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Heterotrophic cultivation of Chlorella pyrenoidosa based on straw substrate was proposed as a promising approach in this research. The straw pre-treated by ammonium sulfite method was enzymatically hydrolyzed for medium preparation. The highest intrinsic growth rate of C. pyrenoidosa reached to 0.097 h −1 in hydrolysate medium, which was quicker than that in glucose medium. Rising nitrogen concentration could significantly increase protein content and decrease lipid content in biomass, meanwhile fatty acids composition kept stable. The highest protein and lipid content in microalgal biomass reached to 62% and 32% under nitrogen excessive and deficient conditions, respectively. Over 40% of amino acids and fatty acids in biomass belonged to essential amino acids (EAA) and essential fatty acids (EFA), which were qualified for high-value uses. This research revealed the rapid biomass accumulation property of C. pyrenoidosa in straw hydrolysate medium and the effectiveness of nitrogen regulation to biomass composition at heterotrophic condition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lignin removal rate of CS pretreated with NaOH-heat was as high as 77%. • The highest RS yield of 46.1 g/100 g RM was obtained from 2% NaOH-heat pretreated CS. • 4% NaOH-heat pretreated CS had the minimum HY of 44.27 mL/g TS. • 2% NaOH pretreatment increased the HY of CS by 31.9%. • HPLT of CS was shortened by 58.8% after 2% NaOH pretreatment. The effects of different pretreatment methods, including hydrothermal, acid, alkali, acid-heat and alkali-heat on lignin removal, reducing sugar (RS) yield and photo-fermentative biohydrogen production (PFHP) capability of corn stover (CS) were studied. NaOH-heat pretreatment was the most effective for lignin removal from CS, and the lignin removal rate reached 77%. All the studied pretreatment methods improved the total RS yield of CS, and the highest total RS yield (46.1 g/100 g raw material (RM)) was obtained from 2% NaOH-heat pretreated CS. 2% NaOH pretreatment realized the best PFHP of CS, which increased the hydrogen yield (HY), maximal hydrogen production rate (HPR) and highest hydrogen content (HC) by 31.9%, 50.9% and 20.1% respectively, and shortened hydrogen production lag time (HPLT) by 58.8% over that of untreated CS. However, NaOH-heat and 4% NaOH pretreatment weakened the PFHP capability of CS. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three mixotrophic microalgae strains were isolated from wastewater treatment plant. [•] Heterotrophically cultivate the strains in domestic wastewater under dark condition. [•] The strains obtained high-lipid contents during the heterotrophic cultivation. [•] Over half of DOC in wastewater was removed by the microalgae strains. [•] Assimilation efficiency of DOC in domestic wastewater for the strains was acquired. [ABSTRACT FROM AUTHOR]

Highlights: [•] Soluble algae products could significantly inhibit the growth of Scenedesmus sp. LX1. [•] All of the fractions of SAP could inhibit the growth of Scenedesmus sp. LX1. [•] Organic bases and HIA expressed the strongest inhibition on growth. [•] HIA could significantly inhibit the lipid accumulation of Scenedesmus sp. LX1. [•] Molecular weight and fluorescence spectroscopy of HIA were investigated. [Copyright &y& Elsevier]

[Display omitted] • Photocatalysis of nano-TiO 2 was combined with photo-fermentative hydrogen production. • The addition of nano-TiO 2 increased the photo-fermentative hydrogen yield by 32.6%. • Nano-TiO 2 decreased the optimal process conditions for hydrogen production. • Concentration of intermediate byproducts was reduced with nano-TiO 2 addition. • Nano-TiO 2 promoted HAU-M1 to metabolize butyric acid and acetic acid. This study explored the interrelationship between nano-TiO 2 addition and photo-fermentative hydrogen production (PFHP) of corn straw. The maximum cumulative hydrogen volume (CHV) was up to 688.8 mL under the optimal photo-fermentative process conditions with nano-TiO 2 addition of 300 mg/L. Initial pH and interaction between substrate concentration and light intensity had highly significant effects on PFHP of corn straw with nano-TiO 2 addition. With the improvement of CHV, nano-TiO 2 addition decreased the optimal initial pH and substrate concentration for PFHP of corn straw. Moreover, nano-TiO 2 addition promoted the metabolism of butyric acid and acetic acid by photosynthetic bacteria HAU-M1, and significantly reduced the total concentration of intermediate byproducts during hydrogen production to a low level of 1.6–2.5 g/L, thus making the CHV, maximum hydrogen production rate (HPR) and average hydrogen content (HC) increased by 32.6%, 27.9% and 8.3% respectively over the control without nano-TiO 2 addition. [ABSTRACT FROM AUTHOR]

• Pretreatment effectively destroyed the structure of corn straw. • Enzymatic saccharification of corn straw was improved after pretreatment. • 2% NaOH-Heat treatment achieved the maximum reducing sugars release of 23.07 g/L. • 2% NaOH treatment obtained the maximum hydrogen yield of 137.76 mL/g TS. • Proper pretreatment enhanced the hydrogen production performance of corn straw. In this study, the effects of different pretreatment methods, including hydrothermal, acid, alkali, acid-heat, and alkali-heat on the structural characteristics, enzymatic saccharification and photo-fermentative bio-hydrogen production performance of corn straw were investigated. Results revealed that all the studied pretreatments effectively destroyed the corn straw structure and improved its enzymatic saccharification potential. The alkali-heat and alkali pretreatment showed significant advantage in reducing sugars release, and the highest total reducing sugar concentration of 23.07 g/L was obtained under the pretreatment condition of 2% NaOH-Heat. The maximum cumulative hydrogen yield of 137.76 mL/g TS was achieved from 2% NaOH pretreated corn straw, while corn straw pretreated with 4% NaOH-heat had the minimum cumulative hydrogen yield of 44.20 mL/g TS. These results suggest that appropriate pretreatment can effectively destroy the corn straw structure and enhance its enzymatic saccharification and hydrogen production performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Combined ultrasonic and ionic liquid pretreatment was applied to PFHP. • Delignification of biomass and hydrogen yield were positive correlated. • Pretreatment temperature had the strongest linear correlation with HY. • Combined energy production approaches might be useful for improved ECE. Combined pretreatment methods were assumed to further enhance photo-fermentative biohydrogen production (PFHP) from lignocellulosic biomass. For this purpose, an ultrasonication assisted ionic liquid pretreatment was applied to Arundo donax L. biomass for PFHP. The optimal condition for the combined pretreatment was 16 g/L of 1-Butyl-3-methylimidazolium Hydrogen Sulfate ([Bmim]HSO 4) combined with ultrasonication at a solid to liquid ratio (SLR) of 1:10 for 1.5 h under 60 °C. Under this condition, the maximum delignification of 22.9 % was obtained, in addition, the hydrogen yield (HY) and energy conversion efficiency (ECE) were enhanced by 1.5-fold and 46.4 % (p < 0.05) compared to untreated biomass, respectively. Moreover, heat map analysis was performed to evaluate the correlation between pretreatment conditions and corresponding results, suggesting pretreatment temperature had the strongest (absolute value of Pearson's r was 0.97) linear correlation with HY. Combined multiple energy production approaches might be useful for further improved ECE. [ABSTRACT FROM AUTHOR]

[Display omitted] • Light absorption range of TiO 2 /ACF broadens from the UV region to the visible region. • Cumulative hydrogen production with TiO 2 /ACF addition was nearly doubled. • The addition of TiO 2 /ACF shortened the photo-fermentation period from 84 h to 48 h. • TiO 2 /ACF promoted metabolic pathway of HAU-M1 to convert acetate and butyrate to H 2. • Characterization results after fermentation confirmed the reusability of TiO 2 /ACF. In this study, titanium dioxide/activated carbon fiber (TiO 2 /ACF) was synthesized by liquid-phase deposition method and the effect of TiO 2 /ACF on the performance of photo-fermentation biohydrogen production (PFHP) from corn stover under visible light catalysis was discussed. Results show the maximum cumulative hydrogen yield (CHY) obtained under the optimal conditions was 74.0 ± 1.3 mL/g TS with TiO 2 /ACF addition of 100 mg/L, which was twice that without TiO 2 /ACF addition (36.9 ± 1.0 mL/g TS). Initial pH value had the most significant effect on CHY. The addition of TiO 2 /ACF promoted the metabolic pathway of nitrogenase to reduce H+ produced by consuming acetic acid and butyric acid to hydrogen, and also shortened the photo-fermentation period. By scanning electron microscopy and X-ray diffraction analysis, the morphology and phase structure of TiO 2 /ACF after PFHP did not change significantly. This study laid the foundation for the reuse of TiO 2 and its practical application in PFHP. [ABSTRACT FROM AUTHOR]

• Three ILs pretreatment of Arundo donax L. were compared. • [Bmim]HSO 4 pretreatment obtained relative higher delignification. • 16 g/L [Bmim]HSO 4 pretreatment enhanced the hydrogen yield by 35.3%. • Saccharification of feedstock played a key role in hydrogen production. Ionic liquids (ILs) pretreatment has been regarded as a promising green way to treat lignocellulosic biomass. 1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF 4), 1-allyl-3-methylimidazolium chloride ([Amim]Cl), and 1-Butyl-3-methylimidazolium Hydrogen Sulfate ([Bmim]HSO 4) with different loadings (2, 4, 8, and 16 g/L) were adopted to pretreat the Arundo donax L.. 16 g/L [Bmim]HSO 4 pretreated Arundo donax L. obtained the highest sugar yield of 7.9 g/L during the enzymatic hydrolysis and hydrogen yield of 106.1 mL/g TS during the photo-fermentation, which were 68.8 % and 35.3 % higher than those of untreated Arundo donax L., respectively. Moreover, volatile fatty acids (VFAs) distribution revealed that acetic acid was the main by-product during hydrogen production process with ILs pretreated Arundo donax L.. Besides, the relationship between sugar yield and hydrogen yield was the closest based on scatter matrix analysis. This study helps to understand of correlation between ILs pretreatment with the behavior of bioenergy production. [ABSTRACT FROM AUTHOR]

• Giant reed was firstly used for photo-fermentative hydrogen production. • NaOH and Ca(OH) 2 pretreatments of giant reed were compared. • NaOH pretreatment obtained higher hydrogen yield than Ca(OH) 2 pretreatment. • NaOH pretreatment resulted in 25% increase in energy conversion efficiency. Giant reed was the first time used for photo-fermentative hydrogen production with HAU-M1 bacteria. Effects of NaOH and Ca(OH) 2 pretreatments of giant reed on structural changes, enzymatic digestibility, hydrogen production, and energy conversion efficiency were evaluated. Compared to Ca(OH) 2 pretreatment, NaOH pretreatment removed more dry matter and lignin at the same loading. The highest glucose yield (44.9%) of NaOH pretreatment was 1.74-fold higher than that of Ca(OH) 2 pretreatment. 20% NaOH pretreated giant reed biomass achieved the highest hydrogen yield (98.3 mL/g TS), which was 20% and 70% higher than the highest level of Ca(OH) 2 pretreated (20% Ca(OH) 2) and untreated giant reed, respectively. Only giant reed biomass pretreated with 20% NaOH resulted in a significant (p < 0.05) increase (25%) in energy conversion efficiency. [ABSTRACT FROM AUTHOR]

Highlights • GVL/H 2 O pretreatment retarded the enzymatic hydrolysis efficiency of Avicel. • Alkaline post-incubation partially removed ester groups of GVL/H 2 O treated Avicel. • Removal of hemicellulose and lignin by alkaline incubation improved glucose yield. • Alkaline post-incubation enhanced cellulase adsorption capacity and affinity to CS. Abstract The impact of γ-valerolactone/water (GVL/H 2 O) pretreatment coupled with alkaline post-incubation on the digestibility of cellulose substrates was investigated. When Avicel was pretreated by GVL/H 2 O with H 2 SO 4 as catalyst, the glucan conversion decreased from 27% (untreated Avicel) to 16% due to the esterification of cellulose after pretreatment. After incubation of GVL/H 2 O pretreated Avicel with 1% NaOH at 50 °C for 1 h, the glucan conversion enhanced to 20%. When corn stover (CS) pretreated by GVL/H 2 O with 25 mM H 2 SO 4 was used as substrate, alkaline post-incubation removed 72% and 50% of the hemicellulose and lignin, respectively, and increased the glucan conversion by 1.9-fold consequently. Moreover, higher cellulases adsorption capacity, affinity and binding strength on GVL/H 2 O pretreated CS was achieved after alkaline post-incubation. These results indicated that the improved digestibility of GVL/H 2 O pretreated lignocellulose by alkaline post-incubation was attributed to the depletion of ester groups on cellulose and removal of hemicellulose and lignin. [ABSTRACT FROM AUTHOR]

Managing wastewater treatment plant (WWTP) based on respirometric analysis is a new and promising field. In this study, a multi-dimensional respirogram space was constructed, and an important index R es/t (ratio of in-situ respiration rate to maximum respiration rate) was derived as an alarm signal for the effluent quality control. A smaller R es/t value suggests better effluent. The critical R′ es/t value used for determining whether the effluent meets the regulation depends on operational conditions, which were characterized by temperature and biomass ratio of heterotrophs to autotrophs. With given operational conditions, the critical R′ es/t value can be calculated from the respirogram space and effluent conditions required by the discharge regulation, with no requirement for calibration of parameters or any additional measurements. Since it is simple, easy to use, and can be readily implemented online, this approach holds a great promise for applications. [ABSTRACT FROM AUTHOR]

Robustness of an activated sludge system, describing uncertainty and operational risk, was evaluated using the absence or presence of calcium-induced enhancement of respiration (CaER) effect. Generally, the fast-growing system was susceptible to external environmental variations, of which the sludge exhibited significant CaER effect under normal operational conditions, while the slow growing system showed less significant CaER effect. However, sludge in both systems exhibited CaER effect under stressed conditions of decreasing temperature or ammonia shocking. Therefore, the absence of CaER effect indicates a more robust system, while the presence of CaER effect indicates a susceptible system. Additionally, a method to identify safe and dangerous shocking was established by a hybrid usage of absence or presence of CaER effect and recovery index (RI) curve type. The evaluation of robustness could help determining when adjustment should be really taken to cope with the uncertainty, and thus holds a high promise for field application. [ABSTRACT FROM AUTHOR]

Microalgae are potential candidates for the production of valuable products, such as renewable biodiesel, health products and pigments. However, low biomass productivity has restricted their large-scale applications. In this study, the effects of two auxins (one natural type of indole-3-acetic acid (IAA) and the other synthetic type of 2,4-dichlorophenoxyacetic acid (2,4-D)) on the growth and fatty acid methyl esters (FAMEs) production of a freshwater microalgae Scenedesmus sp. LX1 were investigated. Both auxins showed a “low dosage-promotion and high dosage-inhibition” effect on the growth and FAMEs accumulation. The optimum dosage of IAA and 2,4-D were 1 mg L −1 and 0.1 mg L −1 , respectively. Moreover, the IAA could increase the monounsaturated fatty acid content. The auxins may promote the growth by enhancing the photosynthetic activity through increasing chlorophyll contents. Therefore, auxin significantly enhanced microalgal growth and FAMEs accumulation, and has a potential for application in developing efficient microalgal cultivation. [ABSTRACT FROM AUTHOR]

Taken common agricultural residues as substrate, dark fermentation bio-hydrogen yield capacity from asynchronous saccharification and fermentation (ASF) and simultaneous saccharification and fermentation (SSF) was investigated. The highest hydrogen yield of 472.75 mL was achieved with corncob using ASF. Hydrogen yield from corn straw, rice straw, corncob and sorghum stalk by SSF were 20.54%,10.31%,13.99% and 5.92% higher than ASF, respectively. The experimental data fitted well to the modified Gompertz model. SSF offered a distinct advantage over ASF with respect to reducing overall process time (60 h of SSF, 108 h of ASF). Meanwhile, SSF performed better than SSF with respect to shortening the lag-stage. The major metabolites of anaerobic fermentation hydrogen production by ASF and SSF were butyric acid and acetic acid. [ABSTRACT FROM AUTHOR]

Burkholderia sp. ZD1, aerobically utilizes 2-picolinic acid as a source of carbon, nitrogen and energy, was isolated. ZD1 completely degraded 2-picolinic acid when the initial concentrations ranged from 25 to 300 mg/L. Specific growth rate ( μ ) and specific consumption rate ( q ) increased continually in the concentration range of 25–100 mg/L, and then declined. Based on the Haldane model and Andrew’s model, μ max and q max were calculated as 3.9 and 16.5 h −1 , respectively. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to determine the main intermediates in the degradation pathway. Moreover, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was innovatively used to deduce the ring cleavage mechanism of N-heterocycle of 2-picolinic acid. To our knowledge, this is the first report on not only the utilization of 2-picolinic acid by a Burkholderia sp., but also applying FT-ICR-MS and ATR-FTIR for exploring the biodegradation pathway of organic compounds. [ABSTRACT FROM AUTHOR]

In this study, it was found that the type of phenolic acids derived from rice straw was the major factor affecting ethanol fermentation by Pichia stipitis . The aim of this study was to investigate the inhibitory effect of phenolic acids on ethanol fermentation with rice straw. Different cellulases produced different ratios of free phenolic acids to soluble conjugated phenolic acids, resulting in different fermentation efficiencies. Free phenolic acids exhibited much higher inhibitory effect than conjugated phenolic acids. The flow cytometry results indicated that the damage to cell membranes was the primary mechanism of inhibition of ethanol fermentation by phenolic acids. The removal of free phenolic acids from the hydrolysates increased ethanol productivity by 2.0-fold, indicating that the free phenolic acids would be the major inhibitors formed during saccharification. The integrated process for ethanol and phenolic acids may constitute a new strategy for the production of low-cost ethanol. [ABSTRACT FROM AUTHOR]

Microbial electrosynthesis (MES) is a promising technology for the reduction of carbon dioxide into value-added multicarbon molecules. In order to broaden the product profile of MES processes, we developed a two-stage process for microbial conversion of carbon dioxide and electricity into long chain alkyl esters. In the first stage, the carbon dioxide is reduced to organic compounds, mainly acetate, in a MES process by Sporomusa ovata . In the second stage, the liquid end-products of the MES process are converted to the final product by a second microorganism, Acinetobacter baylyi in an aerobic bioprocess. In this proof-of-principle study, we demonstrate for the first time the bacterial production of long alkyl esters (wax esters) from carbon dioxide and electricity as the sole sources of carbon and energy. The process holds potential for the efficient production of carbon-neutral chemicals or biofuels. [ABSTRACT FROM AUTHOR]

A 4 m 3 pilot-scale baffled continuous-flow photoreactor with four sequential chambers (#1–#4) was established and tested to evaluate its photo-fermentative hydrogen production from wastewater that contains (10 g/L glucose using a functional consortium at 30 °C, under light with an intensity of 3000 ± 200 lux with a hydraulic retention time (HRT) of 24–72 h. The hydrogen production rate and the broth characteristics varied significantly in the flow direction. The hydrogen production rate was highest in chamber #1, and lower in chambers #2–#4 at an HRT of 72 h, while the peak production rate shifted to the latter chambers as the HRT was shortened. The overall H 2 production rate increased as HRT decreased, but was not consistent with the predictions that were based on the complete-mixing assumption. [ABSTRACT FROM AUTHOR]

Sporomusa ovata DSM-2662 produces high rate of acetate during microbial electrosynthesis (MES) by reducing CO 2 with electrons coming from a cathode. Here, we investigated other Sporomusa for MES with cathode potential set at −690 mV vs SHE to establish if this capacity is conserved among this genus and to identify more performant strains. S. ovata DSM-2663 produced acetate 1.8-fold faster than S. ovata DSM-2662. On the contrary, S. ovata DSM-3300 was 2.7-fold slower whereas Sporomusa aerivorans had no MES activity. These results indicate that MES performance varies among Sporomusa . During MES, electron transfer from cathode to microbes often occurs via H 2 . To establish if efficient coupling between H 2 oxidation and CO 2 reduction may explain why specific acetogens are more productive MES catalysts, the metabolisms of the investigated Sporomusa were characterized under H 2 :CO 2 . Results suggest that other phenotypic traits besides the capacity to oxidize H 2 efficiently are involved. [ABSTRACT FROM AUTHOR]

[Display omitted] • A pilot BES-AD with modular electrode for treating membrane manufacturing wastewater. • The BOD 5 /COD of wastewater was increased from 0.239 to 0.398 at applied voltage of 0.9 V. • The synergistic effect and enrichment of core genera were spatially selective. • The construction and operation costs of system were low at $1708.8/m3 and $0.76/m3. The large-scale application of bioelectrochemical coupled anaerobic digestion (BES-AD) is limited by the matching of electrode configuration and the applicability of real wastewater. In this study, a pilot-scale BES-AD system with an effective system volume of 5 m3 and a 1 m3 volume of a carbon fiber brush electrode module was constructed and tested for treatment of the membrane manufacturing wastewater. The results showed that the BOD 5 /COD of the wastewater was increased from 0.238 to 0.398 when the applied voltage was 0.9 V. The pollutants such as N, N- Dimethylacetamide and glycerol in wastewater were degraded significantly. The microorganisms in the electrode modules were spatially enriched. The fermenters (Norank_f__ML635J-40_aquatic_group , 6.55 %; unclassified_f__Propionibacteriaceae , 5.25 %) and degraders (Corynebacterium , 29.31 %) were mostly enriched at the bottom, while electroactive bacteria (Pseudomonas , 29.39 %, Geobacter , 7.86 %) were mostly enriched at the top. Combined with the economical construction and operation cost ($1708.8/m3 and $0.76/m3) of the BES-AD system. [ABSTRACT FROM AUTHOR]

• [Bmim]acetate pretreatment was applied to giant reed biomass for H 2 production. • Pretreatment temperature was not positively correlated with HY. • The optimal [Bmim]acetate pretreatment condition enhanced the HY by 61.7 %. • Retention time had the strongest effect on delignification, sugar yield, and HY. Ionic liquids (ILs) have been considered as promising alternatives to traditional reagent for lignocellulosic biomass pretreatment because of their tunable physicochemical and "green" properties. In the study, the influence of 1-Butyl-3-methylimidazolium acetate ([Bmim]acetate) pretreatment of giant reed on H 2 yield improvement via photo-fermentation (PF) was evaluated. Under the optimal pretreatment conditions (6 g/L [Bmim]acetate at 70 °C for 4 h), the delignification of giant reed was up to 26.7 %. In addition, the sugar yield (9.5 g/L) and hydrogen yield (72.3 mL/g TS) from giant reed were enhanced by 1.7-fold and 61.7 % over those of untreated giant reed, respectively. Moreover, ternary analysis showed that retention time had the strongest effect on delignification, sugar yield and hydrogen yield of giant reed compared to pretreatment temperature and [Bmim]acetate loading. These experimental results indicated that [Bmim]acetate pretreatment of giant reed is an effective approach to enhance the hydrogen yield via PF. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-stage autotrophic bacterial cellulose production from C1 gases was demonstrated. • C. autoethanogenum produced ethanol and acetate from H 2 :CO:CO 2 gases. • Gas fermentation products were then converted into BC by K. sucrofermentans. • Mixotrophic BC production was also shown with gas fermentation products and glucose. • Mixotrophic BC was more robust and porous with higher crystallinity. Gas fermentation is a well-established process for the conversion of greenhouse gases from industrial wastes into valuable multi-carbon chemicals. Here, a two-stage process was developed to expand the product range of gas fermentation and synthesized the versatile biopolymer bacterial cellulose (BC). In the first stage, the acetogen Clostridium autoethanogenum was cultivated with H 2 :CO:CO 2 and produced ethanol and acetate. In the second stage, BC-synthesizing Komagataeibacter sucrofermentans was grown in the spent medium from gas fermentation. K. sucrofermentans was able to produce BC autotrophically from gas-derived metabolites alone as well as mixotrophically with the addition of exogenous glucose. In these circumstances, 1.31 g/L BC was synthesized with a major energetic contribution from C1 gas fermentation products. Mixotrophic BC characterization reveals unique properties including augmented mechanical strength, porosity, and crystallinity. This proof-of-concept process demonstrates that BC can be produced from gases and holds good potential for the efficient conversion of C1 wastes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solid carriers were added and kept suspended by aeration in this ssPBR. [•] Microalgae could attach and grow on the carriers. [•] By catching carriers, microalgae could easily be separated from liquid phase. [•] Biomass production in ssPBR was increased by adding solid carriers. [Copyright &y& Elsevier]

Highlights: [•] Nitrogen could be removed efficiently by anammox reaction from modified greenhouse turtle breeding wastewater. [•] Anammox contribution to nitrogen removal was always dominant with the different COD strengths. [•] Anammox bacteria, denitrifiers and ammonia-oxidizing bacteria coexist for synergetic removal of nitrogen. [Copyright &y& Elsevier]

Microalgal growth is the key to the coupled system of wastewater treatment and microalgal biomass production. In this study, Monod model, Droop model and Steele model were incorporated to obtain an integrated growth model describing the combined effects of nitrogen, phosphorus and light intensity on the growth rate of Scenedesmus sp. LX1. The model parameters were obtained via fitting experimental data to these classical models. Furthermore, the biomass production of Scenedesmus sp. LX1 in open pond under nutrient level of secondary effluent was analyzed based on the integrated model, predicting a maximal microalgal biomass production rate about 20 g m −2 d −1 . In order to optimize the biomass production of open pond the microalgal biomass concentration, light intensity on the surface of open pond, total depth of culture medium and hydraulic retention time should be 500 g m −3 , 16,000 lx, 0.2 m and 5.2 d in the conditions of this study, respectively. [ABSTRACT FROM AUTHOR]

• 24 h dark + 24 h light duration alternation improved the HY by 6.7 %. • LCE was enhanced by 114.7 % via 24 h dark + 24 h light duration alternation. • Light period after inoculation had the closest relation with average HPR. • Decreased dark period after inoculation would increase the HY. Suitable illumination project would help in achieving high light conversion efficiency (LCE) for photo-fermentation. This study proposed an improvement strategy for LCE of photo-fermentative hydrogen production (PFHP) with a photosynthetic consortium by adopting light–dark duration alternation. For this purpose, 6 projects (continues light, 24 h light + 24 h dark, 24 h dark + 24 h light, 48 h light + 48 h light, 48 h dark + 48 h light, and continues dark) light disturbances were carried out to estimate the strategy. The fluctuation of cell growth (OD660) was corresponded to the light–dark alternation. 24 h dark + 24 h light alternation achieved the maximum hydrogen yield (HY) of 390.9 mL/g TS cell (6.7 % higher than continuous light) and maximum improvement of LCE of 114.7%. Moreover, heat map analysis revealed that the light period after inoculation had the closest relation (Pearson's r = 1) with the average hydrogen production rate (HPR) of photo-fermentation. Besides, decreased dark period after inoculation would increase the hydrogen yield of photo-fermentation. [ABSTRACT FROM AUTHOR]

[Display omitted] • BES with stainless-steel electrode was applied to treat practical refractory wastewater. • A comparison of six cathode in BES was presented. • SSM-100 μm was considered to be the most cost-effective electrode material. • The synergistic effects between exoelectrogens and fermenters were enhanced. • Abundances of metabolic genes and functional genera were raised in BES-SSM-100 μm. The large-scale application of the bioelectrochemical system (BES) is limited by the cost-effective electrode materials. In this study, five kinds of stainless-steel materials were used as the cathode of the BES coupled with anaerobic digestion (BES-AD) for the treatment of diluted N, N-dimethylacetamide (DMAC) wastewater. Compared with a carbon-cloth cathode, BES-AD with a stainless-steel cathode had more engineering due to its low cost, although the operating efficiencies were slightly inferior. Stainless-steel mesh with a 100 µm aperture (SSM-100 μm) was the most cost-effective electrode and the implanted BES exhibited better COD removal efficiency, electrochemical performance and biodegradability. Analysis of microbial community revealed the synergetic effect between exoelectrogen and fermentative bacteria had been strengthened in the SSM-100 μm cathode biofilm. Function analysis of the microbial community based on PICRUSt predicted metagenomes revealed that the metabolic pathways of xenobiotics biodegradation and metabolism in the SSM-100 μm cathode were stimulated. [ABSTRACT FROM AUTHOR]

• Degree of conversion of substrate can be used to evaluate the efficiency of the pre-treatment process. • High solids concentration and low specific energy input for sonication will give positive energy balance. • Temperature increase during sonication will impact the energy and GHG emissions. • Ultrasonication of sludge at low specific energy is energy surplus process. This paper presents the greenhouse gas (GHG) emissions during ultrasonication of sludge and anaerobic digestion (AD) of the ultrasonicated sludge using mass-energy balance. Computation of the net energy (energy recovered - energy input) revealed that high solids concentration with low sonication specific energy provides positive net energy. Moreover, the GHG emissions can be minimised at low sonication specific energy input and high solids concentration compared to that of the control without sonication. Increase in temperature of sludge during sonication will reduce the energy input required for raising the sludge temperature to AD temperature and thus decreases the GHG emissions. With energy recovery from the methane produced in AD, the total GHG emissions can further be reduced, lower than that without energy recovery from methane. [ABSTRACT FROM AUTHOR]

• Bio-hydrogen production potential from shrub landscaping waste was evaluated. • Buxus megistophylla was proved to be the optimal substrate. • The maximum cumulated hydrogen yield was 73.82 ± 0.06 mL/g TS after optimization. Shrub landscaping waste, derived from afforestation of city, has increased annually, making it a promising feedstock for energy production. In this work, the photo-fermentation bio-hydrogen production potential from shrub landscaping waste was evaluated. Eight kinds of shrub landscaping wastes (Photinia fraseri, Buxus megistophylla, Buxus sinica, Pittosporum tobira, Sabina Chinensis, Berberis thunbergii, Ligustrum vicaryi and Ligustrum quihoui) were selected as substrate and the photo-fermentation bio-hydrogen production process of which was optimized. Buxus megistophylla was found to be the most suitable substrate for photo-fermentation bio-hydrogen production. Moreover, the initial pH value, temperature and substrate concentration had significant influence on photo-fermentation bio-hydrogen production. The maximum cumulated hydrogen yield of Buxus megistophylla was 73.82 ± 0.06 mL/g TS under the optimal conditions of light intensity of 3000 Lux, substrate mass concentration of 21.49 g/L, temperature of 29.78 °C, inoculant amount of 25% and initial pH value of 6.78. [ABSTRACT FROM AUTHOR]

• Correlations between PFHP and co-substrate utilization was investigated. • Glycerol addition of 15 g/L can achieve 294% increase in H 2 yield. • Initial and final E h had the strongest relationship with H 2 yield improvement. • Arundo donax L./glycerol ratio played a key role during PFHP process. This study aimed to explore the correlation between hydrogen yield improvement of photo-fermentation of Arundo donax L. and glycerol addition. Different glycerol concentrations (g/L) (0, 10, 15, 20, and 30) were replenished to establish co-substrate system. And statistical analysis was introduced to evaluate the correlation. The maximum hydrogen yield improvement (294%) was obtained from glycerol addition of 15 g/L in comparison with mono-substrate system of Arundo donax L. Under the optimal glycerol addition (15 g/L), the glycerol/ Arundo donax L. ratio, C/N ratio, initial medium redox potential (E h), and solid/liquid ratio were 1:1, 25.1, 57 mV, and 1/68, respectively. In addition, canonical correlation analysis (CCA) indicated that initial and final medium redox potential (E h) had the strongest relationship with yield improvement of photo-fermentation. Moreover, Pearson's correlation analysis claimed that Arundo donax L./glycerol ratio played a key role during the photo-fermentative hydrogen production (PFHP) process. [ABSTRACT FROM AUTHOR]

• The first study to provide new insights into bio-leach Mn from EMS. • Open the door to the metabolic characteristics of Y1 by using waste. • Demonstrated for the first time the carbon source metabolic pathways of Y1. The related microbial metabolomics on biological recovery of manganese (Mn) from Electrolytic Manganese Slag (EMS) has not been studied. This study aimed at open the door to the metabolic characteristics of microorganisms in leaching Mn from EMS by using waste molasses (WM) as carbon source. Results show Microbacterium trichothecenolyticum Y1 (Y1) could effectively leach Mn from EMS in combination with using waste molasses as carbon and energy sources. For the first time, Y1 was identified to be capable of generating and then metabolizing several organic acids or other organic matter (e.g., fumaric acid, succinic acid, malic acid, glyoxylic acid, 3-hydroxybutyric acid, glutaric acid, L(+)-tartaric acid, citric acid, tetrahydrofolic acid, and L-methionine). The production of organic acids by Y1 bacteria was promoted by EMS with the carbon source. This study demonstrated for the first time that metabolic characteristics and carbon source metabolic pathways of Y1 in bioleaching of Mn from EMS. [ABSTRACT FROM AUTHOR]

• Various energy grasses can be used for bio-hydrogen production from photocatalysis. • Three methods were used to measure hydrogen production results. • Energy grasses most suitable for bio-hydrogen production were obtained. • Enzymolysis time had obvious effect on bio-hydrogen production from energy grasses. Energy grass is an ideal raw material of biomass energy, and hydrogen energy is one of the ideal renewable energy. In order to study the feasibility of different energy grasses for hydrogen production from photosynthetic organisms, the enzymatic hydrolysis of energy grasses is a very necessary process. Therefore, biohydrogen production from photo-fermentation by using energy grasses as substrates was investgated by changing enzymolysis time. The hydrogen production results were evaluated by the experimental results of hydrogen yield, hydrogen production rate and hydrogen production efficiency. The experimental results showed that Medicago sativa L. with enzymolysis time of 60 h had the highest hydrogen yield, which was 147.64 mL. The highest hydrogen production rate was 5.53 mL/(h·g TS), which was obtained from Arundo donax with enzymolysis time of 36 h, and the highest hydrogen production efficiency was 1.15 mL/(h·g TS), which was obtained from Miscanthus with enzymolysis time of 0 h. [ABSTRACT FROM AUTHOR]

• As a carbon source, molasses was also used as an adsorbent and reductant. • The removal efficiencies of Zn(II), Cr(VI), Cd(II), and Cr(total) were above 90%. • The removal path of heavy metals and the contribution of each path were elucidated. In this study, two bacteria strains (Enterobacter sp. SL and Acinetobacter sp. SL-1) and waste molasses (carbon source) were used to remove Zn(II), Cd(II), Cr(VI), and Cr(Total) in the liquid solution (87 mg·L). The results showed the removal efficiencies of Cr(Total) and Cr(VI) could reach over 98.00% after reaction, and the removal efficiencies of Zn(II) and Cd(II) were all about 90.00% by the synergistic actions of microorganisms and waste molasses. In this process, waste molasses provides nutrients for microorganisms and has the characteristics and capability of Cr, Zn, and Cd. Microorganisms mainly use biological adsorption (36.95% and 45.69%) and metabolism (24.37% and 17.05% by producing humic-acid and fulvic-acid like substances) to remove Zn(II) and Cd(II), while waste molasses could to remove Cr(Total) (81.24%) and Cr(VI) (75.90%). This study has potential application value for the treatment of wastewater containing high concentrations of heavy metals. [ABSTRACT FROM AUTHOR]

• A high-efficiency process for bioreducing/removal of Cr(VI) was developed. • The Enterobacter sp. SL can use waste molasses as carbon source for growth. • The process works well in a wide pH range and with the coexistence of polyions. • The major reduction products and microbes can be removed by sludge separation. • The treated Cr-containing wastewater is of high quality. A technology utilizes bacteria Enterobacter sp. SL grown in an anaerobic reactor with waste molasses as carbon source to bio-reduce hexavalent chromium [Cr(VI)] in wastewater and then remove total chromium has been developed. The performance was elucidated through different initial and operating experiments conditions, and the associated mechanism of Cr(VI) reduction was explained. Results show that Cr(VI) removal is 99.91% at 25 h in the anaerobic reactor initially containing bacteria of 5% (v/v), (NH 4) 2 Fe(SO 4) 2 ·6H 2 O of 0.5 g·L−1, waste molasses of 2.5 g·L−1, Cr(VI) of 100 mg·L−1, pH of 6.0, and with the operational temperature of 45 °C. After 120 h reaction, Cr(total) removal reached 91.10%. The major reduction products [FeS, Cr 2 O 3 , Cr(OH) 3 , S0 granules] together with microbes was removed by sludge separation with Cr(VI) in the supernatant (0.027 mg·L−1) being much lower than that (not excess 0.2 mg·L−1) of Electroplating Pollutant Emission Standard. [ABSTRACT FROM AUTHOR]