In microalgae, efficient lipid extraction remains a key challenge, and the application of pretreatment methods alters lipid chemistry and affects fuel quality, both of which are poorly understood. This study analyzed microwave, sonication, acid, and freeze-thaw pretreatments for enhanced lipid accessibility in Chlorella pyrenoidosa prior to transesterification. Pretreated biomass was transesterified for biodiesel production via H2SO4 and NaOH-catalyzed in-situ and ex-situ routes. Acid pretreatment degraded lipid quality showing acid value (AV) rising from 39.43 ± 2.03 in unpretreated sample to 59.21 ± 4.3 mg KOH g−1, peroxide value (PV) from 3.39 ± 0.4 to 26.7 ± 1.34 meq kg−1, and malondialdehyde (MDA) concentration from 0.05 to 0.1 μmol L−1, indicating a rise in free fatty acid (FFA) content and oxidative degradation of polyunsaturated lipids. This degradation lowered both iodine value (110.2 to 24.5) and degree of unsaturation (113.2 to 19.8), increased cetane number (48.2 to 67.2), and improved cold-flow properties (8.45 °C to 4.4 °C) in acid-pretreated acid-catalyzed ex-situ route produced biodiesel. This sample exhibited the highest saturated fatty acid methyl ester (SFAME) (24.8 ± 1.4%) and total FAME (47.1 ± 1.7%) GC-MS peak area (%). Hydrocarbon co-production occurred across all routes, with NaOH catalysis maximizing the relative production at 33.9 ± 1.1%. This study demonstrated that the type of pretreatment and catalyst choice significantly affect lipid quality and subsequent product formation, thereby demonstrating the need for a joint optimization of these processes for the development of a viable microalgal biodiesel and hydrocarbon production pathway.

Abstract Anaerobic digestate obtained from a digester operated on food waste was further treated in a dual-chamber microbial fuel cell (D-MFC) for nutrient recovery. Digestate was fed to the D-MFC at different dilutions [chemical oxygen demand (COD): 1,000–5,000 mg/L] in fed-batch mode and at different organic loading rates (OLRs) (0.85–1.70 kg/m 3 /day) in continuous mode. Peak power densities of 2.02 and 1.72 W/m 3 were achieved at a COD concentration of 3,000 mg/L and OLR of 1.35 kg/m 3 /day, respectively, due to strengthened metabolic activity of exoelectrogens. However, at an excessively high OLR, reactor performance declined due to variation in the microbial community structure, facilitating the dominance of non-exoelectrogens over exoelectrogenic microorganisms. Based on D-MFC operation over 80 days, the average COD and ammonia ( NH 4 + - N ) removal efficiencies were 96 ± 1 percent and 62 ± 3 percent, respectively, while phosphorus release increased the average PO 4 3 − - P concentrations to 33 mg/L in anode effluent. Further, struvite precipitation led to NH 4 + - N and PO 4 3 − - P recovery of 87 percent and 94 percent, respectively, thus yielding 3.17 kg struvite/m 3 of treated digestate. Technoeconomic analysis for a 2,000 L D-MFC indicated a payback period of six years for the initial capital expenditure based on revenue generation from recovered nutrients and wastewater treatment. Overall, the long-term operational stability and enhanced nutrient recovery prove this approach to be a promising solution for AD effluent management on a large scale.

This study assessed the efficiency of freshwater microalgae Scenedesmus obliquus and Chlorella pyrenoidosa for treating beverage wastewater containing high COD (5015 mg L- 1) with low nitrogen (11 mg L- 1) and phosphorus (7 mg L- 1) concentrations. Using response surface methodology, fed-batch experiments optimized illumination wavelength, temperature, and photoperiod for COD removal, biomass production, and lipid content. S. obliquus achieved the highest COD removal (83 %) at 35 degrees C with 16 h of red illumination, outperforming C. pyrenoidosa (75 %). White illumination maximized biomass concentration, yielding nearly 4.8 g L- 1 for both strains. Although blue illumination improved lipid accumulation (42-48 %), net lipid yield peaked at 1.17-1.24 g L- 1 under conditions that also maximized COD removal. Both strains demonstrated similar adaptability and performance, with operational factors significantly impacting responses, achieving a biomass heating value of 18-23 MJ kg- 1. The findings highlight the potential of two microalgae for nutrient-poor beverage wastewater treatment at laboratory scales.

Rapid electric vehicle (EV) adoption in India raises concerns about their climate benefits, as existing studies often overlook spatiotemporal variations. This study develops a state-level hourly marginal emission factor framework derived from grid generation to evaluate EV charging emissions. Annual well-to-wheel emissions are evaluated across convenience, overnight, midday, and MEF-optimized charging. Results show that national MEFs are highest during afternoon and evening peaks and lowest during overnight, with spatial variation ranging from 0.03-1.12 kg CO₂/kWh. Convenience charging yields highest emissions at 4.59 Mt CO₂/year, while MEF-optimized charging, which aligns EV usage with lowest MEF hours, reduces emissions by 34.83%. As MEF-optimized charging adoption increases, charging emissions reduce nearly linearly, from 3.8% at 10% adoption to 35% at 100% adoption relative to baseline. Sustained renewable integration could lower MEFs by up to 91.3% by 2060. EV charging should be guided by time and location-specific MEFs, integrated into smart charging platforms.

Bio-flocculation is an environmentally friendly, low-cost, and sustainable method for harvesting microalgae biomass. This study identified key operational trends from published literature to guide the optimization of various bio-flocculation techniques, followed by experimental validation of fungal-assisted microalgae harvesting. The fungal species Aspergillus awamori was used to flocculate two widely used microalgae cultures, Scenedesmus obliquus and Chlorella vulgaris. The optimum conditions for obtaining maximum harvesting efficiency as obtained from statistical analysis of published literature are: (i) Fungi-assisted bio-flocculation: Neutral pH and fungi-tomicroalgae ratio >0.5:1, (ii) Self-flocculating microalgae: Neutral pH and flocculating-to-non-flocculating microalgae ratio >0.5:1, (iii) Biopolymer-based flocculation: Neutral pH with a dosage >200 mg/L, (iv) Plant-based bio-flocculation: Alkaline pH and dosage <= 50 mg/L, (v) Microbial flocculation: Alkaline pH, temperature <30 degrees C, and dosage >50 mg/L. Following this, the flocculation experiments done on microalgae cultures showed that fungi: microalgae dosage ratio of 1:1 for S. obliquus and 2:1 for C. pyrenoidosa is optimum for obtaining the highest harvesting efficiency. After fungal flocculation, spent medium was recycled for effective microalgae re-cultivation, and harvested microalgae of fungal cultures was effectively re-cultivated, thereby improving resource efficiency. In conclusion, this study establishes fungi-assisted bio-flocculation as a promising, sustainable technique for microalgae harvesting and nutrient recovery with the potential for large-scale implementation.

Electric vehicle (EV) emission reduction potential varies by region due to traffic conditions, electricity grid mix, and local policies. This study presents a framework for estimating Well-toWheel (WTW) emissions of electric four-wheelers using tailored driving cycles and local electricity grid consumption data. Tailored driving cycles, developed through a hybrid genetic algorithm-based approach, reflect mixed traffic conditions in two Indian cities. Energy consumption from developed driving cycles, combined with regional grid emissions, yields an emission factor of 204 gCO2/km in the cleaner-grid and 226 gCO2/km in the coal-dependent region. Sensitivity analysis shows driving cycle variation affects WTW factors more than the grid mix, raising emissions by 91.2-128.7% compared to standard tests. State-level emission projections show near-zero WTW emissions by 2060 (low-carbon) and 2070 (net-zero) due to grid decarbonization. The results highlight the need for localized emission modeling to capture spatial disparities and support more effective, region-specific sustainable mobility policies.

Pharmaceuticals such as antibiotics and antifungals pose significant environmental risks because of their persistence and potential toxicity; however, microalgae-based treatment approaches have demonstrated promising removal capabilities. Among these, azithromycin, a commonly used macrolide antibiotic, and fluconazole, a systemic triazole antifungal, are frequently used and detected as persistent pollutants in aquatic ecosystems. This study investigates the removal of azithromycin (AZ), fluconazole (FL), and their mixture (AZ + FL) from synthetic wastewater using the marine microalga Pavlova salina. At 10 mg/L, removal rates were 87% for AZ and 97% for FL, but these dropped to 31% and 26%, respectively, at 200 mg/L. AZ exhibited stronger inhibition of algal growth, particularly above 100 mg/L, leading to cellular damage and loss of viability. Biodegradation was the primary removal mechanism, with minor contributions from bioaccumulation (2%) and biosorption (2%) at higher concentrations. AZ had the highest inhibitory effect, followed by AZ + FL and FL. The half-maximal inhibitory concentration (IC50) values were 2.22 mg/L for AZ, 39.24 mg/L for FL, and 6.11 mg/L for AZ + FL, with antagonistic interactions mitigating AZ's negative effects in mixtures. Seven AZ metabolites and six FL metabolites were identified in the study, including two toxic transformation products for FL that were more toxic than the parent compounds. Increasing AZ, FL, and AZ + FL concentrations from 0 to 200 mg/L boosted microalgal lipid production by factors of 1.62, 1.53, and 1.85, respectively, suggesting potential for combined wastewater treatment and biofuel production. A statistically significant difference (P < 0.05) in pharmaceutical removal efficiency, microalgal growth, inhibition ratio, and lipid production was observed at different concentrations for the pharmaceuticals. Insights into the removal mechanisms and degradation by-products will guide the design of effective treatment systems.

CO2 capture and utilization via microbial electrosynthesis (MES) holds promise for climate mitigation, but its industrial scalability is limited by low production rates and expensive electrode materials. This study investigates the impact of three different carbon-based cathodes: carbon felt (CF), carbon cloth with graphite granules (CCGG), and carbon felt with stainless steel mesh (CF-SS) on the synthesis rates of medium-chain fatty acids (MCFAs). Experiments were conducted in batch mode using a long-term enriched mixed culture, with a CO2 flow rate of 6.7 mol m-2 d- 1 (400 mL d- 1) applied on alternate days and ethanol (2300 mg L- 1) supplied as an additional electron donor to facilitate microbial chain elongation. All reactors were operated at a constant cell potential of 2.8 V using a direct current power supply. Caproic acid concentrations reached 1310 +/- 50 mg L- 1 for CF, 1210 +/- 40 mg L- 1 for CC-GG, and 915 +/- 20 mg L- 1 for CF-SS. However, no statistically significant differences in caproic acid yields were observed among the cathodes, CF showed the shortest lag phase, with production starting after 2 days. Combined with its lower cost, ease of handling, and operational simplicity, this offers practical advantages for MES operation. Thus, while all cathodes demonstrated similar performance, CF appears to be a promising and economically attractive option for industrial MES applications.

Global climate change destabilizes ecosystems, weather, and human livelihoods. Because it uses the industrial farming model, agriculture generates 10% of the global greenhouse gas emissions. However, food production must increase by 70% by 2050; achieving this goal under the evolving and dynamic climate change and its impacts and repercussions is challenging. This review explores how environmental adaptation engineering can transform agriculture to a sustainable, resilient, low-carbon system that balances productivity with environmental stewardship, and describes policies and practices supporting this transformation. It uses a comprehensive bibliometric analysis, updated climate data (e.g., IPCC AR6), and an integrative literature review of agricultural practices, environmental engineering innovations, adaptive biotechnologies, socioeconomic aspects, community involvement, and policy implications. It introduces the novel ecological farm model that aligns climate resilience, resource efficiency, and circular economy principles. It innovatively bridges a gap in the literature by synthesizing advances in hydroponics, anaerobic digestion, and microalgae technologies as an integrated adaptation strategy to address agricultural vulnerabilities under climate change. It highlights the potential of these environmental engineering solutions to manage waste, reduce emissions, generate renewable biofuels, sequester and convert CO2 into biomass, optimize water use, recover nutrients, enhance crop quality and yield, and restore the environment. We highlight how important community engagement, knowledge sharing, and capacity building are in adopting adaptation practices across diverse socioeconomic settings. By integrating these approaches, adaptation engineering can align agricultural productivity with ecological responsibility. The findings suggest that incorporating adaptive technologies in agriculture is crucial to mitigate climate impacts and build sustainable, inclusive, and resilient food systems, ensuring long-term environmental and societal well-being.

This study aimed to assess the biochemical methane potential (BMP) of microalgal substrates grown on high-strength beverage wastewater as a potential end-use application for biomass. Two microalgal species, Scenedesmus obliquus and Chlorella pyrenoidosa, were cultivated in standard Blue Green-11 (BG-11) media and high-strength beverage wastewater with a COD of around 5,000 mg L-1. A BMP of 185.53 +/- 2.66 mL CH4 g-1 VSadded was obtained from Scenedesmus grown in BG-11 media, which increased to 336.35 +/- 26.56 mL CH4 g-1 VSadded after being grown in beverage wastewater. Similar increasing patterns were also observed in the case of Chlorella, where the BMP increased from 179.64 +/- 4.14 to 245.51 +/- 29.35 mL CH4 g-1 VSadded when changing the media from BG-11 to beverage wastewater. After lipid extraction, microalgae substrates yielded higher methane production, with 393.66 +/- 41.08 and 421.86 +/- 47.52 mL CH4 g-1 VSadded from Scenedesmus and Chlorella, respectively. Theoretical methane estimation from carbohydrate, protein, and lipid contents resulted in overestimating BMP. However, ANOVA statistics highlighted significant differences in experimental methane yields, and the modified Gompertz model validated the predicted BMP with the experimental values, with an R2 above 0.94. Overall, this study outlines the potential for biomethane enhancement from microalgae grown in wastewater, with an extended energy recovery opportunity after lipid extraction.

Azithromycin (AZ), a broad-spectrum antibiotic, is commonly found in aquatic habitats. This study investigated two microalgae-microbial fuel cell (m-MFC) configurations, A-AZ-MFC (AZ in the anode) and C-AZ-MFC (AZ in the cathode), which were run in fed-batch mode under open- and closed-circuit conditions (10-200 mg/L AZ). AZ removal increased from 43 % in an open circuit to 83 % when the circuit was closed in A-AZ-MFC and from 68 % to 84 % in C-AZ-MFC. While both A-AZ-MFC and C-AZ-MFC achieved comparable AZ degradation (83-84 %), A-AZ-MFC demonstrated superior electrochemical output (Power density: 275 mW/m3; Net energy recovery: 0.11 kWh/kg COD; Coulombic efficiency: 26 %) and higher microbial tolerance (IC50 = 77.02 mg/L), indicating effective electron transfer and steady biofilm activity. Both designs achieved successful detoxification, as evidenced by comparable transformation product profiles and lower effluent toxicity. These findings demonstrate m-MFCs, especially anode-optimized systems, as sustainable platforms for the removal of antibiotics and the production of bioenergy.

Anodic heterotrophic denitrification in MFC has emerged as a sustainable solution for treatment of NO 3 rich wastewater, however maximizing the coulombic efficiency during this process is a major challenge and necessitates reactor modification. Therefore, the novelty of this study involves application of dual-electrode three chambered MFC (T-MFC), designed by providing multiple pathway for electron flow between the anode and cathode to improve electron recovery, reduce internal losses and facilitate efficient denitrification. Under NO 3 -N concentration of 250-600 mg/L, T-MFC achieved a maximum current generation, and power density of 1750-2690 mu A, and 167-239 mW/m2, respectively, with increased coulombic efficiency of 17-26 %. The attained electrochemical performance of T-MFC was found to be significantly higher compared to traditional dual chamber MFC (D-MFC) setups due to low charge transfer resistance. This is attributable to improved microbial-electrode interaction, increased energy gain during substrate oxidation and occurrence of interspecies electron transfer phenomenon in T-MFC. Microbial community analysis confirmed the strengthening of denitrifying exoelectrogenic phyla Proteobacteria abundance from 39 to 80 % on increasing the NO 3 -N concentration up to 600 mg/L from 250 mg/L. Thus, the study demonstrated capability of T-MFC in accelerating the treatment of NO 3 -N enriched wastewater and concomitantly maximizing the electron recovery to boost the power output. Overall, the findings of this study will provide valuable insight for the future advancement of multi-electrode based reactor configurations.

Emerging technologies aim to convert CO2 into biofuels and chemicals, reducing greenhouse gas emissions. Microbial electrosynthesis (MES) offers promise for producing organic products, but challenges remain in energy efficiency and medium-chain fatty acid (MCFA) synthesis. This study demonstrates long-term, continuous caproic acid production in an integrated dark fermentation-MES (DF-MES) system using enriched mixed cultures. A maximum caproic acid production rate of 0.47 ± 0.16 g L-1 d-1 was achieved, with a 73 % selectivity, 83 % carbon recovery and 94 % electron recovery. Integration of DF reduced external energy demand by 60 %, while continuous operation increased production rates by 14.6 % over batch mode, maintained stability for over three months. These findings highlight DF-MES integration as a viable approach to reducing energy demand while ensuring sustained caproic acid production.

Balancing the surface area of electrodes to reactor volume (SA/V) ratio in microbial electrosynthesis (MES) systems is crucial for enhancing electron transfer, biofilm development, and product yield. Batch MES experiments were conducted using cathodes with SA/V ratios of 40 cm2 L-1 (MES-1), 150 cm2 L-1 (MES-2), 260 cm2 L-1 (MES-3) and 333 cm2 L-1 (MES-4), selected based on statistical analysis of previous studies. Among these, MES-3 (260 cm2 L-1) demonstrated the highest caproic acid production of 1.5 ± 0.2 g L-1 and selectivity 67 %, outperforming MES-1, MES-2, and MES-4 by 2.1, 1.4, and 4.4 times, respectively. MES-3 had improved mass and electron transfer while maintaining effective microbe-electrode interactions. Additionally, MES-3 showed the lowest energy consumption (6.5 ± 2.3 kWh mol-1 VFAs) and a higher electron recovery efficiency (55.8 ± 18.3 % at 2.5 V). These results demonstrate that balancing SA/V ratio is key to enhancing MES performance and sustainable MCFA production.

Electric vehicle (EV) emission studies often rely on standard driving cycles and homogeneous grid compositions, neglecting regional variations. This study assesses EV well-to-wheel (WTW) emissions using a clustering-based optimized driving cycle model. Scenario-based WTW framework analyzes the emission impact of EV penetration, grid decarbonization, and internal combustion engine vehicle (ICEV) retirement policies at state and national levels through 2030. Tailored driving cycle estimates EV energy consumption (0.144 kWh/km) and emission factor (213 g CO2/km) using powertrain simulations, 45 % and 69.41 % higher than traditional cycle evaluations, respectively. 30 % EV penetration and accelerated grid decarbonization could potentially reduce sales emissions by 26.35 % (Telangana) and 33.98 % (India), though raise stock emissions. Early ICEV retirement would potentially reduce stock emissions by 20.54 % (Telangana) and 28.69 % (India). Vehicle kilometer traveled is identified as a crucial parameter impacting emissions. Transport decarbonization requires faster electrification, cleaner grid, early ICEV retirements, reduced travel demand, and enhanced battery efficiency.

Precise evaluation of vehicular emissions in real-world conditions is essential for assessing air quality and determining the efficacy of emission control policies. A critical research gap exists regarding the comparative study between Bharat Stage VI (BS-VI) and BS-VI compliant vehicles in various diverse Indian driving conditions. Laboratory-based measurement often fails to captures detailed emission profiles in complex traffic conditions. This study addresses this gap by analyzing the emissions from BS-IV petrol, BS-IV diesel, and BS-VI petrol vehicles in Indian driving conditions using a portable emission measurement system (PEMS). We developed a novel framework that integrates vehicle specific power (VSP) with unsupervised techniques to identify and analyze the distinct emission profiles over various driving conditions. The best clustering algorithm’s results (k means) were used to compare and assess the emissions characteristics of BS-VI and BS-IV vehicles under various driving conditions. Result showed that CO2 and NOx emissions were highest for all three vehicle types during transitions from idle to minor acceleration and lowest during idling/creeping. BS-VI petrol vehicles demonstrated a substantial decrease (25 to 90

The study employed a central composite design (CCD) response surface method (RSM) to optimize initial CO2 levels, nitrate concentrations, and ZnO nanoparticle concentration in the culture media for enhancing biomass, lipid, and carbohydrate yield in Chlorella pyrenoidosa. The predicted second-order quadratic model for response variables was found to be significant (p < 0.01), and the analysis of variance (ANOVA) showed a high coefficient of determination with R2 being 0.99 for biomass, 0.98 for lipid, and 0.99 for carbohydrate. The maximum biomass, lipid, and carbohydrate yield of 1.5 ± 0.06 g L−1, 43.6 ± 1.9

Per- and poly-fluoroalkyl substances (PFAS) are emerging contaminants, posing adverse impacts on water and soils due to their persistence, chemical transformations, and bioaccumulation. With over 15,000 different PFAS compounds being identified globally, their toxic effects and half-life spanning from 72 h to 8.5 years in humans are a serious concern. Bioremediation has emerged as an environmentally-friendly and cost-effective approach for PFAS degradation. However, there is still limited understanding of PFAS interactions with microorganisms and the roles of promising microbes in transforming PFAS into non-toxic end products. The knowledge about biotransformation of PFAS is essential to ameliorate the adaptation of microorganisms to local matrix and environment as well as to strengthen the natural enzymatic pathways and activities at a commercial scale, which is a major challenge. This review aims to address these gaps by providing a comprehensive analysis of recent developments in the bioremediation of PFAS-contaminated soil and water systems. The review focuses on the capabilities of phytoremediation, bioelectrochemical systems, and microbial species, including bacteria, fungi, and microalgae. Additionally, this study offers an in-depth overview of PFAS sources, their physicochemical characteristics, and their environmental fate and transport. Furthermore, it examines microbial metabolic activity, the formation of degradation intermediates, the role of co-metabolism, and the behaviour of microorganisms under PFAS stress as well as highlights future research directions. The key findings from this review include: 1) microbial community composition, field application, presence of co-substrate and cationic complexation govern biotransformation and fate of PFAS 2) long chain PFAS are more susceptible to accumulate in the roots due to high hydrophobicity, and 3) algae-bacteria symbiotic relationships prevent microalgae growth inhibition and stimulates PFAS removal. Overall, this review emphasizes the potential of bioprocesses for large-scale PFAS bioremediation, contributing to environmental protection and mitigating the risks associated with PFAS contamination.

The development of precise vehicle emission models is crucial for estimating vehicular exhaust emissions. Though measuring emissions using an on-board emissions measurement system can be promising, it is essential to improve the precision of emission rates (ERs) prediction through effective statistical methods. A novel framework of simple linear regression (SLR), support vector regression (SVR), and piecewise linear regression (PLR) approaches was employed to develop a speed-based emission model. In total, 30 trips data from six professional drivers were collected to understand the variability of tailpipe emissions. The developed SLR, SVR, and PLR models demonstrated high accuracy, as indicated by mean absolute percentage error (MAPE), root-mean-square error (RMSE), and coefficient of determination (R2) values. PLR outperformed SLR, and SVR in predicting CO, CO2, HC and NOx ERs. These models can be useful tools for policymakers to understand emissions in heterogeneous traffic conditions and develop appropriate solutions to improve air quality.

The possibility of producing hydrogen and methane from sedimented pulp and paper mill waste fibre was explored for the first time in a double-stage process. Hydrogen and methane production was compared in batch experiments under four different conditions: two-stage hydrogen and methane production under (i) mesophilic (37 °C) and (ii) thermophilic (55 °C) and one-stage methane production under (iii) mesophilic and (iv) thermophilic conditions. Among these conditions studied, two-stage thermophilic anaerobic digestion achieved the highest hydrogen yield (42.1 ± 2.91 mL/g VS) and methane yield (334 ± 26.8 mL/g VS) at 55 °C. The experimental results were fitted to modified Gompertz equation, and a strong correlation was built from the overall magnitude of the regression (R2 ranged from 0.996to 0.989) between the experimental data and the applied equation. Total energy yield from the two-stage thermophilic process was higher (3.7 kWh/L) than the one-stage process (1.7 kWh/L). The two-stage treatment also reduced the treatment time by half. Knowledge gained from this study will provide a basis for future investigation of two-stage treatment of sedimented fibres.