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The aim of this study was to optimise airflow rate for glucoamylase and protease production from waste bread via solid state fermentation by Aspergillus awamori in packed bed bioreactors. Airflow rates, between 0.40 and 3.00 vvm, were tested. In all experiments, the fungal growth was almost uniform throughout the solids. Fungi grew both on and within the substrate and fungal cakes were formed. The highest glucoamylase and protease activities were recorded as 130.8 U/g bread (db) and 80.3 U/g bread (db) in the experiments with 1.50 wm airflow rate, respectively. These values are 27.2% and 32.3% higher than the glucoamylase and protease activities obtained in petri dish experiments with static air. At 1.50 vvm airflow rate, the dry weight of the solids had decreased to 46% of the initial value at the end of the fermentation. The temperature of the solids increased up to 37.5 °C with high axial temperature gradients due to high metabolic activity. The average moisture content of the solids first decreased to 150% (db) and then increased to 275% (db) by the end of the fermentation. Both above and below 1.50 wm airflow rate, enzyme production and fungal growth were affected significantly. Also, a Gaussian-based mathematical model was developed to model the effects of airflow rate on enzyme production. The model fitted almost seamlessly to the experimental data. Thus, this study clearly showed the effects of aeration on glucoamylase and protease production from waste bread under solid state fermentations. [ABSTRACT FROM AUTHOR]

When it is not consumed, bread presents a major source of food waste, both in terms of the amount and its economic value. However, bread also possesses the characteristics of an ideal substrate for solid state fermentation. Yet nearly all wasted bread ends up in landfill sites, where it is converted into methane by anaerobic digestion. Governments are finally taking action and, according to the EU Landfill Directive, for example, biodegradable municipal waste disposed into landfills must be decreased to 35% of 1995 levels, by 2020. Solid state fermentation of waste bread for the production of value added products is a novel idea, which could help with the achievement of this target. In this study, glucoamylase and protease production from waste bread pieces, via solid state fermentation, was investigated in detail. The optimum fermentation conditions for enzyme production were evaluated as, 20 mm particle size, 1.8 (w/w, db) initial moisture ratio, and duration of 144h. Under these conditions, glucoamylase and protease activities reached up to 114.0 and 83.2 U/g bread (db), respectively. This study confirms that waste bread could be successfully utilised as a primary raw material in cereal based biorefineries. [ABSTRACT FROM AUTHOR]

Background Agitated behaviours among persons with dementia are distressing to both patients and their caregivers. As pharmacological interventions may be limited by their potentially adverse effects, the use of complementary therapies for treatment of agitation has become more popular and aromatherapy is the fastest growing one. Objectives This study investigates the effectiveness of lavandula angustifolia (lavender) in treating agitated behaviours of demented people in Hong Kong. Methods It was a cross-over randomized trial. Seventy Chinese older adults with dementia were recruited; half were randomly assigned to the active group (lavender inhalation) for three weeks and then switched to control group (sunflower inhalation) for another three weeks; the other half did the opposite. Clinical response was evaluated using the Chinese versions of Cohen-Mansfield Agitation Inventory (CCMAI) and Neuropsychiatric Inventory (CNPI). Results The mean CCMAI total scores decreased from 24.68 to 17.77(t = 10.79, df = 69, p < 0.001). The CNPI scores changed from 63.17 (SD = 17.81) to 58.77 (SD = 16.74) (t = 14.59, df = 69, p < 0.001) after receiving Treatment A (Lavandula Angustifolia). There were no period and sequential effects noted. Conclusion In summary, lavender is effective as an adjunctive therapy in alleviating agitated behaviours in Chinese patients with dementia. In a patient population particularly vulnerable to side effects of psychotropic medications, aromatherapy using lavender may offer an alternative option. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Algal cells are known for improved accumulation of long chain fatty acids when grown in continuous flow cultures under conditions where nutrients, such as nitrogen and/or phosphorous, are limited. Food waste has been shown to be an appropriate source of carbon, nitrogen and phosphorous compounds to be used as nutrients in heterotrophic microalgal biomass production. Food waste, however, has unpredictable contents of the three mentioned compounds, which makes an application in continuous flow cultures where defined concentrations of nutrients are required challenging. Therefore, this study aimed on developing continuous flow cultures of the heterotrophic microalga Chlorella pyrenoidosa solely based on mixed restaurant food waste for improved fatty acid production. Food waste was enzymatically digested using amylolytic or proteolytic enzymes, and the obtained hydrolysate was used for the cultivation of C. pyrenoidosa in continuous flow cultures under nitrogen and/or phosphate limitation. In a nutrient sufficient batch culture, C. pyrenoidosa contained 103.8 mg g −1 lipids, while up to three times more lipids was found in biomass cultured under nutrient limited conditions. C. pyrenoidosa also accumulated up to 619.0 mg g −1 carbohydrates. With decreasing dilution rate and increasing nutrient stress, the carbohydrate content could be decreased to 390.9 mg g −1 . The outcomes of this study extended our understanding on how to utilize complex media in continuous flow cultures of algal cells which are carried out under specific nutrient limitation for improved fatty acid accumulation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Permeate turbidity stayed at around 3–4 NTU when TMP was larger than −2.5 kPa. • The AnSFDMBR functioned continuously for 243 days with TMP-based backwashing. • EPSs did not accumulate in the dynamic layer during the fouling phase. • The impact of the total organic sulfur in EPSs on fouling was investigated. • Total organic sulfur and polysaccharides accumulated on mesh during fouling phase. A side-stream cross-flow anaerobic self-forming dynamic membrane bioreactor (AnSFDMBR) connected with an up-flow anaerobic sludge blanket (UASB) reactor was used to replace the UASB and middle settling tank in sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI) process. To reduce the water and energy consumption for AnSFDMBR backwashing, the optimum condition of trans -membrane pressure (TMP)-based backwashing were investigated under sequential batch operations. Based on the optimum condition, a lab-scale AnSFDMBR was operated continuously for 243 days without a drop in flux, with good effluent quality. In the sequential batch operation study, AnSFDMBR showed no significant accumulation of total extracellular polymeric substances (EPSs) during 40 days of operation without backwashing. Polysaccharides slightly accumulated in the dynamic layer regardless of the final TMP and operation duration, indicating that TMP-based backwashing is suitable for the studied AnSFDMBR system. In long-term operation with TMP-based backwashing, total EPSs in dynamic layer to sludge ratio dramatically dropped during the fouling phase. According to the evaluation of total organic sulfur (TOS) in dynamic layer and mesh EPSs, it was found that TOS, mainly poly-sulfur generated in UASB reactor, played a critical role in fouling in saline wastewater treatment. TOS deposited on the mesh over 40% by weight of the total EPS in the fouling phase clearly led to system fouling. Additional sequential batch operations with different seawater percentages (%V/V) (control, 10%, 20%, 30% and 50%) demonstrated that the TOS accumulation on the mesh increased with time and salinity which also aligned with the long-term operation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tomato waste enhances I. galbana cultivation efficiency for producing fucoxanthin. • Soluble lycopene and β-carotene upregulated genes expressions PSY , LCYB , and ZEP3. • Hydrolyzed tomato waste in growth medium enhances fucoxanthin synthesis. • Tomato waste as nutrient source sustainably yields valuable products in microalgae. Vegetable waste, rich in bioactive compounds, offers a promising resource for producing value-added products. This study explored the use of tomato waste, containing glucose (40 mg/g), lycopene (95.12 μg/g), and β-carotene (24.31 μg/g), for cultivating fucoxanthin-rich Isochrysis galbana. Water-soluble lycopene (2.0 μg/mL) and β-carotene (0.4 μg/mL) effectively upregulated key carotenoid synthesis genes and boosted cell growth and fucoxanthin production (3.64 and 3.60 pg/cell, respectively) within 10 days in a mixotrophic culture. Optimized tomato waste hydrolysate achieved a high cell density of 1.21 × 107 cells/mL, 2.13 g/L biomass, and 21.02 mg/g fucoxanthin. This study highlights the potential of combining tomato waste with microalgae for a novel and innovative approach towards waste management and resource utilization. [ABSTRACT FROM AUTHOR]

Fossil fuel shortage is a major challenge worldwide. Therefore, research is currently underway to investigate potential renewable energy sources. Biodiesel is one of the major renewable energy sources that can be obtained from oils and fats by transesterification. However, biodiesel obtained from vegetable oils as feedstock is expensive. Thus, an alternative and inexpensive feedstock such as waste cooking oil (WCO) can be used as feedstock for biodiesel production. In this project, techno-economic analyses were performed on the biodiesel production in Hong Kong using WCO as a feedstock. Three different catalysts such as acid, base, and lipase were evaluated for the biodiesel production from WCO. These economic analyses were then compared to determine the most cost-effective method for the biodiesel production. The internal rate of return (IRR) sensitivity analyses on the WCO price and biodiesel price variation are performed. Acid was found to be the most cost-effective catalyst for the biodiesel production; whereas, lipase was the most expensive catalyst for biodiesel production. In the IRR sensitivity analyses, the acid catalyst can also acquire acceptable IRR despite the variation of the WCO and biodiesel prices. [ABSTRACT FROM AUTHOR]

[Display omitted] • N. oceanica purified tofu wastewater (TFW) and produced eicosapentaenoic acid (EPA) • N. oceanica with fed-batch mode boosted TFW contaminants removal by 86.99 ∼ 98.14 % • TFW - fed N. oceanica accomplished a superior biomass 26.37 g/L and EPA yield 43.5 mg/g. • Eicosapentaenoic acid derived from TFW-fed N. oceanica exerted hypolipidemic effect. Seeking environmentally-friendly and resource-recycling strategies for tofu wastewater (TFW) treatment could effectively mitigate harsh ecological impacts and resource wastage caused by direct discharge. This study investigated the feasibility on the utilization of Nannochloropsis oceanica (N. oceanica) for TFW eutrophication mitigation and eicosapentaenoic acid valorization. The findings demonstrated that employing N. oceanica resulted in significant removal rates for total phosphorus, total nitrogen, ammonia nitrogen, and chemical oxygen demand by 88.60 %, 97.02 %, 94.22 %, and 98.02 % under fed-batch treatment mode. Such nutrients removal efficiency met discharge permit standards while accomplished a superior biomass at 26.37 g/L and EPA yield at 43.5 mg/g by N. oceanica , representing 2.61- and 2.52-fold more than that of batch treatment mode. Furthermore, TFW feeding enhanced the cytomembrane fluidity of N. oceanica and promoted TFW nutrients uptake into cells consequently boosted the nutrients removal efficiency. Simultaneously, TFW feeding upregulated enzymes such as antioxidases, desaturases and elongases responsible for EPA biosynthesis in N. oceanica to collectively protect EPA from oxidation stress and stimulate proactive accumulation. EPA derived from TFW-fed N. oceanica exhibited promising in vitro antihyperlipidaemia efficacy in constructed hyperlipopyte HepG-2 cells. Further, the molecular docking indicated that the hypolipidemic activity partly contributed to that EPA inhibited PPARα signaling to trigger fatty acids β -oxidation and cholesterol transport suppression. The outcomes present a viable route that utilization of microalgae for TFW eutrophication mitigation and EPA valorization to advance carbon neutrality and resource recycling. [ABSTRACT FROM AUTHOR]

The feasibility of using pastry waste as resource for glucoamylase (GA) production via solid state fermentation (SSF) was studied. The crude GA extract obtained was used for glucose production from mixed food waste. Our results showed that pastry waste could be used as a sole substrate for GA production. A maximal GA activity of 76.1 ± 6.1 U/mL was obtained at Day 10. The optimal pH and reaction temperature for the crude GA extract for hydrolysis were pH 5.5 and 55 °C, respectively. Under this condition, the half-life of the GA extract was 315.0 minutes with a deactivation constant (kd) 2.20 × 10-3minutes-1. The application of the crude GA extract for mixed food waste hydrolysis and glucose production was successfully demonstrated. Approximately 53 g glucose was recovered from 100 g of mixed food waste in 1 h under the optimal digestion conditions, highlighting the potential of this approach as an alternative strategy for waste management and sustainable production of glucose applicable as carbon source in many biotechnological processes. [ABSTRACT FROM AUTHOR]

This article presents an inductive citation analysis to examine diffusion patterns and knowledge networks in the economic, geographical/environmental, and socio-cultural domains of tourism research. Articles typical of these specializations were selected from the latest issues of Annals of Tourism Research, Journal of Travel Research, and Tourism Management, to begin with the tracking of major sources of knowledge for research in a sub-domain. Citation data collection followed a theoretical sampling approach for a scrutiny of three 'generations' of intellectual connections. Analyses and sorting of subjects and coauthorship networks were facilitated by ATLAS.ti. Diffusion patterns are visualized through 'pointed and high' versus 'thick and flat' tree diagrams for these subdomains. The study also describes knowledge networks typically embedded in the coauthorship patterns of the major sources. While the study lends to discussions on intellectual connections, this set of inductively derived results should be read in caution of the research design, the behavior of citation, and the perspectives of the authors. [ABSTRACT FROM AUTHOR]

[Display omitted] • LCA study of fermentative production of succinic acid using bread waste. • GHG emissions and non-renewable energy use (NREU) are evaluated. • Processes using steam and heating oil are found to be environmental hotspots. • GHG emissions and NREU were significantly lower than fossil based succinic acid. According to the US Department of Energy, succinic acid (SA) is a top platform chemical that can be produced from biomass. Bread waste, which has high starch content, is the second most wasted food in the UK and can serve as a potential low cost feedstock for the production of SA. This work evaluates the environmental performance of a proposed biorefinery concept for SA production by fermentation of waste bread using a cradle-to-factory gate life cycle assessment approach. The performance was assessed in terms of greenhouse gas (GHG) emissions and non-renewable energy use (NREU). Waste bread fermentation demonstrated a better environmental profile compared to the fossil-based system, however, GHG emissions were about 50 % higher as compared to processes using other biomass feedstocks such as corn wet mill or sorghum grains. NREU for fermentative SA production using waste bread was significantly lower (~ 46 %) than fossil-based system and about the same as that of established biomass-based processes, thus proving the great potential of waste bread as a valuable feedstock for bioproduction of useful chemicals. The results show that steam and heating oil used in the process were the biggest contributors to the NREU and GHG emissions. Sensitivity analyses highlighted the importance of the solid biomass waste generated in the process which can potentially be used as fish feed. The LCA analysis can be used for targeted optimization of SA production from bread waste, thereby enabling the utilization of an otherwise waste stream and leading to the establishment of a circular economy. [ABSTRACT FROM AUTHOR]

Techno-economic analysis was conducted to evaluate a food and beverage (F&B) waste valorisation process for sugar syrup production via integrated biorefinery. A comprehensive process model was developed with a capacity of 10 metric tons (MT) hour-1 of food waste and 14 MT hour-1 of beverage waste. Three scenarios were proposed with different types of sugar syrups as the main products: Scenario 1) fructose syrup, Scenario 11) high fructose syrup-42, and Scenario III) glucose-rich syrup. Mass balance showed conversion yields of 0.24 MT sugar syrups per MT of F&B waste, while lipids (0.07 MT per MT of F&B waste) and insect feed (0.44 MT per MT of F&B waste) were the co-products proposed to be used for other industrial biorefinery processes. All scenarios were observed to be economically self-sustainable with net profit generation (US$11 -26 million year-1) and positive net present values (USS92-294 million). Along with the net production costs (USS443-665 MT~1), the sugar syrups derived from the F&B waste have relatively low minimum selling prices of US$157-747 MT-1 at a 5% discount rate. Lastly, sensitivity analysis was performed which found that the prices of sugar syrups were the largest determinants of their profitability. This study proposes a significant techno-economic basis for F&B waste biorefinery, which offers a successful demonstration for food and drink industries adopting these biotechnological processes for the same plant size. [ABSTRACT FROM AUTHOR]

Conversion of food and beverage (F&B) waste into high fructose syrup (HFS) was proposed in this study. Hydrolysate obtained from saccharification of mixed F&B waste is rich in glucose (260.3 ± 7.8 g L−1) and fructose (54.1 ± 1.6 g L−1) but also contains trace preservatives, caffeine, colourants, ions and soluble proteins. Over 99% of these impurities were removed by adsorption and ion exchange chromatography, followed by enzymatic isomerisation where glucose was converted to reach 50% of fructose content. Pilot scale downstream processing was successfully conducted with more than 89% of sugars recovered from the hydrolysate. Mass balance analysis indicated an overall conversion yield of 0.08 kg HFS per kg of mixed F&B waste and meanwhile the HFS also conforms to industrial standards. This proposed process is believed to promote the development of a circular economy by recycling F&B waste as a renewable resource for HFS production. [ABSTRACT FROM AUTHOR]

Abundant textile waste has raised increasing concerns worldwide in developing novel circular textiles approach. This study investigated the optimum cellulase production from textile waste by Aspergillus niger CKB. Textile wastes consisting of cotton and polyester in various ratios were used as low-cost feedstock. Three types of cultivation media were compared in solid state fermentation and Mandels medium with yeast extract selected due to its superior cellulase production. Conditions including moisture, pH, inoculum size and organic nitrogen were evaluated and optimised via response surface methodology. Supplementary carbon sources and cellulase inducers were also employed to enhance fungal growth and cellulase production. The results indicated that the optimised fermentation method significantly improved cellulase producing efficiency and enzyme activity by 88.7% and 25.8%, respectively. The maximum cellulase activity reached 1.56 FPU g-1 in 6 days. The outcomes led to the efficient recovery of glucose and polyester, which could contribute to a closed-loop recycling strategy for the textile industry, and enable the transition to an advanced circular textiles economy. [ABSTRACT FROM AUTHOR]

Textile waste is one type of municipal solid waste growing rapidly in recent years. In Hong Kong, 306 t of textile waste were produced daily in 2015 and more than 90% of these ended up in landfill. This is the first paper which utilizes textile wastes as substrate for cellulase production via submerged fungal fermentation, the resultant fungal cellulase was subsequently utilised in textile waste hydrolysis for recovery of glucose and polyester. Trichoderma reesei ATCC 24449 was selected with the highest cellulase activity (18.75 FPU/g) after cultivation using textile blending cotton/polyester 40/60 as substrate. Cellulase production was upscaled in a 5-L bioreactor and the resultant cellulase was used in textile waste hydrolysis. Glucose recovery yield of 41.6% and 44.6% were obtained using fungal cellulase and commercial cellulase, respectively. These results suggest the proposed process has a great potential in treating textile waste and facilitating the recovery of glucose and polyester as value-added products. [ABSTRACT FROM AUTHOR]

This study demonstrates the feasibility of poly(lactic acid) fibre production using fermentative lactic acid from food waste. Poly(lactic acid) was synthesized through ring-opening polymerization, in which the precursor lactide was produced by a novel catalytic method. Zinc oxide aqueous nanoparticle (30–40 nm) dispersion was applied as efficient catalyst due to its large surface area and rapid equilibrium between polymerization and depolymerization. Under optimal reaction conditions, lactide was produced at yields of 91–92% within 8 h, significantly improving the synthesis efficiency compared to the conventional tin-based catalytic method. The pure lactide product facilitated the conversion of food waste derived lactic acid to high molecular weight poly(lactic acid) (150,000 g mol −1 ), which was subsequently spun to fibres with promising tensile and thermal properties for potential applications in textile and bioplastics. [ABSTRACT FROM AUTHOR]

Waste valorisation practices have attracted a significant amount of attention in recent years with the aim at managing waste in the most sustainable way. Most of the studies focused on converting solid waste feedstock for value-added chemicals and fuels production. However, less effort has been devoted on liquid waste such as beverage waste which is a significant sewage stream in urban area. In this study, a bioconversion process was developed to produce low-cost fructose syrup using beverages waste as feedstock. The process composed of enzymatic hydrolysis, activated carbon treatment, ion exchange chromatography and ligand exchange chromatography. Beverages waste collected from local supermarket was treated by commercial pectinase and sucrase. Optimisation study on enzyme activities indicated that both enzymes were most active at 50 °C and pH of 4.0-4.5. Hydrolysate containing 36.0 g/L glucose and 45.0 g/L fructose was then de-colourised in the activated carbon treatment. Also, more than 98% ions were removed after the cation and anion exchange chromatography. Lastly, high fructose syrup was produced by ligand exchange chromatography at a fructose separation efficiency of 74.9%. A total of 47.5% sugars in the hydrolysate were recovered as high fructose syrup, while the remaining sugars were in the glucose-rich stream. The proposed method would be a green and sustainable process for nutrient recovery in beverage waste valorisation. Future study should focus on increasing fructose separation efficiency by using simulated moving bed system and the enhancement of fructose production yield by isomerisation of glucose-rich stream. [ABSTRACT FROM AUTHOR]

Soil acidification is the main cause for aggravation of soil cadmium (Cd) pollution. Biochar treatment can increase the soil pH and decrease the Cd availability in soils. However, there is limited information in literature on the comprehensive assessment of the response of Cd fractions to biochar. Therefore, in the present meta-analysis study, we evaluate the response of Cd fractions to biochar application in soils with different pH and to further examine the effect of physicochemical properties of biochar on Cd. Results from the overall analysis indicated that biochar treatment increased the soil pH by 7.0%, thereby decreasing the amount of available Cd (37.3%). In acidic soil, biochar significantly reduced the acid-soluble fraction (Acid-Cd) of Cd by 36.8%, while Oxidizable fraction of Cd (Oxid-Cd, 20.9%) and Residual fraction of Cd (Resid-Cd, 22.2%) were significantly increased. In neutral soils, only Acid-Cd was significantly reduced (33.0%) in the presence of biochar. In alkaline soils, biochar caused significant reduction in Acid-Cd of 12.4% and an increase in Oxid-Cd and Resid-Cd of 26.6% and 47.8%, respectively. Further, our findings showed that biochar with cation exchange capacity >100 cmol+/kg effectively decreased Acid-Cd (32.4%), while biochar with the percentage of hydrogen <2% was more contributory in increasing Resid-Cd (64.3%). These results demonstrate the importance of soil pH in regulating the biological effectiveness of Cd in soil and the complexation between the functional groups of biochar and Cd, and provide key information for the remediation of Cd pollution in soils with different pH by biochar. [ABSTRACT FROM AUTHOR]

Background: Integrating waste management with fuels and chemical production is considered to address the food waste problem and oil crisis. Approximately, 600 million tonnes crude glycerol is produced from the biodiesel industry annually, which is a top renewable feedstock for succinic acid production. To meet the increasing demand for succinic acid production, the development of more efficient and cost-effective production methods is urgently needed. Herein, we have proposed a new strategy for integration of both biodiesel and SA production in a biorefinery unit by construction of an aerobic yeast Yarrowia lipolytica with a deletion in the gene coding succinate dehydrogenase subunit 5. Results: Robust succinic acid production by an engineered yeast Y. lipolytica from crude glycerol without pretreatment was demonstrated. Diversion of metabolic flow from tricarboxylic acid cycle led to the success in generating a succinic acid producer Y. lipolytica PGC01003. The fermentation media and conditions were optimized, which resulted in 43 g L-1 succinic acid production from crude glycerol. Using the fed-batch strategy in 2.5 L fermenter, up to 160 g L-1 SA was yielded, indicating the great industrial potential. Conclusions: Inactivation of SDH5 in Y. lipolytica Po1f led to succinic acid accumulation and secretion significantly. To our best knowledge, this is the highest titer obtained in fermentation on succinic acid production. In addition, the performance of batch and fed-batch fermentation showed high tolerance and yield on biodiesel by-product crude glycerol. All these results indicated that PGC01003 is a promising microbial factorial cell for the highly efficient strategy solving the environmental problem in connection with the production of value-added product. [ABSTRACT FROM AUTHOR]

Polycondensation and ring-opening polymerization are two important polymer synthesis methods. Poly(lactic acid), the most typical biodegradable polymer, has been researched extensively from 1900s. It is of significant importance to have an up-to-date review on the recent improvement in techniques for biodegradable polymers. This review takes poly(lactic acid) as the example to present newly developed polymer synthesis techniques on polycondensation and ring-opening polymerization reported in the recent decade (2005-2015) on the basis of industrial technique modifications and advanced laboratory research. Different polymerization methods, including various solvents, heating programs, reaction apparatus and catalyst systems, are summarized and compared with the current industrial production situation. Newly developed modification techniques for polymer properties improvement are also discussed based on the case of poly(lactic acid). [ABSTRACT FROM AUTHOR]

Sludge, a byproduct produced from numerous industrial activities, has been recognized as an ecological burden for the society. However, viewing the sludge, as a carbon-rich material, has stimulated new gateways for the production of porous activated carbons for water treatment applications. Herein, various textural properties of the sludge-based activated carbons have been compiled and critically reviewed with the focus on surface area, pore size and pore size distribution for both physically and chemically activated carbons. It has been found that chemical activation using various activating agents yields more superior adsorbents with high specific surface areas than physical activation methods. Moreover, the potential of sludge-derived activated carbons for the sequestration of metals and dyes from aqueous media has been discussed. Furthermore, the adsorption mechanism in several adsorbent–adsorbate systems and the effect of various parameters on the adsorption behavior of different dyes and metals on sludge-based activated carbons have been reviewed. It has been shown that the pollutant uptake capacities of the adsorbents derived from sewage sludge are not only governed by the textural properties of the adsorbents, but also by their surface properties, such as the functional groups and the surface charge and thus it is proposed that both of these crucial factors be considered concurrently. [ABSTRACT FROM AUTHOR]

Lipase produced by Aspergillus niger is widely used in various industries. In this study, extracellular lipase production from an industrial producing strain of A. niger was improved by medium optimization. The secondary carbon source, nitrogen source, and lipid were found to be the three most influential factors for lipase production by single-factor experiments. According to the statistical approach, the optimum values of three most influential parameters were determined: 10.5 g/L corn starch, 35.4 g/L soybean meal, and 10.9 g/L soybean oil. Using this optimum medium, the best lipase activity was obtained at 2,171 U/mL, which was 16.4% higher than using the initial medium. All these results confirmed the validity of the model. Furthermore, results of the Box-Behnken Design and quadratic models analysis indicated that the carbon to nitrogen (C/N) ratio significantly influenced the enzyme production, which also suggested that more attention should be paid to the C/N ratio for the optimization of enzyme production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluation of bread waste (BW) as feedstock for 2,3-butanediol (BDO) production. • Glucose yield of 330–530 g/kg BW was obtained by acid and enzymatic hydrolysis. • BDO titer of 144.5 g/L and yield of 0.47 g/g was achieved on pure glucose. • BDO titer of 135.4 g/L with a yield of 0.42 g/g was amassed from acid hydrolysed BW. • Enzyme hydrolysed BW generated 138.8 g/L BDO with a yield of 0.48 g/g. Bread is Europe's most wasted food, and the second most wasted food after potatoes in UK. Bread waste (BW) is a clean source of high-quality fermentable sugars. In this study, the potential of Enterobacter ludwigii to accumulate 2,3-butanediol (BDO) from BW was evaluated. Initially, the optimal inoculum size and yeast extract concentration were determined, followed by extraction of sugars from BW using acid and enzymatic hydrolysis. A glucose yield of 330–530 g/kg BW was obtained, and the sugars released were utilised for BDO production by E. ludwigii. The fed-batch cultivation using pure glucose and glucose rich hydrolysates from acid and enzymatic hydrolysis resulted in BDO titres of 144.5, 135.4, and 138.8 g/L, after 96 h, with yield of 0.47, 0.42 and 0.48 g/g yield, respectively. The innovation of the work is valorisation of BW to BDO with a circular biorefining approach and thus, reducing BW disposal and associated environmental burden. [ABSTRACT FROM AUTHOR]

The recycling of waste printed circuit boards (PCBs) has become one of the global challenges in the technological era. The colossal volume of waste PCB generated annually coupled with its toxic nature and the existence of highly-precious metals in its composition intensifies the problems associated with waste PCB management and recycling. The two prevalent waste management options, landfill disposal and incineration, are being phased out for this special waste as a result of public health concerns. Hence, in the past few decades, several PCB recycling schemes are being introduced. The most efficient and environmentally-sound practice for waste PCB recycling has been the separation of metallic and nonmetallic fraction of PCBs by extensively-studied physico-mechanical approaches. Although the metallic fraction can be directly rendered into the market due to its high value, the nonmetallic fraction (NMF) is either disposed of in landfills causing secondary pollution or used as a low-value filler with the sole purpose of its safe disposal. This study presents a brief overview of the utilization of NMF as a filler in various industries. The main objective of the present review is to thoroughly examine the novel, highly efficient application of NMF as precursor for the production of a mesoporous structured adsorbent and its application in the removal of a myriad of heavy metals in single- and multi-component systems. In addition, the effects of the operational parameters on the adsorption behavior of the adsorbent material have been provided. Moreover, a comprehensive overview of the adsorption system modelling for single and binary-component systems for this novel material has been compiled. [ABSTRACT FROM AUTHOR]

In this paper, the techno-economic study for a pilot-scale production of succinic acid from food waste via fermentation was evaluated. The pilot plant was based in Hong Kong and designed for converting 1 tonne/day of bakery waste into succinic acid. The mass and energy balance of the process was simulated by computer package Super- Pro Designer®. The total capital investment for the plant and the total production cost were US$ 1,118,243 and US$ 230,750/year respectively. Overall revenue generated from the process was US$ 374,041/year. The return on investment, payback period and internal rate of return of the project were 12.8%, 7.2 years and 15.3% respectively. The findings indicated that the fermentative succinic acid production from bakery waste was feasible. This is important for attracting investment and industrialization interest on the biorefinery process using domestic wastes as raw materials. [ABSTRACT FROM AUTHOR]

The transition from a fossil fuel-based economy to a bio-based economy necessitates the exploitation of synergies, scientific innovations and breakthroughs, and step changes in the infrastructure of chemical industry. Sustainable production of chemicals and biopolymers should be dependent entirely on renewable carbon. White biotechnology could provide the necessary tools for the evolution of microbial bioconversion into a key unit operation in future biorefineries. Waste and by-product streams from existing industrial sectors (e.g., food industry, pulp and paper industry, biodiesel and bioethanol production) could be used as renewable resources for both biorefinery development and production of nutrient-complete fermentation feedstocks. This review focuses on the potential of utilizing waste and by-product streams from current industrial activities for the production of chemicals and biopolymers via microbial bioconversion. The first part of this review presents the current status and prospects on fermentative production of important platform chemicals (i.e., selected C2--C6 metabolic products and single cell oil) and biopolymers (i.e., polyhydroxyalkanoates and bacterial cellulose). In the second part, the qualitative and quantitative characteristics of waste and by-product streams from existing industrial sectors are presented. In the third part, the techno-economic aspects of bioconversion processes are critically reviewed. Four case studies showing the potential of case-specific waste and by-product streams for the production of succinic acid and polyhydroxyalkanoates are presented. It is evident that fermentative production of chemicals and biopolymers via refining of waste and by-product streams is a highly important research area with significant prospects for industrial applications. [ABSTRACT FROM AUTHOR]

Anaerobic fermentation (AF) is a widely used process for the transformation of organic waste into biogas. However, despite its ubiquitous use, it has several limiting factors, including low yield, redox imbalance, high concentration of inhibitors, and a long retention time. Integration of pyrolysis with AF improves efficiency and facilitates effective biomass utilization in a closed-loop approach. Research trends emphasize the inclusion of biochar derived from biomass to improve the stability and efficiency of AF and facilitate biogas up-gradation (H 2 S removal). However, there is a lack of consolidated scientific understanding regarding the complex interactions of biochar and AF microbial communities, in addition to its potential amendment advantages. Therefore, this review summarizes biomass utilization for biochar production using various pyrolysis methods and its use as an effective inclusion material to improve AF performance. Specifically, the influence of biochar amendments in AF is discussed in terms of microbial colonization, direct interspecies electron transfer, minimization of organic load, and buffering maintenance. Moreover, the role of AF digestate biochar in nutrient recycling and utilization as a soil conditioner is elaborated. The progressive integration of pyrolysis and AF offers the complete decoupling of biomass, enhances AF performance, and promotes the establishment of a sustainable bioprocess by inducing the circular bioeconomy. • Biochar amendments in anaerobic fermentation (AF) improve the process efficiency. • Biochar inclusion in AF offers DIET, microbial colonization, and maintain buffering. • Pyrolysis conditions and biomass type has a significant influence on biochar composition. • Progressive integration of pyrolysis and AF maximize the resource recovery in closed-loop. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanism in synergistic effect of microbial consortia is reported for the first time. • Increase Addition of one strain changes the microbial consortia structure and function. • Balanced structure and enriched key genes enable microbial consortia specific ability. • Ethanol with the highest yield that is ever reported was achieved at 0.28 g/g. A consortium (HPP) with improved ability in biomass conversion was achieved by adjusting the proportion of Pseudoxanthomonas taiwanensis in a natural consortium (HP), but the mechanism behind was unknown. Herein, the diversities of microbial community structure and gene functions of the consortia were analyzed first, and found that HPP had a more balanced microbial structure with enriched gene pathways related to cellular processes, environmental information processing and metabolism. Then, key genes responsible for biomass conversion were further analyzed, finding that their abundance and distribution contributed to HPP's efficient biomass conversion. Finally, consolidated bioprocessing of agricultural wastes by HPP was carried out to verify its enhanced ability, and ethanol with the highest yield that was ever reported was achieved at 0.28 g/g. This is the first study which reported the underlying mechanisms for synergistic effects of microbial consortia, and will guide the artificial construction of complex microbial consortium for specific purpose. [ABSTRACT FROM AUTHOR]