Search

Paper mill sludge (PMS), a lignocellulosic waste from paper industry, is an ecological burden of environmental concern. Present study explored PMS as substrate for prodigiosin production in solid state fermentation (SSF) and concurrent source of cellulose for Cellulose nanocrystals (CNCs) preparation, using Serratia marcescens NITDPER1. Batch studies revealed maximum pigment production 47 ± 3.2 mg/L after 60 h and ligninolytic potentials via kraft lignin degradation (59 % after 72 h), lignin-mimicking dye decolourization and lignin monomer utilization. In SSF, highest yield was 30.05 ± 1.7 mg/g (24 h) with growth-associated (α = 20.84) and non-growth associated (β = 0.63) parameters determined through Luedeking-Piret model. Lambda max (535 nm), Thin-Layer Chromatography (TLC) (Rf = 0.9), High-Performance Liquid Chromatography (HPLC) (RT = 2.865), Fourier-transform infrared spectra (FT-IR) and Nuclear magnetic resonance (NMR) confirmed it as prodigiosin that exhibited antioxidant potential (IC50 = 47 ± 3.5 μg/mL). After SSF, the delignified (54 %) residual PMS was utilized for preparing CNCs, that displayed particle size 130.8 nm, zeta potential -13.4 mv, polydispersity index 0.404, stability upto 490 °C and revealed desirable properties in Field-emission scanning electron microscopy (FESEM), FT-IR and X-ray diffraction (XRD). Phytotoxicity studies confirmed both prodigiosin and CNCs as non-toxic. This study unveiled biorefinery perspectives for paper industries through production of two commercially important commodities from waste using eco-friendly approach.

This study deals with the decolourisation and detoxification of rayon grade pulp paper mill effluent by mixed culture of three bacterial strains having ligninolytic enzyme activity. These strains were identified as IITRP1 Pseudochrobactrum glaciale (FJ581024), IITRP2 Providencia rettgeri (GU193984) and RCT2 Pantoea sp. (FJ755943) based on 16S rRNA gene sequencing. The results showed that mixed culture effectively reduced colour 96.02%, chemical oxygen demand (COD) 91% and biological oxygen demand (BOD) 92.59% of the pulp paper mill effluent within 216 h of the incubation period. Maximum enzyme activity for lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase were recorded at 48, 72 and 144 h of the incubation period, respectively. The high performance liquid chromatography (HPLC) analysis of bacterial degraded samples showed 90% reduction of lignin and chlorophenol compared to the untreated sample. Further, gas chromatography–mass spectroscopy (GC–MS) analysis revealed that majority of the compounds present in the untreated sample were completely removed and only few metabolites were generated after bacterial treatment. The toxicity assessment of the pulp paper mill effluent on Vicia faba L. showed 40% reduction after bacterial treatment. However, untreated effluent sample showed inhibition of seed germination and α-amylase activity.

To convert bleached softwood paper grade pulp into dissolving pulp for viscose application, two stages of treatments consisting of enzymatic treatment and alkaline peroxide treatment were investigated. It was found that high reactivity (about 80%) of pulp could be achieved by endoglucanases (EG)-rich industrial cellulase treatment, and the alpha-cellulose content as well as the viscosity of enzymatically treated pulp can be further adjusted by the alkaline peroxide treatment with certain dosages of NaOH and H2O2 to finally meet the quality requirements of dissolving pulp. The resulting pulp with 68.7% of reactivity, 92.1% of alpha-cellulose content, and 506.9 mL/g of pulp viscosity could be obtained after the two stages of treatments. The appropriate dosage of EG-rich cellulase was 300 IU/g bone dry pulp in the stage of enzymatic treatment, while the suitable dosages of NaOH and H2O2 were 9 wt% and 1 wt%, respectively, in the stage of alkaline peroxide treatment. (C) 2013 Elsevier B.V. All rights reserved.

During past decades, the considerable efforts have been made to utilize lignocellulose as biomass feedstock for the optimal production of bio-ethanol as an alternative source of fuel. In this work, the effective bioconversion of paper sludge to ethanol was investigated by using Zymomonas mobilis NBRC 13756. Major components of the raw paper sludge were carbohydrates and ash. Fermentation utilizing strains of Z. mobilis instead of traditional yeasts and the use of simultaneous saccharification and fermentation (SSF) process have been proposed due to their high ethanol yields with cost-effectiveness. Free cells of Z. mobilis resulted in no ethanol production even after 24 h of incubation because cells’ growth was inhibited by metal ions contained in the paper sludge. The application of SSF with Ca-alginate-immobilized cells of Z. mobilis was performed and 18 g/L of ethanol was obtained after 48 h of incubation at an initial paper sludge concentration of 200 g/L. In addition, the repeated batch fermentation of Ca-alginate-immobilized Z. mobilis cells was attempted for producing ethanol up to run 4. Our work suggests that Ca-alginate-immobilized cells of Z. mobilis could effectively produce ethanol from paper sludge not only under the batch fermentation but also under the repeated batch fermentation.

Concentrated sludge generated in large amounts by the wastewater treatment facilities of recycling paper plants raises a serious disposal problem requiring urgent solution. This recycled paper sludge (RPS) is an industrial waste with high polysaccharide content. As previously demonstrated, cellulosic and hemicellulosic fractions of RPS can be completely converted by enzymatic hydrolysis (using Celluclast ® 1.5 L with Novozym ® 188) into the constitutive glucose and xylose. These monosaccharides can be used on fermentation media to obtain a variety of products, such as lactic acid, which has an expanding market as precursor of biodegradable polylactides. Hence the purpose of the present work is to evaluate the performance of RPS as feedstock for fermentative production of lactic acid (LA) with Lactobacillus rhamnosus ATCC 7469, a very efficient lactic acid bacterium. Maximum production of lactic acid from RPS was obtained by performing the hydrolysis and fermentation steps simultaneously on medium supplemented with MRS components and calcium carbonate. L. rhamnosus produced 73 g L −1 of lactic acid, corresponding to a maximum productivity of 2.9 g L −1 h −1 , with 0.97 g LA produced per g of carbohydrates on initial substrate. A process simplification was also implemented by minimizing RPS supplementation and suppressing Novozym cellobiase addition.

The filamentous microalgae Tribonema sp. was cultured in the effluents of different stages (the primary clarifier, the anaerobic and the anaerobic/oxic) of the traditional Anaerobic/Oxic (A/O) process for evaluating the recycling and treatment efficiency of the petrochemical wastewater in this paper. It was observed that Tribonema sp. grew in the anaerobic effluent had the ideal growth states and wastewater treatment efficiency. The biomass concentration, the chemical oxygen demand (COD), and total nitrogen (TN) removal rates were 4.4 g/L, 98.4% and 96.8%, respectively, for Tribonema sp. grown in the anaerobic effluent. Moreover, the total phosphorus (TP) and organic contaminants were almost completely removed and the oil content of the microalgae reached the highest (36.1%) in the anaerobic effluent. The filamentous microalgae Tribonema sp. cultivation directly integrated with the treatment of anaerobic effluents is demonstrated as an alternative approach to the traditional oxic stage in the A/O process.

The downstream process of microalgae derived products is pinned by the harvesting/dewatering of microalgae biomass. Thus, a significant part in the industrial application of microalgae is to find a method to harvest microalgae on a large scale with a low energy cost and high financial efficiency. Foam separation technology is a simple, mild and efficient separating method based on bubbles as separating medium to separate substances of surfactivity. In this study, the cocamidopropyl betaine (CAPB), a natural surfactant, was used to harvest the freshwater microalgae Desmodesmus brasiliensis by foam separation. The paper shows when pH = 3, the recovery rate of cocamidopropyl betaine (CAPB) as surfactant (R(%) = 93.63 ± 1.75) can match the traditional surfactant CTAB, with a much larger enrichment ratio (E = 23.12 ± 0.028). Response Surface Methodology (RSM) was used to optimize the recovery rate R(%) after obtaining the optimum condition of harvesting the Desmodesmus brasiliensis and finally the optimum result of R (%) = 94.4 was reached. Compared with traditional centrifuge separation, the amount of algae lutein from Desmodesmus brasiliensis collected by foam separating was larger than that by centrifuge separation, suggesting this cheap and natural surfactant has the potential to be applied in commercial-scale microalgae biomass recovery and especially in boosting lutein yeild.

The aim of this study was to conduct an economic assessment of the entire polyhydroxybutyrate (PHB) production process by Cupriavidus necator, using citric molasses as carbon source and employing propylene carbonate as solvent coupled with different extraction pretreatment methods. Four extraction alternatives were assayed. The alternatives that uses high pressure and heat to pretreat the biomass showed equally lower production costs (US$ 4.28 per kg) and better economic indicators among evaluated scenarios. It was observed that method’s extraction capacity is not decisive in selecting the best alternative, but there must be the simultaneous analysis of extractability capacity and expenditures in equipment and utilities. Through five times increase in production capacity, the production cost significantly decreased, reaching US$ 2.71 per kg. Furthermore, achieving high cellular concentration can be responsible for a reduction of up to 18% in the production cost.

Periodic withdrawal and replenishment of powdered activated carbon (PAC) hybrid membrane bioreactor (MBR) is required for stable performance. The influence of the replenishment of powdered activated carbon (PAC) on sludge filterability and microbial community in hybrid MBRs was investigated. Results showed that the removal of organic matter and nitrogen were not significantly affected by the PAC refreshment, while soluble microbial products (SMP) concentration decreased and extracellular polymeric substance (EPS) increased with increasing PAC replacement ratio. MBR system with PAC replenishment exhibited low fouling propensity and prolonged filtration agreed well with fouling rate and resistance analysis. Molecular weight distribution of SMP in MBR confirmed the synergistic effects of PAC adsorption/biodegradation and membrane interception on organics removal. Microbial activity was positive associated with the PAC replenishment ratio. Moreover, the high-throughput sequencing indicated that due to fresh PAC added, the increased abundance of Proteobacteria, Bacteroidetes and Nitrospira guaranteed the pollutant removal, and the membrane fouling caused by Planctomycetes and Betaproteobacteria decreased. An optimal PAC replenishment ratio at 1.67% achieved the effective membrane fouling mitigation and enhanced dominant bacterial structure. PAC refreshment is considered to be a promising way to advance the application of MBR.

A multipurpose fixed-bed bioreactor was evaluated, to simplify the process of producing lipase and its application in biocatalysis. Rhizomucor miehei lipase was produced by solid-state fermentation (SSF) in the fixed-bed bioreactor and generated a fermented solid with 30 U/g lipase activity and a synthesis capacity of 80% (conversion at 6 h of reaction in a standard stirred reactor). The fermented solid was then dried by forced aeration in the same column (1.0 L air/min, 35 °C) and the dried fermented solid (5 wt.% water) showed the same synthesis capacity as the freeze-dried standard, with high storage stability at 4 °C and 25 °C (14 months with no decrease in synthesis capacity). The reaction performed in the multipurpose bioreactor (one-pot system) showed relatively low conversion (30% of the conversion obtained in the stirred reactor at 6 h) when only babassu cake was employed as the fermentation substrate, due to the preferred pathways formed as a consequence of bed retraction during drying. Therefore, SSF was carried out with a mixture of 60:40 wt.% babassu cake and palm fiber (used to give structure to the fermented solid and prevent retraction during drying), and the reaction in the one-pot system reached a maximum conversion of 71%.

A lab-scale rotating drum biological contactor (RDBC) was implemented and accessed concerning abiotic oxygen transfer rate and treatment capacity for domestic sewage. The dissolved oxygen (DO) transfer test showed that the rotational speed and the submergence level of drum greatly affected the DO in bulk liquid with the volumetric oxygen transfer coefficient KLa of 2.3-25.9 h−1, effectively achieving anaerobic/anoxic/aerobic conditions in the reactor. The post-denitrification process was proposed using the RDBC to degrade the synthetic nitrogen-containing sewage wastewater. When the hydraulic retention time was 16 h, the flow distribution ratio was 3:1 and the anoxic rotational speed was 6 rpm, the effluent NH4+-N and TN were 2.3 mg L−1 and 7.3 mg L−1 with the NH4+-N and TN removal efficiency of 94.1% and 80.9%, respectively. The Nitrosomonas europaea and Candidatus Kuenenia dominated in the anoxic carried-biofilm, indicating that the coexisting of aerobic and anaerobic ammonium oxidation bacteria enhanced the TN loss in the post-anoxic tank. This study provides an innovative non-aeration technology for biological wastewater treatment and has implications to simplify operation and save energy.

The aim of this study was to evaluate and compare the treatment of petrochemical wastewater with an integrated anaerobic baffled reactor and microbial electrolysis cell (ABR-MEC) and anaerobic baffled reactor (ABR). For this purpose, the effect of hydraulic retention time (HRT) and applied voltage on the performance of ABR-MEC reactor were investigated in four phases. Regarding the results, the maximum COD removal efficiency in the ABR-MEC reactor was higher than that in ABR reactor, i.e. 96.5% versus 66.7%. Also, the maximum of yield CH4 in ABR-MEC reactor was 1.4-fold than ABR reactor. The results show that the applied voltages can increase the removal of chemical oxygen demand, methane production, accelerate the conversion of volatile fatty acids and maintain the appropriate pH range for methanogen growth.

Microalgae-bacteria consortia is considered to be an efficient way to improve wastewater treatment. However, the interactions between microalgae and bacteria were not clear. In this study, commercially available bacterial inoculum were used as bio-augmentation to improve the performance of microalgae-based wastewater treatment. Co-occurrence network analysis was used to investigate the interactions between microalgae and bacteria. Results showed that bio-augmentation could increase both microalgal growth and wastewater treatment efficiency. Microalgal biomass increased by 1.2 times. Removal efficiencies of total organic carbon, ammonium nitrogen and total phosphorus increased by 5.27%, 3.41%% and 5.74%, respectively. Decreasing trends for Cyanobacteria and Salinarimonas but increasing trends for Cyclobacteriaceae were observed in the microalgal culture system with bio-augmentation. Greater variations of microbial community were found in the treatment without bio-augmentation. Co-occurrence network analysis showed that the main functions of microbial community in the treatment with bio-augmentation were both nutrient removal and organic pollutant degrading. For the treatment without bio-augmentation, main function of microbial community was nutrient removal. It indicated that bio-augmentation increased the number of organic degrading bacteria, such as Bacillus and Paenibacillaceae. The interactions between these bacteria and microalgae promoted the degradation of organic pollutants in the wastewater, providing sufficient inorganic carbon sources for the photosynthesis of microalgae and thus promoting the growth of microalgae and the removal of nitrogen and phosphorus from wastewater.

To solve the problem of slow hydrolysis rate during anaerobic digestion, 20 kHz of ultrasound and energy density of 0.5 W/mL were applied as pretreatments for mesophilic anaerobic digestion of waste activated sludge. The sludge was digested at hydraulic retention time (HRT) of 20 d after sonication of 0–100 min. Results showed that ultrasonic pretreatment was beneficial to the dissolution of soluble chemical oxygen demand (SCOD) from the waste activated sludge, coupled with the rapid degradation in the dewatering performance of the sludge. In the succeeding anaerobic digestion, when sonication of the treated sludge was more than 80 min, the removal rate of total chemical oxygen demand (TCOD) and the sludge reduction rate also decreased significantly. Gas and methane productions were highest at the reactor fed with sludge sonicated at 80 min. At this condition, the content of CH4 was more than 53.8%, and the average yield of methane was about 36.2 mL/gVS. Through the analysis of microbial diversity, we observed that hydrolytic and acidification bacteria were abundant in the reactors. Methanocorpusculum and Methanosaeta were the alternating dominant methanogens in the anaerobic reactors, with adding sludge suffered different ultrasonic time. In the sludge pretreated with ultrasonication after 80 min, the relative abundance of Methanocorpusculum decreased rapidly, and the dominant substrate for anaerobic methanogenesis changed from hydrogen to acetic acid.

The occurrence of various antibiotics in wastewater treatment systems continues to arouse extensive attention. However, the effects of low concentration of antibiotics on wastewater treatment performance and the related functional bacteria, especially under long-term operation, remain largely unknown. In this study, a lab-scale anaerobic-aerobic system was established to evaluate the impacts of 5 mg l−1 tetracycline on the performance of a lab-scale wastewater treatment system and the abundance of the related functional bacteria. The results indicated that Tc exposure had little effect (p > 0.05) on the efficiency of COD removal during the whole period of 200 days, but significantly decreased ammonia removal (p

A kinetic model describing acetone-butanol-ethanol (ABE) production applicable to both single substrate fermentations of glucose and xylose as well as co-fermentation of the substrates has been developed. The model accounts for carbon catabolite repression as well as the inhibition of kinetic rates at high substrate concentrations (∼90 g l−1). Model parameters were obtained through kinetic fitting to previously report experimental data. The model was used to study the design and operation of a continuous ABE fermentation process (with and without recycle of biomass). For continuous operation, it was shown that multiple steady-states exist at low dilution rates. For operation with recycle of biomass, the influence of recycle rate on both biomass concentration and ABE productivity were studied. The results indicate that for a range of recycle and dilution rates, ABE productivity can increase to 16 g l−1 h−1 (10 times higher than that without biomass recycling), consistent with experimental results.

The Cannibal process is a commercial method for excess sludge reduction in activated sludge plants with small sizes. However, the relatively low efficiency in sludge reduction (up to 50%) for some plants is the main impediment to its more widespread adoption. This study provides a biological method for upgrading Cannibal process. The suggested method includes disruption of cell to cell communication between bacterial communities in aerobic flocs in order to increase endogenous respiration. A quorum quenching (QQ) agent is applied in the aerobic tank in order to increase the free bacteria population, which leads to enhanced microbial predation and a decrease in extracellular polymeric substances. The sludge production yield (Yobs) of three pilots including a control sequencing batch reactor (SBR), a Cannibal system, and a QQ-Cannibal system was 0.5, 0.38, and 0.29, respectively. The results of a respirometery study also indicated that enhanced endogenous respiration caused sludge reduction in the QQ-Cannibal pilot system.

In this work, bioaugmentation strategy was tested to enhance electricity production efficiency from municipal waste liquor feedstock in microbial fuel cells (MFC). During the experiments, MFCs inoculated with a mixed anaerobic consortium were enriched by several pure, electro-active bacterial cultures (such as Propionibacterium freudenreichii, Cupriavidus basilensis and Lactococcus lactis) and behaviours were assessed kinetically. It turned out that energy yield could be enhanced mainly at high substrate loadings. Furthermore, energy production and COD removal rate showed an optimum and could be characterized by a saturation range within the applied COD loadings, which could be elucidated applying the Monod-model for describing intracellular losses. Polarization measurements showed the positive effect of bioaugmentation also on extracellular losses. The data indicated a successful augmentation process for enhancing MFC efficiency, which was utmost in case of augmentation strain of Propionibacterium freudenreichii.

In the pursuit of renewable sources for biogas generation, microalgae biomass constitutes a promising alternative. In this work, thermally pretreated Scenedesmus obtusiusculus was evaluated as source of biomass for methane production, in systems operated under batch and semi-batch regime. In batch experiments, methane production yields ranging from 109.3 to 192.7 mL CH4/g VSadded were observed with thermally-pretreated (98 °C, 6 h) microalgae biomass at concentrations between 1 and 10 g tCOD/L. On the other hand, the system operated under semi-batch mode for 50 days attained a volumetric methane production rate of 1.15 L CH4/L-d with a methane yield of 177.9 mL CH4/g VSadded at an organic loading rate of 10 g tCOD/L-d and a reaction time of 12 h. These results demonstrate that methane production from microalgae biomass in a semi-batch reactor is possible at low reaction time (12 h) and high organic loading rate using a moderate-temperature pretreatment for the microalgae biomass.

The goal of this work was to evaluate the efficiency of an air-cathode microbial fuel cell (MFC), operating in semi-continuous downflow mode. The MFC was inoculated with a consortium of Shewanella oneidensis and Clostridium butyricum. It was fed using a synthetic medium with progressively increasing dairy wastewater (DWW) concentrations in the startup (15 days), acclimatization (30 days), and treatment (75 days) phases. This approach enabled removal of 89% of the total COD and 91% of the total BOD, after 90 days of operation. These efficiencies were improved with step change of external resistance (Rext.) from 1.0 to 0.5 kΩ. Electrochemical impedance spectroscopy analysis indicated the formation of more complex biointerface associated with change of Rext. The maximum power density was 3.5 W∙m-3 at 1.0 A∙m-3, during the startup, while the Coulombic efficiency (CE) was 4.5 at the end of the operation. The MFC process showed high efficiency for the removal of organic nitrogen (85%), phosphorus (92%), nitrate (100%), and sulfate (88%). Additionally, the treated DWW effluent presented no acute toxic effect towards Daphnia similis. Overall, it could be concluded that applying gradual increments of the DWW concentration resulted in highly efficient treatment.

Reusing biocatalysts and repeated-batch process are promising approaches for the reduction of time and costs of a fermentation process. The present study investigated the use of α-amylase, glucoamylase, and cells of Saccharomyces cerevisiae immobilized on bacterial cellulose (BC) in repeated-batch simultaneous saccharification and fermentation (SSF) process for ethanol production from cassava pulp (CP). Ratio between the immobilized α-amylase and glucoamylase, and concentration of CP were optimized to achieve high CP saccharification efficiency, and the immobilized enzymes and cells were reused for four times in five consecutive batches of SSF. The optimum ratio between immobilized α-amylase and glucoamylase, and CP concentration were 75:25 by mass, and 60 g/L, respectively, yielding 0.74 gglucose/gCP (80% hydrolysis efficiency). Repeated-batch SSF gave an overall ethanol yield of 0.28 g/gCP, and an ethanol production rate of 0.27 g/h, whereas a batch SSF gave a yield of 0.3 gethanol/gCP and a production rate of 0.036 gethanol/h. The results reported in this study revealed the applicability of BC as a supporting material for enzymes and cells immobilizations, and the feasibility of the repeated-batch SSF process in ethanol fermentation.

Intermittently aerated activated sludge processes save energy by minimizing the total aeration time per day without deteriorating effluent water quality. Swine wastewater contains high, often widely fluctuating concentrations of biochemical oxygen demand (BOD) and nitrogen. BOD-based aeration control would therefore be a useful method to reduce the energy demands of aeration, but requires a reliable BOD sensor for swine wastewater. In this study we developed a novel approach for BOD- and pH-based intermittent aeration control (BAC) using a BOD biosensor based on exoelectrogenic bacteria and tested it at four swine wastewater treatment plants. This BAC system reduced aeration energy in the plants by 15–36% compared to fixed aeration cycle operations while maintaining low concentrations of BOD and total nitrogen in the effluent. The energy saved per wastewater volume was 477–1012 kWh/m3/yr, equivalent to a reduction of 2.2–7.0 t-CO2/m3/yr in greenhouse gas emissions. The biosensor was equipped with an internet connection to allow for remote monitoring of water quality data with a smartphone, saving labour in the operational management of the plants. Aquabacterium and the aerobic denitrifier Thauera were detected as the predominant genera in the activated sludge.

Anammox is a novel and efficient nitrogen removal technique, while the long start-up time limits its industrial application, thus carriers are always utilized to accelerate its start-ups. Meanwhile, the preservation of anammox bacteria is a key element in its application. Therefore, it is also quite significant to evaluate the effect of carriers in reactivation of the anammox process after preservation. Through addition of polyurethane sponge in the upflow anaerobic sludge blanket (UASB) reactor (R1), comparing with the one without polyurethane sponge addition (R2), the time for anammox start-up was shorten by 28%, and the reactivation time was reduced by 50%. The preservation in 4 ℃ did not significantly affect the survival of anammox bacteria, but significantly decreased their nitrogen removal rate (NRR). Moreover, during the preservation, the decomposed EPS in R1 (44%) was less compared to that in R2 (66%). It took 36 days for R1 to recover the NRR (0.084 kg·N·m-3·d-1), but took 60 days for R2. At the end of reactivation, the abundance of Candidatus (Ca.) Brocadia and Ca. Kuenenia (both are anammox bacteria) was 4.5% and 2.7%, respectively, in R1, whereas there was no identified Ca. Kuenenia and the Ca. Brocadia was only 0.2% in R2. Therefore, the addition of polyurethane sponge could short the start-up and reactivation time for anammox process by retaining more anammox bacteria in the reactor.

Utilization of macroalgal biomass through the anaerobic digestion (AD) system can overcome algal pollution while providing alternative and renewable energy as fuel scarcity increases. To achieve this objective, Sargassum fulvellum biomass was used as the feedstock for the batch AD process. Original-sized algal biomass (So) of 106 µm–4.75 mm particle size, reduced-sized biomass of 75–850 µm (mechanically pretreated, Sr), chemically pretreated reduced-sized wet biomass with 40 mL/L (Sac1), 20 mL/L (Sac2) of 2 M HCl and with 10 mL/L (Sal1) and 5 mL/L (Sal2) of 6 N NaOH, and biologically pretreated original particle size biomass (Se) with 1 mL/L of cellulase enzyme were employed as feedstocks for digestion. Mechanical pretreatment of Sargassum fulvellum (Sr) without chemical addition resulted in 142.91 ± 0.004 mL CH4/gVS, which is higher than chemically pretreated reduced-sized macroalgae in So, Sac1, Sac2, Sal1, and Sal2 by 52.34%, 9.83%, 15.89%, 12.73%, and 18.26%, respectively. Biological treatment reduced methane yield in Se by 9.49% than the original-sized algal biomass (So). In addition, the rate of hydrolysis and maximum biomethane production potential improved after mechanical pretreatment by a maximum of 45.60% and 48.71%, respectively. This study indicates that the utilization of marine biomass as an alternative resource for biomethane production can be achieved, with an optimum methane production from mechanically pretreated macroalgae without chemical addition.

The green microalga, Scenedesmus incrassulatus PPAY1 was cultivated in vertical tubular photobioreactor under batch/fed-batch modes. Biodiesel derived glycerol waste (BDGW) was applied as a cheap main nutrient source. For batch cultivation (BC), maximum biomass concentration was reached at 2.83 gL-1when 20 gL-1 BGW was used. In contrast, in the case of fed-batch cultivation (FBC), the maximum algae and lipid contents were achieved at 5.65 gL-1 and 58.27%, respectively when 30 and 20 gL-1 BDGW were applied. The highest lipid yield of 2.94 gL-1was found at 30 gL-1 BDGW. The analysis of the fatty acid content revealed that palmitic acid-, oleic acid- and linoleic acid- were mainly found in both BC and FBC conditions. As expected, FBC was in a better culture strategy than BC. BDGW could be used directly without any pretreatment in both algal biomass growth and microalgal oil accumulation which simplifies cultivation and reduces operating costs during biodiesel production.

Ligninolytic enzyme production by solid-state cultures of Phanerochaete chrysosporium BKM-F-1767 was investigated by employing different agro-industrial wastes, such as fishery residues, brewery waste, apple waste (pomace) and pulp and paper industry sludge. Different enzyme inducers, such as veratryl alcohol, Tween-80 and CuSO 4 at concentrations of 2 mM, 0.5% (v/w) and 3 mmole/kg, respectively were also tested. Use of veratryl alcohol and Tween-80 resulted in maximum manganese peroxidase (MnP) activity of 17.36 ± 0.5, 540.2 ± 5.1, 631.25 ± 14, and 507.5 ± 26.87 U/gds (units/gram dry substrate), respectively, for different wastes. Maximum lignin peroxidase (LiP) activity of 141.38 ± 3.39 and 14.1 ± 0.5 U/gds was attained with pomace and pulp and paper, respectively. Laccase activities were found to be insignificant for all wastes. Addition of Tween-80 and CuSO 4 resulted in highest values of MnP activity of 17.4 ± 0.6, 291 ± 2.8, 213.5 ± 3, and 213.2 ± 3.2 U/gds for fishery waste, brewery waste, pomace and pulp and paper industry sludge, respectively. Addition of CuSO 4 to the culture medium enhanced laccase activity. Maximum laccase activities of 738.97 ± 9.2, 719.97 ± 14.6, 308.8 ± 12.1, and 94.44 ± 1.2 U/gds were obtained for brewery waste, pomace, pulp and paper industry sludge and fishery waste, respectively. Brewery wastes and pomace served as excellent sources for the production of MnP, LiP and laccases.

The present article explores the idea of exposing an enzyme-substrate complex to an induced magnetic field aiming at biogas production. Sugar beet pulp was used as a substrate and pectinase as an enzyme. Fermentation experiments were carried out in an 11 L working volume stainless steel bioreactor. Additionally, the influence of substrate sonication, prior to the enzymatic pretreatment, on the methane production and specific energy gain was investigated. The enzyme-substrate mixture, when exposed to an induced magnetic field, increased methane production from SBP up to 62 % and when sonication was added to the process, the increase in methane production was up to 79 %. The results indicate that exposing an enzyme-substrate mixture to an induced magnetic field can increase biogas production and its methane content with a higher specific energy gain than when sonication was added to the process.

Gas fermentation is an attractive route to produce alternative fuels and chemicals from non-food feedstocks, such as waste gas streams from steel mills and synthesis gas produced from agricultural residues through gasification. An improved strain of Clostridium autoethanogenum, an acetogenic bacteria, was developed by LanzaTech and shows high potential in production of ethanol and 2,3-butanediol from industry waste gas (mainly CO/CO2) via gas fermentation. In this study, a spatiotemporal metabolic model was formulated and evaluated using steady-state CO fermentation data collected from a laboratory-scale bubble column reactor. The spatiotemporal model was comprised of a genome-scale reconstruction of Clostridium autoethanogenum metabolism and multiphase convection-dispersion equations that govern transport of CO, secreted byproducts and biomass. The model provided good agreement with measured ethanol, acetate and biomass concentrations obtained at a single gas flow rate. Then to obtain satisfactory steady-state predictions at three gas flow rates, the upper bound of the proton exchange flux in the genome-scale reconstruction was correlated with the gas flow rate as an indirect means to account for the effects of acetate secretion on extracellular pH. We believe the modeling method established by this work has strong potential to facilitate commercial-scale design of gas fermentation processes for production of biofuel and biochemicals.

We present a start-up method for complete autotrophic nitrogen removal via the nitrite (CANON) granular sludge process by controlling the DO concentration. More specifically, we initially increase the activity of anaerobic ammonia-oxidizing bacteria (AnAOB) and, subsequently, gradually increase the activity of ammonia oxidizing bacteria (AOB). The results indicate the optimum process parameters to be an 8 h reaction period and an aeration/non-aeration time ratio of 1.0 h/0.25 h. These conditions maintain a high activity for both AOB and AnAOB and are also conducive to sludge granulation. Following 64 days of continuous operation, the mean particle size of the sludge increased to 992 µm, while the proportion of granular sludge accounted for approximately 87.16%, and the proportion of sludge with a particle size ≥ 1000 µm was 36.66%. Both AOB and AnAOB became the dominant bacterial genera in the CANON reaction system, while nitrite-oxidizing bacteria were successfully discharged from the reaction system.

The utilization of crude waste streams and the development of novel bioprocessing routes are necessary in order to expand the industrial implementation of bio-based succinic acid production. This work focuses on the utilization of zero cost municipal organic biowaste for the production of bio-based succinic acid using the engineered yeast strain Yarrowia lipolytica PSA02004. Fermentation advances focused on pH regulation towards reduced NaOH requirements. Optimum initial carbon source concentration (100–120 g/L) in crude hydrolysates was estimated in shake flask cultures. Optimum kLα (183.2 h−1) in fed-batch cultures resulted in 42.2 g/L succinic acid with 0.38 g/g yield and 0.84 g/L/h productivity. A two-stage pH regulation strategy was employed to enhance succinic acid production efficiency and reduce NaOH requirements. The gradual reduction of pH from 6 to 5.5 resulted in 54.4 g/L succinic acid with 0.44 g/g yield and 0.82 g/L/h productivity and 43% lower NaOH consumption. The minimum selling price of succinic acid was estimated at $2.7/kg and $2.94/kg at annual production capacity of 50,000 t when the production cost of organic biowaste derived sugars were considered at $10/tTS and $110/tTS, respectively. The global warming potential and abiotic depletion potential were estimated at 2.72 kgCO2-eq/kgSA and 33.4 MJ/kgSA, respectively. Results showed that pH regulation is an important operating parameter towards the sustainable succinic acid production using municipal organic biowaste.

Biolubricants do not cause the environmental pollution resulting from the manufacturing and use of mineral-based lubricants, but the commonly adopted chemical method of preparing biolubricants using expensive vegetable oils as raw materials is still environmentally and economically unsatisfactory. In this study, R. glutinis lipid with a high oleic-acid content was esterified with trimethylolpropane (TMP) by using the Candida sp. 99–125 enzyme in a solvent-free system, and the effect of the microbial oil with the high oleic-acid content on the performance of resulting biolubricants was investigated. The purpose of this study was to solve the problems of pollution caused by the chemical synthesis of biolubricants and of the uneconomical use of vegetable oils as raw materials. Further, this study aimed to improve the performance of biolubricants by using the microbial lipid with a high oleic-acid content. As a result of optimization of the reaction conditions, the yield of trimethylolpropane fatty acid triester (TFAT) reached 89.5%. The synthesized biolubricants had excellent low-temperature lubrication performance (pour point = − 45 °C), and the physicochemical performance reached the ISOVG-46 grade. The results of the high-frequency reciprocating friction test (HRFT) show that the products have better tribological properties than mineral-based lubricants of the same viscosity grade (friction coefficient = 0.085; average wear scar diameter = 187 µm).

Membrane fouling, especially that caused by microbes is the main reason restricting the application of membrane technology in wastewater treatment. In this study, shortcut nitrification (SN) of ammonia was achieved in a new hybrid membrane aerated biofilm reactor (H-MBfR) where fixed fiberfill was used as the auxiliary biofilm carrier to alleviate membrane fouling through most biomass transfer. The experiment showed that the NO2− accumulation capacity of the reactor was stable and that the NAE was greater than 80 %. The oxygen transfer efficiency reached 71.09 % because the membrane module was used to provide oxygen to the reactor. Microbial community analysis showed that the percentages of Nitrosomonas in the two biofilm-samples collected from the membrane and fiberfill were 37.47 % and 10.99 %, respectively. Microorganisms in the reactor mainly concentrated on the fiberfill, and the biomass on the surface of the membrane accounted for only 19.53 % of the total biomass. The results indicated that the addition of fiberfill effectively improved membrane fouling by reducing the biomass on the membrane surface. This research makes possible the practical application of the SN process and is an insightful method for meeting the challenge of membrane fouling.

Microalgal-nitrifying bacterial photobioreactors have attracted much research attention; however, the impact of high ammonia concentrations on the performance of the process is still unclear. In this study, anaerobic digester effluent with total ammonia nitrogen concentration: 1042 ± 53 mg-N/L (free ammonia: 112 ± 25 mg-NH3/L) at three different dilution conditions (no dilution and 2- and 4-fold) were used to prepare three different total ammonia nitrogen concentrations and the removal of ammonia from the former in photobioreactors were evaluated. During the experimental period (11 days), ammonia removal reached 61.7 %–79.0 % for the 2- and 4-fold dilution conditions, while there was less than 12.8 % removal in the no-dilution condition. Free ammonia is known to be toxic to both microalgae and nitrifying bacteria; therefore, ammonia removal in the reactor is strongly controlled (p

Microbial fuel cell (MFC) is a sustainable electrochemical bioreactor that enables biomass harvesting to produce energy. Shewanella oneidensis, one of the widely used exoelectrogens in MFCs, can only utilize a limited spectrum of carbon sources. To enable the use of abundant carbon sources in MFCs, a lactate-mediated Saccharomyces cerevisiae and S. oneidensis microbial consortium was constructed to utilize 2 g/L xylose or 1 g/L glucose-xylose in generating electricity. The designed system achieved a constant supply of lactate to S. oneidensis, in which the lactate concentration was maintained at 0−0.1 g/L. Meanwhile, the output current promoted the metabolic rate of the carbon sources as well. Finally, the flavin biosynthesis pathway was incorporated into S. oneidensis to enhance the power production of the consortium, and the maximum output power density of 238.7 ± 14.5 mW/m2 was reached. This high-performance power generation could be attributed to the ‘division-of-labor’ between the fermenter and exoelectrogen based on the programmed cooperation and mutualistic interactions among individuals.

Surfactin, a potent lipopeptide biosurfactant, possesses versatile bioactive properties and has potential industrial applications. However, high production costs and low yields have obstructed its large-scale industrial production. Studies on strategies to produce surfactin from kitchen waste (KW) as a low-cost substrate are indeed far lacking. In our work, we have provided two strategies for pretreating KW. Commercial enzymes (CEs) and enzyme-producing fungi were applied for KW treatment. The maximum yield of surfactin was 75.707 mg.gds−1 using Bacillus amyloliquefaciens HM618 with CE mixture-treated KW. When B. amyloliquefaciens HM618 was co-cultured with lipase-producing Aspergillus nidulan to pretreat KW, the surfactin yield was maximized to 65.404 mg.gds−1, which was higher than that under the lipase-pretreated KW alone. This co-culture system could achieve simultaneous enzymolysis and fermentation. Hence, it is feasible for enzyme producers to replace CEs to pretreat KW and achieve simultaneous enzymolysis and surfactin fermentation. Our work provides strategies for the resource utilization of KW and how to realize the synchronization of KW enzymatic hydrolysis and fermentation.

The nitrification process demands higher oxygen supply, which is fulfilled through external aeration in wastewater treatment. To perform nitrification without external aeration, this study developed a novel rotating sponge (RS) reactor and estimated its oxygen transfer capability. The reactor obtained an oxygen transfer coefficient (KLa) value of over 100 d−1 at 40 rounds per hour (rph), which is one-eighth of the rotational speed of conventional rotational biological contactors. Within 53 days of operation, reactor achieved 97% nitrification efficiency with an effluent NH4+-N concentration of 1 mgL−1. On the other hand, the volumetric oxygen transfer rate in the reactor was 245 mg-O2L−1d−1 at 10 rph during the experimental period. However, the average volumetric oxygen consumption rate during nitrification was 187 mg-O2L−1d−1, which was below the oxygen transfer rate. Microbial community analysis revealed high relative abundance of bacteria such as Nitrosomonas, Nitrospira, and Nitrobacter in the RS reactor, which contributed to nitrification.

In this study, integrated fixed-film activated sludge (IFAS) microbial development and degradation efficiency were investigated for oil sands process-affected water (OSPW) remediation. IFAS microbial community was characterized using 454 high-throughput 16S rRNA gene pyrosequencing that revealed that the IFAS seed sludge (activated sludge [AS] from the Gold Bar Wastewater Treatment Plant [GBWTP]) showed the greatest richness and evenness of bacterial community, as compare to other biomass samples. The Chao 1 value and the Shannon diversity index showed that the bacterial richness and microbial diversity in biofilms were significantly higher than those in flocs in both IFAS systems. Proteobacteria, Nitrospirae, Acidobacteria, and Bacteroidetes were dominant phyla in both flocs and biofilms in IFAS reactors. It is also noted that the phyla and class distributions of flocs and biofilms were significantly different. Principal coordinate analysis (PCoA) indicated that there were substantial differences between OSPW indigenous microbes and flocs and biofilm microbes in IFAS. Overall, a relatively low ozone dose (30 mg/L utilized) combined with IFAS reactor treatment significantly increased the organic contaminants removal. The combined ozonation and IFAS system showed the promise for OSPW treatment.

Solid-state fermentation could be used to produce low-cost pectinases that could then be used to saccharify pectin in citrus waste biorefineries. Recently, we produced pectinases in a pilot-scale packed-bed bioreactor, growing Aspergillus niger on a substrate mixture consisting of 27 kg of wheat bran and 3 kg of sugarcane bagasse (dry mass). However, the agglomeration of particles and shrinkage of the bed created preferential flow paths, leading to overheating within the bed and poor uniformity of pectinase levels at the end of the fermentation. In the current work, we used intermittent agitation as a strategy to minimize agglomeration, comparing one agitation (10 h), three agitations (at 8, 10 and 12 h) and five agitations (every 2 h from 8 to 16 h). The pectinase activity in the bed was uniform after agitation, but poor uniformity occurred when the bed was left unmixed for more than 10 h. The best regime was that with three agitations: For 15 samples removed from different vertical and horizontal positions of the bed at 20 h, the average pectinase activity was 22 U g−1, with a sample standard deviation of 2 U g−1. We conclude that the use of intermittently-mixed packed-bed bioreactors is a promising strategy for producing pectinases in solid-state fermentation.

The anammox-enriched granular sludge was successfully formed during the long-term biogranulation experiment lasting over 330 days. The cultivation was conducted at 30 ◦C in a 10-L sequencing batch reactor (SBR) fed with synthetic medium containing ammonia, nitrite and trace elements. The properties of the developed granules were investigated in terms of the biomass activity (including the growth rate of anammox bacteria), size distribution of the granules as well as nitrogen removal performance and pathways. The compositions of the microbial communities in the inoculum sludge and ultimate granules were compared using the metagenomic analysis. The mean particle size of the biomass increased from 290 m (inoculum sludge) to 728 m (ultimate granules). The overall nitrogen removal rate (NRR) and specific anammox activity (SAA) reached themaximumvalue of 5.3 kg Nm−3 d−1 and 1.6 kg NkgVSS−1 d−1, respectively. In the matured granules, Planctomycetes were the most abundant phylum (aprox. 44% of total 16S rRNA reads), exclusively represented by Candidatus Brocadia. Based on the 16S rRNA reads frequency derived from Planctomycetes in the total metagenomic library and volatile suspended solids (VSS) concentrations of the inoculum sludge and ultimate granules, the observed specific growth rate of anammox bacteria was estimated at 0.14 d−1 over the entire study period.

The start-up of completely autotrophic nitrogen removal over nitrite (CANON) process was investigated by seeding nitritation granular sludge in a continuous stirred tank reactor with typical geometry. Nitrogen loading rate (NLR) was increased from 1.5 to 3.3 kg N m−3 d−1, by shortening hydraulic retention time from 2.0 to 0.9 h under oxygen-limiting conditions. An extremely high nitrogen removal rate (NRR) of 2.83 kg N m−3 d−1 was achieved, due to the high specific NRR of huge biomass in the reactor. With the improvement of granular structure compactness, it was believed that the EPS accumulation could be beneficial to enhance nitrogen removal performance of granules. In addition, high-throughput pyrosequencing analysis revealed that a co-culture of aerobic and anaerobic ammonium oxidizing bacteria, affiliated to genera Nitrosomonas and Candidatus Kuenenia respectively, had been established in mature CANON granules, while the growth of nitrite oxidizing bacteria (Nitrospira spp.) was effectively suppressed through substrate competitions between three groups of bacteria. Therefore, a single continuous reactor with granules is applicable to achieve high performance CANON process for treating ammonium-rich wastewater.

The biochemical methane potential (BMP) assays were used as a tool to investigate methane potential of chicken manure (CM) and three co-substrates (chicken processing waste, Miscanthus and seagrass) in mono-digestion and co-digestion studies for selecting regional biomass in a bid to support the expansion of a full-scale biogas plant. Two types of kinetic models (first order and modified Gompertz models) were also applied to study the kinetics of the degradation process. The results show that all feedstock were converted to methane. The experimental methane production of chicken processing waste (CPW) and CM decreased about 27–35% compared to calculated methane production. However, the methane production rate/hydrolysis rates of mono digestion of chicken processing waste and co-digestion with CM were above 2 times quicker under the inoculum to substrate (I/S) ratio of 6 than that at the I/S ratio of 2 and 4. Miscanthus co-digestion effect was influenced by its composition and seagrass (SG) showed synergetic effect evidenced by high methane yield (which was 11–34% higher than the yield achieved from calculated BMP).

To investigate methanogenesis performance of upflow anaerobic sludge blanket (UASB) reactor started up using acidified granular sludge, we operated two UASBs with different initial organic loading rates (OLR) for treating supernatant of hydrothermally treated municipal sludge (SHTMS) over a 180-day period. Under a high OLR of 3.7–4.1 g COD/(L d), the Rh reactor obtained a maximum methane conversion efficiency of 61 % along with high volatile fatty acid (VFA) accumulation from day 0 to day 105. By contrast, under a low OLR of 1.9–2.1 g COD/(L d), the Rl reactor achieved a higher methane conversion efficiency of 85 %–88 % along with low VFA accumulation. Both reactors successfully completed start-up from day 60 to day 70. When the OLRs of both reactors were adjusted to 3.1–3.3 g COD/(L d) from day 106 to day 180, the same methane conversion efficiency of 71 % and methane yield of 285 mL CH4/g CODinfluent were achieved. Although Methanobacterium, Methanosarcina, Methanosaeta, and Methanomassiliicoccus were predominant in both reactors, they were not significantly correlated with OLR. Firmicutes, Synergistetes, and Bacteroidetes were the most dominant bacterial phyla, and the enriched bacterial microorganisms were deemed likely to survive in the Rl resctor with low OLR start-up. Therefore, the initial OLR has a substantial effect on the degradation performance and the microbial community variations in UASB reactors for SHTMS treatment.

Carbon sequestration using microalgae can be performed from bicarbonate (a product of carbon dioxide capture) and/or carbon dioxide. To implement either process successfully, the capability of microalgal strains is the most important criteria. In this work, a thermophilic microalgal Scenedesmus acuminatus TH04 was investigated to optimize its growth and carbon fixation in bicarbonate-based and carbon dioxide-based reactor systems. Culture variables including temperature, light intensity, pH, and aeration rate, concentration of NaHCO3, Na2CO3, CO2 and triethylenetetramine (TETA) were examined. The S. acuminatus TH04 strain achieved the highest biomass production and bicarbonate fixation efficiency of 1.7 g/L and 100 %, respectively, with 4.2 g NaHCO3/L. In a single photobioreactor (PBR), the maximum biomass production and CO2 fixation efficiency of 4.7 g/L and 9.8 % were achieved under the optimal conditions of CO2 of 5% (v/v), aeration rate of 0.1 vvm, TETA of 5 mM and Na2CO3 of 50 mM. Remarkably, a sequence of ten PBRs increased CO2 fixation efficiency by S. acuminatus TH04 to 93.9 %. The S. acuminatus TH04 strain demonstrated a highly potential capability in simultaneous production of biomass and carbon fixation from HCO3− and CO2 as carbon sources.

A novel deep-bed solid-state bioreactor was designed and fabricated for cellulolytic enzymes production using mixed fungal cultures. Better temperature and moisture control was achieved through a unique bioreactor design comprising an outer wire-mesh frame with internal air distribution along with near-saturation conditions within the cabinet. Without airflow through the internal distributors, maximum temperatures of 48 °C and 52 °C were observed during half- and full-capacity operation. These were reduced to 44 °C and 43 °C on resumption of airflow. In terms of cellulolytic enzyme production, no significant differences occurred in filter paper activity with depth in half-capacity operation; however, in full-capacity operation, top-level filter paper activity (5.39 FPU/g-solids) was significantly different from middle- and bottom-level activity. Top level beta-glucosidase, endocellulase, and xylanase activities were significantly (P < 0.05) different from middle and bottom levels in both half- and full-capacity operation. A two-phase coupled heat and mass transfer model was developed that predicted the experimental trends reasonably well. Model predictions confirmed that cabinet temperature of 30 °C and distributor airflow rate of 3.42 kg h−1 during operation enabled effective temperature control.

In addition to leveraging some environmental and energy benefits, microalgae can also be used as a potentially sustainable source for carotenoids like lutein for healthcare applications. As light influences biosynthesis of lutein in microalgae, it would be interesting to investigate the role of incremental illumination in enhancing photosynthetic efficiency and consequent lutein production, while sequestering CO 2 simultaneously. Thus, in this study, an optimal light feeding strategy coupled with a semi-continuous reactor operation was developed for achieving the above-mentioned goals. At a light intensity of 260 μmol m −2 s −1 as optimized in batch mode, baseline lutein productivity of 4.32 mg L −1 d −1 was obtained, when culturing Chlorella minutissima under optimal process conditions. On switching over to incremental illumination modes, the linear light-feeding (Strategy-III) resulted in higher lutein productivity of 5.35 mg L −1 d −1 with photosynthetic efficiency of 8.38%. When Strategy-III was integrated with semi-continuous mode involving 20% medium replenishment, lutein productivity, photosynthetic efficiency and CO 2 sequestration rate were further enhanced by 19%, 41% and 34% respectively. Moreover, on this process optimization and integration, light-energy consumption was significantly reduced by 32%, in comparison with constant-illumination. Thus, this optimal production strategy resulted in significantly higher lutein productivity, content and photosynthetic efficiency, as compared to the relevant studies reported in literature.

Methane-production microbial electrolysis cells (MECs) have been widely reported as an efficient strategy to enhance anaerobic digestion of waste activated sludge (WAS). However, the primary mechanism for accelerating the decomposition of complex substrates contained in WAS remains unclear as so far. In this study anaerobic sludge digestion operated in a single-chamber methane-production MEC was investigated. It was found that the decomposition rate of proteins and carbohydrates were significantly accelerated in MEC, which resulted in the improvement of methane production as compared with the common anaerobic sludge digester. The energy income from the increased methane production was equivalent to 13.4 times as more as the electric energy supply. Further bacterial community analysis showed that anaerobic fermentative bacteria were largely enriched in MEC especially its anodic biofilm. Together with anodic exoelectrogenic bacteria (mainly Geobacter species) accounting for the dominant part of bacterial community in the anodic biofilm, it was suggested that the potential for syntrophic interaction between anaerobic fermentative bacteria and anodic exoelectrogenic bacteria enriched might be the important reason for accelerating the decomposition of complex substrates contained in WAS, which further resulted in the high-efficiency methane production as well as energy recovery.

Two-stage aerobic coupled process consisted of anoxic, aerobic-1 with low DO and aerobic-2 with high DO (short for “A-LO-HO” process), was applied for post-treatment of poultry manure wastewater, which suffered by high ammonia nitrogen and high salinity. Outstanding NH4+-N removal efficiency of 99.5% was obtained, and the COD removal efficiency was about 75%, even under the severe stress. Multiple molecular technologies, include DGGE, real time PCR and high-throughput sequencing were applied to reveal the microbial community of the sludge. The reasonable distribution of the dominant bacteria Nitrosomonas and Nitrobacter would explain the synergistic effect of the partial nitrification in “A-LO” section and the completed nitrification in “HO” section. The microbial community and EPS analysis further confirmed the outstanding nitrifying ability, good salt-tolerant ability, and unaffected sedimentation property of the sludge with particular enhanced features which is acclimated for long time by the targeted coupled process and suitable for this kind of wastewater treatment.

This study combined an algae treatment with post-ozonation for the robust treatment of piggery effluent in which high levels of organic constituents, inorganic nutrients, color, and salts remained. Due to a nearly complete light limitation resulting from a high level of color, the algae treatment was conducted with continuous O 2 supplementation instead of using the combination of high lighting and CO 2 injection. The microalga Acutodesmus obliquus KGE-17 showed tolerance to high salinity (up to 5.2% as chloride) and was capable of utilizing dissolved organics (1923 mg-COD/(g-cell)(day)) under the heterotrophic growth conditions. The use of A . obliquus for remediation of piggery effluent also resulted in an operational simplicity in the simultaneous removal of nitrogen and phosphorus in a single treatment process, in contrast to conventional biological nutrient removal processes. Subsequent ozonation was successful in decolorizing the algae-treated wastewater and in improving the biodegradability of residual organics in post-treatment processes.

The effect of cellulases and beta-glucanases was evaluated for energy savings in the papermaking refining process. Two commercial enzyme preparations, Celluclast 1.5 L® (cellulases mixture) and Viscozyme L® (carbohydrases mixture) were used to improve the refining process of a bleached Eucalyptus globulus kraft pulp, using different enzyme dosages and different reaction times. This treatment improved pulp drainability (expressed as Schopper–Riegler degree) by up to 80% at the same level of refining energy (1500 PFI revolutions). These results were more significant for cellulases treatment. Pulp degradation was evaluated by the pulp viscosity determination, which was in agreement with the fibre length determination that showed a slight reduction with the enzymatic treatment. The strength properties of the pulp were not affected by enzyme treatment; in fact an increase was observed in paper internal bonding.

Flue gases emitted from industrial plants mainly contribute to global CO2 emissions. Sequestrations of CO2 from the flue gas could reduce the impact of CO2 on global warming. In this study, recombinant cyanobacterial strains with enhanced photosynthetic activity, cell growth, and ethanol production were generated by co-overexpressing ictB, ecaA, and groESL, along with a heterologous ethanol synthesis pathway (pdc-adhII genes from Zymomonas mobilis) in S. elongatus PCC7942. The engineered S. elongatus PCC7942 exhibited a significant improvement in cell growth and ethanol production under a simulated flue gas consisted of 25% CO2, 80−90 ppm SO2, 90−100 ppm NO. The present work represents the first attempt of direct photoconversion of CO2 from flue gases to ethanol via expression of ictB, ecaA, groESL, and pdc-adhII in S. elongatus. The transgenic cyanobacterium becomes useful for sequestrations of CO2 directly from flue gases with the simultaneous production of bioethanol.