Environmental impact assessment via life cycle analysis on ultrafiltration membrane fabricated from polyethylene terephthalate waste to treat microalgal cultivation wastewater for reusability.

The current study had conducted the life cycle analysis (LCA) to assess the environmental impact of microalgal wastewater treatment via an integrated membrane bioreactor. The functional unit selected for this analysis was 1 kg of treated microalgal wastewater with contaminants eliminated by ultrafiltration membrane fabricated from recycled polyethylene terephthalate waste. Meanwhile, the applied system boundary in this study was distinguished based on two scenarios, namely, cradle-to-gate encompassed wastewater treatment only and cradle-to-cradle which included the reutilization of treated wastewater to cultivate microalgae again. The environmental impacts and hotspots associated with the different stages of the wastewater treatment process had clearly elucidated that membrane treatment had ensued the highest impact, followed by microalgal harvesting, and finally cultivation. Among the environmental impact categories, water-related impact was found to be prominent in the following series: freshwater ecotoxicity, freshwater eutrophication and marine ecotoxicity. Notably, the key performance indicator of all environmental impact, i.e., the global warming potential was found to be very much lower at 2.94 × 10-4 kg CO2 eq as opposed to other literatures reported on the LCA of wastewater treatments using membranes. Overall, this study had proffered insights into the environmental impact of microalgal wastewater treatment and its stimulus for sustainable wastewater management. The findings of this study can be instrumental in making informed decision for optimizing microalgal wastewater treatment and reutilization assisted by membrane technology with an ultimate goal of enhancing sustainability.

Biotreatment of Industrial Wastewater using Microalgae: A Tool for a Sustainable Bioeconomy.

Fresh water is one of the essential sources of life, and its requirement has increased in the past years due to population growth and industrialization. Industries use huge quantities of fresh water for their processes, and generate high quantities of wastewater rich in organic matter, nitrates, and phosphates. These effluents have contaminated the freshwater sources and there is a need to recycle this wastewater in an ecologically harmless manner. Microalgae use the nutrients in the wastewater as a medium for growth and the biomass produced are rich in nutrition that can cater growing food and energy needs. The primary and secondary metabolites of microalgae are utilized as biofuel and as active ingredients in cosmetics, animal feed, therapeutics, and pharmaceutical products. In this review, we explore food processing industries like dairy, meat, aquaculture, breweries, and their wastewater for the microalgal growth. Current treatment methods are expensive and energy demanding, which indirectly leads to higher greenhouse gas emissions. Microalgae acts as a potential biotreatment tool and mitigates carbon dioxide due to their high photosynthetic efficiency. This review aims to address the need to recycle wastewater generated from such industries and potentiality to use microalgae for biotreatment. This will help to build a circular bioeconomy by using wastewater as a valuable resource to produce valuable products.

An optimized approach towards bio-capture and carbon dioxide sequestration with microalgae Phormidium valderianum using response surface methodology.

As carbon dioxide emissions rise, there's need for alternative strategies, including microorganisms, to capture and mitigate them. The present study investigated on the capability and tolerance of microalgal strain, Phormidium valderianum to capture gaseous CO2 at varying levels (5-30 %). A biomass productivity of 0.0216 ± 0.027 gL-1day-1 and rate of CO2 fixation of 0.035 gL-1day-1 was obtained for 25 % CO2 concentration. From this study, it is evident that higher CO2 levels led to elevated carbohydrate concentration. In addition, protein concentration doubled with the introduction of 25 % CO2. In optimization studies, pH 10, 25 % CO2, and 200 mg/L of Ca(OH)2 concentration was found to be optimal for biomass growth. A higher rate of CO2 fixation of 0.315 gL-1day-1 was achieved at these optimum conditions using response surface methodology. Furthermore, the study demonstrated that microalgae, Phormidium valderianum has the potential to serve as a promising alternative for capturing CO2 emissions.

Maximization of growth and lipid production of a toxic isolate of Anabaena circinalis by optimization of various parameters with mathematical modeling and computational validation.

Toxic cyanobacterial blooms are recurrent for few decades throughout the globe, due to climate change, atmospheric warming and various anthropogenic activities with severe impacts of potential toxins on various ecosystems finally affecting the entire environment. These cyanobacteria are merely unexplored regarding their biochemical components except toxins. Variable influences and interactions of different factors including nitrogen, carbon, and availability of light are well known to crucially regulate cyanobacterial growth and metabolism. Thus, current research work is motivated for the evaluation and optimization of the effects of the aforementioned vital factors for improvement of biomass and lipid production of a freshwater, toxic strain of Anabaena circinalis. The modelling and optimization of factors such as nitrogen, light intensity and bicarbonate concentration (source of carbon) to maximize growth and lipid production were based on 20 design point experiments by Response Surface Methodology (RSM) and optimized values were further improved and validated by Particle Swarm Optimization (PSO) algorithm. The maximum optima were obtained 1.829 g L-1 and 39.64 % for biomass production and lipid content respectively from PSO optimization with two different sets of optimal values of factors. It shows 0.44 % and 2.77 % higher values of responses than that of RSM optimization. These asynchronous findings pioneered the enhanced lipid accumulation as well as the growth of a toxic cyanobacterium by optimizing interaction effects of culture conditions through various statistical and computational approaches.

Investigation on the utilization of coal washery rejects by different microbial sources for biogenic methane production.

High energy consumption and depletion of fossil fuels lead to the introduction of new technologies to produce alternative fuels with fewer emissions of greenhouse gases. The present investigation was focused to utilize the waste coal washery rejects as a substrate to produce biogenic methane under optimum conditions. Experiments were performed to explore the efficiency of non-coal samples (cow dung, distillery anaerobic digester sludge) and coal mines enriched samples in the degradation of coal washery rejects. Further cow dung, distillery anaerobic sludge, and coal washery rejects were taken at various concentrations to develop anaerobic slurry and analysed for its biogas production. The anaerobic slurry which contains 1:1:1 of cow dung, distillery anaerobic sludge, and coal washery rejects produced methane of around 55.7%. The coal enriched samples showed a maximum of 22.6% of methane. Subsequently, the best methane-producing anaerobic non-coal consortiums were compared with coal enriched microbial culture in converting coal washery rejects of 10 g/l to methane. Results revealed that cow dung inoculum and coal mine enriched inoculum source produced the nearly same amount of methane. This study suggested that the selected anaerobic slurries and coal enriched samples can utilize sub-bituminous coal washery rejects in methane production. Thus, these consortiums can be applied in converting a large amount of coal washery rejects into methane thus can lead to the reclamation of the site.

A comparative assessment of growth, pigment and enhanced lipid production by two toxic freshwater cyanobacteria Anabaena circinalis FSS 124 and Cylindrospermopsis raciborskii FSS 127 under various combinations of nitrogen and phosphorous inputs.

Nitrogen and phosphorous are important nutritional regulators for the growth of cyanobacteria, thereby having a significant impact in bloom formation by toxic species. Usage of toxic cyanobacteria for increasing valuable metabolite production by nutrient manipulation is still unexplored. Hence, the current work is aimed to estimate and compare growth, pigment, and increased lipid production coupled with the identification of fatty acids between two toxic strains-Anabaena circinalis FSS 124 and Cylindrospermopsis raciborskii FSS 127 under various combinations of these two nutrients. Low level of nitrogen and phosphorous enhanced lipid content in both strains (˃ 20% and 30% respectively) and C. raciborskii, respectively. Lipid productivity in low phosphorous concentration (P0.5) was achieved significantly high in C. raciborskii. Similarly, a substantial amount of carotenoids was obtained at reduced nitrogen and phosphorous in C. raciborskii accompanied by lessened growth and Chl a concentration. Unlikely, enough biomass (˃ 2 g L-1) was produced at high nutrient levels in both species. Comparative statistical significance (p < 0.05) was found between two species regarding biomass production, chlorophyll concentration, lipid content, and productivity and between these factors in each species under both nutrient variations. FAME of Cylindrospermopsis is composed of saturated fatty acids (˃ 50%) and MUFA (˃ 25%) while Anabaena contains PUFA (˃ 21%) additionally. However, the study highlights C. raciborskii as potential lipid and carotenoid producer at nutrient stress and finds a novel way to utilize these cyanobacterial biomasses, which cause immense environmental hazards and life threats.

A novel method for improving laccase activity by immobilization onto copper ferrite nanoparticles for lignin degradation.

In this paper, a novel method for simultaneous enhancement of catalytic activity and reusability of laccase was carried out to overcome the limitations on industrial application of laccase. The immobilization of laccase onto copper ferrite magnetic nanoparticles (CuMNPs) and ferrite magnetic nanoparticles (MNPs) were optimized at 50 mM glutaraldehyde concentration and 1:5 enzyme:nanoparticles (NPs) ratio for 9 h of cross-linking time, yielding a maximum activity recovery of 94.68 ± 0.92% and 89.78 ± 1.24%, respectively. The laccase immobilized NPs were characterized using physico-chemical methods such as SEM-EDAX, FTIR, XRD, TGA and VSM and the laccase immobilized CuMNPs showed 18% higher activity as compared to free enzyme. The prepared CuMNPs and MNPs showed superior thermal stability (50-70 °C) with t1/2 increased by 5.7 and 4.1 folds, respectively, as compared to free laccase. The laccase in immobilized forms exhibited higher kinetic potential and stable at wide temperature and pH range. In addition, laccase immobilized NPs retained more than 70% residual activity during reuse up to 6 cycles and storing for 20 days at 4 °C. The laccase immobilized CuMNPs showed higher delignification (43.28 ± 1.46%) on Ipomoea carnea than laccase immobilized MNPs.

Evaluation and characterization of novel sources of sustainable lignocellulosic residues for bioethanol production using ultrasound-assisted alkaline pre-treatment.

In recent years, research is focused on finding a sustainable and eco-friendly lignocellulosic biomass for the effective production of bioethanol to meet the world's energy demand. The present study investigates the bioethanol production potential of four different lignocellulosic biomass residues viz., Saccharum arundinaceum (hardy sugar cane), Arundo donax (giant reed), Typha angustifolia (narrow-leaved cattail), and Ipomoea carnea (pink morning glory). The maximum reducing sugar release showed 185.00 ±â€¯1.57, 213.73 ±â€¯3.47, 187.57 ±â€¯2.14, 294.08 ±â€¯3.98 mg/g and fermentation efficiency of 72.60 ±â€¯8.17%, 82.59 ±â€¯7.42%, 77.45 ±â€¯7.35%, and 85.04 ±â€¯8.37% which was analyzed by estimating the percentage of bioethanol yield were achieved for Saccharum arundinaceum, Arundo donax, Typha angustifolia, and Ipomoea carnea, respectively. The chemical composition of biomass was characterized using National Renewable Energy Limited (NREL) protocol. The effect of ultrasound (US)-assisted alkaline pre-treatment on the four biomasses was characterized by different techniques. The cavitation phenomena of US-assisted alkaline pre-treatment was evident from the decreased value of lignin percentage, increased surface porosity and area, changes in crystallinity index (CrI) values and in the functional groups of biomass. The results revealed that all the four lignocellulosic biomass residues could be utilized as an effective and sustainable source for the production of bioethanol using US-assisted sodium hydroxide as a pre-treatment tool.

Suitability of Dicloster acuatus MH013435 and Kalenjinia gelatinosa MH012185 for growth in Garcinia cambogia washwater effluent with efficient nutrient removal.

The present study investigates the suitability of growing Dicloster acuatus MH013435 and Kalenjinia gelatinosa MH012185 in Garcinia cambogia washwater for biomass production and nutrient removal. In recent years, the wastewater effluent treatment with microalgae is gaining importance since it serves multiple purposes including CO2 sequestration, production of biofuel feedstock and value-added biochemicals in addition to wastewater treatment. Contaminated washwater is generated at a significant quantity during extraction of hydroxycitric acid from G. cambogia and it represents a serious environmental concern when discharged without proper processing. However, this G. cambogia washwater can be used as a low-cost source of nutrients for microalgal growth. The two microalgal species D. acuatus MH013435 and K. gelatinosa MH012185 demonstrated robust growth in washwater and achieved maximum biomass concentration of 0.68 and 0.63 g/L dry weight. The nitrate was removed to an extent of 98.5 and 99.6% whereas chloride removal was 72 and 80.5%, sulfate concentration got reduced by 98 and 98.7% and phosphate got reduced to 95 and 92% for D. acuatus MH013435 and K. gelatinosa MH012185, respectively. The results indicate the suitability of D. acuatus MH013435 and K. gelatinosa MH012185 in treating G. cambogia washwater with efficient nutrient removal.

Screening of microalgae for treating Garcinia cambogia wash water with potential lipid production.

The microalgae-based water treatment is gaining importance in recent years as it serves multiple purposes of which includes water treatment and biofuel production. Garcinia cambogia, a Malabar tamarind is a tropical fruit and the active ingredient hydroxycitric acid is popularly used as a weight-loss supplement. After extraction of the hydroxycitric acid, the wash water of G. cambogia is considered as an effluent. The potential microalgal species that can grow and treat G. cambogia wash water were isolated and identified as Dicloster acuatus BVR1 and Kalenjenia gelanitosa BVR2. Both the microalgal species adapted to G. cambogia wash water and entered exponential phase after sixth day with maximum specific growth rate of 0.310 day-1 for D. acuatus and 0.296 day-1 for K. gelanitosa during tenth day. The biomass productivity of D. acuatus was 0.03 g L-1 day-1 which is 58% higher than K. gelanitosa with 0.019 g L-1 day-1. The microalgal strains besides water treatment were subsequently subjected for lipid extraction and lipid productivity determination. The lipid productivity of D. acuatus was 2.68 mg L-1 day-1 which is lesser compared to 3.38 mg L-1 day-1 for K. gelatinosa. Both the microalgal isolates were promising for G. cambogia wash water treatment and lipid production. Hence, an environment friendly approach of water treatment with simultaneous lipid production for biofuel conversion is conducted.