Treatment of Dichloromethane Using Gliding Arc Plasma

Decomposition of dichloromethane (CH₂Cl₂) using a gliding plasma was examined and reported in this paper. The effects of initial concentrations of CH₂Cl₂, total gas flow rates, and input frequency have been studied to evaluate the performance of gliding arc on CH₂Cl₂ decomposition. Using atmospheric pressure air as the carrier gas, experimental results indicate that the maximum conversion of CH₂Cl₂ was 95.1% at a total gas flow rate of 180 L/hr containing 1% by volume of CH₂Cl₂. The reaction occurred at an exothermic condition and gaseous products are dominated by CO, CHCl₃, and Cl₂. CO₂ and CCl₄ are also detected in the product stream in small amounts. The conversion of CH₂Cl₂ increases with the increasing applied voltage and decreasing total gas flow rate.     

Biodegradability oriented treatability studies on high strength segregated wastewater of a woolen textile dyeing plant

Textile dyeing and finishing industry involves considerable amount of water usage as well as polluted and highly colored wastewater discharges. Biological treatability by means of mineralization, nitrification and denitrification of high strength woolen textile dye bathes, first- and second-rinses is presented. COD fractionation study was carried out and kinetic parameters were determined. Biodegradability of organic compounds in highly loaded composite wastewater after segregation and the effluent of applied biological treatment of high strength composite wastewater were measured by determining oxygen consumption rates. The results were used in terms of assessing an alternative method for inert COD fractionation. The study implied that about 80% soluble COD, 50% color and 75% toxicity reduction were possible by single sludge biological processes. Sixteen per cent of total COD was found to be initially inert. Inert fraction was increased to 22% by production of soluble and particulate microbial products through biological treatment.     

Influence of methanol on retention of hydrophobic organic chemicals in soil leaching column chromatography

The influence of methanol in methanol-water mixed eluents on the capacity factor (k'), an important parameter which could depict leaching potential of hydrophobic organic chemicals (HOCs) in soil leaching column chromatography (SLCC), was investigated. Two reference soils, GSE 17201 obtained from Bayer Landwirtschaftszentrum, Monheim, Germany and SP 14696 from LUFA, Spencer, Germany, were used as packing materials in soil columns, and isocratic elution with methanol-water mixtures at different volume fractions of methanol (phi) were tested. Short-term exposure of the column (packed with the GSE 17201 soil) to the eluents increased solute retention by a certain (23% log-unit) degree evaluated through a correlation with the retention on the same soil column but unpreconditioned by methanol-containing eluents. Long-term exposure of soil columns to the eluents did not influence the solute retention. A log-linear equation, log k' = log k'(w) - S(phi), could well and generally describe the retention of HOCs in SLCC. For the compounds of homologous series, logk'(w) had good linear relationship with S, indicating the hydrophobic partition mechanism existing in the retention process.     

Toxicity evaluation of reactive dyestuffs, auxiliaries and selected effluents in textile finishing industry to luminescent bacteria Vibrio fischeri

The toxicity of 17 selected process effluents, 11 reactive dyestuffs and 8 auxiliaries from a textile dyeing and finishing mill in Ayazaga, Istanbul, Turkey was evaluated by bioluminescence test using bacteria Vibrio fischeri in LUMIStox 300. The EC20 and EC50 for auxiliaries, the EC20 for dyestuffs were determined. For selected process effluents GL-values, the dilution level at which a wastewater sample causes less than 20% inhibition, were examined. Our results demonstrate that the toxicity assessment with luminescent bacteria is effective and of practical use for chemicals applied in textile finishing industry with the limitation of the deep dark-colored dye bath samples and for the related effluents. Inhibition effects of numerous dyestuffs as well as auxiliaries to luminescent bacteria differed considerably with a range 5-600 mg l(-1) for EC20 and 9-6930 mg l(-1) for EC50, respectively. Among 17 effluents, I sample exhibited high toxicity (GL = 100), 7 showed moderate toxicity (GL = 12-32), and 9 had a GL-value <10 indicating a low or no toxicity.     

Linear solvation energy relationships regarding sorption and retention properties of hydrophobic organic compounds in soil leaching column chromatography

The capacity factors of a series of hydrophobic organic compounds (HOCs) were measured in soil leaching column chromatography (SLCC) on a soil column, and in reversed-phase liquid chromatography on a C18 column with different volumetric fractions (phi) of methanol in methanol-water mixtures. A general equation of linear solvation energy relationships, log(XYZ) XYZ0 + mV(I)/100 + spi + bbetam + aalpham, was applied to analyze capacity factors (k'), soil organic partition coefficients (Koc) and octanol-water partition coefficients (P). The analyses exhibited high accuracy. The chief solute factors that control logKoc, log P, and logk' (on soil and on C18) are the solute size (V(I)/100) and hydrogen-bond basicity (betam). Less important solute factors are the dipolarity/polarizability (pi*) and hydrogen-bond acidity (alpham). Log k' on soil and log Koc have similar signs in four fitting coefficients (m, s, b and a) and similar ratios (m:s:b:a), while log k' on C18 and logP have similar signs in coefficients (m, s, b and a) and similar ratios (m:s:b:a). Consequently, logk' values on C18 have good correlations with logP (r > 0.97), while logk' values on soil have good correlations with logKoc (r > 0.98). Two Koc estimation methods were developed, one through solute solvatochromic parameters, and the other through correlations with k' on soil. For HOCs, a linear relationship between logarithmic capacity factor and methanol composition in methanol-water mixtures could also be derived in SLCC.     

Triazines in the aquatic systems of the Eastern Chinese Rivers Liao-He and Yangtse

The results of a one-year monitoring program on the two Eastern Chinese River systems, i.e. the Liao-He and the Yangtse, with special emphasis on the presence of triazine herbicides are presented. Sediment, suspended solids and water samples from both rivers were analyzed. Additionally, recovery experiments on the SPE-in-field-enrichment procedure and the extraction methods were performed. The samples were measured by gas chromatography coupled with mass spectrometry, electron capture detection and a newly developed mu-plasma atomic emission detector. A typical result of a one-year monitoring was obtained in case of the Liao-He: During winter, at low water period, low triazine values were found. A similar situation was found in early spring. Highest concentrations of atrazine up to 1600 ng/l were found in late spring in the water samples. Maximum concentrations of atrazine, simazine, propazine, simetryn and prometryn were observed in this season as a result of the actual use of triazines. Finally, after the high water period in autumn the triazine concentrations decreased. Additionally, atrazine adsorbed on sediment (up to 2.8 ng/g) and suspended solids was determined (up to 8 ng/l) during late spring sampling. Therefore, the logarithm of the organic carbon based sorption coefficient of atrazine could be calculated. Low levels of atrazine were measured in the water of Yangtse (up to 18.3 ng/l). The concentrations from all sampling points and sampling stations of a particular sampling date were similar, which indicates a homogeneous distribution of this herbicide. Due to the high discharge rate of up to 79,000 m3/s in case of the Yangtse a considerable mass transport of up to 57.5 kg per day atrazine may take place, even at concentrations below the European drinking water limit of 100 ng/l.     

Bioassay zur Bestimmung von TCDD-Toxizit?ts?quivalenten (TEQ) von Umweltproben und Reststoffen

Zusammenfassung  Polychlorierte aromatische Kohlenwasserstoffe (PHAK), z.B. 2,3,7,8-Tetrachlordibenzo-p-dioxin (TCDD), weisen eine Vielzahl von toxischen Wirkungen und biologischen Effekten auf. Die Substanzklasse der PHAK besitzt die Eigenschaft der Bindung an ein cytosolisches Rezeptor-Protein, gefolgt von der Synthese bestimmter Genprodukte, u.a. von Cytochrom P450 1A1 (CYP 1A1). In dieser Arbeit wird ein Bioassay beschrieben, der erlaubt, die Induktion von CYP 1A1 als Summenparameter für die biologische Wirksamkeit der kritischen, halogenierten Verbindungen in komplexen Umweltmatrizes zu bestimmen. Zur Abtrennung von Substanzen aus den Extrakten von Umweltproben (z. B. Naturstoffe und polyzyklische aromatische Kohlenwasserstoffe), die den Bioassay st?ren k?nnen, wurde ein Ein-S?ulen-Clean-up entwickelt. Die biologisch ermittelten TEQ-Werte stimmen gut mit den Resultaten der chemischen Analytik überein. Der Bioassay in Kombination mit dem Clean-up bietet eine zeitsparende und kostengünstige M?glichkeit zur Untersuchung von Umweltproben.      

Bioconcentration of superlipophilic persistent chemicals

According to present understanding, persistent superlipophilic chemicals — such as octachlorodibenzo-p-dioxin, octachlorodibenzofuran, Mirex etc — with log K_ow > 6 and cross sections > 9.5 Å, bioconcentrate in aquatic organisms only little from ambient water. The most convincing argument against it is that in bioconcentration experiments with superlipophilic chemicals amounts applied exceeded water solubility by several orders of magnitude. This paper describes various methods for determining bioconcentration factors (BCF) of superlipophilic compounds. As exemplified with octachlorodibenzo-p-dioxin, BCF values evaluated by these methods match well with those calculated by QSARs for fish and mussels based on log K_ow and water solubility. As expected, these BCF values exceed previous values by several orders of magnitude. For BCF evaluation of superlipophilic chemicals in aquatic organisms we recommend:

1. flow-through systems, kinetic method (OECD guideline No. 305 E)
2. ambient concentrations < water solubility
3. during the uptake and especially during the elimination phase no toxic effects of the test organisms should occur.