Assessment of Arthrobacter viscosus as reactive medium for forming permeable reactive biobarrier applied to PAHs remediation

Polycyclic aromatic hydrocarbons (PAHs) are significant environmental contaminants as they are present naturally as well as anthropogenically in soil, air and water. In spite of their low solubility, PAHs are spread to the environment, and they are present in surface water, industrial effluent or groundwater. Amongst all remediation technologies for treating groundwater contaminated with PAHs, the use of a permeable reactive biobarrier (PRBB) appears to be the most cost-effective, energy efficient, and environmentally sound approach. In this technology, the microorganisms are used as reactive medium to degrade or stabilize the contaminants. The main limits of this approach are that the microorganisms or consortium used for forming the PRBB should show adequate characteristics. They must be retained in the barrier-forming biofilm, and they should also have degradative ability for the target pollutants. The aim of the present work is to evaluate the viability of Arthrobacter viscosus as bioreactive medium for forming PRBB. Initially, the ability of A. viscosus to remove PAHs, benzo[a]anthracene 100 μM and phenanthrene 100 μM was evaluated operating in a batch bench-scale bioreactor. In both cases, total benzo[a]anthracene and phenanthrene removals were obtained after 7 and 3 days, respectively. Furthermore, the viability of the microorganisms was evaluated in the presence of chromium in a continuous mode. As a final point, the adhesion of A. viscosus to sepiolite forming a bioreactive material to build PRBB was demonstrated. In view of the attained results, it can be concluded that A. viscosus could be a suitable microorganism to form a bioreactive medium for PAHs remediation.This work has been supported by the Spanish Ministry of Economy and Competitiveness and FEDER Funds (Project CTM 2011-25389). Marta Pazos received financial support under the Ramon y Cajal programme and Marta Cobas under the final project master grant "Campus do Mar Knowledge in depth"

Selection of diazotrophic bacterial communities in biological sand filter mesocosms used for the treatment of phenolic-laden wastewater

Agri effluents such as winery or olive mill waste-waters are characterized by high phenolic concentrations. These compounds are highly toxic and generally refractory to biodegradation. Biological sand filters (BSFs) represent inexpensive, environmentally friendly, and sustainable wastewater treatment systems which rely vastly on microbial catabolic processes. Using denaturing gradient gel electrophoresis and terminal-restriction fragment length polymorphism, this study aimed to assess the impact of increasing concentrations of synthetic phenolic-rich wastewater, ranging from 96 mg L−1 gallic acid and138 mg L−1 vanillin (i.e., a total chemical oxygen demand (COD) of 234 mg L−1) to 2,400mg L−1 gallic acid and 3,442 mg L−1 vanillin (5,842 mg COD L−1), on bacterialcommunities and the specific functional diazotrophic community from BSF mesocosms. This amendment procedure instigated efficient BSF phenolic removal, significant modifications of the bacterial communities, and notably led to the selection of a phenolic-resistant and less diverse diazotrophic community. This suggests that bioavailable N is crucial in the functioning of biological treatment processes involving microbial communities, and thus that functional alterations in the bacterial communities in BSFs ensure provision of sufficient bioavailable nitrogen for the degradation of wastewater with a high C/N ratio.Web of Scienc

Genome-wide analysis of Sphingomonas wittichii RW1 behaviour during inoculation and growth in contaminated sand.

The efficacy of inoculation of single pure bacterial cultures into complex microbiomes, for example, in order to achieve increased pollutant degradation rates in contaminated material (that is, bioaugmentation), has been frustrated by insufficient knowledge on the behaviour of the inoculated bacteria under the specific abiotic and biotic boundary conditions. Here we present a comprehensive analysis of genome-wide gene expression of the bacterium Sphingomonas wittichii RW1 in contaminated non-sterile sand, compared with regular suspended batch growth in liquid culture. RW1 is a well-known bacterium capable of mineralizing dibenzodioxins and dibenzofurans. We tested the reactions of the cells both during the immediate transition phase from liquid culture to sand with or without dibenzofuran, as well as during growth and stationary phase in sand. Cells during transition show stationary phase characteristics, evidence for stress and for nutrient scavenging, and adjust their primary metabolism if they were not precultured on the same contaminant as found in the soil. Cells growing and surviving in sand degrade dibenzofuran but display a very different transcriptome signature as in liquid or in liquid culture exposed to chemicals inducing drought stress, and we obtain evidence for numerous 'soil-specific' expressed genes. Studies focusing on inoculation efficacy should test behaviour under conditions as closely as possible mimicking the intended microbiome conditions

Polycyclic Aromatic Hydrocarbons in Air

Policiklički aromatski ugljikovodici (PAU) spojevi su koji se sastoje od dva ili više kondenziranih aromatskih prstenova. Nastaju prilikom nepotpunog izgaranja ili pirolize organskih tvari. Dokazano je da neki PAU imaju kancerogena, a neki mutagena svojstva, pa je stoga potrebno kontinuirano pratiti koncentracije PAU u zraku, vodi i tlu, te pokušati sanirati izvore PAU. PAU s dva ili tri aromatska prstena postojani su u plinovitoj fazi, dok se PAU s više aromatskih prstenova nalaze u zraku uglavnom vezani na čestice. Visoke koncentracije PAU prisutne su u atmosferi urbanih područja, a najviše su zimi kada su pojačane emisije iz kućnih ložišta. U ljetno doba koncentracije su niže jer je većina policikličkih aromatskih ugljikovodika nestabilna na visokim temperaturama, a osim toga dolazi do njihove oksidacije i fotooksidacije. Metode mjerenja PAU u zraku uključuju uzorkovanje prosisavanjem na filterski papir ili kruti adsorbens, ekstrakciju i kromatografsku analizu. U ovom radu prikazani su rezultati mjerenja benzo[a]pirena (BaP) kao glavnog predstavnika PAU na nekim lokacijama u svijetu. Razine BaP u svijetu uspoređene su s rezultatima mjerenja provedenim do sada u Hrvatskoj.Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds consisting of two or more condense aromatic rings. They are products of incomplete combustion or pyrolysis of organic matter. Because some PAHs such as Benzo[a]pyrene (BaP) are proven carcinogens and mutagens, it is necessary to continuously monitor their concentrations in the air, water, and soil. PAHs with two or three aromatic rings are stable in the gas phase, while most PAHs with five or more aromatic rings bond to particles. Higher concentrations of PAHs are present in the atmosphere of urban areas, mostly in the winter, due to heating. In the summer, these concentrations drop because most PAHs are unstable at high temperatures and break down by oxidation and photooxidation. Measurements of PAHs in the air include sampling on the filter paper or solid adsorbent, extraction, and chromatographic analysis. This review presents the measurements of BaP in some locations in the world and compares them with the findings in Croatia

Chemical Methods for Determination of Hydroxylated Metabolites of Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls in Biological Material

U ovome preglednom radu prikazani su postupci analize hidroksiliranih metabolita policikličkih aromatskih ugljikovodika i poliklorbifenila u ljudima i životinjama. Ti metaboliti služe kao biomarkeri izloženosti ljudi i životinja navedenim zagađivalima, no neki od njih i sami posjeduju toksična svojstva. Analiziraju se najčešće u urinu koji je kao uzorak najdostupniji, ali se isto tako mogu analizirati i u ljudskoj, odnosno životinjskoj jetri, žuči i masnom tkivu. Analiza metabolita aromatskih zagađivala važna je zbog određivanja biodostupnosti aromatskih zagađivala, njihove potencijalne toksičnosti u ljudskom organizmu, ali i zbog toksičnosti samih metabolita. Napredak analitičkih metoda omogućio je simultanu analizu velikog broja metabolita u uzorcima. Nove tehnike ekstrakcije i selektivnije i preciznije kvalitativne i kvantitativne analize omogućuju detekciju vrlo niskih koncentracija metabolita. Pri tome dodatnu prednost imaju jednostavne tehnike koje zahtijevaju manje kemikalija i vremena za analizu.This review presents methods for the analysis of hydroxylated metabolites of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in humans and animals. These metabolites serve as biomarkers of human and animal exposure to the mentioned pollutants, but some metabolites also have toxic properties. Most are analysed in urine, which is the most accessible sample, but they can also be analysed in human and animal liver, bile, and adipose tissue. Their analysis is important for assessing bioavailability of aromatic pollutants and their toxicity in human organism, but also the toxicity of metabolites themselves. Advancements in analytical methods have made it possible to analyse multiple metabolites in a sample at the same time. New extraction techniques and more precise and selective qualitative and quantitative analyses can now detect very low metabolite oncentrations. An extra advantage is that these simple techniques require less chemicals and time

Kinetics of carbon and nitrogen assimilation by heterotrophic microorganisms during wastewater treatment

The present study highlights microbial assimilation of carbon (glucose) and nitrogen (NH3–N) from wastewater using heterotrophic bioconversion process. Experiments were conducted to study the role of heterotrophic microbes towards removal of carbon and nitrogen at varying initial concentrations of carbon (COD, 533 to 1600 mg/l) and nitrogen (NH3–N, 73 to 249 mg/l) keeping the initial biomass of microorganisms constant. Removal of COD and ammonia from wastewater represented a first-order rate reaction, upon analysis of kinetics, indicating that the rate of reaction is dependent on the initial concentration of nutrients available. Rate equations were developed using the Monod model, and the maximum specific consumption rate (k4) and half saturation constant (Ks) values for NH3–N and COD were found to be 2.59 mg/l/h and 64.13 mg/l/h and 38.46 mg/l and 2162.69 mg/l, respectively. Assimilation of NH3–N followed the Freundlich isotherm model. The mass transfer coefficient for COD and NH3–N were found to be 0.13 h−1 and 0.81 h−1 respectively. The NH3–N is converted to N2O during nitrification, and observed values of N2O coincided with the empirically predicted values indicating the activity of heterotrophic nitrifiers. The regeneration/doubling time of heterotrophic microbial biomass varied from 26 to 121 h. Statistical techniques, viz. analysis of variance, multi-linear regression analysis and principal component analysis, validated the results

Assessment of Ambient Air Quality in Urban Centres of Haryana (India) in Relation to Different Anthropogenic Activities and Health Risks

The original publication is available at www.springerlink.com . Copyright Springer DOI : 10.1007/s10661-005-9161-xConsidering the mounting evidences of the effects of air pollution on health, the present study was undertaken to assess the ambient air quality status in the fast growing urban centres of Haryana state, India. The samples were collected for total suspended particulate matter (TSPM), respirable suspended particulate matter (PM10), sulfur dioxide (SO2), and for oxides of nitrogen (NO2) during different seasons from 8 districts of Haryana during January, 1999 to September, 2000. The four types of sampling sites with different anthropogenic activities i.e. residential, sensitive, commercial and industrial were identified in each city. The ambient air concentration of TSPM and PM10 observed was well above the prescribed standards at almost all the sites. The average ambient air concentrations of SO2 and NO2 were found below the permissible limits at all the centres. Comparatively higher concentration of SO2 was observed during winter seasons, which seems to be related with the enhanced combustion of fuel for space heating and comparatively stable atmospheric conditions. Air Quality Index (AQI) prepared for these cities shows that residential, sensitive and commercial areas were moderately to severely polluted which is a cause of concern for the residents of these cities. The high levels of TSPM and SO2 especially in winter are of major health concern because of their synergistic action. The data from Hisar city reveals a significant increase in the total number of hospital visits/admissions of the patients with acute respiratory diseases during winter season when the level of air pollutants was high.Peer reviewe

Assessment of fluoride in groundwater and urine, and prevalence of fluorosis among school children in Haryana, India

Abstract Considering the health effects of fluoride, the present study was undertaken to assess the concentration of fluoride in groundwater, and urine of school children in Bass region of Haryana state. Fluoride in groundwater was observed to vary from 0.5 to 2.4 mg/l with an average concentration of 0.46 mg/l. On the other hand, F− in urine ranged from below the detection limit to 1.8 mg/l among girls and 0.17–1.2 mg/l among the boys. Higher average concentration of fluoride in urine (0.65 mg/l for boys and 0.34 mg/l for girls) may be ascribed to exposure to bioavailable fluoride through food, milk, tea, toothpaste, etc., in addition to intake through groundwater. Relatively more intake of water and food by the boys might be the reason for more cases of severe dental fluorosis (44%) among boys compared to girls (29% cases of moderate to severe dental fluorosis). The groundwater quality for drinking was compromised with respect to dissolved solids, hardness, magnesium ions, and dissolved iron. Hydro-geochemical investigation revealed that rock–water interaction, in terms of direct cation exchange, dominantly regulates groundwater chemistry, and groundwater is of Ca-Na-HCO3 type

Comparison of batch mode and dynamic physiologically based bioaccessibility tests for PAHs in soil samples

A fed state in vitro methodology capable of use in commercial testing laboratories has been developed for measuring the human ingestion bioaccessibility of polyaromatic hydrocarbons (PAHs) in soil (Fed ORganic Estimation human Simulation Test- FOREhST). The protocol for measuring PAHs in the simulated gastro-intestinal fluids used methanolic KOH saponification followed by a combination of polymeric sorbent solid phase extraction and silica sorbent cartridges for sample cleanup and preconcentration. The analysis was carried out using high pressure liquid chromatography with fluorescence detection. The repeatability of the method, assessed by the measurement of the bioaccessibility of 6 PAHs (benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[ah]anthracene, and indeno[1,2,3-c,d]pyrene) in eleven gas works soils, was 10% RSD. The method compared well with the results from an independent dynamic human simulation reactor comprising of the stomach, duodenal and colon compartments tested on the same soils. The measured bioaccessible fraction of the soils varied from 10−60% for soils containing 10−300 mg kg−1 PAH (the sum of the six studied) with total organic carbon concentrations in the soils ranging from 1−13%. A multiple regression model showed that the PAH bioaccessible fraction could be explained using the PAH compound, the soil type and the total PAH to soil organic carbon content. The method described here has potential for site specific detailed quantitative risk assessment either to modify the risk estimation or to contribute to the risk evaluation