title: Protozoan indicators and extracellular polymeric substances alterations in an intermittently aerated membrane bioreactor treating mature landfill leachate.
abstract: A membrane bioreactor was operated under intermittent aeration and various organic loading rates (OLR: 0.070, 0.159 and 0.291 g COD L-1d-1) to remove carbon and nitrogen from mature landfill leachate, where external carbon source (glycerol) addition resulted in effective nitrate removal. A relative increase in soluble microbial product (SMP) over extracellular polymeric substances (EPS) was observed at the highest OLR and glycerol addition, whereas no membrane biofouling occurred. SMP (proteins and carbohydrates) and carbohydrate EPS correlated positively and negatively, respectively, with suspended solids and transmembrane pressure (TMP). Moreover, proteinous SMP significantly correlated with carbon and nitrogen load. Principal component analysis also revealed the influence of leachate organic and nitrogen content on biomass production, TMP and sessile ciliate densities. Although filamentous index (FI) was sustained at high levels (3-4), with Haliscomenobacter hydrossis being the main filamentous bacterium identified, no bulking phenomena occurred. High glycerol addition resulted in a rapid increase in sessile ciliate population. Increased Epistylis and Vorticella microstoma population was detected by microscopic examination during high glycerol addition, while a remarkable Rhogostoma population (supergroup Rhizaria) was identified by molecular techniques. The contribution of Rhizaria in nitrogen processes may lead to the dominance of Rhogostoma during landfill leachate treatment.
authors.affiliation: a Laboratory of Wastewater Management and Treatment Technologies, Department of Environmental Engineering , Democritus University of Thrace , Xanthi , Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Remmas
authors.affiliation: a Laboratory of Wastewater Management and Treatment Technologies, Department of Environmental Engineering , Democritus University of Thrace , Xanthi , Greece.
authors.forename: Paraschos
authors.initials: P
authors.lastname: Melidis
authors.affiliation: a Laboratory of Wastewater Management and Treatment Technologies, Department of Environmental Engineering , Democritus University of Thrace , Xanthi , Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Paschos
authors.affiliation: a Laboratory of Wastewater Management and Treatment Technologies, Department of Environmental Engineering , Democritus University of Thrace , Xanthi , Greece.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Statiris
authors.affiliation: a Laboratory of Wastewater Management and Treatment Technologies, Department of Environmental Engineering , Democritus University of Thrace , Xanthi , Greece.
authors.forename: Spyridon
authors.initials: S
authors.lastname: Ntougias
mesh_terms: D041963:Bacteroidetes / Q000187:drug effects / Q000302:isolation & purification; D001704:Biopolymers / Q000032:analysis* / Q000378:metabolism; D019149:Bioreactors; D016798:Ciliophora / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D016054:DNA, Protozoan / Q000235:genetics; D005990:Glycerol / Q000494:pharmacology; D008567:Membranes, Artificial; D010802:Phylogeny; D011156:Population Density; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D056901:Rhizaria / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
chemical_list: D001704:Biopolymers; D016054:DNA, Protozoan; D008567:Membranes, Artificial; D012337:RNA, Ribosomal, 18S; D014874:Water Pollutants, Chemical; D005990:Glycerol
keywords: Protozoan diversity; Rhogostoma (Rhizaria); amoebae; ciliates; extracellular polymeric substances (EPS)