WWTP in 10 out of the 15 general categories, and it is the most relevant scenario from the socio, environmental, and economic aspects.

The effects of hydraulic/pneumatic fracturing-enhanced remediation (FRAC-IN) at a site contaminated by chlorinated ethenes: A case study

A low-permeability locality with heterogeneous geology contaminated primarily by tetrachloroethene (PCE) present partially in the free phase in the unsaturated zone was treated on a pilot scale via direct push pneumatic fracturing combined with the hydraulic delivery of a remediation suspension consisting of milled iron, sulphidated nanosized zerovalent iron and sand in guar gum solution. Afterwards, a whey solution was injected into the fractures as a carbon source for bacteria. The unsaturated and saturated zones were treated. Long-term monitoring of the groundwater revealed that the abiotic reduction of PCE and trichloroethene was the dominant remediation processes for several months after the injections. A complex microbial consortium was developed that was capable of effective, long-term chlorinated ethenes (ClE) dechlorination. The consortium consisted mainly of Dehalococcoides but also of other anaerobic bacterial strains capable of partial dechlorination of ClE, including the sulphate-reducing bacteria; Geobacter and Desulfitobacterium. The average chlorine number in the groundwater decreased from 3.65 to 1.38 within 2.5 years after the injections, while the average ClE concentration increased from 13.5 to 31.5 mgL^-1 because of the substantial acceleration of the ClE mass-transfer to the groundwater caused by the treatment. The remediation processes remained fully active for 2.5 years.

Engineered in situ biogeochemical transformation as a secondary treatment following ISCO - A field test

ISCO using activated sodium persulphate is a widely used technology for treating chlorinated solvent source zones. In sensitive areas, however, high groundwater sulphate concentrations following treatment may be a drawback. In situ biogeochemical transformation, a technology that degrades contaminants via reduced iron minerals formed by microbial activity, offers a potential solution for such sites, the bioreduction of sulphate and production of iron sulphides that abiotically degrade chlorinated ethenes acting as a secondary technology following ISCO. This study assesses this approach in the field using hydrochemical and molecular tools, solid phase analysis and geochemical modelling. Following a neutralisation and bioaugmentation, favourable conditions for iron- and sulphate-reducers were created, resulting in a remarkable increase in their relative abundance. The abundance of dechlorinating bacteria (Dehalococcoides mccartyi, Dehalobacter sp. and Desulfitobacterium spp.) remained low throughout this process. The activity of iron- and sulphate-reducers was further stimulated through application of magnetite plus starch and microiron plus starch, resulting in an increase in ferrous iron concentration (from <LOQ to 337 mg/l), a decrease in sulphate concentration by 74-95% and production of hydrogen sulphide (from <LOQ to 25.9 mg/l). At the same time, a gradual revival of dechlorinators and an increase in ethene concentration was also observed. Tetrachloroethene and trichloroethene concentrations decreased by 98.5-99.98% and 75.4-98.5%, respectively. A decline in chlorine number indicated that biological dechlorination contributed to CVOC removal. This study brings new insights into biogeochemical processes that, when properly engineered, could provide a viable solution for secondary treatment.

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.

Stratification of chlorinated ethenes natural attenuation in an alluvial aquifer assessed by hydrochemical and biomolecular tools

Biomolecular and hydrochemical tools were used to evaluate natural attenuation of chlorinated ethenes in a Quaternary alluvial aquifer located close to a historical source of large-scale tetrachloroethylene (PCE) contamination. Distinct stratification of redox zones was observed, despite the aquifer's small thickness (2.8 m). The uppermost zone of the target aquifer was characterised by oxygen- and nitrate-reducing conditions, with mixed iron- to sulphate-reducing conditions dominant in the lower zone, along with indications of methanogenesis. Natural attenuation of PCE was strongly influenced by redox heterogeneity, while higher levels of PCE degradation coincided with iron- to sulphate reducing conditions. Next generation sequencing of the middle and/or lower zones identified anaerobic bacteria (Firmicutes, Chloroflexi, Actinobacteria and Bacteroidetes) associated with reductive dechlorination. The relative abundance of dechlorinators (Dehalococcoides mccartyi, Dehalobacter sp.) identified by real-time PCR in soil from the lower levels supports the hypothesis that there is a significant potential for reductive dechlorination of PCE. Local conditions were insufficiently reducing for rapid complete dechlorination of PCE to harmless ethene. For reliable assessment of natural attenuation, or when designing monitoring or remedial systems, vertical stratification of key biological and hydrochemical markers should be analysed as standard, even in shallow aquifers.

Development of water-soluble 3,5-dinitrophenyl tetrazole and oxadiazole antitubercular agents

In this work, four series of tertiary amine-containing derivatives of 3,5-dinitrophenyl tetrazole and oxadiazole antitubercular agents were prepared, and their in vitro antimycobacterial effects were evaluated. We found that the studied compounds showed lipophilicity-dependent antimycobacterial activity. The N-benzylpiperazine derivatives, which had the highest lipophilicity among all of the series, showed the highest in vitro antimycobacterial activities against Mycobacterium tuberculosis CNCTC My 331/88 (H₃₇Rv), comparable to those of the first-line drugs isoniazid and rifampicin. The presence of two tertiary amines in these N-benzylpiperazine derivatives enabled us to prepare water-soluble dihydrochloride salts, overcoming the serious drawback of previously described 3,5-dinitrophenyl tetrazole and oxadiazole lead compounds. The water-soluble 3,5-dinitrophenyl tetrazole and oxadiazole antitubercular agents described in this work are good candidates for further in vitro and in vivo pharmacokinetic and pharmacodynamic studies.

Microbial degradation of chloroethenes: a review

Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit. Recent research has focused on optimising these natural processes to serve as effective bioremediation technologies, with particular emphasis on (a) the diversity and role of bacterial groups involved in dechlorination microbial processes, and (b) detection of bacterial enzymes and genes connected with dehalogenation activity. In this review, we summarise the different mechanisms of chloroethene bacterial degradation suitable for bioremediation and provide a list of dechlorinating bacteria. We also provide an up-to-date summary of primers available for detecting functional genes in anaerobic and aerobic bacteria degrading chloroethenes metabolically or co-metabolically.

Combined nano-biotechnology for in-situ remediation of mixed contamination of groundwater by hexavalent chromium and chlorinated solvents

The present report describes a 13month pilot remediation study that consists of a combination of Cr(VI) (4.4 to 57mg/l) geofixation and dechlorination of chlorinated ethenes (400 to 6526μg/l), achieved by the sequential use of nanoscale zerovalent iron (nZVI) particles and in situ biotic reduction supported by whey injection. The remediation process was monitored using numerous techniques, including physical-chemical analyses and molecular biology approaches which enabled both the characterization of the mechanisms involved in pollutant transformation and the description of the overall background processes of the treatment. The results revealed that nZVI was efficient toward Cr(VI) by itself and completely removed it from the groundwater (LOQ 0.05mg/l) and the subsequent application of whey resulted in a high removal of chlorinated ethenes (97 to 99%). The persistence of the reducing conditions, even after the depletion of the organic substrates, indicated a complementarity between nZVI and the whey phases in the combined technology as the subsequent application of whey phase partially assisted the microbial regeneration of the spent nZVI by promoting its reduction into Fe(II), which further supported remediation conditions at the site. Illumina sequencing and the detection of functional vcrA and bvcA genes documented a development in the reducing microbes (iron-reducing, sulfate-reducing and chlororespiring bacteria) that benefited under the conditions of the site and that was probably responsible for the high dechlorination and/or Cr(VI) reduction. The results of this study demonstrate the feasibility and high efficiency of the combined nano-biotechnological approach of nZVI and whey application in-situ for the removal of Cr(VI) and chlorinated ethenes from the groundwater of the contaminated site.

Development of 3,5-Dinitrobenzylsulfanyl-1,3,4-oxadiazoles and Thiadiazoles as Selective Antitubercular Agents Active Against Replicating and Nonreplicating Mycobacterium tuberculosis

Herein, we report the discovery and structure-activity relationships of 5-substituted-2-[(3,5-dinitrobenzyl)sulfanyl]-1,3,4-oxadiazoles and 1,3,4-thiadiazoles as a new class of antituberculosis agents. The majority of these compounds exhibited outstanding in vitro activity against Mycobacterium tuberculosis CNCTC My 331/88 and six multidrug-resistant clinically isolated strains of M. tuberculosis, with minimum inhibitory concentration values as low as 0.03 μM (0.011-0.026 μg/mL). The investigated compounds had a highly selective antimycobacterial effect because they showed no activity against the other bacteria or fungi tested in this study. Furthermore, the investigated compounds exhibited low in vitro toxicities in four proliferating mammalian cell lines and in isolated primary human hepatocytes. Several in vitro genotoxicity assays indicated that the selected compounds have no mutagenic activity. The oxadiazole and thiadiazole derivatives with the most favorable activity/toxicity profiles also showed potency comparable to that of rifampicin against the nonreplicating streptomycin-starved M. tuberculosis 18b-Lux strain, and therefore, these derivatives, are of particular interest.

Combined abiotic and biotic in-situ reduction of hexavalent chromium in groundwater using nZVI and whey: A remedial pilot test

The paper describes a pilot remediation test combining two Cr(VI) geofixation methods - chemical reduction by nanoscale zero-valent iron (nZVI) and subsequent biotic reduction supported by whey. Combination of the methods exploited the advantages of both - a rapid decrease in Cr(VI) concentrations by nZVI, which prevented further spreading of the contamination and facilitated subsequent use of the cheaper biological method. Successive application of whey as an organic substrate to promote biotic reduction of Cr(VI) after application of nZVI resulted in a further and long-term decrease in the Cr(VI) contents in the groundwater. The effect of biotic reduction was observed even in a monitoring well located at a distance of 22 m from the substrate injection wells after 10 months. The results indicated a reciprocal effect of both the phases - nZVI oxidized to Fe(III) during the abiotic phase was microbially reduced back to Fe(II) and acted as a reducing agent for Cr(VI) even when the microbial density was already low due to the consumed substrate. Community analysis with pyrosequencing of the 16S rRNA genes further confirmed partial recycling of nZVI in the form of Fe(II), where the results showed that the Cr(VI) reducing process was mediated mainly by iron-reducing and sulfate-reducing bacteria.

Anaerobic in situ biodegradation of TNT using whey as an electron donor: a case study

Contamination by 2,4,6-trinitrotoluene (TNT), an explosive extensively used by the military, represents a serious environmental problem. In this study, whey has been selected as the most technologically and economically suitable primary substrate for anaerobic in situ biodegradation of TNT. Under laboratory conditions, various additions of whey, molasses, acetate and activated sludge as an inoculant were tested and the process was monitored using numerous chemical analyses including phospholipid fatty acid analysis. The addition of whey resulted in the removal of more than 90% of the TNT in real contaminated soil (7 mg kg(-1) and 12 mg kg(-1) of TNT). The final bioremediation strategy was suggested on the basis of the laboratory results and tested under real conditions at a TNT contaminated site in the Czech Republic. During the pilot test, three repeated injections of whey suspension into the sandy aquifer were performed over a 10-month period. In total, approximately 5m(3) of whey were used. A substantial decrease in the TNT groundwater concentration from the original levels (equalling 1.49 mg l(-1) to 8.58 mg l(-1)) was observed in most of the injection wells, while the concentrations of the TNT biotransformation products were found to be elevated. Pilot-scale application results showed that the anoxic and/or anaerobic conditions in the aquifer were sufficient for TNT bio-reduction by autochthonous microorganisms. Whey application was not accompanied by undesirable effects such as a substantial decrease in the pH or clogging of the wells. The results of the study document the suitability of application of whey to bioremediate TNT contaminated sites in situ.

An exploratory study investigating the perception that ICT capital projects are different

Purpose

– The purpose of this study/paper is evidence to suggest that information communication technology (ICT) capital projects are different from non-ICT projects and that as a result the appraisal of such projects is more difficult. This may suggest that organisations would use dissimilar financial and risk assessment models or place different importance levels on such models between the two types of investment. The purpose of this paper is to investigate this issue and present the results of research into the practices of organisations in Czech Republic that have recently undertaken an appraisal of both ICT and non-ICT capital projects.

Design/methodology/approach

– A factual and attitudinal survey was developed and conducted during the end of 2011, addressed to organisations based in the Czech Republic. The object of the survey was the identification of current practices in respect of the appraisal of both ICT and non-ICT projects and the opinions of senior executives on a number of important issues regarding such practices. This paper focuses on the issues relating to ICT projects being “different” from non-ICT projects.

Findings

– The empirical findings support the literature in that ICT projects are, in many respects, different from non-ICT projects. However, the evidence indicates that, in practice, there is no significant difference in the financial and risk assessment models used in their appraisal. This indicates that any perceived difficulties, which may infer that the projects are “different”, are overcome (or ignored), to some extent, when it comes to the formal financial and risk assessment stage of project appraisal. There is also evidence to suggest that practitioners use assessment models that academics regard as unsophisticated. The findings also show that strategic issues are more important with respect of ICT projects than non-ICT projects. The research therefore supports the view that ICT projects are perceived to be different, but that the current conventional (financial and risk) appraisal models are adequate to appraise such capital projects, provided they are supported by a strategic assessment.

Research limitations/implications

– As the findings are based on a survey of companies in the Czech Republic only, we accept that the research results may have some limitations in terms of drawing general conclusions. The concern over drawing general conclusions is also brought about by the relatively low response rate, although the rate is in line with previous published research.

Practical implications

– ICT projects are different and as such these differences must be taken into account when appraising capital projects. The evidence supports the need for practitioners to review their appraisal of ICT capital projects, by adopting more sophisticated financial and risk models (as prescribed by academics) and linking their appraisal to corporate strategic goals. Future research should be aimed at identifying the formal and informal strategic approaches adopted by practitioners in the appraisal of ICT capital projects.

Originality/value

– This is the only survey to simultaneously address the appraisal issues concerning both ICT and non-ICT projects in the Czech Republic. As such, it gives a valuable insight into the practices of Czech Republic organisations in their appraisal of ICT and non-ICT capital projects. The identification of the four main problem areas with respect to the appraisal of ICT projects will help to focus academic research in the future.

Nanoscale zero-valent iron application for in situ reduction of hexavalent chromium and its effects on indigenous microorganism populations

Because of its high toxicity and mobility, hexavalent chromium is considered to be a high priority pollutant. This study was performed to carry out a pilot-scale in-situ remediation test in the saturated zone of a historically Cr(VI)-contaminated site using commercially available nanoscale zero-valent iron (nZVI). The site was monitored before and after the nZVI application by means of microbial cultivation tests, phospholipid fatty acid analysis (PLFA) and toxicological tests with Vibrio fischeri. Injection of nZVI resulted in a rapid decrease in the Cr(VI) and total Cr concentrations in the groundwater without any substantial effect on its chemical properties. The ecotoxicological test with V. fischeri did not indicate any negative changes in the toxicity of the groundwater following the application of nZVI and no significant changes were observed in cultivable psychrophilic bacteria densities and PLFA concentrations in the groundwater samples during the course of the remediation test. However, PLFA of soil samples revealed that the application of nZVI significantly stimulated the growth of Gram-positive bacteria. Principle component analysis (PCA) was applied to the PLFA results for the soil samples from the site in order to explain how Cr(VI) reduction and the presence of Fe influence the indigenous populations. The PCA results clearly indicated a negative correlation between the Cr concentrations and the biota before the application of nZVI and a significant positive correlation between bacteria and the concentration of Fe after the application of nZVI.

Oxidation and amidation of salicylate by Streptomyces species

Seven streptomycete strains were tested for biotransformation of salicylate. The products were identified by nuclear magnetic resonance spectroscopy and three types of conversion were found. Streptomyces cinnamonensis and Streptomyces spectabilis formed gentisate and salicylamide concurrently. Streptomyces rimosus transformed salicylate to salicylamide. Streptomyces lividans, Streptomyces coelicolor, Streptomyces griseus and Streptomyces avermitilis produced only gentisate. Time course studies of salicylate conversion by thin-layer chromatography and high pressure liquid chromatography showed that salicylamide was accumulated in the culture broth, whereas gentisate was further metabolized.Key words: salicylate, gentisate, salicylamide, biotransformation, Streptomyces spp.

Retrospective monitoring and inventory of soil contamination in relation to systematic monitoring

Retrospective monitoring of soil contamination has been performed in the Czech Republic. This kind of monitoring is based on the comparison of the heavy metals content in soil samples taken during a systematic soil survey (1960-1970) and in samples taken at the present time. The anticipated high degree of soil pollution in the Czech Republic has not been proved. Most of the contaminated soils were found to be loaded just 20-35 years ago. Retrospective monitoring is considered to be an accelerating tool for determining the strategy of the systematic monitoring of soil contamination. This procedure stimulated the development of the multi-step system of soil loading limits.

Assignment of Nitrogen Stereochemistry of Agroclavine and Elymoclavine 6-N-Oxides

Both possible 6-N-oxides of agroclavine (I) and elymoclavine (II) were prepared by hydrogen peroxide oxidation. Their 1H and 13C NMR spectra were assigned and the conformation of the D ring (half-chair) was determined. Absolute configuration at 6-N was established by NMR and molecular modelling.

Oxidative and Basic Transformations of Some 1-Heteroaryloligophenylpyridinium Salts. Limitations to the Applicability of Ferricyanide Oxidation

Ferricyanide oxidation of 2,3,4,6-tetraphenyl-1-(2'-pyridyl)pyridinium perchlorate (III) gave, in addition to the biheterocyclic product Ib, two pyrrole derivatives IIb and IIc and in some conditions also the diketone IV. Additional pyrrole derivatives, VII and IX, were obtained analogously from the thiazole 2,4,6-triphenylpyridinium salts V and VIb. Alkalysis of the thiazole salts V and VIb and of the imidazole salts VIc and VId using alcoholic KOH afforded the biheterocyclic products XI-XIV. The mechanisms of the conversions involved are discussed.