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Alteration of a bacteriocin-producing hydrophilic bacterium, Lactococcus lactis IO-1, into a hydrophobic material with potential antimicrobial activity using chitosan was investigated and compared with five other bacterial species with industrial importance. The negatively charged bacterial cells were neutralized by positively charged chitosan, resulting in a significant increase in the hydrophobicity of the bacterial cell surface. The largest Gram-positive B. megaterium ATCC 14581 showed a moderate response to chitosan while the smaller E. coli DH5α, L. lactis IO-1 and P. putida F1 exhibited a significant response to an increase in chitosan concentration. Because L. lactis IO-1 is a good source for natural peptide lantibiotic that is highly effective against several strains of food spoilage organisms and pathogens, hydrophobic material derived from L. lactis IO-1 and chitosan is a promising novel material with antimicrobial activity for the food and pharmaceutical industries., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In this study, six N-acyl-homoserine lactone (AHL) molecules (C6-HSL, C8-HSL, C10-HSL, 3-oxo-C6-HSL, 3-oxo-C8-HSL and 3-oxo-C10-HSL) were each dosed into a bioreactor and seeded using autotrophic nitrifying sludge (ANS). The effects of the AHLs on cell adhesion, nitrification and sludge granulation were investigated. The results indicated that the efficiencies of cell adhesion and ammonia removal both had a close correlation with the side chain length and β position substituent group of the AHLs. The best-performing AHL in terms of accelerating bacterial attached-growth was 3-oxo-C6-HSL, whereas C6-HSL outperformed the others in terms of the ammonia degradation rate. The addition of 3-oxo-C6-HSL or C6-HSL increased the biomass growth rate, microbial activity, extracellular proteins and nitrifying bacteria, which can accelerate the formation of nitrifying granules. Consequently, selecting AHL molecules that could improve bacteria in attached-growth mode and nitrification efficiency simultaneously will most likely facilitate the rapid granulation of nitrifying sludge., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study investigated the damages of microbial cell structures, as well as the relationships between these damages and the release of cellular organic matter in the pretreatment of waste activated sludge (WAS) by using alkaline pretreatment as model. In the alkaline pretreatment of WAS, the most damage of bound extracellular polymeric substances (EPS), cell walls, cell membranes, and cell nuclei occurred at pH 11.5-12.0 (46.2%), pH 11.0-11.5 (27.3%), pH 9.0-10.0 (34.2%), and pH 11.5-12.0 (44.4%), respectively. The damage percentages of these cell structures in the pH stabilization stage were low because most of the damages occurred when the pH increased. The structural integrities of sludge microorganisms were all damaged in the pH increase stage. The damages of EPS, cell walls, and cell membranes were significantly correlated with the release of cellular organic matter, and these damages were necessary to release the cellular matter in WAS., (Copyright © 2015. Published by Elsevier Ltd.)

An entrapment of nitrifiers into gel matrix is employed as a tool to fulfill partial nitrification under non-limiting dissolved oxygen (DO) concentrations in bulk solutions. This study aims to clarify which of these two attributes, inoculum type and DO concentration in bulk solutions, is the decisive factor for partial nitrification in an entrapped-cell based system. Four polyvinyl alcohol entrapped inocula were prepared to have different proportions of nitrite-oxidizing bacteria (NOB) and nitrite-oxidizing activity. At a DO concentration of 3 mg l(-1), the number of active NOB cells in an inoculum was the decisive factor for partial nitrification enhancement. However, when the DO concentration was reduced to 2 mg l(-1), all entrapped cell inocula showed similar degrees of partial nitrification. The results suggested that with the lower bulk DO concentration, the preparation of entrapped cell inocula is not useful as the DO level becomes the decisive factor for achieving partial nitrification., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

This study monitored the granulation process of an aggregating functional consortium X9 that was consisted of Pseudomonas putida X-1, Acinetobacter sp. X-2, Alcaligenes sp. X-3 and Comamonas testosteroni X-4 in shaken reactors. The growth curve of X9 was fit using logistic model as follows y=1.49/(1+21.3*exp(-0.33x)), the maximum specific cell growth rate for X9 was 0.33 h(-1). Initially X9 consumed polysaccharides (PS) and secreted proteins (PN) to trigger granulation. Then X9 grew in biomass and formed numerous micro-granules, driven by increasing hydrophobicity of cell membranes and of accumulated extracellular polymeric substances (EPS). In later stage the intracellular cyclic diguanylate (c-di-GMP) was at high levels for inhibiting bacteria swarming motility, thereby promotion formation of large aerobic granules. The findings reported herein advise the way to accelerate granule formation and to stabilize operation in aerobic granular reactors., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The objective of the study was to test the hypothesis that the attachment of polycyclic aromatic hydrocarbons (PAHs)-degrading bacteria can promote desorption of PAHs from humin, thereby increasing their bioavailability. Biodegradation of humin-bound phenanthrene (PHE) - a model compound for PAHs - was investigated using two PHE-degrading bacteria, Sphingobium sp. PHE3 and Micrococcus sp. PHE9, respectively. Sorption data of PHE to humin fitted well into the modified Freundlich equation. Further, a new sorption band appeared at 1262cm(-1), demonstrating intermolecular interactions between PHE and humin. Interestingly, approximately 65.3% of humin-bound PHE was degraded by both strains, although only about 17.8% of PHE could be desorbed from humin by Tenax extraction. Furthermore, both strains grew well in mineral medium and also attached to humin surfaces for substrate uptake. It is proposed that the attached bacteria could possibly consume PHE on the humin via interactions between bacterial surfaces and humin, thereby overcoming the low PHE bioavailability and resulting in enhanced degradation., (Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.)

Microscopic observation and settling test were carried out to investigate the structure, density and settlability of anammox granules taken from a high-rate upflow anaerobic sludge blanket (UASB) reactor. The results showed that the anammox granules were irregular in shape and uneven on surface, and their structure included granule, subunit, microbial cell cluster and single cell. The gas pockets were often observed in the anammox granules, and they originated from the obstruction of gas tunnel by extracellular polymer substances (EPSs) and the inflation of produced dinitrogen gas. The volume of gas pockets became larger with the increasing diameter of anammox granules, which led to the decreasing density and the floatation of anammox granules. The diameter of anammox granules should be controlled at less than 2.20mm to avoid the granule floatation. A hypothesized mechanism for the granulation and floatation of anammox biomass was proposed., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Anaerobic digestion of food waste was conducted at high OLR from 3.7 to 12.9 kg-VS m(-3) day(-1) for 225 days. Periods without organic loading were arranged between the each loading period. Stable operation at an OLR of 9.2 kg-VS (15.0 kg-COD) m(-3) day(-1) was achieved with a high VS reduction (91.8%) and high methane yield (455 mL g-VS-1). The cell density increased in the periods without organic loading, and reached to 10.9×10(10) cells mL(-1) on day 187, which was around 15 times higher than that of the seed sludge. There was a significant correlation between OLR and saturated TSS in the sludge (y=17.3e(0.1679×), r(2)=0.996, P<0.05). A theoretical maximum OLR of 10.5 kg-VS (17.0 kg-COD) m(-3) day(-1) was obtained for mesophilic single-stage wet anaerobic digestion that is able to maintain a stable operation with high methane yield and VS reduction., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The effects of turning on the microbial consortia during swine manure composting were investigated. To focus on microbial migration, two types of composting runs, with and without turning, were conducted. In both cases, the material was composted in three separate reactors set at 30, 50, and 70 °C. For the runs with turning, the material was removed from the reactors, pooled, mixed, and redistributed daily, whereas for those without turning, the compost was agitated inside the reactors. The microbial consortia were compared by PCR-DGGE for composting without turning at different temperatures; this revealed the temperature preferences of the microorganisms, in situ--i.e., whether they were mesophilic, thermotolerant, thermophilic, or microorganisms that could adapt to a wide range of temperatures. Moreover, most of these microorganisms, except for the enteric bacteria, survived stably during composting with turning, irrespective of the temperature, and the microbial consortia became similar across the three reactors., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The potential of Phragmites australis was evaluated for the removal of three veterinary drugs, enrofloxacin (ENR), ceftiofur (CEF) and tetracycline (TET), from aquatic mediums. Results showed that the plant promoted the removal of 94% and 75% of ENR and TET, respectively, from wastewater. Microbial abundance estimation revealed that microorganisms were not a major participant. Occurrence of drugs adsorption to plant roots was observed in small extension. Therefore, main mechanisms occurring were drug removal by plant uptake and/or degradation. Present results demonstrated the potential of P. australis-planted beds to be used for removal of pharmaceuticals from livestock and slaughterhouse industries wastewater., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Limited filamentous bulking (LFB) was proposed to save aeration energy consumption and enhance the capacity of filaments to degrade substrates with low concentrations in activated sludge systems. Operational parameters favorable for maintaining the LFB state were investigated in an anoxic-oxic reactor treating domestic wastewater. The experiments showed that the LFB state would deteriorate with sharply decreasing temperature, reducing substrate gradients or removing anoxic zones. The balance between filaments and floc-formers could be achieved by controlling dissolved oxygen and sludge loading rates to be in optimal ranges. Eikelboom Type 0041 and CandidatusMicrothrix parvicella were the filamentous bacteria responsible for the LFB state. However, the excess growth of Eikelboom Type 021N and Sphaerotilus natans were observed when serious bulking occurred under low substrate gradients. It was demonstrated that stable maintenance of LFB for energy saving was feasible by process control and optimization., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

To investigate the inducements of increase of cell hydrophobicity from aerobic biofloc (ABF) and granular sludge (AGS), in this study, as the first time the hydrophilic and hydrophobic bacterial communities were analyzed independently. Meanwhile, the effect of extracellular polymers (EPS) on the cell hydrophobicity is also studied. Few Bacteroidetes were detected (1.35% in ABF and 3.84% in AGS) in hydrophilic bacteria, whereas they are abundant in the hydrophobic cells (47.8% and 43% for ABF and AGS, respectively). The main species of Bacteroidetes changed from class Sphingobacteria to Flavobacteria in AGS. On the other hand, EPS is directly responsible to cell hydrophobicity. For AGS, cell hydrophobicity was sharply decreased after EPS extraction. Both quantity and property of the extracellular protein are related to hydrophobicity. Our results showed the variation of cell hydrophobicity was resulted from variations of both bacterial population and EPS., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This study investigated the fate of enhanced biological phosphorus removal (EBPR) and changes in microbial speciation in a sequencing batch reactor (SBR) fed with aspartate and glutamate. It involved SBR operation for 288 days, batch tests for observation of metabolic functions together with microscopic and phylogenetic analyses. Polyphosphate accumulating organisms (PAOs) were observed in abundance with complete removal of phosphorus. Fluorescence in situ hybridization (FISH) combined with 4',6-dia-midino-2-phenylindole (DAPI) staining confirmed the accumulation of polyphosphate by Rhodocyclus-related and Actinobacterial PAOs. Aspartate seemed to favor the competitive growth of Rhodocyclus-related PAOs since EBPR population used the common biochemical pathways followed by Rhodocyclus-related PAOs in the aspartate fed batch tests. In the glutamate fed batch reactors, however, Actinobacterial PAOs appeared to be competitively selected which explains the lower levels of PHA generation. Even though operational conditions did not change, effective EBPR could not be maintained during the latter part of the study., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The biodegradation and inhibition kinetics of a commercial nonylphenol ethoxylate formulation were modelled for an activated sludge system fed with a synthetic substrate and nonylphenol ethoxylate mixture. Kinetic and stoichiometric coefficients of the proposed activated sludge model were obtained by employing on-line respirometry. Experimental as well as model results confirmed that nonylphenol ethoxylate exhibited non-competitive inhibition on the hydrolysis process with a coefficient of 150mg/L on the basis of COD and negatively influenced biomass growth through a competitive inhibition mechanism with a coefficient of 500mg/L on the basis of COD, when the biomass was not acclimated. Upon acclimation of the activated sludge system, the inhibition concentration for non-competitive inhibition on hydrolysis was increased to 5000mg/L, practically showing no inhibition, and the coefficient of competitive inhibition increased to 450mg/L, corresponding to a significant decrease in the inhibitory effects of NPEO on growth., (Copyright 2010 Elsevier Ltd. All rights reserved.)

This study describes the performance of a microbial biocathode, based on a hydrogenophilic methanogenic culture, capable of reducing carbon dioxide to methane, at high rates (up to 0.055 + or - 0.002 mmol d(-1) mgVSS(-1)) and electron capture efficiencies (over 80%). Methane was produced, at potentials more negative than -650 mV vs. SHE, both via abiotically produced hydrogen gas (i.e., via hydrogenophilic methanogenesis) and via direct extracellular electron transfer. The relative contribution of these two mechanisms was highly dependent on the set cathode potential. Both cyclic voltammetry tests and batch potentiostatic experiments indicated that the capacity for extracellular electron transfer was a constitutive trait of the hydrogenophilic methanogenic culture. In principle, both electrons and carbon dioxide required for methane production could be obtained from a bioanode carrying out the oxidation of waste organic substrates., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Phenol biodegradation in a batch jet loop bioreactor (JLB) using activated sludge was investigated. The biodegradation experiments were conducted at different phenol concentrations (S(0)) from 50 to 1000 mg/l. The results of the biodegradation of phenol by JLB show that a good phenol removal of 100%. The biodegradation capacity of the JLB was higher than that of the stirred tank reactor reported in literatures. The Haldane equation was adopted in order to describe the relation between the specific growth rates (micro) and S(0). Kinetic constants of Haldane equation were micro(m) = 0.119 1/h, K(s) = 11.13 mg/l and K(i) = 250.88 mg/l. Model equations were simulated using the MATHCAD 7.0 software's ordinary differential equation solver. Simulations were performed at each experiment with different initial phenol concentrations., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Marsh-pond-marsh (MPM) constructed wetlands were designed for the treatment of swine wastewater. The goal of this study was to characterize bacterial communities in these wetlands and determine the nutrient removal from influent to effluent. Surface soil samples were collected and analyzed by culture-dependent and culture-independent techniques. The results showed that the bacterial colony forming units (CFU) and the average concentrations of total nitrogen, NH(4)(+), total phosphorous (TP) and PO(4)(3-) from the influent to the effluent decreased. The NH(4)(+) and the PO(4)(3-) concentrations showed the most dramatic changes, with decreases of 39.97% and 16.92%, respectively. Data of culture-independent samples produced by using PCR-denaturing gradient gel electrophoresis (DGGE) technique showed that the Shannon diversity index and richness decreased significantly (P<0.05) from influent to effluent. Bacterium species distributions strongly correlated with the concentrations of TP, NH(4)(+) and the PO(4)(3-). Sequencing of partial 16S rRNA genes fragments revealed that the total bacterial community composition was dominated by Pseudomonas sp., Arthrobacter sp., Bacillus sp. and other soil bacteria. Anammox (anaerobic ammonium oxidation) stains were detected. Phylogenetic analysis demonstrated that some of the partial 16S rRNA gene sequences had close relationships with unculturable denitrification bacteria. The activities of these bacteria might contribute to the nutrient removal in the wetlands.

Nano-scale zero-valent iron particles (NZVI) are increasingly being used to treat sites contaminated with chlorinated solvents. This study investigated the effect of NZVI on dechlorinating microorganisms that participate in the anaerobic bioremediation of such sites. NZVI can have a biostimulatory effect associated with water-derived cathodic H(2) production during its anaerobic corrosion (730+/-30 micromol H(2) was produced in 166 h in abiotic controls with 1 g/L NZVI) or an inhibitory effect upon contact with cell surfaces (assessed by transmission electron microscopy). Methanogens, which are known to compete for H(2) with dechlorinators, were significantly biostimulated by NZVI and methane production increased relative to NZVI-free controls from 58+/-5 to 275+/-2 micromol. In contrast, bacteria dechlorinating TCE were inhibited by NZVI, and the first-order degradation rate coefficient decreased from 0.115+/-0.005 h(-1) (R(2)=0.99) for controls to 0.053+/-0.003 h(-1) (R(2)=0.98) for treatments with 1 g/L NZVI. Ethene production from TCE was initially inhibited by NZVI, but after 331 h increased to levels observed for an NZVI-free system (7.6+/-0.3 micromol ethene produced in 502 h compared to 11.6+/-0.5 mmol in the NZVI-free system and 3.8+/-0.3 micromol ethene for NZVI alone). Apparently, cathodic H(2) was utilized as electron donor by dechlorinating bacteria, which recovered following the partial oxidation and presumably passivation of the NZVI. Overall, these results suggest that reductive treatment of chlorinated solvent sites with NZVI might be enhanced by the concurrent or subsequent participation of bacteria that exploit cathodic depolarization and reductive dechlorination as metabolic niches.

An attempt has been made to produce low cost MFC from the commercially available earthen pots in India, without involving any costly membrane. This MFC gave a maximum power output of 16.8 W/m(3) at a Coulombic efficiency (CE) of 31.3% with graphite plate cathode. With stainless steel mesh cathode and KMnO(4) as cathodic electrolyte the power production and CE of 70.48 W/m(3) and 64.5%, respectively, was obtained. The performance of this earthen pot MFC was evaluated with biotic and abiotic cathode. Although, biofilm formation on the cathode is observed to be helpful in enhancing power out put, the thicker biofilm on the cathode showed reduction in power. This MFC demonstrated competitive performance as compared to MFC incorporated with membrane. This low cost MFC, with total production cost of less than 1.0$, as per Indian market, demonstrated its utility as a wastewater treatment and onsite power generation device.

Strategies are being developed to harvest the energy content of the wasted sludge generated from the treatment of domestic wastewater. Sludge can be hydrolysed and fermented, giving a mixture of volatile fatty acids (VFAs). Based on the composition of such a fermented stream, synthetic media were created and tested for VFA conversion in microbial fuel cells (MFCs). Mainly acetate and propionate were preferred as electron donors in the mixed VFA system, which generated a power density of 49+/-1 mW L(NAC)(-1). The other VFAs (butyrates/valerates/caproic acid) were also removed, albeit at lower rates. In single VFA tests, each VFA could be removed, but particularly i-butyrate did not provide significant current generation. PCR-DGGE indicated that the microbial community structure was highly determined by the fed VFA, rather than by the initial inoculum. The communities were dominated by Proteobacteria such as Geobacter, Comamonas, Pseudomonas and Pelobacter species. This study demonstrated the feasibility of using fatty acids, as present in fermented sludge hydrolysates, for current generation.

Waste removal efficiency of gas-liquid biofilter reactors for waste water treatment depends on its flow regime and residence time distribution (RTD) as key parameters of bio-reactor performance. The present study reports RTD regime in a fibrous fixed bed biofilm reactor related to a fluid velocity range appropriate for biofilm operation. The data from tracer experiments are correlated in terms of the one-parameter "tanks-in-series" model. The aerated fibrous bed reactor RTD function is found to be dependent on net liquid and gas phase superficial velocity U(L) and U(G). Liquid internal recirculation exhibited small effect comparable with the effect of net liquid flow. A power law relationship relating the number of perfectly mixed cells with liquid and gas superficial velocity is elaborated. Assuming similarity of the prototype and real vessels' flow fields, the equation as well as its corresponding range of fluid velocity can be used for bio-reactor design and scale-up. Comparison over the model parameters obtained in fixed bed bubble columns at low fluid velocity shows the results of this study to be comparable with previous data of mesh wire packing.

In situ cell separation and immobilization of bacterial cells for biodesulfurization were developed by using superparamagnetic Fe(3)O(4) nanoparticles (NPs). The Fe(3)O(4) NPs were synthesized by coprecipitation followed by modification with ammonium oleate. The surface-modified NPs were monodispersed and the particle size was about 13 nm with 50.8 emu/g saturation magnetization. After adding the magnetic fluids to the culture broth, Rhodococcus erythropolis LSSE8-1 cells were immobilized by adsorption and then separated with an externally magnetic field. The maximum amount of cell mass adsorbed was about 530 g dry cell weight/g particles to LSSE8-1 cells. Analysis showed that the nanoparticles were strongly absorbed to the surface and coated the cells. Compared to free cells, the coated cells not only had the same desulfurizing activity but could also be easily separated from fermentation broth by magnetic force. Based on the adsorption isotherms and Zeta potential analysis, it was believed that oleate-modified Fe(3)O(4) NPs adsorbed bacterial cells mainly because of the nano-size effect and hydrophobic interaction.

Three Microbial Fuel Cells (MFCs) were fluidically connected in series, with a single feed-line going into the 1st column through the 2nd column and finally as a single outflow coming from the 3rd column. Provision was also made for re-circulation in a loop (the outflow from the 3rd column becoming the feed-line into the 1st column) in order to extend the hydraulic retention time (HRT) on treatment of landfill leachate. The effect of increasing the electrode surface area was also studied whilst the columns were (fluidically) connected in series. An increase in the electrode surface area from 360 to 1080 cm(2) increased the power output by 118% for C2, 151% for C3 and 264% for C1. COD and BOD(5) removal efficiencies also increased by 137% for C1, 279% for C2 and 182% for C3 and 63% for C1, 161% for C2 and 159% for C3, respectively. The system when configured into a loop was able to remove 79% of COD and 82% of BOD(5) after 4 days. These high levels of removal efficiency demonstrate the MFC system's ability to treat leachate with the added benefit of generating energy.

Performance of two dual chambered mediator-less microbial fuel cells (MFCs) was evaluated at different sludge loading rate (SLR) and feed pH. Optimum performance in terms of organic matter removal and power production was obtained at the SLR of 0.75 kg COD kg VSS(-1) d(-1). Maximum power density of 158 mW/m(2) and 600 mW/m(2) was obtained in MFC-1 (feed pH 6.0) and MFC-2 (feed pH 8.0), respectively. Internal resistance of the cell decreased with increase in SLR. When operated only with biofilm on anode, the maximum power density was 109.5 mW/m(2) in MFC-1 and 459 mW/m(2) in MFC-2, which was, respectively, 30% and 23.5% less than the value obtained in MFC-1 and MFC-2 at SLR of 0.75 kg COD kg VSS(-1) d(-1). Maximum volumetric power of 15.51 W/m(3) and 36.72 W/m(3) was obtained in MFC-1 and MFC-2, respectively, when permanganate was added as catholyte. Higher feed pH (8.0) favoured higher power production.

The study regards para-nitrophenol (p-NP) removal by a mixed culture in a batch reactor under aerobic conditions performed at low ratio substrate (p-NP) to p-NP degrading microorganisms (0.09 < I(0)/(X(B,PNP))(0) < 0.80 g COD(PNP)g VSS(-1)). p-NP biodegradation was modelled with a dual-biomass kinetic including Haldane formalism. The purpose was to examine the effect of operating conditions of acclimation phases in the kinetic parameters estimated by respirometric measurements. The experiments were conducted with a series of successive additions of p-NP and a biogenic substrate (Ss) in different proportions (0 < R = Ss/I < 6.6). To place emphasis on decisive role played by frequency and amount of p-NP supply, a parallel was drawn with continuous processes, characterising acclimation cycles by different organic loading rate (207 < OLR < 1490 mg COD(PNP) l(-1) d(-1)). During acclimation, results showed progressively decreasing half saturation constant (K(s)(PNP)) values (11.4-1.21 mg CODl(-1)) whereas inhibition coefficient K(I)(PNP) increased (72.4-289 mg CODl(-1)), as the specific degradation rate increased. The inverse behaviour was observed during starvation periods. At the end of acclimation, higher values of growth yield (0.39 < Y(PNP) < 0.63 mg COD(X) mg COD(PNP)(-1)) and maximum growth rate (1.09 < mu(max)(PNP) < 2.01 d(-1)) were obtained for cycles with low R.

Biogas and methane yields of food and green wastes and their mixture were determined using batch anaerobic digesters at mesophilic (35+/-2 degrees C) and thermophilic (50+/-2 degrees C) temperatures. The mixture was composed of 50% food waste and 50% green waste, based on the volatile solids (VS) initially added to the reactors. The thermophilic digestion tests were performed with four different feed to inoculum (F/I) ratios (i.e., 1.6, 3.1, 4.0 and 5.0) and the mesophilic digestion was conducted at one F/I (3.1). The results showed that the F/I significantly affected the biogas production rate. At four F/Is tested, after 25 days of thermophilic digestion, the biogas yield was determined to be 778, 742, 784 and 396 mL/g VS for food waste, respectively; 631, 529, 524 and 407 mL/g VS for green waste, respectively; and 716, 613, 671 and 555 mL/g VS for the mixture, respectively. About 80% of the biogas production was obtained during the first 10 days of digestion. At the F/I of 3.1, the biogas and methane yields from mesophilic digestion of food waste, green waste and their mixture were lower than the yields obtained at thermophilic temperature. The biogas yields were 430, 372 and 358 mL/g VS, respectively, and the methane yields were 245, 206, and 185 mL/g VS, respectively.

Feasibility of using chocolate industry wastewater as a substrate for electricity generation using activated sludge as a source of microorganisms was investigated in two-chambered microbial fuel cell. The maximum current generated with membrane and salt bridge MFCs was 3.02 and 2.3 A/m(2), respectively, at 100 ohms external resistance, whereas the maximum current generated in glucose powered MFC was 3.1 A/m(2). The use of chocolate industry wastewater in cathode chamber was promising with 4.1 mA current output. Significant reduction in COD, BOD, total solids and total dissolved solids of wastewater by 75%, 65%, 68%, 50%, respectively, indicated effective wastewater treatment in batch experiments. The 16S rDNA analysis of anode biofilm and suspended cells revealed predominance of beta-Proteobacteria clones with 50.6% followed by unclassified bacteria (9.9%), alpha-Proteobacteria (9.1%), other Proteobacteria (9%), Planctomycetes (5.8%), Firmicutes (4.9%), Nitrospora (3.3%), Spirochaetes (3.3%), Bacteroides (2.4%) and gamma-Proteobacteria (0.8%). Diverse bacterial groups represented as members of the anode chamber community.

A novel bioflocculant-producing bacterium, ZHT4-13, was isolated from Ruditapes philippinarum conglutination mud. By biomicroscope morphological observation, 16S rDNA sequence identification and physiological and biochemical characteristics, strain ZHT4-13 was identified as Rothia sp. The bioflocculant MBF4-13 produced by strain ZHT4-13 had a flocculating efficiency of 86.22% for 5 g L(-1) Kaolin clay suspension when the initial pH was 9 and the temperature was 20 degrees C. It had flocculating effect in a wide range, pH 1-13 and temperature 4-100 degrees C. Analysis of MBF4-13 by UV-Vis spectrophotometer, Fourier-transform infrared spectrophotometer (FT-IR) and (1)H nuclear magnetic resonance (NMR) indicated that the main component of MBF4-13 is polysaccharide. The culture conditions to produce strain ZHT4-13 were optimized with orthogonal design of experiments. MBF4-13 had high efficiency in decolorizing dye solutions, had some abilities to remove heavy metal ions (Cr(2)O(7)(2-), Ni(2+)) and improve performance of activated sludge.

This study determines cellulose solubilization kinetics from controlled batch digestions and shows the effect of inoculum biomass concentrations. Separate measurements and analyzes were performed for sessile biomass (biofilms) and planktonic biomass (free suspensions). Experiments were conducted using either leachate enriched on cellulose or rumen fluid as inoculum to assess if the effect of biomass concentration was consistent for microbial populations from different source environments. All batch digestions were fitted to a first-order kinetic model (R(2) ranging from 0.94 to 0.99). Regression analysis used to compare the first-order hydrolysis rate showed that the first-order hydrolysis rate was most strongly correlated with the concentration of sessile biomass rather than with the concentration of total or planktonic biomass. The correlation between solubilization rate and sessile biomass was statistically the same for the rumen and leachate inoculated reactors indicating that at low concentration ratios of inoculum to cellulose, the rate of cellulose solubilization is dependant primarily on sessile biomass concentration rather than the species profile of the cellulolytic community.

An up-flow fixed-bed (UFB) bioreactor with patented functional polyurethane foam (FPUF) carriers was used to treat sulfide in hydrocarbon wastewater. Community compositions of autotrophic and heterotrophic bacteria were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). DGGE results showed that a relatively stable bacterial community composed of heterotrophic and autotrophic bacteria formed in the bioreactor by the end of experiment, which ensured 92-100% sulfide removal efficiencies. Furthermore, autotrophic genera of Thiobacillus and Thiomonas, as well as those of the heterotrophic genus of Acinetobacter survived and exhibited high sulfide oxidation activity under all three operational conditions. Different special genera were also observed under each operational condition, such as the halophilic genus of Nesterenkonia. In addition, a new genus of sulfide oxidation bacteria was found in the bioreactor, which had the ability to synthesize cytoplasm from organic compounds. These genera have wide applications for the treatment of sulfide in hydrocarbon wastewater.

The present study was aimed at elucidating the role of biosurfactant product isolated from a marine bacterium in removing heavy metals from heavy metal containing solutions. In this study, metal removal was biosurfactant-mediated. Efficiency of metal removal depended on the concentration of the metal as well as that of the biosurfactant. At a concentration 5x, the critical micelle concentration (CMC), almost complete removal of 100 ppm of lead and cadmium occurred. Atomic absorption spectroscopy (AAS) studies also showed metal removal at a concentration less than the CMC in contrast to earlier findings that only micelles are involved in metal removal. Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy (EDS) further substantiated these findings.

In this work, it has been studied the production of electricity and the oxidation of the pollutants contained in a synthetic wastewater fed with glucose and peptone of soybean as carbon sources, using a mediator-less microbial fuel cell (MFC). Special attention has been paid to the acclimation stage, in which it was found that with high hydraulic and solid retention times it is possible to obtain a very efficient process with a 90% COD removal and practically total conversion of COD into electricity (considering the typical stoichiometric yield of heterotrophic biomass). The influence of concentration sludge was studied working with three different amounts of suspended solids, from 120 to 14000 mg. The maximum power density increased exponentially with the concentration sludge from 2.1 mW m(-2) to 11 mW m(-2) at the highest concentration sludge. More over, the percentage of the influent COD used to produce electricity was higher than 100% when the highest sludge concentration was used. This was explained taking into account the endogenous metabolism of micro-organisms presented in the system. Moreover, wastewater with two different compositions, but with the same COD concentration, were studied. One with 50% of glucose and 50% of peptone of soybean and the other, with 80% of peptone and 20% of glucose. Spite of the wastewater with 50% of glucose is more biodegradable than the other composition used, the microbial fuel cell performance obtained was lower than with the other (2.1 mW m(-2) with respect to 6.8 mW m(-2) when 80% of peptone was used). This means that the degradation of peptone occurs through the production of intermediates that favour electricity.

Microbial fuel cells (MFCs) are considered as a promising way for the direct extraction of biochemical energy from biomass into electricity. However, scaling up the process for practical applications and mainly for wastewater treatment is an issue because there is a necessity to get rid of unsustainable platinum (Pt) catalyst. In this study, we developed a low-cost cathode for a MFC making use of sputter-deposited cobalt (Co) as the catalyst and different types of cathode architecture were tested in a single-chambered air-cathode MFC. By sputtering the catalyst on the air-side of the cathode, increased contact with ambient oxygen significantly resulted in higher electricity generation. This outcome was different from previous studies using conventionally-coated Pt cathodes, which was due to the different technology used.

The EU Animal By-Products Regulations forbid the burial of livestock carcasses on land. Farmers would benefit from the availability of biosecure and economically viable alternatives for storing and disposing of dead animals. We assessed the efficacy of bioreduction vessels as a mechanism of storing and reducing the volume of fallen livestock prior to ultimate disposal. Two experimental scenarios were tested: (1) a single input of 300 kg of dead sheep with no further inputs for 3 months, and (2) a continuous 'on-farm' addition of dead sheep over 12 months (ca. 2-3t animals vessel(-1)). The trials involved half-filling the vessels with water, addition of the dead sheep with subsequent heating (40 degrees C) and aeration of the liquor. Each trial was repeated three times. Our results showed a complete biodigestion and liquefaction of the animals alongside a significant bioreduction in the volume of the liquid. No pathogens could be detected in either the waste or the gaseous emissions. Calculations showed that bioreduction may offer significant long-term savings for farmers in terms of animal disposal costs. Our findings suggest that bioreduction may offer a practical, biosecure, and cost-effective method of storing fallen livestock prior to disposal via rendering or incineration.

In this study, a short pre-aeration step was investigated as pre-treatment for thermophilic anaerobic digestion of the organic fraction of municipal solid waste (OFMSW). It was found that pre-aeration of 48 h generated enough biological heat to increase the temperature of bulk OFMSW to 60 degrees C. This was sufficient self-heating of the bulk OFMSW for the start-up of thermophilic anaerobic digestion without the need for an external heat source. Pre-aeration also reduced excess easily degradable organic compounds in OFMSW, which were the common cause of acidification during the start-up of the batch system. Careful consideration however must be taken to avoid over aeration as this consumes substrate, which would otherwise be available to methanogens to produce biogas. To accelerate methane production and volatile solids destruction, the anaerobic digestion in this study was operated as a wet process with the anaerobic liquid recycled through the OFMSW. Appropriate anaerobic liquid inoculum was found to be particularly beneficial. It provided high buffer capacity as well as suitable microbial inoculum. As a result, acidification during start-up was kept to a minimum. With volatile fatty acids (VFAs-acetate in particular) and H2 accumulation typical of hydrolysis and fermentation of the easily degradable substrates during start-up, inoculum with high numbers of hydrogenotrophic methanogens was critical to not only maximise CH4 production but also reduce H2 partial pressure in the system to allow VFAs degradation. In a lab-scale bioreactor, the combined pre-aeration and wet thermophilic anaerobic digestion was able to stabilise the OFMSW within a period of only 12 days. The stabilised inert residual material can be used as a soil amendment product.

The electricity generation, electrochemical and microbial characteristics of five microbial fuel cells (MFCs) with different three-dimensional electrodes (graphite and carbon felt, 2mm and 5mm graphite granules and graphite wool) was examined in relation to the applied loading rate and the external resistance. The graphite felt electrode yielded the highest maximum power output amounting up to 386Wm(-3) total anode compartment (TAC). However, based on the continuous current generation, limited differences between the materials were registered. Doubling the loading rate to 3.3gCODL(-1)TACd(-1) resulted only in an increased current generation when the external resistance was low (10.5-25 Omega) or during polarization. Conversely, lowering the external resistance resulted in a steady increase of both the kinetic capacities of the biocatalyst and the continuous current generation from 77 (50 Omega) up to 253 (10.5 Omega)Am(-3)TAC. Operating a MFC at an external resistance close to its internal resistance, allows to increase the current generation from enhanced loading rates while maximizing the power generation.

Calibration model using near-infrared reflectance spectroscopy (NIRS) for estimation of SCO content in solid-state fermented mass was established. The NIRS calibration model was derived by partial least-squares (PLS) regression and prediction of SCO contents of independent solid-state fermented mass samples fermented by different oleaginous fungi showed the model to be rapid and accurate, giving R(2)-value higher than 0.9552 and root mean standard error of prediction (RMSEP) value lower than 0.5772%. The established NIRS calibration model could be used to estimate the SCO contents of the solid-state fermented masses and will provide much convenience to the research of SCO production in solid-state fermentation.

A procedure was proposed to mimic marine microbial fuel cell (MFC) in liquid phase. A graphite anode and a stainless steel cathode which have been proven, separately, to be efficient in MFC were investigated. A closed anodic compartment was inoculated with sediments, filled with deoxygenated seawater and fed with milk to recover the sediment's sulphide concentration. A stainless steel cathode, immersed in aerated seawater, used the marine biofilm formed on its surface to catalyze oxygen reduction. The cell implemented with a 0.02m(2)-graphite anode supplied around 0.10W/m(2) for 45 days. A power of 0.02W/m(2) was obtained after the anode replacement by a 0.06m(2)-stainless steel electrode. The cell lost its capacity to make a motor turn after one day of operation, but recovered its full efficiency after a few days in open circuit. The evolution of the kinetic properties of stainless steel was identified as responsible for the power limitation.

In this study a pilot-scale membrane bioreactor (MBR) and a conventional activated sludge plant (CASP), treating the same tannery wastewaters and in the same operating conditions, have been compared in order to evaluate the overall treatment efficiency, the presence and distribution of Gram negative bacteria and the kinetics of nitrifying bacteria. Process efficiency was evaluated in terms of organic and nitrogen compounds: the MBR showed a higher COD removal (+4%) and a more stable and complete nitrification. The Gram negative bacteria were detected by fluorescent in situ hybridization (FISH) with phylogenetic probes monitoring of alpha-, beta- and gamma-Proteobacteria, of the main ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria of the Nitrobacter and Nitrospira genera. The results showed that the main differences between the two sludges were: the higher abundance of alpha- and gamma-Proteobacteria in the MBR bioreactor and the presence of AOB aggregates only on the surfaces of MBR flocs. Finally, the titrimetric (pH-stat, DO-stat) tests showed similar values of the kinetic parameters of the nitrifiers both in MBR and CASP sludge.

In this study, cellulose hydrolysis activity of two mixed bacterial consortia (NS and QS) was investigated. Combination of NS culture and BHM medium exhibited better hydrolytic activity under the optimal condition of 35 degrees C, initial pH 7.0, and 100rpm agitation. The NS culture could hydrolyze carboxymethyl cellulose (CMC), rice husk, bagasse and filter paper, among which CMC gave the best hydrolysis performance. The CMC hydrolysis efficiency increased with increasing CMC concentration from 5 to 50g/l. With a CMC concentration of 10g/l, the total reducing sugar (RS) production and the RS producing rate reached 5531.0mg/l and 92.9mg/l/h, respectively. Furthermore, seven H2-producing bacterial isolates (mainly Clostridium species) were used to convert the cellulose hydrolysate into H2 energy. With an initial RS concentration of 0.8g/l, the H2 production and yield was approximately 23.8ml/l and 1.21mmol H2/g RS (0.097mmol H2/g cellulose), respectively.

A new method was developed for a simple non-destructive characterization of bacterial mass in flow systems. Results of partition and transport experiments showed that adsorption of a CAT molecule into the cellular mass resulted in its retardation during flow, which was a good measure of the biomass quantity and distribution. Three dyes, acridine orange (AO), toluidine blue (TB), and safranin O (SO), were chosen as CATs to demonstrate their utility to quantitatively characterize the biomass, its location and morphology in flow system. The results clearly demonstrated the applicability of AO, TB, and SO as cellular absorptive tracers in columnar flow experiments.

Biofilm processes are commonly used for nitrification. Operationally, a whitish heterotrophic biofilm layer tends to develop onto nitrifying biofilm when it has been exposed to organic carbon-containing wastewater for a prolonged period. The development of a heterotrophic biofilm layer could lead to deterioration in nitrification activities and biofilm morphology. The recovery characteristics, in terms of biofilm morphology and nitrification activities, of deteriorated biofilm particles (i.e. nitrifying biofilm particles covered with heterotrophic outgrowth) were investigated by transferring the deteriorated biofilm particles (from an Ultra-Compact Biofilm Reactor (UCBR) which was part of a packed bed-UCBR system used for treating organic carbon and ammonia-containing wastewater) to a UCBR fed solely with ammonia wastewater (referred to as 'Recovery-UCBR'). At a hydraulic retention time (HRT) of 8.7 h and a sand-carrier concentration of 4.0% (v/v), density of the outer heterotrophic biofilm layer reduced progressively which led to subsequent detachment of this layer from the nitrifying biofilm particles. As a result, morphology of the nitrifying biofilm improved gradually in the Recovery-UCBR. A stable nitrification rate of up to 1.74 kg NH4+-N/m3 d was obtained in the Recovery-UCBR.