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In order to understand the inhibitory mechanism of metabolic uncoupler in biofilm, this study investigated the effect of TCS on B. subtilis biofilm formation, flocculability, surface characteristics and thermodynamic properties. An optimal concentration of TCS, a metabolic uncoupler, was observed to substantially inhibit biofilm formation and the secretion of extracellular polymeric substances (EPS). The effect of TCS on the zeta potential and flocculability of bacterial suspension implied the addition of 100 μg L -1 TCS increased the net negative charge of cell surface which induced the reduction of B. subtilis flocculability. Meanwhile, the effects of TCS on bacterial surfacial thermodynamic properties were analyzed by the Derjaguin-Landau-Verwey-Overbeek (DLVO) and extend DLVO (XDLVO) theories. As DLVO and XDLVO predicted, the primary energy barrier between bacterial cells incubated with 100 μg L -1 TCS were increased compared to that of control, indicating that B. subtilis incubated with 100 μg L -1 TCS must consume more energy to aggregate or form biofilm., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Commercialization of microalgal cultivation has been well realized in recent decades with the use of effective strains that can yield the target products, but it is still challenged by the high costs arising from mass production, harvesting, and further processing. Recently, more interest has been directed towards the utilization of waste resources, such as sludge digestate, to enhance the economic feasibility and sustainability of microalgae production. Anaerobic digestion for waste disposal and phototrophic microalgal cultivation are well-characterized technologies in both fields. However, integration of anaerobic digestion and microalgal cultivation to achieve substantial economic and environmental benefits is extremely limited, and thus deserves more attention and research effort. In particular, combining these two makes possible an ideal 'waste biorefinery' model, as the C/N/P content in the anaerobic digestate can be used to produce microalgal biomass that serves as feedstock for biofuels, while biogas upgrading can simultaneously be performed by phototrophic CO 2 fixation during microalgal growth. This review is thus aimed at elucidating recent advances as well as challenges and future directions with regard to waste biorefineries associated with the integration of anaerobic waste treatment and microalgal cultivation for bioenergy production., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Synergistic system of dark fermentation and algal culture was initially operated at batch mode to investigate the energy production and nutrients removal from molasses wastewater in butyrate-type, ethanol-type and propionate-type fermentations. Butyrate-type fermentation was the most appropriate fermentation type for the synergistic system and exhibited the accumulative hydrogen volume of 658.3 mL L -1 and hydrogen yield of 131.7 mL g -1 COD. By-products from dark fermentation (mainly acetate and butyrate) were further used to cultivate oleaginous microalgae. The maximum algal biomass and lipid content reached 1.01 g L -1 and 38.5%, respectively. In continuous operation, the synergistic system was stable and efficient, and energy production increased from 8.77 kJ L -1  d -1 (dark fermentation) to 17.3 kJ L -1  d -1 (synergistic system). Total COD, TN and TP removal efficiencies in the synergistic system reached 91.1%, 89.1% and 85.7%, respectively. This study shows the potential of the synergistic system in energy recovery and wastewater treatment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In this study, a novel method to treat the persulfate-ZVI dewatered WAS by producing a magnetic biochar as an environmentally friendly biosorbent (nZVI-WSBC) to remove heavy metals (HMs) from wastewaters was proposed. The nZVI-WSBC exhibited good adsorption property of Pb 2+ and the adsorption isotherm data were fitted well to Langmuir isotherm. Corresponding reaction kinetics fitted well with the pseudo second-order adsorption model. Notably, nZVI-WSBC was successfully used for efficient removal of HMs from real. This study comprehensively demonstrates the mechanisms between Pb 2+ and nZVI-WSBC surfaces, providing a breakthrough in making a sustainable biosorbent from the dewatered iron-containing WAS., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Commercial production of polystyrene (PS) -a persistent plastic that is not biodegradable at appreciable rates in most environments-has led to its accumulation as a major contaminant of land, rivers, lakes, and oceans. Recently, however, an environment was identified in which PS is susceptible to rapid biodegradation: the larval gut of Tenebrio molitor Linnaeus (yellow mealworms). In this study, we evaluate PS degradation capabilities of a previously untested strain of T. molitor and assess its survival and PS biodegradation rates for a range of conditions (two simulated food wastes, three temperatures, seven PS waste types). For larvae fed PS alone, the %PS removed in the short (12-15 h) residence time of the mealworm gut gradually increased for 2-3 weeks then stabilized at values up to 65%. Thirty two-day survival rates were >85% versus 54% for unfed larvae. For mealworms fed ∼10% w/w PS and ∼90% bran, an agricultural byproduct, rates of PS degradation at 25 °C nearly doubled compared to mealworms fed PS alone. Polymer residues in the frass showed evidence of partial depolymerization and oxidation. All of the tested PS wastes degraded, with the less dense foams degrading most rapidly. Mealworms fed bran and PS completed all life cycle stages (larvae, pupae, beetles, egg), and the second generation had favorable PS degradation, opening the door for selective breeding., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Biobutanol is gaining more attention as a potential alternative to ethanol, and the demand for fermentative biobutanol production has renewed interest. The main challenge faced in biobutanol production is the availability of feedstock. Using conventional agricultural biomass as feedstock is controversial and less efficient, while microalgae, the third generation feedstock, are considered promising feedstock for biobutanol production due to their high growth rate and high carbohydrates content. This review is primarily focused on biobutanol production by using carbohydrate-rich microalgal feedstock. Key technologies and challenges involved in producing butanol from microalgae are discussed in detail and future directions are also presented., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The properties of biochar derived from waste activated sludge and anaerobic digestion sludge under pyrolysis temperature varying from 400°C to 800°C were investigated. The heavy metals adsorption efficiency of the sludge-derived biochar was also examined. Among the biochar samples tested, ADSBC600 possessing highly porous structure, special surface chemical behaviors and high thermal stability was found to remove Pb 2+ from aqueous solutions efficiently with an adsorption capacity of 51.20mg/g. The Pb 2+ adsorption kinetics and isotherm for ADSBC600 can be described using the pseudo second-order model and Langmuir isotherm, respectively. Analysis of the characteristics of biochar before and after metal treatment suggests that electrostatic attraction, precipitation, surface complexation and ion exchange are the possible Pb 2+ removal mechanisms. This study demonstrates a successful example of waste refinery by converting anaerobic digestion sludge to feasible heavy metal adsorbents to implement the concept of circular economy., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: The light/dark cycle is one of the most important factors affecting the microalgal growth and lipid accumulation. Biomass concentration and lipid productivity could be enhanced by optimization of light/dark cycles, and this is considered an effective control strategy for microalgal cultivation. Currently, most research on effects of light/dark cycles on algae is carried out under autotrophic conditions and little information is about the effects under mixotrophic cultivation. At the same time, many studies related to mixotrophic cultivation of microalgal strains, even at large scale, have been performed to obtain satisfactory biomass and lipid production. Therefore, it is necessary to investigate cellular metabolism under autotrophic and mixotrophic conditions at different light/dark cycles. Even though microalgal lipid production under optimal environmental factors has been reported by some researchers, the light/dark cycle and temperature are regarded as separate parameters in their studies. In practical cases, light/dark cycling and temperature variation during the day occur simultaneously. Therefore, studies about the combined effects of light/dark cycles and temperature variation on microalgal lipid production are of practical value, potentially providing significant guidelines for large-scale microalgal cultivation under natural conditions., Results: In this work, cell growth and lipid accumulation of an oleaginous microalgal mutant, Scenedesmus sp. Z-4, were investigated at five light/dark cycles (0 h/24 h, 8 h/16 h, 12 h/12 h, 16 h/8 h, and 24 h/0 h) in batch culture. The results showed that the optimal light/dark cycle was 12 h/12 h, when maximum lipid productivity rates of 56.8 and 182.6 mg L -1  day -1 were obtained under autotrophic and mixotrophic cultivation, respectively. Poor microalgal growth and lipid accumulation appeared in the light/dark cycles of 0 h/24 h and 24 h/0 h under autotrophic condition. Prolonging the light duration was unfavorable to the production of chlorophyll a and b, which was mainly due to photooxidation effect. Polysaccharide was converted into lipid and protein when the light irradiation time increased from 0 to 12 h; however, further increasing irradiation time had a negative effect on lipid accumulation. Due to the dependence of autotrophically cultured cells on light energy, the light/dark cycle has a more remarkable influence on cellular metabolism under autotrophic conditions. Furthermore, the combined effects of temperature variation and light/dark cycle of 12 h/12 h on cell growth and lipid accumulation of microalgal mutant Z-4 were investigated under mixotrophic cultivation, and the results showed that biomass was mainly produced at higher temperatures during the day, and a portion of biomass was converted into lipid under dark condition., Conclusions: The extension of irradiation time was beneficial to biomass accumulation, but not in favor of lipid production. Even though effects of light/dark cycles on autotrophic and mixotrophic cells were not exactly the same, the optimal lipid productivities of Scenedesmus sp. Z-4 under both cultivation conditions were achieved at the light/dark of 12 h/12 h. This may be attributed to its long-term acclimation in natural environment. By combining temperature variation with optimal light/dark cycle of 12 h/12 h, this study will be of great significance for practical microalgae-biodiesel production in the outdoor conditions.

Mycelia pellets were employed as biological carrier in a continuous stirred tank reactor to reduce biomass washout and enhance hydrogen production from cornstalk hydrolysate. Hydraulic retention time (HRT) and influent substrate concentration played critical roles on hydrogen production of the bioreactor. The maximum hydrogen production rate of 14.2mmol H 2 L -1 h -1 was obtained at optimized HRT of 6h and influent concentration of 20g/L, 2.6 times higher than the counterpart without mycelia pellets. With excellent immobilization ability, biomass accumulated in the reactor and reached 1.6g/L under the optimum conditions. Upon further energy conversion analysis, continuous hydrogen production with mycelia pellets gave the maximum energy conversion efficiency of 17.8%. These results indicate mycelia pellet is an ideal biological carrier to improve biomass retention capacity of the reactor and enhance hydrogen recovery efficiency from lignocellulosic biomass, and meanwhile provides a new direction for economic and efficient hydrogen production process., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A new pretreatment method based on tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide was tried to enhance sludge disintegration, and improved sludge biodegradability and subsequent volatile fatty acid (VFA) production. Sludge activity decreased to less than 10% after 2 days pretreatment using 20mg/g-TSS THPS, which also obviously destroyed EPS and cell membrane, and dissolved more biodegradable substances (48.8%) than raw sludge (19.7%). Moreover, 20mg/g-TSS THPS pretreatment shortened fermentation time to 4days and improved VFA production to 2778mg COD/L (4.35 times than that in control). Therein, the sum of n-butyric, n-valeric and iso-valeric acids unexpectedly accounted for 60.5% of total VFA (only 20.1% of that in control). The more high molecular weight VFAs (C4-C5) than low molecular VFAs (C2-C3) resulted from THPS pretreatment benefited to subsequent medium-chain volatile acids (C6-C12) generation to realize the separation and recovery of organic carbon more efficiently., (Copyright © 2017. Published by Elsevier Ltd.)

The success of denitrifying sulfide removal (DSR) processes, which simultaneously degrade sulfide, nitrate and organic carbon in the same reactor, counts on synergetic growths of autotrophic and heterotrophic denitrifiers. Feeding wastewaters at high C/N ratio would stimulate overgrowth of heterotrophic bacteria in the DSR reactor so deteriorating the growth of autotrophic denitrifiers. The DSR tests at C/N=1.26:1, 2:1 or 3:1 and S/N =5:6 or 5:8 under anaerobic (control) or micro-aerobic conditions were conducted. Anaerobic DSR process has <50% sulfide removal with no elemental sulfur transformation. Under micro-aerobic condition to remove <5% sulfide by chemical oxidation pathway, 100% sulfide removal is achieved by the DSR consortia. Continuous-flow tests under micro-aerobic condition have 70% sulfide removal and 55% elemental sulfur recovery. Trace oxygen enhances activity of sulfide-oxidizing, nitrate-reducing bacteria to accommodate properly the wastewater with high C/N ratios., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This paper presents the results of an extended ASM2 model for the modeling and calibration of the role of extracellular polymeric substances (EPS) in phosphorus (P) removal in an anaerobic-aerobic process. In this extended ASM2 model, two new components, the bound EPS (X EPS ) and the soluble EPS (S EPS ), are introduced. Compared with the ASM2, 7.71, 8.53, and 9.28% decreases in polyphosphate (polyP) were observed in the extended ASM2 in three sequencing batch reactors feeding with different COD/P ratios, indicating that 7.71-9.28% of P in the liquid was adsorbed by EPS. Sensitive analysis indicated that, five parameters were the significant influential parameters and had been chosen for further model calibration by using the least square method to simulate by MATLAB. This extended ASM2 has been successfully established to simulate the output variables and provides a useful reference for the mathematic simulations of the role of EPS in biological phosphorus removal process., (Copyright © 2017. Published by Elsevier Ltd.)

Integrated simultaneous desulfurization and denitrification (ISDD) process has proven to be feasible for the coremoval of sulfate, nitrate, and chemical oxygen demand (COD). In this study, we aimed to reveal the microbial community dynamics in the ISDD process with different influent nitrate (NO 3 - ) concentrations. For all tested scenarios, full denitrification was accomplished while sulfate removal efficiency decreased along with increased influent NO 3 - concentrations. The proportion of S 0 to influent SO 4 2- maintained a low level (5.6-17.0%) regardless of the increased influent NO 3 - concentrations. Microbial community analysis results showed that higher influent NO 3 - concentrations affected the microbial community structure greatly. Phyla Proteobacteria, Spirochaetae, Firmicutes, Synergistetes, and Chloroflexi dominated in all the community compositions, of which Proteobacteria exhibited a clear difference among eight microbial samples. Members of δ-Proteobacteria, with 16S rRNA gene sequences related to Desulfobulbus, were clearly decreased at influent NO 3 -  = 3000 and 3500 mg/L, suggesting an inhibitory effect of NO 3 - on sulfate reduction. In contrast, as influent NO 3 - concentration increased, microbial community was notably enriched in γ-Proteobacteria and ε-Proteobacteria, which revealed the enrichment of 16S rRNA gene sequences related to Pseudomonas (γ-Proteobacteria), and Arcobacteria and Sulfurospirillum (ε-Proteobacteria)., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Although outdoor cultivation systems have been widely used for mass production of microalgae at a relatively low cost, there are still limited efforts on outdoor cultivation of carbohydrate-rich microalgae that were further used as feedstock for fermentative bioethanol production. In particular, the effects of seasonal changes on cell growth, CO 2 fixation, and carbohydrate production of the microalgae have not been well investigated., Results: This work demonstrates the feasibility of using outdoor tubular photobioreactors (PBR) for whole-year-round cultivation of a carbohydrate-rich microalga Scenedesmus obliquus CNW-N in southern Taiwan. Time-course profile of the carbohydrate content under nitrogen-deficient conditions was monitored to assess the seasonal changes. The optimal CO 2 fixation rate and carbohydrate productivity were 430.2 mg L -1 d -1 and 111.8 mg L -1 d -1 , respectively, which were obtained during the summer time. Under nitrogen starvation, the microalgal biomass can accumulate nearly 45-50% of carbohydrates, mainly composed of glucose that accounted for 70-80% of the total carbohydrates in the microalgal cells. This glucose-rich microalgal biomass is apparently a very suitable carbon source for bioethanol fermentation., Conclusion: This work shows the feasibility of combining CO 2 fixation and bioethanol production using microalgae grown in outdoor photobioreactors as feedstock. The understanding of the seasonal changes in the carbohydrate productivity makes this approach more practically viable. The novel strategy proposed in this study could be a promising alternative to the existing technology dealing with CO 2 mitigation and biofuels production.

In this paper, we report air concentrations of BDE-209 in both gas- and particle-phases across China. The annual mean concentrations of BDE-209 were from below detection limit (BDL) to 77.0 pg·m -3 in the gas-phase and 1.06-728 pg·m -3 in the particle-phase. Among the nine PBDEs measured, BDE-209 is the dominant congener in Chinese atmosphere in both gas and particle phases. We predicted the partitioning behavior of BDE-209 in air using our newly developed steady state equation, and the results matched the monitoring data worldwide very well. It was found that the logarithm of the partition quotient of BDE-209 is a constant, and equal to -1.53 under the global ambient temperature range (from -50 to +50 °C). The gaseous fractions of BDE-209 in air depends on the concentration of total suspended particle (TSP). The most important conclusion derived from this study is that, BDE-209, like other semivolatile organic compounds (SVOCs), cannot be sorbed entirely to atmospheric particles; and there is a significant amount of gaseous BDE-209 in global atmosphere, which is subject to long-range atmospheric transport (LRAT). Therefore, it is not surprising that BDE-209 can enter the Arctic through LRAT mainly by air transport rather than by particle movement. This is a significant advancement in understanding the global transport process and the pathways entering the Arctic for chemicals with low volatility and high octanol-air partition coefficients, such as BDE-209.

A mathematical model of carbon, nitrogen and sulfur removal (C-N-S) from industrial wastewater was constructed considering the interactions of sulfate-reducing bacteria (SRB), sulfide-oxidizing bacteria (SOB), nitrate-reducing bacteria (NRB), facultative bacteria (FB), and methane producing archaea (MPA). For the kinetic network, the bioconversion of C-N by heterotrophic denitrifiers (NO 3 - →NO 2 - →N 2 ), and that of C-S by SRB (SO 4 2- →S 2- ) and SOB (S 2- →S 0 ) was proposed and calibrated based on batch experimental data. The model closely predicted the profiles of nitrate, nitrite, sulfate, sulfide, lactate, acetate, methane and oxygen under both anaerobic and micro-aerobic conditions. The best-fit kinetic parameters had small 95% confidence regions with mean values approximately at the center. The model was further validated using independent data sets generated under different operating conditions. This work was the first successful mathematical modeling of simultaneous C-N-S removal from industrial wastewater and more importantly, the proposed model was proven feasible to simulate other relevant processes, such as sulfate-reducing, sulfide-oxidizing process (SR-SO) and denitrifying sulfide removal (DSR) process. The model developed is expected to enhance our ability to predict the treatment of carbon-nitrogen-sulfur contaminated industrial wastewater., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Lipid/carbohydrate content and ratio are extremely important when engineering algal cells for liquid biofuel production. However, conventional methods for such determination and quantification are not only destructive and tedious, but also energy consuming and environment unfriendly. In this study, we first demonstrate that Raman spectroscopy is a clean, fast, and accurate method to simultaneously quantify the lipid/carbohydrate content and ratio in living microalgal cells., Results: The quantification results of both lipids and carbohydrates obtained by Raman spectroscopy showed a linear correspondence with that obtained by conventional methods, indicating Raman can provide a similar accuracy to conventional methods, with a significantly shorter detection time. Furthermore, the subcellular resolution of Raman spectroscopy enabled not only the concentration mapping of lipid/carbohydrate content in single living cells, but also the evaluation of standard deviation between the biomass accumulation levels of individual algal cells., Conclusions: In this study, we first demonstrate that Raman spectroscopy can be used for starch quantification in addition to lipid quantification in algal cells. Due to the easiness and non-destructive nature of Raman spectroscopy, it makes a perfect tool for the further study of starch-lipid shift mechanism.

VFA production from excess sludge (ES) was greatly enhanced by a low-cost and high-efficient treatment: 0.67mg/L free nitrous acid (FNA) pretreatment combined with 0.04g/g TSS rhamnolipid (RL) addition (FNA+RL), which significantly shortened fermentation time to 3days and increased VFA production to 352.26mgCOD/g VSS (5.42 times higher than raw ES). Propionic and acetic acids were the two leading components (71.86% of the total VFA). Mechanism investigation manifested FNA+RL improved the biodegradability of ES, achieved positive synergetic effect on solubilization, hydrolysis and acidification efficiencies, and inhibited methanation. Microbial community distribution further explained the above phenomena. The bacteria related to polysaccharides/protein utilization and VFA generation, including Clostridium, Megasphaera and Proteiniborus, were mainly observed in FNA+RL, whereas gas-forming bacteria Anaerolineae and acid-consuming bacteria Proteobacteria were assuredly suppressed. Besides, Propionibacterineae associated with propionic acid generation was exclusively enriched in sole RL and FNA+RL., (Copyright © 2016. Published by Elsevier Ltd.)

The aim of this study is to evaluate the feasibility of using lipid-accumulating microalgae to remove cephalosporin antibiotics 7-amino cephalosporanic acid (7-ACA) from wastewater with the additional benefit of biofuels production. Three isolated microalgal strains (namely, Chlorella sp. Cha-01, Chlamydomonas sp. Tai-03 and Mychonastes sp. YL-02) were cultivated under 7-ACA stress and their biomass productivity, lipid production and N-NO 3 - consumption were monitored. It was found that 7-ACA had slight inhibition effects on the microalgal growth at the ratio of 12.0% (Cha-01), 9.6% (YL-02), 11.7% (Tai-03). However, lipid accumulation in the three microalgae was not influenced by the presence of 7-ACA. The investigation on the 7-ACA removal mechanisms during microalgal growth shows that 7-ACA was mainly removed by microalgae adsorption as well as hydrolysis and photolysis reactions. This study demonstrates that using microalgae to treat antibiotic-containing wastewater is promising due to the potential of simultaneous antibiotic removal and biofuel production., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Poor flocculation of photo fermentative bacteria resulting in continuous biomass washout from photobioreactor is a critical challenge to achieve rapid and stable hydrogen production. In this work, the aggregation of Rhodopseudomonas faecalis RLD-53 was successfully developed in a photobioreactor and the effects of different carbon sources on hydrogen production and aggregation ability were investigated. Extracellular polymeric substances (EPS) production by R. faecalis RLD-53 cultivated using different carbon sources were stimulated by addition of L-cysteine. The absolute ζ potentials of R. faecalis RLD-53 were considerably decreased with addition of L-cysteine, and aggregation barriers based on DLVO dropped to 15-43 % of that in control groups. Thus, R. faecalis RLD-53 flocculated effectively, and aggregation abilities of strain RLD-53 cultivated with acetate, propionate, lactate and malate reached 29.35, 32.34, 26.07 and 24.86 %, respectively. In the continuous test, hydrogen-producing activity was also promoted and reached 2.45 mol H 2 /mol lactate, 3.87 mol H 2 /mol propionate and 5.10 mol H 2 /mol malate, respectively. Therefore, the aggregation of R. faecalis RLD-53 induced by L-cysteine is independent on the substrate types, which ensures the wide application of this technology to enhance hydrogen recovery from wastewater dominated by different organic substrates.

Although microalgae can serve as an appropriate alternative feedstock for biofuel production, the high microalgal cultivation cost has been a major obstacle for commercializing such attempts. One of the feasible solution for cost reduction is to couple microalgal biofuel production system with wastewater treatment, as microalgae are known to effectively eliminate a variety of nutrients/pollutants in wastewater, such as nitrogen/phosphate, organic carbons, VFAs, pharmaceutical compounds, textile dye compounds, and heavy metals. This review aims to critically discuss the feasibility of microalgae-based wastewater treatment, including the strategies for strain selection, the effect of wastewater types, photobioreactor design, economic feasibility assessment, and other key issues that influence the treatment performance. The potential of microalgae-bacteria consortium for treatment of industrial wastewaters is also discussed. This review provides useful information for developing an integrated wastewater treatment with microalgal biomass and biofuel production facilities and establishing efficient co-cultivation for microalgae and bacteria in such systems., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Waste biorefinery aims to maximize the output of value-added products from various artificial/agricultural wastes by using integrated bioprocesses. To make waste biorefinery economically feasible, it is thus necessary to develop a low-cost, environment-friendly technique to perform simultaneous biodegradation and bioconversion of waste materials. Cell-surface display engineering is a novel, cost-effective technique that can auto-immobilize proteins on the cell exterior of microorganisms, and has been applied for use with waste biofinery. Through tethering different enzymes (e.g., cellulase, lipase, and protease) or metal-binding peptides on cell surfaces, various yeast strains can effectively produce biofuels and biochemicals from sugar/protein-rich waste materials, catalyze waste oils into biodiesels, or retrieve heavy metals from wastewater. This review critically summarizes recent applications of yeast cell-surface display on various types of waste biorefineries, highlighting its potential and future challenges with regard to commercializing this technology., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

With the increasing energy crisis and rising concern over climate change, the development of clean alternative energy sources is of great importance. Biohydrogen produced from lignocellulosic biomass is a promising candidate, because of its positives such as readily available, no harmful emissions, environment friendly, efficient, and renewable. However, obstacles still exist to enable the commercialization of biological hydrogen production from lignocellulosic biomass. Thus the objective of this work is to provide update information about the recent progress on lignocellulosic hydrogen conversion via dark fermentation. In this review, the most important technologies associated with lignocellulosic hydrogen fermentation were covered. Firstly, pretreatment methods for better utilization of lignocellulosic biomass are presented, at the same time, hydrolysis methods assisting to achieve efficient hydrogen fermentation were discussed. Afterwards, issues related to bioprocesses for hydrogen production purposes were presented. Additionally, the paper gave challenges and new insights of lignocellulosic biohydrogen production., (Copyright © 2016. Published by Elsevier Ltd.)

The study provided a cost-effective and high-efficiency volatile fatty acid (VFA) production strategy by co-fermentation of food waste (FW) and excess sludge (ES) without artificial pH control. VFA production of 867.42mg COD/g-VS was obtained under the optimized condition: FW/ES 5, solid retention time 7d, organic loading rate 9g VS/L-d and temperature 40°C. Mechanism exploration revealed that the holistic biodegradability of substrate was greatly enhanced, and proper pH range (5.2-6.4) was formed by the high buffering capacity of the co-fermentation system itself, which effectively enhanced hydrolysis yield (63.04%) and acidification yield (83.46%) and inhibited methanogenesis. Moreover, microbial community analysis manifested that co-fermentation raised the relative abundances of hydrolytic and acidogenic bacteria including Clostridium, Sporanaerobacter, Tissierella and Bacillus, but suppressed the methanogen Anaerolineae, which also facilitated high VFA production. These results were of great guiding significance aiming for VFA recovery from FW and ES in large-scale., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Biofuels from microalgae is now a hot issue of great potential. However, achieving high starch productivity with photoautotrophic microalgae is still challenging. A feasible approach to enhance the growth and target product of microalgae is to conduct mixotrophic cultivation. The appropriate acetate addition combined with CO2 supply as dual carbon sources (i.e., mixotrophic cultivation) could enhance the cell growth of some microalgae species, but the effect of acetate-mediated mixotrophic culture mode on carbohydrate accumulation in microalgae remains unclear. Moreover, there is still lack of the information concerning how to increase the productivity of carbohydrates from microalgae under acetate-amended mixotrophic cultivation and how to optimize the engineering strategies to achieve the goal. This study was undertaken to develop an optimal acetate-contained mixotrophic cultivation system coupled with effective operation strategies to markedly improve the carbohydrate productivity of Chlorella sorokiniana NIES-2168. The optimal carbohydrate productivity of 695 mg/L/d was obtained, which is the highest value ever reported. The monosaccharide in the accumulated carbohydrates is mainly glucose (i.e., 85-90%), which is very suitable for bio-alcohols fermentation. Hence, by applying the optimal process developed in this study, C. sorokiniana NIES-2168 has a high potential to serve as a feedstock for subsequent biofuels conversion., (Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Waste activated sludge is a valuable resource containing multiple nutrients, but is currently treated and disposed of as an important source of pollution. In this work, waste activated sludge after ultrasound pretreatment was reused as multiple nutrients for biofuel production. The nutrients trapped in sludge floc were transferred into liquid medium by ultrasonic disintegration during first 30 min, while further increase of pretreatment time only resulted in slight increase of nutrients release. Hydrogen production by Ethanoligenens harbinense B49 from glucose significantly increased with the concentration of ultrasonic sludge, and reached maximum yield of 1.97 mol H2/mol glucose at sludge concentration of 7.75 g volatile suspended solids/l. Without addition of any other chemicals, waste molasses rich in carbohydrate was efficiently turned into hydrogen with yield of 189.34 ml H2/g total sugar by E. harbinense B49 using ultrasonic sludge as nutrients. The results also showed that hydrogen production using pretreated sludge as multiple nutrients was higher than those using standard nutrients. Acetic acid produced by E. harbinense B49 together with the residual nutrients in the liquid medium were further converted into hydrogen (271.36 ml H2/g total sugar) by Rhodopseudomonas faecalis RLD-53 through photo fermentation, while ethanol was the sole end product with yield of 220.26 mg/g total sugar. Thus, pretreated sludge was an efficient nutrients source for biofuel production, which could replace the standard nutrients. This research provided a novel strategy to achieve environmental friendly sludge disposal and simultaneous efficient biofuel recovery from organic waste., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Vermiculite is one of matrix material used for constructed wetland (CW) for the treatment of municipal wastewater. Arthrobacter sp. strain C21 (CGMCC No. 7671), isolated from a constructed wetland receiving municipal wastewater, forms biofilm on the surface of vermiculite. Di-(2-ethylhexyl) phthalate (DEHP), a typical phthalate pollutant in environment, can be degraded by the biofilm of strain C21 formed on vermiculite. Results of laboratory studies indicated that DEHP was removed from aqueous phase via biodegradation, adsorption by vermiculite, and adsorption by biofilm biomass. Synergistic effect of these three reactions enhanced the overall DEHP removal efficiency. During a batch incubation test with vermiculite and the cell suspension, bacterial adhesion to the media surface occurred within 5h and the phthalate esters (PEs) removal was due to both biodegradation and vermiculite adsorption. As the biofilm developed on surface of vermiculite (5-36 h), biodegradation became the predominance for PEs removal. As mature biofilm was formed (36-54 h), the adsorption of PEs by biofilm biomass became a main driving force for the removal of PEs from aqueous phase. The content of extracellular polymers (EPS) of the biofilm and DEHP removal performance showed a significant positive correlation (rp>0.86)., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Sulfide biooxidation by the novel sulfide-oxidizing bacteria Pseudomonas sp. C27, which could perform autotrophic and heterotrophic denitrification in mixotrophic medium, was studied in batch and continuous systems. Pseudomonas sp. C27 was able to oxidize sulfide at concentrations as high as 17.66 mM. Sulfide biooxidation occurred in two distinct stages, one resulting in the formation of sulfur with nitrate reduction to nitrite, followed by thiosulfate formation with nitrite reduction to N2. The composition of end-products was greatly impacted by the ratio of sulfide to nitrate initial concentrations. At a ratio of 0.23, thiosulfate represented 100% of the reaction products, while only 30% with a ratio of 1.17. In the continuous bioreactor, complete removal of sulfide was observed at sulfide concentration as high as 9.38 mM. Overall sulfide removal efficiency decreased continuously upon further increases in influent sulfide concentrations. Based on the experimental data kinetic parameter values were determined. The value of maximum specific growth rate, half saturation constant, decay coefficient, maintenance coefficient and yield were to be 0.11 h(-1), 0.68 mM sulfide, 0.11 h(-1), 0.21 mg sulfide/mg biomass h and 0.43 mg biomass/mg sulfide, respectively, which were close to or comparable with those reported in literature by other researches.

Phthalates are widely used in consumer products. People are frequently exposed to phthalates due to their applications in daily life. In this study, 14 phthalate metabolites were analyzed in 108 urine samples collected from Chinese young adults using high-performance liquid chromatography-tandem mass spectrometry. The total concentrations of 14 phthalate metabolites ranged from 71.3 to 2670 ng/mL, with the geometric mean concentration of 306 ng/mL. mBP and miBP were the two most abundant compounds, accounting for 48% of the total concentrations. Principal component analysis suggested two major sources of phthalates: one dominated by the DEHP metabolites and one by the group of mCPP, mBP and miBP metabolites. The estimated daily intakes of DMP, DEP, DBP, DiBP and DEHP were 1.68, 2.14, 4.12, 3.52 and 1.26-2.98 μg/kg-bw/day, respectively. In a sensitivity analysis, urinary concentration and body weight were the most influential variables for human exposure estimation. Furthermore, cumulative risk for hazard quotient (HQ) and hazard index (HI) were evaluated. Nearly half of Chinese young adults had high HI values exceeding the safe threshold. This is the first study on the occurrence and human exposure to urinary phthalate metabolites with Chinese young adults., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Waste-derived acetic acid (HAc) is an attractive feedstock for microbe-mediated biofuel production. However, fermentative conversion of HAc from waste-activated sludge (WAS) has low yield because of the high concentration of proteins not readily utilizable by microorganisms without prior hydrolysis. We investigated a combined technology for HAc augmentation during sludge protein fermentation. The maximal HAc yield increased over two-fold, reaching 0.502 ± 0.021 g/g protein (0.36 ± 0.01 g COD/g COD, ∼52% of the total volatile fatty acids) when synthetic sludge protein was heated at 120 °C for 30 min, treated at pH 12 for 24 h, and fermented at pH 9 for 72 h. Comprehensive analysis illustrated that the heat-alkaline pretreatment significantly induced protein fragmentation, simultaneously increasing the efficiency of protein biohydrolysis (from 35.5% to 85.9%) by inducing conformational changes indicative of protein unfolding. Consequently, the native α-helix content was decreased from 67.3% to 32.5% by conversion to an unordered shape, whose content increased from 27.5% to 45.5%; disulfide bonds were cleaved, whereas the main S-S stretching pattern was altered from gauche-gauche-gauche to gauche-gauche-trans, consequently causing increased protein susceptibility to proteolytic hydrolysis (76.3% vs. 47.0%). Economic analysis indicated that anaerobic fermentation with appropriate heat-alkaline pretreatment is a cost-effective approach for waste conversion to energy sources such as HAc., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Hydrogen recovery through solar-driven biomass conversion by photo-fermentative bacteria (PFB) has been regarded as a promising way for sustainable energy production. However, a considerable fraction of organic substrate was consumed for the growth of PFB as biocatalysts, furthermore, these PFB were continuously washed out from the photobioreactor in continuous operation because of their poor flocculation. In this work, PFB bioaggregate induced by L-cysteine was applied in a sequencing batch photobioreactor to enhance continuous hydrogen production and reduce biomass washout. The effects of the hydraulic retention time (HRT), influent concentration and light intensity on hydrogen production of the photobioreactor were investigated. The maximum hydrogen yield (3.35 mol H2/mol acetate) and production rate (1044 ml/l/d) were obtained at the HRT of 96 h, influent concentration of 3.84 g COD/l, and light intensity of 200 W/m(2). With excellent settling ability, biomass accumulated in the photobioreactor and reached 2.15 g/l under the optimum conditions. Structural analysis of bioaggregate showed that bacterial cells were covered and tightly linked together by extracellular polymeric substances, and formed a stable structure. Therefore, PFB bioaggregate induced by L-cysteine is an efficient strategy to improve biomass retention capacity of the photobioreactor and enhance hydrogen recovery efficiency from organic wastes.

4-Chloronitrobenzene (4-CNB) is one of the highly toxic contaminants that may lead to acute, chronic or persistent physiological toxicity to ecology and environment. Conventional methods for removing 4-CNB from aquatic environment may be problematic due to inefficiency, high cost and low sustainability. This study develops a pilot-scale bioelectrochemical system (BES, effective volume of 18 L) and examines its performance of bioelectrochemical transformation of 4-CNB to 4-chloroaniline (4-CAN) under continuous operation. The results demonstrate that the initial 4-CNB concentration in the influent and hydraulic retention time (HRT) has a significant impact on 4-CNB reduction and 4-CAN formation. Compared with the conventional anaerobic process in the absence of external power supplied, the 4-CNB conversion efficiency can be enhanced with power supplied due to microbial-mediated electron transfer at the negative cathode potential. At a voltage of 0.4 V and HRT of 48 h, the 4-CNB reduction and 4-CAN formation efficiency reached 99% and 94.1%, respectively. Based on a small external voltage applied, the pilot-scale BES is effective in the conversion of 4-CNB to 4-CAN, an intermediate that is of less toxicity and higher bioavailability for subsequent treatment. This study provides a new strategy and methods for eliminating 4-CNB, making wastewater treatment more economical and more sustainable.

In order to investigate the possibility of the normal bioanode and bioanode switched to biocathode for the bio-electrochemical degradation of the antibiotic chloramphenicol (CAP), both the bioanode acclimated with CAP and the biocathode inversed from bioanode were monitored for CAP degradation in the bio-electrochemical system. The results demonstrated that the normal enriched bioanode could simultaneously generate current and degrade CAP (k = 0.098 5, 35 mg x L(-1) of CAP) after a long-term acclimation by gradually increasing the concentration of CAP from 5 mg x L(-1) to 80 mg x L(-1). After switching bioanode to biocathode, the cathode biofilm was still capable of catalyzing CAP degradation, although it was influenced to some extent due to changed electrode potential from -0.20 V to -0.40 V vs. standard hydrogen electrode (SHE). The k of biocathode was 0.264 3, significantly higher than that of abiotic cathode (k = 0.160 9). This mode of biocathode, which was switched from bioanode, not only had the ability of reducing nitro group in CAP but also catalyzed the complete dechloridation and carbanyl group reduction of the side chain of aromatic amine product.

A continuous mixed immobilized sludge reactor (CMISR) using activated carbon as support carrier for dark fermentative hydrogen production from enzymatic hydrolyzed food waste was developed. The effects of immobilized sludge packing ratio (10-20%, v/v) and substrate loading rate (OLR) (8-40kg/m(3)/d) on biohydrogen production were examined, respectively. The hydrogen production rates (HPRs) with packing ratio of 15% were significantly higher than the results obtained from packing ratio of 10% and 20%. The best HPR of 353.9ml/h/L was obtained at the condition of packing ratio=15% and OLR=40kg/m(3)/d. The Minitab was used to elicit the effects of OLR and packing ratio on HPR (Y) which could be expressed as Y=5.31 OLR+296 packing ratio+40.3 (p=0.003). However, the highest hydrogen yield (85.6ml/g food waste) was happened at OLR of 16kg/m(3)/d because of H2 partial pressure and oxidization/reduction of NADH., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Global expectations for wastewater service infrastructure have evolved over time, and the standard treatment methods used by wastewater treatment plants (WWTPs) are facing issues related to problem shifting due to the current emphasis on sustainability. A transition in WWTPs toward reuse of wastewater-derived resources is recognized as a promising solution for overcoming these obstacles. However, it remains uncertain whether this approach can reduce the environmental footprint of WWTPs. To test this hypothesis, we conducted a net environmental benefit calculation for several scenarios for more than 50 individual countries over a 20-y time frame. For developed countries, the resource recovery approach resulted in ∼154% net increase in the environmental performance of WWTPs compared with the traditional substance elimination approach, whereas this value decreased to ∼60% for developing countries. Subsequently, we conducted a probabilistic analysis integrating these estimates with national values and determined that, if this transition was attempted for WWTPs in developed countries, it would have a ∼65% probability of attaining net environmental benefits. However, this estimate decreased greatly to ∼10% for developing countries, implying a substantial risk of failure. These results suggest that implementation of this transition for WWTPs should be studied carefully in different temporal and spatial contexts. Developing countries should customize their approach to realizing more sustainable WWTPs, rather than attempting to simply replicate the successful models of developed countries. Results derived from the model forecasting highlight the role of bioenergy generation and reduced use of chemicals in improving the sustainability of WWTPs in developing countries.

Granulation of biochar powder followed by immobilization of ferric oxides on the macroporous granular biochar (Bg-FO-1) substantially enhanced phosphate removal from water. BET analysis confirmed that both granulation and ferric oxides loading can increase the surface areas and pore volumes effectively. Bg-FO-1 was proven to be a favorable adsorbent for phosphate. The phosphate adsorption capacity was substantially increased from 0 mg/g of raw biochar powder to 0.963 mg/g (Bg-FO-1). When the ferric oxides loading was prior to granulation, the adsorption capacity was decreased by 59-0.399 mg/g, possibly due to the decrease of micropore and mesopore area as well as the overlaying of binders to the activated sites produced by ferric oxides., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

An ozone/ultrasound lysis-cryptic growth technology combining a continuous flow anaerobic-anoxic-microaerobic-aerobic (AAMA+O3/US) system was investigated. Techno-economic evaluation and sludge lyses return ratio (r) optimization of this AAMA+O3/US system were systematically and comprehensively discussed. Economic assessment demonstrated that this AAMA+O3/US system with r of 30% (AAMA+O3/US2# system) was more economically feasible that can give a 14.04% saving of costs. In addition to economic benefits, a 55.08% reduction in sludge production, and respective 21.17% and 5.45% increases in TN and TP removal efficiencies were observed in this AAMA+O3/US2# system. Considering the process performances and economic benefits, r of 30% in AAMA+O3/US2# system was recommended. Excitation-emission matrix and Fourier transform infrared spectra analyses also proved that less refractory soluble microbial products were generated from AAMA+O3/US2# system. Improvement in 2,3,5-triphenyltetrazolium chloride electron transport system (TTC-ETS) activity in AAMA+O3/US2# further indicated that a lower sludge lyses return ratio stimulated the microbial activity., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: Integrating hydrogen-producing bacteria with complementary capabilities, dark-fermentative bacteria (DFB) and photo-fermentative bacteria (PFB), is a promising way to completely recover bioenergy from waste biomass. However, the current coupled models always suffer from complicated pretreatment of the effluent from dark-fermentation or imbalance between dark and photo-fermentation, respectively. In this work, an integrated dark and photo-fermentative reactor (IDPFR) was developed to completely convert an organic substrate into bioenergy., Results: In the IDPFR, Ethanoligenens harbinese B49 and Rhodopseudomonas faecalis RLD-53 were separated by a membrane into dark and photo chambers, while the acetate produced by E. harbinese B49 in the dark chamber could freely pass through the membrane into the photo chamber and serve as a carbon source for R. faecalis RLD-53. The hydrogen yield increased with increasing working volume of the photo chamber, and reached 3.38 mol H2/mol glucose at the dark-to-photo chamber ratio of 1:4. Hydrogen production by the IDPFR was also significantly affected by phosphate buffer concentration, glucose concentration, and ratio of dark-photo bacteria. The maximum hydrogen yield (4.96 mol H2/mol glucose) was obtained at a phosphate buffer concentration of 20 mmol/L, a glucose concentration of 8 g/L, and a ratio of dark to photo bacteria of 1:20. As the glucose and acetate were used up by E. harbinese B49 and R. faecalis RLD-53, ethanol produced by E. harbinese B49 was the sole end-product in the effluent from the IDPFR, and the ethanol concentration was 36.53 mmol/L with an ethanol yield of 0.82 mol ethanol/mol glucose., Conclusions: The results indicated that the IDPFR not only circumvented complex pretreatments on the effluent in the two-stage process, but also overcame the imbalance of growth and metabolic rate between DFB and PFB in the co-culture process, and effectively enhanced cooperation between E. harbinense B49 and R. faecalis RLD-53. Moreover, simultaneous hydrogen and ethanol production were achieved by coupling E. harbinese B49 and R. faecalis RLD-53 in the IDPFR. According to stoichiometry, the hydrogen and ethanol production efficiencies were 82.67% and 82.19%, respectively. Therefore, IDPFR was an effective strategy for coupling DFB and PFB to fulfill efficient energy recovery from waste biomass.

In this research, sulfamethoxazole (SMX) degradation was investigated using ultrasound (US), ozone (O3) and ultrasound/ozone oxidation process (UOOP). It was proved that ultrasound significantly enhanced SMX ozonation by assisting ozone in producing more hydroxyl radicals in UOOP. Ultrasound also made the rate constants improve by kinetics analysis. When ultrasound was added to the ozonation process, the reaction rate increased by 6-26% under different pH conditions. Moreover, main intermediates oxidized by US, O3 and UOOP system were identified. Although the main intermediates in ozonation and UOOP were similar, the introduction of ultrasound in UOOP had well improved the cleavage of S-N bond. In this condition SMX become much easier to be attacked, which led to enhanced SMX removal rate in UOOP compared to the other two examined processes. Finally, the SMX degradation pathways were proposed., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Biological hydrogen production from lignocellulosic biomass shows great potential as a promising alternative to conventional hydrogen production methods, such as electrolysis of water and coal gasification. Currently, most researches on biohydrogen production from lignocellulose concentrate on consolidated bioprocessing, which has the advantages of simpler operation and lower cost over processes featuring dedicated cellulase production. However, the recalcitrance of the lignin structure induces a low cellulase activity, making the carbohydrates in the hetero-matrix more unapproachable. Pretreatment of lignocellulosic biomass is consequently an extremely important step in the commercialization of biohydrogen, and for massive realization of lignocellulosic biomass as alternative fuel feedstock. Thus, development of a pretreatment method which is cost efficient, environmentally benign, and highly efficient for enhanced consolidated bioprocessing of lignocellulosic biomass to hydrogen is essential., Results: In this research, fungal pretreatment was adopted for enhanced hydrogen production by consolidated bioprocessing performance. To confirm the fungal pretreatment efficiency, two typical thermochemical pretreatments were also compared side by side. Results showed that the fungal pretreatment was superior to the other pretreatments in terms of high lignin reduction of up to 35.3% with least holocellulose loss (the value was only 9.5%). Microscopic structure observation combined with Fourier transform infrared spectroscopy (FTIR) analysis further demonstrated that the lignin and crystallinity of lignocellulose were decreased with better holocellulose reservation. Upon fungal pretreatment, the hydrogen yield and hydrogen production rate were 6.8 mmol H2 g(-1) pretreated substrate and 0.89 mmol L(-1) h(-1), respectively, which were 2.9 and 4 times higher than the values obtained for the untreated sample., Conclusions: Results revealed that although all pretreatments could contribute to the enhancement of hydrogen production from cornstalk, fungal pretreatment proved to be the optimal method. It is apparent that besides high hydrogen production efficiency, fungal pretreatment also offered several advantages over other pretreatments such as being environmentally benign and energy efficient. This pretreatment method thus has great potential for application in consolidated bioprocessing performance of hydrogen production.

Two parallel sequence batch reactors (SBRs) were operated, with and without TCS addition, to research the causes of sludge reduction by uncouplers. Three possible mechanisms of sludge reduction by TCS were studied: (1) occurrence of metabolic uncoupling, (2) consumption of more energy to resist the infection of TCS, (3) promotion of lysis-cryptic growth by TCS addition. Results showed the remarkable reduction of electronic transport system (ETS) activity and specific cellular ATP (SATP) in TCS reactor, which proved the occurrence of metabolic uncoupling. The increasing amounts of extracellular polymeric substances (EPS), as measured by chemical methods and excitation-emission matrix (EEM) fluorescence spectra, implied microorganisms consumed more energy to resist TCS. The similar DNA concentrations of the effluents in two reactors indicated sludge lysis was not intensified by TCS. Therefore, uncoupler might not only cause metabolic uncoupling but also induce more energy consumption in the production of some substances to resist uncoupler., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this study, the effects of thermophilic bacteria pretreatment and elevated fermentation temperature on hydrogen production from sludge were examined. The highest hydrogen yield of 19.9mlH2g(-1) VSS was achieved at 55°C by using pretreated sludge, which was 48.6% higher than raw sludge without pretreatment, and 28.39% higher than when fermented at 35°C. To explore the internal factors of this superior hydrogen production performance, the microbial community and the metabolism analysis were performed by using high-throughput sequencing and excitation-emission matrix. The pretreated sludge showed better utilization of dissolved organic matter and less inhibition of metabolism, especially at thermophilic condition. The 454 sequencing data indicated that microbial abundance was distinctly reduced and extremely high proportion of hydrogen-producing bacteria was found in the thermophilic community (Thermoanaerobacterium accounted for 93.75%). Thus, the pretreated sludge and thermophilic condition showed significant advantages in the hydrogen production using waste sludge as substrate., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Effects of Fe(3+) (0-0.12 g/L), Mg(2+) (0-0.73 g/L) and Ca(2+) (0-0.98 g/L) on the biomass and lipid accumulation of heterotrophic microalgae were investigated in dark environment. The biomass and lipid production exhibited an increasing trend with increasing the concentrations of metal ions. In cultures with 1.2 × 10(-3) g/L Fe(3+), 7.3 × 10(-3) g/L Mg(2+) and 9.8 × 10(-4) g/L Ca(2+), the maximum biomass, total lipid content and lipid productivity reached 3.49 g/L, 47.4% and 275.7 mg/L/d, respectively. More importantly, EDTA addition (1.0 × 10(-3) g/L) could enhance the solubility of metal ions (iron and calcium) and increase their availability by microalgae, which evidently promote the lipid accumulation. Compared with the control, the total lipid content and lipid productivity increased 28.2% and 29.7%, respectively. These show that appropriate concentrations of metal ions and EDTA in the culture medium were beneficial to lipid accumulation of heterotrophic Scenedesmus sp. cells., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this study, three novel multi-sparger multi-stage airlift loop membrane bioreactors (Ms(2)ALMBRs) were set up in parallel for treating synthetic high-strength 7-ACA pharmaceutical wastewater under different HRTs, temperatures and pHs, respectively. During the 200-day operating time, average COD removal efficiencies were 94.96%, 96.05% and 93.9%. While average 7-ACA removal efficiencies were 66.44%, 59.04% and 59.60%, respectively. The optimal conditions were 10h, 15-35°C and 7-9 for HRT, temperature and pH, respectively. Moreover, the sludge characteristics and microorganism drug-resistances were explored. Results showed that different temperatures and pHs influenced contaminant removals by affecting MLSS concentration and β-lactamase activity significantly. In addition, mathematical statistical models, built on the polynomial and linear regression techniques, were developed for exploring the inner relationships between HRT, temperature and pH changes and MLSS concentrations, β-lactamase activities and contaminant removals of the Ms(2)ALMBR system., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this study, ethylenediamine tetraacetic acid (EDTA) was investigated as a new kind of non-polymeric catalyst binder to improve interfacial oxygen reduction reaction (ORR) for the cathode of microbial fuel cell (MFC). The electrochemical analysis and MFC tests show negative correlation between ORR activity and molar concentration of EDTA applied during electrode preparation. In particular, the 0.02mol/L-EDTA yields higher ORR activity than other binder materials like Nafion, water, 0.1mol/L-EDTA and 0.2mol/L-EDTA, as indicated by the strongest response of ORR current and the smallest charge-transfer resistance. Accordingly, the MFC with cathode of 0.02mol/L-EDTA produced a maximum power density of 722mW/m(2), accounting for a value approximately 42% higher than that of commercial Nafion binder (5wt%, 507mW/m(2)). The improved ORR activity should be attributed to the enhanced proton transfer from phosphate ions to EDTA-involved three-phase boundary as a result of dipole ion bonds on nitrogen atoms having unshared pair of electrons in EDTA molecule., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Limited-oxygen mediated synergistic relationships between sulfate-reducing bacteria (SRB), nitrate-reducing bacteria (NRB) and sulfide-oxidizing bacteria (SOB, including nitrate-reducing, sulfide-oxidizing bacteria NR-SOB) were predicted to simultaneously remove contaminants of nitrate, sulfate and high COD, and eliminate sulfide generation. A lab-scale experiment was conducted to examine the impact of limited oxygen on these oxy-anions degradation, sulfide oxidation and associated microbial functional responses. In all scenarios tested, the reduction of both nitrate and sulfate was almost complete. When limited-oxygen was fed into bioreactors, S(0) formation was significantly improved up to ∼ 70%. GeoChip 4.0, a functional gene microarray, was used to determine the microbial gene diversity and functional potential for nitrate and sulfate reduction, and sulfide oxidation. The diversity of the microbial community in bioreactors was increased with the feeding of limited oxygen. Whereas the intensities of the functional genes involved in sulfate reduction did not show a significant difference, the abundance of the detected denitrification genes decreased in limited oxygen samples. More importantly, sulfide-oxidizing bacteria may alter their populations/genes in response to limited oxygen potentially to function more effectively in sulfide oxidation, especially to elemental sulfur. The genes fccA/fccB from nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB), such as Paracoccus denitrificans, Thiobacillus denitrificans, Beggiatoa sp., Thiomicrospira sp., and Thioalkalivibrio sp., were more abundant under limited-oxygen condition., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Growth and lipid production performance of Scenedesmus sp. under different culture modes were investigated. Under heterotrophic aerobic mode, algal biomass concentration and total lipid content reached 3.42 g L(-1) and 43.0 wt.%, which were much higher than those in autotrophic aerobic mode (0.55 g L(-1)/20.2 wt.%). The applied light exposure of 7.0 Wm(-2) was beneficial to biomass and lipid accumulation. Mixotrophic aerobic mode produced the highest biomass concentration of 3.84 g L(-1). The biomass was rich in lipids (51.3 wt.%) and low in proteins (17.9 wt.%) and carbohydrates (10.3 wt.%). However, lower algal biomass concentration (2.93 g L(-1)) and total lipid content (36.1 wt.%) were obtained in mixotrophic anaerobic mode. Mixotrophic aerobic mode gave the maximum heat value conversion efficiency of 45.7%. These results indicate that mixotrophic aerobic cultivation was a promising culture mode for lipid production by Scenedesmus sp., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The biological degradation of nitrate and sulfate was investigated using a mixed microbial culture and lactate as the carbon source, with or without limited-oxygen fed. It was found that sulfate reduction was slightly inhibited by nitrate, since after nitrate depletion the sulfate reduction rate increased from 0.37 mg SO4 (2-)/mg VSS d to 0.71 mg SO4 (2-)/mg VSS d, and the maximum rate of sulfate reduction in the presence of nitrate corresponded to 56 % of the non-inhibited sulfate reduction rate determined after nitrate depleted. However, simultaneous but not sequential reduction of both oxy-anions was observed in this study, unlike some literature reports in which sulfate reduction starts only after depletion of nitrate, and this case might be due to the fact that lactate was always kept above the limiting conditions. At limited oxygen, the inhibited effect on sulfate reduction by nitrate was relieved, and the sulfate reduction rate seemed relatively higher than that obtained without limited-oxygen fed, whereas kept almost constant (0.86-0.89 mg SO4 (2-)/mg VSS d) cross the six ROS states. In contrast, nitrate reduction rates decreased substantially with the increase in the initial limited-oxygen fed, showing an inhibited effect on nitrate reduction by oxygen. Kinetic parameters determined for the mixed microbial culture showed that the maximum specific sulfate utilization rate obtained (0.098 ± 0.022 mg SO4 (2-)/(mg VSS h)) was similar to the reported typical value (0.1 mg SO4 (2-)/(mg VSS h)), also indicating a moderate inhibited effect by nitrate.

Background: Consolidated bioprocessing (CBP) of lignocellulosic biomass to hydrogen offers great potential for lower cost and higher efficiency compared to processes featuring dedicated cellulase production. Current studies on CBP-based hydrogen production mainly focus on using the thermophilic cellulolytic bacterium Clostridium thermocellum and the extremely thermophilic cellulolytic bacterium Caldicellulosiruptor saccharolyticus. However, no studies have demonstrated that the strains in the genus Thermoanaerobacterium could be used as the sole microorganism to accomplish both cellulose degradation and H2 generation., Results: We have specifically screened for moderately thermophilic cellulolytic bacteria enabling to produce hydrogen directly from conversion of lignocellulosic materials. Three new strains of thermophilic cellulolytic bacteria in the genus Thermoanaerobacterium growing at a temperature of 60°C were isolated. All of them grew well on various plant polymers including microcrystalline cellulose, filter paper, xylan, glucose, and xylose. In particular, the isolated bacterium, designated as Thermoanaerobacterium thermosaccharolyticum M18, showed high cellulolytic activity and a high yield of H2. When it was grown in 0.5% microcrystalline cellulose, approximately 82% cellulose was consumed, and the H2 yield and maximum production rate reached 10.86 mmol/g Avicel and 2.05 mmol/L/h, respectively. Natural lignocellulosic materials without any physicochemical or biological pretreatment also supported appreciable growth of strain M18, which resulted in 56.07% to 62.71% of insoluble cellulose and hemicellulose polymer degradation in corn cob, corn stalk, and wheat straw with a yield of 3.23 to 3.48 mmol H2/g substrate and an average production rate of 0.10 to 0.13 mmol H2/L/h., Conclusions: The newly isolated strain T. thermosaccharolyticum M18 displayed effective degradation of lignocellulose and produced large amounts of hydrogen. This is the first report of a Thermoanaerobacterium species presenting cellulolytic characteristics, and this species thus represents a novel cellulolytic bacterium distinguished from all other known cellulolytic bacteria. In comparison, the extraordinary yield and specific rate of hydrogen for strain M18 obtained from lignocellulose make it more attractive in monoculture fermentation. T. thermosaccharolyticum M18 is thus a potential candidate for rapid conversion of lignocellulose to biohydrogen in a single step.

To explore efficient and cost-effective cathode material for microbial fuel cells (MFCs), the present study fabricates a new type of binder-free gas diffusion electrode made of cobalt oxide (Co3O4) micro-particles directly grown on stainless steel mesh (SSM) by using an ammonia-evaporation-induced method. In various electrochemical analyses and evaluations in batch-fed dual-chamber MFCs, the SSM/Co3O4 hybrid electrode demonstrates improved performances in terms of electrocatalytic activity, selectivity, durability and economics toward oxygen reduction reaction (ORR) in pH-neutral solution, in comparison with conventional carbon supported platinum catalyst. This study suggests a new strategy to fabricate a more effective electrode for ORR in MFCs, making it more technically and economically viable to produce electrical energy from organic materials for practical applications., (Copyright © 2013 Elsevier B.V. All rights reserved.)