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Yuan X.,University of Massachusetts Amherst | Kumar A.,Pollution Prevention and Control Core | Sahu A.K.,Aquateam Norwegian Water Technology Center | Ergas S.J.,University of South Florida
Bioresource Technology | Year: 2011

Spirulina platensis was cultivated in a bench-scale airlift photobioreactor using synthetic wastewater (total nitrogen 412mgL-1, total phosphorous 90mgL-1, pH 9-10) with varying ammonia/total nitrogen ratios (50-100% ammonia with balance nitrate) and hydraulic residence times (15-25d). High average biomass density (3500-3800mgL-1) and productivity (5.1gm-2d-1) were achieved when ammonia was maintained at 50% of the total nitrogen. Both high ammonia concentrations and mutual self-shading, which resulted from the high biomass density in the airlift reactor, were found to partially inhibit the growth of S. platensis. The performance of the airlift bioreactor used in this study compared favorably with other published studies. The system has good potential for treatment of high strength wastewater combined with production of algae for biofuels or other products, such as human and animal food, food supplements or pharmaceuticals. © 2010 Elsevier Ltd. Source


Guibaud G.,CNRS Research Group on Water, Soil and Environment | Bhatia D.,CNRS Research Group on Water, Soil and Environment | Bhatia D.,University Paris Est Creteil | d'Abzac P.,CNRS Research Group on Water, Soil and Environment | And 4 more authors.
Journal of the Taiwan Institute of Chemical Engineers | Year: 2012

This work investigates the ability of EPS extracted by cationic exchange resin (CER) from 3 different anaerobic granular sludges to bind Pb or Cd as a function of pH. EPS display a better binding ability for Pb than Cd as it has been often shown in literature. The experimental sorption data show the presence of a pH sorption edge. The experimental data are well fitted by the Kurbatov model. Nevertheless, the molar ratio of proton exchanged with metal ions underlines that other mechanisms are also involved in metal ion sorption by EPS from anaerobic granular sludges. Moreover, the mineral fraction present in extracted EPS and trapped by the organic fraction or under particle form seems to be involved in the metal ions sorption process. © 2011 Taiwan Institute of Chemical Engineers. Source


d'Abzac P.,CNRS Research Group on Water, Soil and Environment | Bordas F.,CNRS Research Group on Water, Soil and Environment | Joussein E.,CNRS Research Group on Water, Soil and Environment | van Hullebusch E.D.,University Paris Est Creteil | And 2 more authors.
Environmental Science and Pollution Research | Year: 2013

Extracellular polymeric substances (EPS) were extracted from four anaerobic granular sludges with different procedures to study their involvement in biosorption of metallic elements. EPS extracts are composed of closely associated organic and mineral fractions. The EPS macromolecules (proteins, polysaccharides, humic-like substances, nucleic, and uronic acids) have functional groups potentially available for the binding of metallic elements. The acidic constants of these ionizable groups are: pK a1 (4-5) corresponding to the carboxyl groups; pK a2 (6-7) corresponding to the phosphoric groups; pK a3 (8-10) and pK a4 (≈10) corresponding to the phenolic, hydroxyl, and amino groups. The polarographic study confirms the higher affinity of the EPS to bind to lead than to cadmium. Moreover, the binding of these metallic compounds with the EPS is a mix of several sorption mechanisms including surface complexation, ion exchange, and flocculation. Inorganic elements were found as ions linked to organic molecules or as solid particles. The mineral fraction affects the binding properties of the EPS, as the presence of salts decreases the EPS binding ability. Calcite and apatite particles observed on SEM images of EPS extracts can also sorb metallic elements through ion exchange or surface complexation. © 2012 Springer-Verlag Berlin Heidelberg. Source


Meulepas R.J.W.,Pollution Prevention and Control Core | Stams A.J.M.,Wageningen University | Lens P.N.L.,Pollution Prevention and Control Core
Reviews in Environmental Science and Biotechnology | Year: 2010

Biological sulfate reduction can be used for the removal and recovery of oxidized sulfur compounds and metals from waste streams. However, the costs of conventional electron donors, like hydrogen and ethanol, limit the application possibilities. Methane from natural gas or biogas would be a more attractive electron donor. Sulfate reduction with methane as electron donor prevails in marine sediments. Recently, several authors succeeded in cultivating the responsible microorganisms in vitro. In addition, the process has been studied in bioreactors. These studies have opened up the possibility to use methane as electron donor for sulfate reduction in wastewater and gas treatment. However, the obtained growth rates of the responsible microorganisms are extremely low, which would be a major limitation for applications. Therefore, further research should focus on novel cultivation techniques. © The Author(s) 2010. Source


Meulepas R.J.W.,Pollution Prevention and Control Core | Meulepas R.J.W.,Wageningen University | Jagersma C.G.,Wageningen University | Khadem A.F.,Radboud University Nijmegen | And 3 more authors.
Applied Microbiology and Biotechnology | Year: 2010

Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SR) is assumed to be a syntrophic process, in which methanotrophic archaea produce an interspecies electron carrier (IEC), which is subsequently utilized by sulfate-reducing bacteria. In this paper, six methanogenic substrates are tested as candidate-IECs by assessing their effect on AOM and SR by an anaerobic methanotrophic enrichment. The presence of acetate, formate or hydrogen enhanced SR, but did not inhibit AOM, nor did these substrates trigger methanogenesis. Carbon monoxide also enhanced SR but slightly inhibited AOM. Methanol did not enhance SR nor did it inhibit AOM, and methanethiol inhibited both SR and AOM completely. Subsequently, it was calculated at which candidate-IEC concentrations no more Gibbs free energy can be conserved from their production from methane at the applied conditions. These concentrations were at least 1,000 times lower can the final candidate-IEC concentration in the bulk liquid. Therefore, the tested candidate-IECs could not have been produced from methane during the incubations. Hence, acetate, formate, methanol, carbon monoxide, and hydrogen can be excluded as sole IEC in AOM coupled to SR. Methanethiol did inhibit AOM and can therefore not be excluded as IEC by this study. © 2010 The Author(s). Source

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