Degradation of phenolics, nitrogen-heterocyclics and polynuclear aromatic hydrocarbons in a rotating biological contactor

The degradation of phenolics, heterocyclics and polynuclear aromatic hydrocarbons (PAHs) in a synthetic biomass gasifier wastewater with average COD of 1388 mg/L was studied in a three stage rotating biological contactor (RBC) using the pyrene degrader, Exiguobacterium aurantiacum and activated sludge consortia (1:3 v/v). As the organic loading rate (OLR) was varied from 3.3 to 14 g/m(2)/d, the COD removal ranged from 63.3% to 92.6%. Complete removal of all the constituents was observed at the lowest OLR of 3.3 g/m(2)/d. At 24 h hydraulic retention time (HRT) and OLR of 6.6 g/m(2)/d complete removal of pyridine, quinoline and benzene and 85-96% removal of phenol, naphthalene, phenanthrene, fluoranthene and pyrene was observed. E. aurantiacum was found to be the dominant bacteria in the biofilm. Clark's model provided good fits to data for all the three stages of the RBC. (C) 2012 Elsevier Ltd. All rights reserved

Treatment of simulated biomass gasification wastewater of varying strength in a three stage rotating biological contactor

Wastewater generated during wet scrubbing of producer gas formed in biomass gasifiers consist mainly of phenolics, heterocyclics, mono and polynuclear aromatic hydrocarbons (PAHs). The concentration of organics in such wastewater is reported to vary over a wide range depending on gasifier operating conditions and water recycling practices. Such variations may impact the performance of biological treatment processes due to the toxic nature of constituents. Treatment of simulated biomass gasification wastewater of varying strength in a rotating biological contactor (RBC), bioaugmented with a novel bacteria, Exiguobacterium aurantiacum, and operated at constant hydraulic retention time (HRT) of 24 h revealed consistently high removal efficiency in the range of 91-92% for organic loading rate (OLR) of 6.7-16.1 g-COD/m(2)/d. Increase in OLR to 39.5 g-COD/m(2)/d caused a marked drop in COD removal efficiency (83%). Greater than 74% removal was observed for all the components although the influent concentration of phenolics and heterocyclics were much higher compared to the PAHs. Abiotic loss in absence of the biofilm was consistently low (12-20% COD removal). Treatment was accompanied by significant reduction in acute toxicity. The biofilm consisting of E. aurantiacum and mixed microbial consortium thus have a good potential for removal of these toxic constituents. (C) 2014 Elsevier B.V. All rights reserved

Batch studies with Exiguobacterium aurantiacum degrading structurally diverse organic compounds and its potential for treatment of biomass gasification wastewater

Biomass gasification wastewater primarily consists of phenolics, nitrogen-heterocyclics and polynuclear aromatic hydrocarbons (PAHs). Biodegradation of these compounds present individually as sole substrate is studied in batch cultures in presence of Exiguobacterium aurantiacum. It demonstrated good potential for degrading phenol, pyridine, quinoline, benzene and naphthalene present at initial concentration (C-in) of 500 mg l(-1). E. aurantiacum could also utilize 3- and 4-ring PAHs, phenanthrene, fluoranthene and pyrene as sole substrate present at 100 mg l(-1) (C-in). While significant increase in absorbance was observed on 3 and 4-ring PAHs, the increase in number concentration of viable cells and extent of degradation was relatively low. E. aurantiacum could effectively degrade a synthetic biomass gasifier wastewater comprised of these compounds with a total COD of 1326 mg l(-1) and biokinetic studies revealed applicability of Monod's kinetics for culture growth on gasifier wastewater. The half velocity constant (K-s) and maximum specific growth rate (mu(max)) were 651 mg l(-1) and 1.86 d(-1), respectively. All components in the wastewater were degraded simultaneously and compounds with comparable concentration depicted comparable degradation rates. E. aurantiacum could degrade the organics in biomass gasification wastewater even when the ammoniacal-nitrogen concentration was increased up to 1000 mg l(-1). Bioaugmentation with E. aurantiacum can significantly enhance biological treatment of biomass gasification wastewater. (C) 2013 Elsevier Ltd. All rights reserved

Predicting response to neoadjuvant chemotherapy in primary breast cancer using volumetric helical perfusion computed tomography: a preliminary study

To investigate whether CT-derived vascular parameters in primary breast cancer predict complete pathological response (pCR) to neoadjuvant chemotherapy (NAC).Twenty prospective patients with primary breast cancer due for NAC underwent volumetric helical perfusion CT to derive whole tumour regional blood flow (BF), blood volume (BV) and flow extraction product (FE) by deconvolution analysis. A pCR was achieved if no residual invasive cancer was detectable on pathological examination. Relationships between baseline BF, BV, FE, tumour size and volume, and pCR were examined using the Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis was performed to assess the parameter best able to predict response. Intra- and inter-observer variability was assessed using Bland-Altman statistics.Seventeen out of 20 patients completed NAC with four achieving a pCR. Baseline BF and FE were higher in patients who achieved a pCR compared with those who did not (P = 0.032); tumour size and volume were not significantly different (P &gt; 0.05). ROC analysis revealed that BF and FE were able to identify responders effectively (AUC = 0.87; P = 0.03). There was good intra- and inter-observer agreement.Primary breast cancers which exhibited higher levels of perfusion before treatment were more likely to achieve a pCR to NAC.aEuro cent CT-derived vascular parameters may be useful in breast cancer treatment.aEuro cent Perfusion CT can help predict response to neoadjuvant chemotherapy in breast cancer.aEuro cent Baseline blood flow and flow extraction product are higher in complete pathological responders.</p