Microcosm studies of microbial degradation in a coal tar distillate plume

Investigation of a groundwater plume containing up to 24 g l(-1) phenolic compounds suggested that over a period of nearly 50 years, little degradation had occurred despite the presence of a microbial community and electron acceptors within the core of the plume. In order to study the effect of contaminant concentration on degradation behaviour, laboratory microcosm experiments were performed under aerobic and anaerobic conditions at four different concentrations obtained by diluting contaminated with uncontaminated groundwater. The microcosms contained groundwater with total phenols at ca. 200, 250, 660 and 5000 mg l(-1), and aquifer sediment that had been acclimatised within the plume for several months. The microcosms were operated for a period of 390-400 days along with sterile controls to ascertain whether degradation was microbially mediated or abiotic. Under aerobic conditions, degradation only occurred at concentrations up to 660 mg l(-1) total phenols. At phenol concentrations below 250 mg l(-1) a benzoquinone intermediate, thought to originate from the degradation of 2,5-dimethylphenol, was isolated and identified. This suggested an unusual degradative pathway for this compound; its aerobic degradation more commonly proceeding via catecholic intermediates. Under anaerobic conditions, degradation only occurred in the most dilute microcosm (total phenols 195 mg l(-1)) with a loss of p-cresol accompanied by a nonstoichiometric decrease in nitrate and sulphate. By inference, iron(III) from the sediment may also have been used as a terminal electron acceptor, in which case the amount of biologically available iron released was calculated as 1.07 mg Fe(III)/g of sediment. The study shows that natural attenuation is likely to be stimulated by dilution of the plume.     

Sediment evidence of early eutrophication and heavy metal pollution of Lake Mälaren, central Sweden

Lake M?laren is the water supply and recreation area for more than 1 million people in central Sweden and subject to considerable environmental concern. To establish background data for assessments of contemporary levels of trophy and heavy metal pollution, sediment cores from the lake were analyzed. Diatom-inferred lake-water phosphorus concentrations suggest that pre-20th century nutrient levels in S?dra Bj?rkfj?rden, a basin in the eastern part of M?laren, were higher (c. 10-20 micrograms TP L-1) than previously assumed (c. 6 micrograms TP L-1). Stable lead isotope and lead concentration analyses from 3 basins (S. Bj?rkfj?rden, Gisselfj?rden and Ask?fj?rden) show that the lake was polluted in the 19th century and earlier from extensive metal production and processing in the catchment, particularly in the Bergslagen region. The lake has experienced a substantial improvement of the lead pollution situation in the 20th century following closure of the mining and metal industry. The lead pollution from the old mining industry was large compared to late-20th century pollution from car emissions, burning of fossil fuels and modern industries.     

Disinfection by-products in Finnish drinking waters

Disinfection by-products (DBPs) were measured in plant effluents of 35 Finnish waterworks, which utilized different treatment processes and raw water sources. DBPs were measured also from the distribution systems of three waterworks. Di- and trichloroacetic acids, and chloroform were the major DBPs found in treated water samples. The concentration of six haloacetic acids (HAA6) exceeded the concentrations of trihalomethanes (THMs). Chlorinated drinking waters (DWs) originating from surface waters contained the highest concentration of HAA6 and THMs: 108 and 26 microg/l, respectively. The lowest concentrations of DBPs were measured from ozonated and/or activated carbon filtrated and chloraminated DWs. Higher concentrations of HAA6, THMs, and adsorbable organic halogens were measured in summer compared to winter. The levels of chlorinated acetic acids, chloroform, and bromodichloromethane correlated positively with mutagenicity. Past mutagenicity levels of DWs were examined. A major reduction in the use of prechlorination, increased use of chloramine disinfection, and better removal of organic carbon were the most important reasons for the 69% decrease in mutagenicity from 1985 to 1994.     

As(III) removal from groundwaters using fixed-bed upflow bioreactors

The application of biological oxidation of iron and manganese, as a potential treatment method for the removal of arsenic from contaminated groundwaters, was examined in this paper. This method was based on the growth of certain species of indigenous bacteria, which are capable of oxidizing the soluble iron and manganese ions; the oxidized forms can be subsequently removed from the aqueous stream by over 97%, through their transformation to insoluble oxides and separation by a suitable filter medium. Arsenic was removed by around 80%, under certain conditions, which were found to be sufficient for Fe(II) removal (dissolved oxygen 2.7 mg/l, redox 280-290 mV, pH 7.2, U 8.25 m/h). The specific treatment technique presents several advantages towards conventional physicochemical treatment methods, such as enhanced coagulation or direct adsorption since: (a) it does not require the addition of other chemicals for oxidizing and removing As(III), (b) it does not require close monitoring of a breakthrough point, as in conventional column adsorption processes and (c) it could find application for the removal of, at least, three groundwater contaminants (Fe, Mn, As).     

Alterations of lipid profile in plasma and liver of diabetic rats: effect of hypoglycemic herbs

The effect of three species of hypoglycemic herbs (Termis, Halfa barr, or Kammun Quaramany) on the lipid profile was investigated in plasma and liver tissues of diabetic and herbs-treated diabetic rats. This profile includes total lipids (TL), triglycerides (TG), cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL). A dose of 1.5 ml of aqueous suspension of each herb/100 g body weight (equivalent to 75 mg/100 g body weight) was orally administered daily to alloxan-diabetic rats for four weeks. The present study showed 2-fold increase (p<0.05) in the plasma glucose level of diabetic rats, which received alloxan as a single dose of 120 mg/kg body weight, relative to the mean value of control group. This elevated glucose level was restored to its normal level after treatment with any one of the three herbs. Furthermore, the levels of TL, TG, cholesterol, LDL and VLDL were significantly (p<0.05) increased in the plasma and the liver tissues of diabetic rats compared to the control group, whereas HDL level was significantly (p<0.05) decreased. The plasma levels of all above parameters were normalized after treatment of the diabetic rats with Kammun Quaramany. Treatment of diabetic rats with Tennis normalized TG, cholesterol, LDL and VLDL levels, but Halfa barr restored the induced levels of plasma cholesterol, LDL and HDL to their normal levels. On the other hand, treatment with any of the three herbal suspensions could not restore the concentrations of the all tested parameters in the liver. These data demonstrated that the glycemic control of any of the three herbal suspensions was associated with their hypocholesterolemic effects on the hypercholesterolemia of the alloxan-induced diabetic rats. Moreover, the Kammun Quaramany showed the most potent effect.     

Bioconversion of olive-mill dry residue by Fusarium lateritium and subsequent impact on its phytotoxicity

The present study investigated the ability of the non-pathogenic fungus Fusarium lateritium to either degrade or modify aromatic substances in olive-mill dry residue (DOR) and to reduce its phytotoxicity. The 80% reduction of ethylacetate extractable phenols in DOR colonized by the fungus for 20 weeks appeared to be due to polymerization reactions of phenol molecules as suggested by mass-balance ultrafiltration and size-exclusion chromatography experiments. Several lignin-modifying oxidases, including laccase, Mn-peroxidase and Mn-inhibited peroxidase were detected in F. lateritium solid-state cultures. Tests performed with tomato seedlings in soils containing 6% (w/w) sterilized non-inoculated DOR showed that the waste was highly phytotoxic. By contract, F. lateritium growth on DOR for 20 weeks led to a complete removal of the waste toxicity and to a higher shoot dry weight of tomato plants than that obtained in the absence of DOR.     

Treatment of chlorinated solvents by TiO2 photocatalysis and photo-Fenton: influence of operating conditions in a solar pilot plant

Titanium dioxide photocatalysis (using 20 0mg l(-1) of TiO2), under aerobic and anaerobic conditions, and photo-Fenton (2 and 56 mg l(-1) iron) were applied to the treatment of different NBCS (non-biodegradable chlorinated solvents), such as dichloroethane, dichloromethane and trichloromethane dissolved in water at 50 mg l(-1). All the tests were performed in a 35-l solar pilot plant with compound parabolic collectors (CPCs) under natural illumination. The two solar treatments were compared with attention to chloride release and TOC mineralisation, as the main parameters. Photo-Fenton was found to be the more appropriate treatment for these compounds, assuming volatilisation as a drawback of photocatalytic degradation of NBCS dissolved in water. In this context, several operating parameters related to NBCS degradation, e.g., treatment time, temperature, hydrogen peroxide consumption and volatility of parent compounds are discussed. The correct choice of operating conditions can very often diminish the problem of volatilisation during treatment.     

Oxidative treatment of simulated dyehouse effluent by uv and near-UV light assisted Fenton's reagent

UV/Fenton, near-UV-visible/Fenton, dark Fenton, and H₂O₂/UV reactions have been used to treat simulated dyehouse effluents representing wastewater from the textile dyeing and rinsing process. Experiments were carried out in a lab - scale photochemical reactor using concentrations of 0.5–25 mM H₂O₂, 0.04-0.5 mM Fe²⁺-ion and different dilutions of textile wastewater. To assess the extent of mineralization, decolourization kinetics and the effect of different fight sources on treatment efficiency, DOC, optical density at 254 nm and 600 nm wavelength and residual H₂O₂ concentrations were measured during the course of the advanced oxidation reactions. Comparative evaluation of the obtained results revealed that the decolourization rate increased with applied H₂O₂ and Fe²⁺-ion dose as well as the strength of the synthetic textile wastewater. The best results were obtained by the near - UV/visible/Fenton process with a decolourization rate constant of 1.57 min⁻¹, a UV_254nm reduction of 97% and a DOC removal of 41% at relatively low doses of the H₂O₂ oxidant and Fe²⁺-ion catalyst within 60 min treatment time.     

Variability of the Ecological and Morphological Characteristics of Field Vole (Microtus agrestis) in the Southern and Middle Urals

Russian Journal of Ecology - The variability of the ecological and morphological characteristics of the field vole was studied on samples collected in its two localities of the Southern Urals and...