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Replication stress causes replication fork stalling, resulting in an accumulation of single-stranded DNA (ssDNA). Replication protein A (RPA) and CTC1-STN1-TEN1 (CST) complex bind ssDNA and are found at stalled forks, where they regulate RAD51 recruitment and foci formation in vivo. Here, we investigate crosstalk between RPA, CST, and RAD51. We show that CST and RPA localize in close proximity in cells. Although CST stably binds to ssDNA with a high affinity at low ionic strength, the interaction becomes more dynamic and enables facilitated dissociation at high ionic strength. CST can coexist with RPA on the same ssDNA and target RAD51 to RPA-coated ssDNA. Notably, whereas RPA-coated ssDNA inhibits RAD51 activity, RAD51 can assemble a functional filament and exhibit strand-exchange activity on CST-coated ssDNA at high ionic strength. Our findings provide mechanistic insights into how CST targets and tethers RAD51 to RPA-coated ssDNA in response to replication stress., During replication stress, the RPA protein complex coats single-stranded DNA to preclude RAD51 loading. Here, the authors show how RPA and CST crosstalk to regulate RAD51 activity.

Synthesizing novel photocatalysts that can effectively harvest photon energy over a wide range of the solar spectrum for practical applications is vital. Porphyrin-derived nanostructures with properties similar to those of chlorophyll have emerged as promising candidates to meet this requirement. In this study, tetrakis(4-carboxyphenyl) porphyrin (TCPP) nanofibers were formed on the surface of ZnO nanoparticles using a simple self-assembly approach. The obtained ZnO/TCPP nanofiber composites were characterized via scanning electron microscopy, X-ray diffraction analysis, and ultraviolet–visible absorbance and reflectance measurements. The results demonstrated that the ZnO nanoparticles with an average size of approximately 37 nm were well integrated in the TCPP nanofiber matrix. The resultant composite showed photocatalytic activity of ZnO and TCPP nanofibers concomitantly, with band gap energies of 3.12 and 2.43 eV, respectively. The ZnO/TCPP photocatalyst exhibited remarkable photocatalytic performance for RhB degradation with a removal percentage of 97% after 180 min of irradiation under simulated sunlight because of the synergetic activity of ZnO and TCPP nanofibers. The dominant active species participating in the photocatalytic reaction were •O2– and OH•, resulting in enhanced charge separation by exciton-coupled charge-transfer processes between the hybrid materials.

Three types of biomass of invasive plants and agrowastes, namely, the wattle bark of Acacia auriculiformis (BA), mimosa (BM), and coffee husks (BC), were converted into biochars through slow pyrolysis and investigated for their ability to remove dyes in water. The properties of the materials were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis. The BET surface area (total pore volume) of BC was 2.62 m2/g (0.007 cm3/g), far below those of BA and BM with 393.15 cm2/g (0.195 m3/g) and 285.53 cm2/g (0.153 m3/g), respectively. The optimal adsorption doses for the removal of methylene blue (MB) were found to be 2, 5, and 5 g/L for BC, BA, and BM, respectively. The suitable pH ranges for MB removal were 6–12 for BA, 7–12 for BC, and 2–10 for BM. The majority of MB (over 83%) was removed in the initial 30 min, followed by a more quasisteady state condition after the removal rate exceeded 90%. The experimental data were fitted with the kinetic models (PFO, PSO, Bangham, IDP), indicating that physicochemical adsorption, pore diffusion process, and multiple stages are the dominant mechanisms for the MB adsorption onto biochars. Finally, BA and BM showed similar adsorption efficiencies, while BC may not be favorable for use as an adsorbent due to its low surface area and low pore volume.

The CO2 methanation reaction of reduced and unreduced Ni based CeO2, Al2O3, TiO2 and Y2O3 supported catalysts was investigated. The Ni/CeO2 and Ni/Y2O3 catalysts exhibited similar CO2 conversions at all reaction temperatures. The catalysts were studied by X-ray diffraction (XRD), H2 chemisorption, H2 temperature-programmed reduction (TPR), and in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS); the results suggested that the reducibility of both metal and support at low temperature, strong metal support interaction and small Ni particle size are important factors for low-temperature CO2 methanation. Based on the DRIFT studies, the difference in the CO2 adsorption properties and reaction pathway depending on the reduced and unreduced Ni based supported catalysts was discussed.

The present study aimed to evaluate the effects of chrysoeriol from Cardiospermum halicacabum in streptozotocin induced Wistar rats. Thirty rats were categorized as control, diabetic control supplemented with 0, 20 mg/kg chrysoeriol and 600 μg/kg BW of glibenclamide for 45-day trial period. Our results indicated that the inclusion of chrysoeriol (20 mg/kg), showed a significant reduction in plasma glucose, hemoglobin and glycosylated hemoglobin level with a rising of plasma insulin sensitivity. Further, downregulated enzymes including glucose 6-phosphatase, fructose 1,6-bisphosphatase, and glycogen phosphorylase as well upregulated enzymes such as hexokinase, glucose-6-phosphate dehydrogenase, pyruvate kinase, and hepatic glycogen content. There was a diminish action found in liver glycogen synthase of tested rat with a rise in gamma-glutamyl transpeptidase, towards normal levels upon treatment with chrysoeriol. The histopathological study confirmed that renewal of the beta cells of pancreatic of chrysoeriol and glibenclamide treated rats. In addition, the molecular docking of chrysoeriol against glycolytic enzymes including hexokinase, glucose-6-phosphate dehydrogenase, pyruvate kinase, using Argus software shows chrysoeriol had greatest ligand binding energy as equivalent to glibenclamide, as a standard drug. Thus, chrysoeriol found to be non-toxic with potential regulation on glycemic control and upregulation of the carbohydrate metabolic enzymes.

Textile effluents contain triazine-substituted reactive dyes that cause health problems such as cancer, birth defects, and hormone damage. An electrochemical process was employed effectively to degrade azo reactive dye with the aim of reducing the production of carcinogenic chemicals during biodegradation. Textile dye C.I. Reactive Red 2 (RR2), a model pollutant that contains dichloro triazine ring, was subjected to the electrocoagulation process using aluminium (Al) electrodes. A maximum of 97% of colour and 72% of chemical oxygen demand (COD) removal efficiencies were achieved and 9.5 kWh/kg dye electrical energy and 0.8 kg Al/kg dye electrode consumption were observed. The dye removal mechanism was studied by analysing the results of UV-Vis spectra of RR2 and treated samples at various time intervals during electrocoagulation. Fourier transform infrared (FTIR) spectra and energy dispersive X-ray (EDX) spectral studies were used for analysing the electrocoagulated flocs. The results indicate that in this process the dye gets removed by adsorption and there is no significant carcinogenic by-product formation during the degradation of dye.

The present study is focused on bio hydrogen (H2) and bioplastic (i.e., poly-β-hydroxybutyrate; PHB) productions utilizing various wastes under dark fermentation, photo fermentation and subsequent dark-photo fermentation. Potential bio H2 and PHB producing microbes were enriched and isolated. The effects of substrate (rice husk hydrolysate, rice straw hydrolysate, dairy industry wastewater, and rice mill wastewater) concentration (10–100%) and pH (5.5–8.0) were examined in the batch mode under the dark and photo fermentation conditions. Using 100% rice straw hydrolysate at pH 7, the maximum bio H2 (1.53 ± 0.04 mol H2/mol glucose) and PHB (9.8 ± 0.14 g/L) were produced under dark fermentation condition by Bacillus cereus. In the subsequent dark-photo fermentation, the highest amounts of bio H2 and PHB were recorded utilizing 100% rice straw hydrolysate (1.82 ± 0.01 mol H2/mol glucose and 19.15 ± 0.25 g/L PHB) at a pH of 7.0 using Bacillus cereus (KR809374) and Rhodopseudomonas rutila. The subsequent dark-photo fermentative bio H2 and PHB productions obtained using renewable biomass (i.e., rice husk hydrolysate and rice straw hydrolysate) can be considered with respect to the sustainable management of global energy sources and environmental issues.

Phytoremediation is a promising green technology for the remediation of various industrial effluents. Notably, aquatic plants are widely applied to remove dyes and toxic metals from polluted environments. In the present study, the phytoremediation potency of aquatic macrophytes such as Pistia stratiotes L, Salvinia adnata Desv, and Hydrilla verticillata (L.f) Royle were assessed based on the removal capability of pollutants from dyeing effluent. Physicochemical characterizations were carried out for industrial wastewater collected from a cotton material dyeing unit located in the Karur District of Tamilnadu, India. The physicochemical characteristics of the dyeing effluent, such as color, odor, pH, total dissolved solids (TDS), alkalinity, acidity, chloride, sulfate, phosphate, nitrate, chemical oxygen demand (COD), fluoride, and toxic metal levels were determined. The core parameters such as total dissolved solid (TDS), chemical oxygen demand (COD), and chloride level were determined and found to be 6500 mg/L, 2400 mg/L, and 2050 mg/L, respectively, which exceeded the regulatory limit prescribed by the Central Pollution Control Board of India. The levels of toxic metals such as Hg, Ni, and Zn were under the acceptable concentration but Cr and Pb levels in the dyeing effluent were a little bit higher. The effluent was subjected to treatment with Pistia stratiotes L, Salvinia adnata Desv and Hydrilla verticillata (L.f) Royle separately. After the treatment, the toxic metal results were recorded as below detectable levels and the same results were obtained for all three aquatic plants samples used for treatment. Among the three plants, P. stratiotes L efficiently removed 86% of color, 66% of TDS, 77% of COD, and 61.33% of chloride. The variation in phytochemicals of the macrophytes was studied before and after treatment using GC&ndash, MS which revealed the reduction of ascorbic acid in the plant samples. The toxic effect of treated effluent was investigated by irrigating an ornamental plant, Impatiens balsamina L. The plant biomass P. stratiotes L obtained after the treatment process was subjected to manure production and its nutrient quality was proved, which can be applied as a soil conditioner. Among the aquatic plants, the results of P. stratiotes L indicated a higher remediation potential, which can be used as an ecologically benign method for treatment of industrial effluents and water bodies contaminated with dyeing effluents.

Zero-valent iron (ZVI) has been widely studied and utilized as a highly reductive agent for environmental remediation. In this study, a ZVI nanoflake-decorated graphene composite was successfully fabricated via the reduction of Fe2+ ions in ethanol solution. The new ZVI nanoflake-decorated graphene composite (GNPs@fZVI) (here GNPs are graphene nanoplates) was thoroughly characterized using scanning electron microscopy, energy dispersive spectroscopy mapping, X-ray diffraction, Fourier-transform infrared spectroscopy, and magnetic measurements. The obtained GNP@fZVI composite consisted of hierarchical ZVI nanoflakes decorated on the surface of the GNPs. The hierarchical ZVI nanosheets presented a top layer of structural flake-like ZVI clusters with an average diameter of 1 μm and a bottom layer of uniform petal-like nanosheets with less than 10 nm thickness. The rhodamine B (RhB) removal performance of the resultant GNP@fZVI composite from aqueous solutions and the factors affecting the RhB removal efficiency of the composites were investigated. The results indicated that the as-prepared GNP@fZVI composite exhibited high RhB removal performance, and its removal efficiency was 100% after only 2.5 h of treatment using 3 g L−1 GNP@fZVI composite. Lastly, the probable simultaneous adsorption and reduction mechanism of the RhB dye using the GNP@fZVI composites was also discussed.

Adsorption technologies are considered to be cost-effective solutions for the removal of toxic residues. In the present study, two types of sulfated TiO2 adsorbents, sulfated–TiO2(A) and sulfated–TiO2(B), were prepared by the wetness impregnation method, and tested for how effectively they could bind to, and hence, remove arsenic. These adsorbents were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The interaction of the arsenic with the sulfate group at the surface of the adsorbent can be deduced by the reduction in the peak intensity of the S O bond at 1219 cm−1, corresponding to the SO42− group. In particular, the number of Lewis and Bronsted acid sites was enhanced in the sulfated–Ti(OH)4 adsorbents, which modulated the surface acidity of titania by controlling the electron density and facilitated the adsorption of arsenic. Our results confirmed that sulfated–TiO2(B) is 20% more efficient at removing arsenic, as compared to TiO2 (60%) and Ti(OH)4 (64%).

We prepared epoxidized soybean oil (ESO) grafted with carboxyl-terminated poly(acrylonitrile-co-butadiene) (CTBN) (ESO-g-CTBN) by a ring-opening reaction between the epoxide group and the carboxyl group. The structural features of the resulting product were determined using modern analytical techniques, such as Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and gel permeation chromatography (GPC). The ESO-g-CTBN was applied as a toughener for an epoxy resin-based composite that was fabricated by blending the epoxy resin with diethylenetriamine (DETA) as the curing agent. The main aim of this procedure is to simultaneously improve the mechanical properties and fracture toughness of a bisphenol A-based epoxy resin. When 15 phr of ESO-g-CTBN was added to the EP/DETA mixture, the resin fracture toughness (KIC) and tensile strength increased from 0.65 to 1.09 MPa m1/2 and from 34.42 to 42.55 MPa, respectively. The ESO-g-CTBN existed in the EP matrix as a separate phase and induced an increase in the KIC via stopping crack growth or changing the crack direction. The epoxydized soybean oil grafted with CTBN (ESO-g-CTBN) was synthesized from ring opening reaction between epoxide group and carboxyl group. The ESO-g-CTBN help to improve the fracture toughness of epoxy resin by the mechanism as shown in the figure.

Highest third worldwide production of the agricultural product namely rice causes a huge quantity of waste residues especially, rice bran concurrently with rice husk. It fabricates the residual wastes nearly of about 31.9 MMT annually throughout the world and owing to the thermal point of view they are not easily upgradable due to high silica content. Meanwhile, rice bran after extrusion in broilers have been used to extract oil containing free fatty acids (FFAs) (15–30%) such as cis–9–, & cis–12–octadecadienoic and cis–9, cis–12 & cis–15–octadecatrienoic oils. Rice bran fatty oil methyl esters are suitably converted into biodiesel for compression ignition (CI) engines via transesterification path in the presence of Ni/H2 heterogeneous basic catalytical environment along with 4–methoxy–2–hydroxybenzalidene–p–toluidine promoter. Owing to significant viscous and volatile nature drawbacks of potential alternative first and second generation biofuels, there occur some troubles in their long application in CI engines could effectively minimized by such a catalytical pathway. The literature has been found a very little research on this oil as a potential substitute for petro–diesel. Finally, the produced rice bran based biodiesel was analyzed for its appropriateness as a fuel for CI engines. The outcomes explored the characteristics for the biodiesel extracted, under the most promising circumstances are resembling those of the petro–based fuels. The observed yields are high when compared to other enzymatic transesterification and homogeneous catalysis. In addition, in vitro microbial and antioxidant potentialities of RBOB were tested and compared with standard controls. Alternatively, low value by–products for the biodiesel industries like glycerol were also obtained and it gave oil suitable to feed the power generators.

In this study, suspensions of core–shell particles dispersed in a silicone oil were fabricated and their rheological properties were evaluated at different external electric field strengths. The core–shell-structured composite materials were synthesized by coating poly(o-toluidine) (PoT) shells on the surfaces of silica particles. The silica particles were extracted from rice husk through acid and thermal treatments. The silica particles were then modified with (3-trimethoxysilyl)propyl methacrylate prior to the coating with the PoT shells. The chemical structures, morphologies, particle sizes, and elemental distributions of both silica and core–shell particles were investigated using scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. Additionally, the rheological properties, chain formations, and dielectric properties of the suspensions were analyzed using rotational rheometry, optical microscopy, and an inductance–capacitance–resistance meter. The shear stress increased with the electric field strength along with the electro-rheological efficiency. The plot of the yield stress against the applied electric field strength exhibited a slope of 1.5. The fabricated core–shell particles are environment-friendly and are promising materials for applications in next-generation electro-rheological fluids.

Honeycomb-type structured nickel-based catalysts based on the binary oxides TiO2, Al2O3, Y2O3, and CeO2 as supporters of CO2 methanation were successfully synthesized under various conditions by using different coating solutions and characterized. The prepared catalysts were further tested, and their CO2 methanation activity, stability, and selectivity were compared under different operating conditions at varying temperatures. The results revealed better CO2 methanation with an isopropanol-coated liquid than with distilled water, Si binder, and Ludox. Among the synthesized catalysts, the 10 wt% Ni/CeO2 honeycomb-type catalyst showed the highest CO2 methanation catalytic activity, stability, and selectivity, with a CO2 conversion efficiency of more than 80% during testing at an optimal temperature of 298 °C, space velocity of 743 h−1, and catalyst loading of 134 g/L. The optimum parameters and CO2 conversion efficiency were verified and reconfirmed through response surface analysis. The 10 wt% Ni/CeO2 catalyst is a promising catalyst with excellent potential for application in CO2 methanation.

An attempt has been made in this review to provide some insights into the possible adsorption mechanisms of hexavalent chromium onto layered double hydroxides-based adsorbents by critically examining the past and present literature. Layered double hydroxides (LDH) nanomaterials are typical dual-electronic adsorbents because they exhibit positively charged external surfaces and abundant interlayer anions. A high positive zeta potential value indicates that LDH has a high affinity to Cr(VI) anions in solution through electrostatic attraction. The host interlayer anions (i.e., Cl−, NO3−, SO42−, and CO32−) provide a high anion exchange capacity (53–520 meq/100 g) which is expected to have an excellent exchangeable capacity to Cr(VI) oxyanions in water. Regarding the adsorption-coupled reduction mechanism, when Cr(VI) anions make contact with the electron-donor groups in the LDH, they are partly reduced to Cr(III) cations. The reduced Cr(III) cations are then adsorbed by LDH via numerous interactions, such as isomorphic substitution and complexation. Nonetheless, the adsorption-coupled reduction mechanism is greatly dependent on: (1) the nature of divalent and trivalent salts utilized in LDH preparation, and the types of interlayer anions (i.e., guest intercalated organic anions), and (3) the adsorption experiment conditions. The low Brunauer–Emmett–Teller specific surface area of LDH (1.80–179 m2/g) suggests that pore filling played an insignificant role in Cr(VI) adsorption. The Langmuir maximum adsorption capacity of LDH (Qomax) toward Cr(VI) was significantly affected by the natures of used inorganic salts and synthetic methods of LDH. The Qomax values range from 16.3 mg/g to 726 mg/g. Almost all adsorption processes of Cr(VI) by LDH-based adsorbent occur spontaneously (ΔG° 0) and increase the randomness (ΔS° >0) in the system. Thus, LDH has much potential as a promising material that can effectively remove anion pollutants, especially Cr(VI) anions in industrial wastewater.

The potential of microbial isolates from septic tank wastewater to generate bioelectricity in microbial fuel cell was investigated. The isolates were identified as Cronobacter sakazakii AATB3 and Pseudomonas otitidis AATB4. The sterilized septic tank wastewater alone was used as an organic matter to study the exact role of the isolates in bioelectricity production and biodegradation of septic tank wastewater. P. otitidis AATB4 achieved the highest bioenergy generation (i.e., power density of 280 mW/m2 and current density of 800 mA/m2), highest COD removal (i.e., 79.1%), and maximum coulombic efficiency of 15.5% at pH 7. The biofilm of P. otitidis AATB4 at the anodic surface contained 49 µg/cm2 of protein and 57 µg/cm2 of carbohydrate. Scanning electron microscope and confocal laser scanning microscope revealed 46 µm biofilm thickness by P. otitidis AATB4 in the electrode for stable power generation. It is concluded that P. otitidis AATB4 can be used as a novel bioelectrogen in microbial fuel cell for sustainable energy production using septic tank wastewater.

Due to the impact of methane, carbon dioxide and nitrous oxide on global warming, the quantity of these greenhouse gases (GHG) emissions from municipal wastewater treatment plants (WWTPs) has attracted more and more attention. Consequently, GHG emissions from the two popular treatment technologies: anaerobic/anoxic/oxic (AAO) process and sequencing batch reactor (SBR) should be properly identified and discussed toward the current situation in developing countries. Direct and indirect carbon dioxide (with and/or without including in Intergovernmental Panel on Climate Change (IPCC) report) are all discussed in this article. This literature study observed that a quantity of total carbon dioxide emissions from SBR (374 g/m3 of wastewater) was double that of AAO whilst 10% of these was direct carbon dioxide. Methane emitted from an SBR was 0.50 g/m3 wastewater while 0.18 g CH4/m3 wastewater was released from an AAO. The level of nitrous oxide from AAO and SBR accounted for 0.97 g/m3 wastewater and 4.20 g/m3 wastewater, respectively. Although these results were collected from different WWTPs and where influent was in various states, GHGs emitted from both biological units and other treatment units in various processes are significant. The results also revealed that aerated zone is the major contributing factor in a wastewater treatment plant to the large amount of GHG emissions.

This study aimed to assess the impacts of organic loading rate (OLR) (435–870 mgCOD/L·d) on nutrients recovery via a double-chamber microbial fuel cell (MFC) for treating domestic wastewater. Electricity generation was also explored at different OLRs, including power density and coulombic efficiency. Experimental results suggested the MFC could successfully treat municipal wastewater with over 90% of organics being removed at a wider range of OLR from 435 to 725 mgCOD/L·d. Besides, the maximum power density achieved in the MFC was 253.84 mW/m2 at the OLR of 435 mgCOD/L·d. Higher OLR may disrupt the recovery of PO43−-P and NH4+-N via the MFC. The same pattern was observed for the coulombic efficiency of the MFC and its highest value was 25.01% at the OLR of 435 mgCOD/L·d. It can be concluded that nutrients and electrical power can be simultaneously recovered from municipal wastewater via the dual-chamber MFC.

Ni supported on calcined ceria nitrate catalyst is highly active and stable for low-temperature CO2 methanation reaction (CO2 conversion: 70% at 180 °C, 0.05 bar, and gas hourly space velocity (GHS...

The present work involves the investigation of biodiesel characteristics derived from rice bran oil via heterogeneous basic catalytic transesterification path as the rice husk contains about 16-20% of crude rice bran oil by its weight. Engine performance and emission characteristics of rice bran oil derived biodiesel blends during fueling a four-stroke, single-cylinder, direct-injection engine at 1500 rpm were investigated. The results indicate that 20% biodiesel blend leads to a lower ignition delay at higher loads which in turn increases the rate of vaporization of the fuel as it has higher cetane umber. This fuel blend has a high in-cylinder peak pressure and heat release rate (HRR) of about 72.1 bar and 70.826 J/degrees CA respectively, during the pre-mixed combustion phase in rapid combustion due to the higher oxygen content. Even though, it has high viscous nature, it possesses highest brake thermal efficiency (BTE) which adds absolute combustion. The exhaust gas temperature (EGT: 7.8221%) increases with load and the observed values were matched with other biofuels. Moreover, the HCs, CO(x )and NOx emissions decrease as the load increases since the increase in fuel atomization promotes the combustion process and thereby decreases the amount of unburnt biodiesel components. At 100% load, the smoke cloudiness level was decreased by about 21.62%. The rice bran oil and the blended (20, 30 and 40%: B20, B30 and B40) samples were tested for their notable in vitro microbial, antioxidant and nuclease bio activities due to the presence of certain bioactive components in the rice bran derived biodiesel. If the rice bran oil (RBO) is converted effectively into biodiesel, thereby it will not only satisfy 60-70% of our diesel requirement but also facilitate a green environment., The present work involves the investigation of biodiesel characteristics derived from rice bran oilviaheterogeneous basic catalytic transesterification path as the rice husk contains about 16–20% of crude rice bran oil by its weight. Engine performance and emission characteristics of rice bran oil derived biodiesel blends during fueling a four-stroke, single-cylinder, direct-injection engine at 1500?rpm were investigated. The results indicate that 20% biodiesel blend leads to a lower ignition delay at higher loads which in turn increases the rate of vaporization of the fuel as it has higher cetane umber. This fuel blend has a high in-cylinder peak pressure and heat release rate (HRR) of about 72.1?bar and 70.826?J/°CA respectively, during the pre-mixed combustion phase in rapid combustion due to the higher oxygen content. Even though, it has high viscous nature, it possesses highest brake thermal efficiency (BTE) which adds absolute combustion. The exhaust gas temperature (EGT: 7.8221%) increases with load and the observed values were matched with other biofuels. Moreover, the HCs, COxand NOxemissions decrease as the load increases since the increase in fuel atomization promotes the combustion process and thereby decreases the amount of unburnt biodiesel components. At 100% load, the smoke cloudiness level was decreased by about 21.62%. The rice bran oil and the blended (20, 30 and 40%: B20, B30 and B40) samples were tested for their notablein vitromicrobial, antioxidant and nuclease bio activities due to the presence of certain bioactive components in the rice bran derived biodiesel. If the rice bran oil (RBO) is converted effectively into biodiesel, thereby it will not only satisfy 60–70% of our diesel requirement but also facilitate a green environment.

Microbial fuel cell (MFC) is currently considered a promising technology for wastewater treatment. This study aims to evaluate the feasibility of a double-chamber MFC in terms of: (i) operating mode (batch mode, self-circulation mode, single-continuous mode) of anolyte on the nutrient accumulation in the catholyte, (ii) aeration conditions (anode effluent with aeration supplied in catholyte; anode effluent without aeration supplied in catholyte; cathode effluent with aeration supplied in catholyte and cathode effluent without aeration supplied in catholyte) on the nutrient recovery and (iii) types of separators (cation exchange membrane (CEM), forward osmosis (FO), and nonwoven (NW)) to remove nutrients toward their recovery from municipal wastewater. Results showed that there was no negligible increase in the phosphate concentration of the catholyte at the three different modes but accumulation of ammonium. At different aeration conditions, nutrients can be recovered by chemical precipitation at high pH generated by the MFC itself. Basically, phosphate was removed by microbial absorption and recovered by chemical precipitation while ammonium was accumulated by current generation and recovered as precipitates. It was found that double-chamber MFC with the CEM as the separator reported the best nutrients removal with >97.58% of NH4+-N and >94.9% of PO43−-P removed/recovered, followed by the MFC with the nonwoven and FO membrane, respectively. Thus, the double-chamber MFC is feasible for recovering nutrients in a comprehensive bioelectrochemical system.

The influence of thermal hydrolysis pretreatment (THP) on physicochemical properties (pH, total solids, volatile solids, chemical oxygen demand, total nitrogen, ammonium nitrogen, volatile fatty acids, viscosity, and cell morphology) and anaerobic biodegradability of highly concentrated waste activated sludge (WAS) with TS content ranging from 1 to 7% was evaluated at different temperatures ranging from 100 to 220 °C. The biomethane potential (BMP) of the WAS was systematically analyzed and evaluated. Images of its cellular structure were also analyzed. The results indicated that THP is a useful method for solubilizing volatile solids and enhancing CH4 production regardless of the TS content of the WAS feed. The ultimate CH4 production determined from the BMP analysis was 313-348 L CH4/kg VS (72.6-74.1% CH4) at the optimum THP temperature of 180 °C. The results showed that THP could improve both the capacity and efficiency of anaerobic digestion, even at a high TS content, and could achieve the dual purpose of sludge reduction and higher energy recovery.

This study investigates the possibility of utilizing waste heat sources such as hot flue gas or hot air for wet torrefaction (WT) processes. Although waste heat sources are cheaper alternatives than pure nitrogen used as purging and pressurizing gas for WT, they contain some fractions of non-inert gases and potentially affect the yield and fuel properties of the solid product (hydrochar). To assess these possible influences, Korean pine (Pinus koraiensis) was subjected to WT in different atmospheres, including N2, CO2, O2, air and synthetic flue gas (SFG), and the produced hydrochars were characterized. The results show that WT in different gas atmospheres at 200 °C and 20 bar yields 72.24–73.82% of hydrochar. In general, the fuel properties of the hydrochars are found to be superior to those of the untreated pine: the O/C ratio decreases from 0.703 (raw pine) to 0.582–0.588 (hydrochars), and the HHV increases from 19.22 MJ/kg (raw pine) to 20.80–20.99 MJ/kg (hydrochars). Furthermore, analysis of variance (ANOVA) and pairwise t-test were performed, and the results reveal that the effects of different atmospheres in WT are not statistically meaningful (p-values >0.05), except for the influence of CO2 on ash content. The results also indicate that the presence of oxidative gases such as O2 and CO2 in WT process at appropriate pressures and temperatures has almost insignificant effects on the yields and fuel properties of the hydrochar products. The findings from this study could encourage the utilization of waste heat sources for WT to reduce operating costs. acceptedVersion

This study investigated the effect of CaO2 pretreatment on sulfonamide antibiotics (SMs) remediation by Chlorella sp. Results showed that a CaO2 dose ranging from 0.05 to 0.1 g/g biomass was the best and led to higher SMs removal efficacy 5-10% higher than the control. The contributions made by cometabolism and CaO2 in SMs remediation were very similar. Bioassimilation could remove 24% of sulfadiazine (SDZ) and sulfamethazine (SMZ), and accounted for 38% of sulfamethoxazole (SMX) remediation. Pretreatment by CaO2 wielded a positive effect on microalgae. The extracellular polymeric substances (EPS) level of the CaO2 pretreatment microalgae was three times higher when subjected to non-pretreatment. For the long-term, pretreatment microalgae removed SMs 10-20% more than the non-pretreatment microalgae. Protein fractions of EPS in continuous operation produced up to 90 mg/L for cometabolism. For bioassimilation, SMX intensity of the pretreatment samples was 160-fold less than the non-treatment one. It indicated the CaO2 pretreatment has enhanced the biochemical function of the intracellular environment of microalgae. Peroxidase enzyme involved positively in the cometabolism and degradation of SMs to several metabolites including ring cleavage, hydroxylation and pterin-related conjugation.

This study investigates the performance of microbial fuel cells (MFC) for on-line monitoring ammonium (NH4+-N) in municipal wastewater. A double chamber microbial fuel cell (MFC) was established in a continuous mode under different influent ammonium concentrations ranging from 5 to 40 mg L−1. Results indicated that excess ammonium would inhibit the activity of electrogenic bacteria in the anode chamber and consequently affect electricity production. An inversely linear relationship between concentration and voltage generation was obtained with coefficient R2 0.99 and the MFC could detect up to 40 mg L−1 of NH4+-N. Notably, no further decline was observed in voltage output and there was in fact a further increase in ammonia concentration (>40 mg L−1). The stability and high accuracy of ammonium-based MFC biosensors exposed competitive results compared to traditional analytical tools, confirming the biosensor's reliability. Furthermore, pH 7.0; R 1000 Ω and HRT of 24 h are the best possible conditions for the MFC biosensor for monitoring ammonium. The simplicity in design and operation makes the biosensor more realistic for practical application.

Microbial fuel cell (MFC) systems are promising technologies for wastewater treatment and renewable energy generation simultaneously. Performance of a double-chamber microbial fuel cell (MFC) to treat synthetic swine wastewater containing sulfonamide antibiotics (SMs) was evaluated in this study. The MFC was operated in continuous modes at different conditions. Results indicated that the current was successfully generated during the operation. The performance of MFC under the sequential anode-cathode operating mode is better than that under the single continuous running mode. Specifically, higher removal efficiency of chemical oxygen demand (>90%) was achieved under the sequential anode-cathode operating mode in comparison with that in the single continuous mode (>80%). Nutrients were also be removed in the MFC's cathode chamber with the maximum removal efficiency of 66.6 ± 1.4% for NH4+-N and 32.1 ± 2.8% for PO43--P. Meanwhile, SMs were partly removed in the sequential anode-cathode operating with the value in a range of 49.4%-59.4% for sulfamethoxazole, 16.8%-19.5% for sulfamethazine and 14.0%-16.3% for sulfadiazine, respectively. SMs' inhibition to remove other pollutants in both electrodes of MFC was observed after SMs exposure, suggesting that SMs exert toxic effects on the microorganisms. A positive correlation was found between the higher NH4+-N concentration used in this study and the removal efficiency of SMs in the cathode chamber. In short, although the continuous flow MFC is feasible for treating swine wastewater containing antibiotics, its removal efficiency of antibiotics requires to be further improved.

This study aims to offer insights into how ciprofloxacin (CIP) impact bacterial community structures in the Sponge-MBR process when CIP is spiked into hospital wastewater. We found that the CIP toxicity decreased richness critical phylotypes such as phylum class ẟ-, β-, ɣ-proteobacteria, and Flavobacteria that co-respond to suppress denitrification and cake fouling to 37% and 28% respectively. Cluster analysis shows that the different community structures were formed under the influence of CIP toxicity. CIP decreased attached growth biomass by 2.3 times while increasing the concentration of permeate nitrate by 3.8 times, greatly affecting TN removal by up to 26%. Ammonia removal was kept stable by inflating the ammonia removal rate (p 0.003), with the wealthy Nitrospira genus guaranteeing the nitrification activity. In addition, we observed an increasing richness of Chloroflexi and Planctomycetes, which may play a role in fouling reduction in the Sponge-MBR. Therefore, if the amount of antibiotics in hospital wastewater continues to increase, it is so important to extend biomass retention for denitrification recovery.

Microbial selenite reduction has increasingly attracted attention from the scientific community because it allows the separation of toxic Se from waste sources with the concurrent recovery of Se nanoparticles, a multifunctional material in nanotechnology industries. In this study, four selenite-reducing bacteria, isolated from a river water sample, were found to reduce selenite by > 85% within 3 d of incubation, at ambient temperature. Among them, strain NDSe-7, belonging to genus Lysinibacillus, can reduce selenite and produce Se nanospheres in alkaline conditions, up to pH 10.0, and in salinity of up to 7.0%. This strain can reduce 80 mg/L of selenite to elemental Se within 24 h at pH 6.0–8.0, at a temperature of 30–40 °C, and salinity of 0.1–3.5%. Strain NDSe-7 exhibited potential for use in Se removal and recovery from industrial saline wastewater with high alkalinity. This study indicates that extremophilic microorganisms for environmental remediation can be found in a conventional environment.

Abundantly available biomass wastes from agriculture can serve as effective environmental remediation materials. In this study, activated biochar was fabricated from macadamia nutshell (MCN) through carbonization and chemical modification. The resultant biochars were used as adsorbents to remove toxic metal ions such as Cu2+ and Zn2+ from aqueous solutions. The results showed that the activated MCN biochar has a high adsorption capacity for toxic metal ions. When MCN biochar was activated with K2CO3, the adsorption efficiencies for Cu2+ and Zn2+ were 84.02% and 53.42%, respectively. With H3PO4 activation, the Cu2+- and Zn2+-adsorption performances were 95.92% and 67.41%, respectively. H2O2-modified MCN biochar had reasonable Cu2+- and Zn2+-adsorption efficiencies of 79.33% and 64.52%, respectively. The effects of pH, adsorbent concentration and adsorption time on the removal performances of Cu2+ and Zn2+ in aqueous solution were evaluated. The results exhibited that the activated MCN biochar showed quick adsorption ability with an optimal pH of 4 and 4.5 for both Cu2+ and Zn2+, respectively.

Accurate DNA replication is essential for maintaining genome stability. However, this stability becomes vulnerable when replication fork progression is stalled or slowed – a condition known as replication stress. Prolonged fork stalling can cause DNA damage, leading to genome instabilities. Thus, cells have developed several pathways and a complex set of proteins to overcome the challenge at stalled replication forks. Oligonucleotide/oligosaccharide binding (OB)-fold containing proteins are a group of proteins that play a crucial role in fork protection and fork restart. These proteins bind to single-stranded DNA with high affinity and prevent premature annealing and unwanted nuclease digestion. Among these OB-fold containing proteins, the best studied in eukaryotic cells are replication protein A (RPA) and breast cancer susceptibility protein 2 (BRCA2). Recently, another RPA-like protein complex CTC1-STN1-TEN1 (CST) complex has been found to counter replication perturbation. In this review, we discuss the latest findings on how these OB-fold containing proteins (RPA, BRCA2, CST) cooperate to safeguard DNA replication and maintain genome stability.

Manganese-oxidizing bacteria have been widely investigated for bioremediation of Mn-contaminated water sources and for production of biogenic Mn oxides that have extensive applications in environmental remediation. In this study, a total of 5 Mn-resistant bacteria were isolated from river water and investigated for Mn removal. Among them, Ochrobactrum sp. NDMn-6 exhibited the highest Mn removal efficiency (99.1%). The final precipitates produced by this strain were defined as a mixture of Mn2O3, MnO2, and MnCO3. Optimal Mn-removal performance by strain NDMn-6 was obtained at a temperature range of 25&ndash, 30 &deg, C and the salinity of 0.1&ndash, 0.5%. More interestingly, strain NDMn-6 could be resistant to salinities of up to 5%, revealing that this strain could be possibly applied for Mn remediation of high salinity regions or industrial saline wastewaters. This study also revealed the potential of self-detoxification mechanisms, wherein river water contaminated with Mn could be cleaned by indigenous bacteria through an appropriate biostimulation scheme.

This study investigated methyl orange (MO) dye adsorption using three biochars produced from agro-waste and invasive plants; the latter consisted of wattle bark (BA), mimosa (BM), and coffee husks (BC). BC had the lowest specific surface area (2.62 m2/g) compared to BA (393.15 m2/g) and BM (285.53 m2/g). The adsorption efficiency of MO was stable at pH 2–7 (95%–96%), whilst it had reduced stability at pH 7–12. Between 0 and 30 min, MO adsorption efficiency was >82%, and at 120 min, representative adsorption equilibrium had occurred. The maximum adsorption capacity of the biochars was 12.3 mg/g. The underlying adsorption mechanisms of the three biochars were governed by electrostatic adsorption and pore diffusion. There was an abundance of active sites for adsorption in BA and BM, while chemical adsorption appeared to be more vital for BC, as it contained more functional groups on its surface. The highest MO adsorption efficiency occurred with BM. BC was not recommended for MO removal, as it was observed to stain the water when a dose exceeding 5.0 g/L was utilized.

The two fresh water microalgae species namely Scenedesmus dimorphus and Scenedesmus obliquus were selected as biomass feedstocks for biodiesel production due to high accumulation of their neutral lipid content which mainly composed of three significant biodiesel fatty acids profile viz saturated fatty acids (SFA: ≈ 53%), mono unsaturated fatty acids (MUFA: ≈ 24%) and poly unsaturated fatty acids (PUFA: ≈ 20%). Both algae strains were cultivated with five different nitrogen nutrients via (NH4)2SO4 (ammonium sulphate: AS), NH4NO3 (ammonium nitrate: AN), KNO3 (potassium nitrate: PN), (NH2)2CO (urea: UR) and NaNO3 (sodium nitrate: SN) of concentration ranging from 0.02 to 0.3 M in agricultural medium. The transesterification of micro algal lipids with absolute ethanol medium in the presence of Ni/H2 catalyst and Ni(II)–Schiff base chelate promoter was carried out to yield more algal oil. The extracted biodiesel components were analyzed cost–effectively using UV–Vis,1H NMR, 13C NMR and GC–MS spectral characterization to explore their biodiesel potentiality. The results revealed that the extracted microalgae biodiesels are quite suitable for biodiesel production with higher oxidation stability and cetane number. In this study, S. dimorphus and S. obliquus in the presence of five different nitrogen nutrients of concentration ranging from 0.02 to 0.3 M agar in cultural medium were observed to stimulate them to produce lipid for biodiesel generation. The transesterification of micro algal lipids with absolute ethanol medium in the presence of Ni/H2 catalyst and Ni(II)–Schiff base chelate promoter was carried out to yield more algal oil. The fatty acid composition of the extracted micro algal oils have been identified via UV–Vis, NMR and GC–MS spectral characterization techniques to investigate their biodiesel potentiality. It is noted that increased UR concentration (up to 0.3 M) can effectively enhances biomass production of S. dimorphus and S. obliquus as increased urea levels may enhances biomass production excluding cells may have a low lipid content, at times.

In recent years, lignin valorization is commercially an important and advanced sustainable process for lignocellulosic biomass-based industries, primarily through the depolymerization path. The conversion of the lignin moieties into biofuels and other high value-added products are still challenging to the researchers due to the heterogeneity and complex structure of lignin-containing biomass. Besides, the involvement of different microorganisms that carries varying metabolic and enzymatic complex systems towards degradation and conversion of the lignin moieties also discussed. These microorganisms are frequently short of the traits which are obligatory for the industrial application to achieve maximum yields and productivity. This review mainly focuses on the current progress and developments in the pretreatment routes for enhancing lignin degradation and also assesses the liquid and gaseous biofuel production by fermentation, gasification and hybrid technologies along with the biorefinery schemes which involves the synthesis of high value-added chemicals, biochar and other valuable products.

Hydrolysis of waste activated sludge (WAS) is a challenging process towards enhanced biofuel production. In this study, an attempt has been made to improve hydrolysis of WAS by zeolite that acts as a cation binding agent and deaggregates sludge flocs and deflocculates it by removing extracellular polymeric substances. The overall result confirmed that 0.04 g/g SS of zeolite was perceived to be the optimum dosage for deaggregation of flocs. The degree of dissociation was in the range of 93%, which reveals that 0.04 g/g SS (suspended solids) of zeolite was best for the deaggregation of flocs. To evaluate the impact of deaggregated WAS on biomass disintegration, the WAS was exposed to microwave (MW) liquefaction. The result of the MW disintegration shows that the solids reduction and lysis rate of floc deaggregated (zeolite mediated microwave liquefaction) (Ze-MWL) sample with the optimum (0.04 g/g SS) dosage of zeolite was 33.1% and 42.8% comparatively more than microwave liquefaction (MWL) (21% and 26.8%) sample alone. Chiefly zeolite usage reduced microwave specific energy applied for liquefaction of sludge. The outcome of hydrogen and methane potential assay (0.18 and 0.59 L/gCOD achieved for Ze-MWL) revealed the role of zeolite in improving microwave mediated WAS liquefaction. Quantification of energy and estimation of cost revealed that the Ze-MW liquefaction was cost-effective by achieving net yield of 26 €/Ton of sludge.

An enhanced dark fermentative hydrogen production via the introduction of nanotechnology, utilizing inorganic/organic nanoparticles (NPs) in the membrane of the bioreactors has been renowned these days. Such a nanotechnology includes metal and metal oxides like copper, gold, palladium, silver, iron-iron oxide, nickel-nickel oxide, silica, titanium oxide and carbon nanoparticles (CNTs) respectively have been revealed a noteworthy development in the dark fermentative hydrogen productivity. The pure/mixed cultures can generate dark fermentative hydrogen from biowastes feedstocks with pure sugars derived NPs and the efficiencies in the productivity depends on the nature and concentration of which the NPs employed. In this review, the prospective responsibilities of the inorganic/organic NPs in the enrichment of dark fermentative hydrogen production have been considered for the utilization of the feedstocks like sugars and biowastes materials. Additionally, certain commercial applications in supportive of the integrative approach of inorganic/organic NPs in the case of dark fermentative hydrogen productivity have been discussed.

The proposed work intended to improve sludge reduction efficiency of dark Fenton (DF) treatment. Dark Fenton reduces 61% of sludge in 90 min under the optimized Fe (II) and H2O2 dosage of 0.008 g/g suspended solids (SS) and 0.032 g/g SS respectively at pH 3. Combination of dark Fenton with disperser (DFD) reduces time required for the treatment from 90 to 30 min with the disperser specific energy input of 835.536 kJ/kg total solids (TS). At 30 min reaction time, mixed liquor suspended solids and total chemical oxygen demand reduction were found to be 65% and 60%, respectively for DFD. The efficiency of DFD treatment revealed best fit with R2 value of 0.989 during pseudo first order kinetic analysis. The synergistic effect of DFD resulted in 29% higher MLSS reduction and 31% higher TCOD reduction than dark Fenton (DF) in 30 min treatment as the obtained MLSS and TCOD reduction at 30 min treatment time was observed to be 65% and 60% in DFD and 36% and 29% in DF, respectively. Although, DFD demands higher energy input (233.69 kWh), it had potency to reduce higher solids concentration in a short duration and this results in a net profit of 12.852 USD/ton of sludge.

Biohydrogen production from agro waste biomass through combinative pretreatments is an emerging cost effective, alternative energy technology. The present study aimed to ascertain the extent to which the combinative dispersion thermochemical disintegration (DTCD) enhances the cost effective and energy efficient biohydrogen production from rice straw. The efficiency of the combinative pretreatment was evaluated in terms of degree of disintegration and biohydrogen generation. The optimal conditions for combinative pretreatments are pH 10, temperature 80 °C, rpm 12000 and disintegration time 30 mins. A higher degree of disintegration of about 20.9% was achieved through DTCD pretreatment when compared to dispersion thermal disintegration (DTD) (13.2%) and disperser disintegration (DD) (9.5%). The specific energy spent to achieve maximal degree of disintegration for the three pretreatments were in the following order: DD (1469 kJ/kg Rice Straw) > DTD (1044 kJ/kg Rice Straw) > DTCD (742 kJ/kg Rice Straw). Hence, a considerable amount of energy could be saved through this combinative pretreatment. First order kinetic model (exponential rise to maximum) of biohydrogen production is helpful in deriving the two parameters of uncertainty: substrate biodegradability and hydrolysis rate constant. These two parameters evaluate the maximal biohydrogen yield potential of rice straw through combinative pretreatments. As expected, a higher biohydrogen yield of about (129 mL/g COD) was observed in DTCD when compared to DTD (81 mL/g COD) DD (58 mL/g COD) and Control (8 mL/g COD). To gain insights into the feasibility of implementing the pretreatment at large scale, scalable studies are essential in terms of energy balance and cost. A higher positive net energy of about 0.39621 kWh/kg rice straw was achieved for DTCD when compared to others.

© 2018 Elsevier Ltd This study aims to investigate the production of volatile fatty acids (VFAs) from low strength wastewater at various hydraulic retention time (HRT) and organic loading rate (OLR) in a continuous anaerobic membrane bioreactor (AnMBR) using glucose as carbon source. This experiment was performed without any selective inhibition of methanogens and the reactor pH was maintained at 7.0 ± 0.1. 48, 24, 18, 12, 8 and 6 h-HRTs were applied and the highest VFA concentration was recorded at 8 h with an overall VFA yield of 48.20 ± 1.21 mg VFA/100 mg COD feed . Three different ORLs were applied (350, 550 and 715 mg COD feed ) at the optimum 8 h-HRT. The acetic and propanoic acid concentration maximums were (1.1845 ± 0.0165 and 0.5160 ± 0.0141 mili-mole/l respectively) at 550 mg COD feed . The isobutyric acid concentration was highest (0.3580 ± 0.0407 mili-mole/l) at 715 mg COD feed indicating butyric-type fermentation at higher organic loading rate.

Nutrients recovery has become a meaningful solution to address shortage in the fertilizer production which is the key issue of nations' food security. The concept of municipal wastewater is based on its ability to be a major potential source for recovered nutrients because of its vast quantity and nutrient-rich base. Microbial fuel cell (MFC) has emerged as a sustainable technology, which is able to recover nutrients and simultaneously generate electricity. In this study a two-chambered MFC was constructed, and operated in a continuous flow mode employing artificial municipal wastewater as a substrate. The effects of hydraulic retention time (HRT) on the recovery of nutrients by MFC were studied. The COD removal rates were insignificantly influenced by varying HRT from 0.35 to 0.69 d, that were over 92%. Furthermore, the recovery rate of nutrients was insignificantly affected while increasing the HRT, which fluctuates from 80% to 90%. In contrast, the maximum power generation declined when HRT increased and the lowest one was 510.3 mV at the HRT of 0.35 d. These results demonstrate that the lab-scale double chamber MFC using municipal wastewater as the substrate can provide a highly effective removal strategy for organic matter, nutrients recovery and electricity output when operating at a specific HRT.

Atomic force microscopy (AFM) has been extensively used for the nanoscale characterization of polymeric materials. The coupling of AFM with infrared spectroscope (AFM-IR) provides another advantage to the chemical analyses and thus helps to shed light upon the study of polymers. In this perspective paper, we review recent progress in the use of AFM-IR in polymer science. We describe first the principle of AFM-IR and the recent improvements to enhance its resolution. We discuss then the last progress in the use of AFM-IR as a super-resolution correlated scanned-probe IR spectroscopy for chemical characterization of polymer materials dealing with polymer composites, polymer blends, multilayers and biopolymers. To highlight the advantages of AFM-IR, we report here several results in studying crystallization of both miscible and immiscible blends as well as polymer aging. Then, we demonstrate how this novel technique can be used to determine phase separation, spherulitic structure and crystallization mechanisms at the nanoscale, which have never been achieved before. The review also discusses future trends in the use of AFM-IR in polymer materials, especially in polymer thin film investigation.

Anaerobic digestion (AD) from organic waste has gained worldwide attention in reducing greenhouse gas emissions, lowering fossil fuel combustion, and facilitating a sustainable renewable energy supply. Biogas mainly consists of methane (CH4) (50–75%), carbon dioxide (CO2) (25–50%), hydrogen sulphides (H2S), hydrogen (H2), ammonia (NH3) (1–2%) and traces of other gases such as oxygen (O2) and nitrogen (N2). Methane can replace fossil fuels in various applications such as heat and power generation and the transportation sector. The degradation of organic waste through an AD process offers many advantages, such as the decrease of pathogens and prevention of odour release. The digestate from anaerobic fermentation is a valuable fertilizer, however, the amount of organic materials currently available for biogas production is still limited. New substrates, as well as more effective conversion technologies, are needed to grow this industry globally. This paper reviewed the latest trends and progress in biogas production technologies including potential feedstock. Recycling of waste has recently become an important topic and has been explored in this paper.

In this study, a novel attempt has been made to generate energy-efficient biomethane from marine macroalgae (Chaetomorpha antennina) by coupling thermochemical liquefaction with a disperser (thermo-chemo disperser (TCD) liquefaction). A temperature of (80 °C), pH 11 and disperser g-force of 1613 g were considered optimal parameters for effective solubilization and energy-efficient methane generation. This combinative liquefaction considerably reduced the treatment time and specific energy from 60 to 15 min and 6294 to 800 kJ/kg TS. The highest volatile fatty acids (VFA) accumulation of 890 mg/L was recorded in TCD compared to a thermo disperser (TD) (750 mg/L) and disperser (D) (322 mg/L) during anaerobic fermentation. TCD enhances the methane production potential of macroalgal biomass and a higher methane production of 215 mL/g VS was achieved for TCD compared to TD (149 mL/g VS) and D samples (100 mL/g VS), respectively. Cost analysis confirmed the field applicability of TCD liquefaction with a net profit of 90 USD/ton of marine macroalgae. A high energy ratio of 1.5 was achieved with the proposed mode of pretreatment (TCD) compared to TD (0.95) and D (0.28) pretreatment. Therefore, C. antennina is considered a suitable feedstock for methane generation.

Antibiotic wastewater has become a major concern due to the toxicity and recalcitrance of antibiotics. Anaerobic membrane bioreactors (AnMBRs) are considered alternative technology for treating antibiotic wastewater because of their advantages over the conventional anaerobic processes and aerobic MBRs. However, membrane fouling remains the most challenging issue in the AnMBRs' operation and this limits their application. This review critically discusses: (i) antibiotics removal and antibiotic resistance genes (ARGs) in different types of AnMBRs and the impact of antibiotics on membrane fouling and (ii) the integrated AnMBRs systems for fouling control and removal of antibiotics. The presence of antibiotics in AnMBRs could aggravate membrane fouling by influencing fouling-related factors (i.e., sludge particle size, extracellular polymeric substances (EPS), soluble microbial products (SMP), and fouling-related microbial communities). Conclusively, integrated AnMBR systems can be a practical technology for antibiotic wastewater treatment.

Photobioreactor technology, especially bubble column configuration, employing microalgae cultivation (e.g., Chlorella sp.), is an ideal man-made environment to achieve sufficient microalgae biomass through its strictly operational control. Nutrients, typically N and P, are necessary elements in the cultivation process, which determine biomass yield and productivity. Specifically, N:P ratios have certain effects on microalgae's biomass growth. It is also attractive that microalgae can sequester CO 2 by using that carbon source for photosynthesis and, subsequently, reducing CO 2 emission. Therefore, this study aims to investigate the effect of N:P ratios on Chlorella sp.’s growth, and to study the dynamic of CO 2 fixation in the bubble column photobioreactor. According to our results, N:P ratio of 15:1 could produce the highest biomass yield (3568 ± 158 mg L −1 ). The maximum algae concentration was 105 × 10 6 cells mL −1 , receiving after 92 h. Chlorella sp. was also able to sequester CO 2 at 28 ± 1.2%, while the specific growth rate and carbon fixation rate were observed at 0.064 h −1 and 68.9 ± 1.91 mg L −1 h −1 , respectively. The types of carbon sources (e.g., organic and inorganic carbon) possessed potential impact on microalgae's cultivation.

This study assessed the impact of swine manure (SM) dilution ratio on the microalgal biomass cultivation and further tested for biohydrogen production efficiency from the mixed microalgal biomass. At first, various solid/liquid (S/L) ratio of the SM ranged from 2.5 to 10 g/L was prepared as a nutrient medium for the algal biomass cultivation without addition of the external nutrient sources over a period of 18 d. The peak biomass concentration of 2.57 ± 0.03 g/L was obtained under the initial S/L loading rates of 5 g/L. Further, the cultivated biomass was subjected to two-step (ultrasonication + enzymatic) pretreatment and evaluated for biohydrogen production potential. Results showed that the variable amount of hydrogen production was observed with different S/L ratio of the SM. The peak hydrogen yield of 116 ± 6 mL/g TSadded was observed at the 5 g/L grown SM mixed algal biomass.