A novel integrated approach employing Desertifilum tharense BERC-3 for efficient wastewater valorization and recycling for developing peri-urban algae farming system.

Peri-urban environments are significant reservoirs of wastewater, and releasing this untreated wastewater from these resources poses severe environmental and ecological threats. Wastewater mitigation through sustainable approaches is an emerging area of interest. Algae offers a promising strategy for carbon-neutral valorization and recycling of urban wastewater. Aiming to provide a proof-of-concept for complete valorization and recycling of urban wastewater in a peri-urban environment in a closed loop system, a newly isolated biocrust-forming cyanobacterium Desertifilum tharense BERC-3 was evaluated. Here, the highest growth and lipids productivity were achieved in urban wastewater compared to BG11 and synthetic wastewater. D. tharense BERC-3 showed 60-95% resource recovery efficiency and decreased total dissolved solids, chemical oxygen demand, biological oxygen demand, nitrate nitrogen, ammonia nitrogen and total phosphorus contents of the water by 60.37%, 81.11%, 82.75%, 87.91%, 85.13%, 85.41%, 95.87%, respectively, making it fit for agriculture as per WHO's safety limits. Soil supplementation with 2% wastewater-cultivated algae as a soil amender, along with its irrigation with post-treated wastewater, improved the nitrogen content and microbial activity of the soil by 0.3-2.0-fold and 0.5-fold, respectively. Besides, the availability of phosphorus was also improved by 1.66-fold. The complete bioprocessing pipeline offered a complete biomass utilization. This study demonstrated the first proof-of-concept of integrating resource recovery and resource recycling using cyanobacteria to develop a peri-urban algae farming system. This can lead to establishing wastewater-driven algae cultivation systems as novel enterprises for rural migrants moving to urban areas.

Synthesis of novel nonsteroidal anti-inflammatory galloyl ß-sitosterol-loaded lignin-capped Ag-based drug.

Biocompatible anti-inflammatory lignin-capped Ag (LCAg) nanoparticles (NPs) were synthesized for the delivery of galloyl ß-sitosterol (Galloyl-BS). ß-Sitosterol (BS) is effective against inflammatory responses, like cancer-induced inflammations. BS was modified via gallic acid esterification to enhance its anti-inflammatory potential. LCAg NPs were synthesized by a green method and loaded with galloyl-BS. For comparison, pure BS was also loaded onto LCAg NPs in a separate assembly. The antioxidant potential of Galloyl-BS was greater (IC50 177 µM) than pure BS. Materials were characterized by FT-IR, SEM, XRD, and Zeta potential. Using UV-Vis spectroscopy, drug release experiments were performed by varying pH, time, concentration, and temperature. Maximum drug release was observed after 18 h at pH 6 and 40 °C. Galloyl-BS showed improved drug loading efficiency, release %age, and antioxidant activity compared to pure BS when loaded onto LCAg NPs. DLCAg exhibited excellent anti-inflammatory activity in rat models. These findings indicate that galloyl-BS (drug)-loaded LCAg (DLCAg) NPs have the potential as an anti-inflammatory agent without any prior release and scavenging in normal cells.

Dental Anxiety and Its Association with Dietary Intake and Food Groups: A Cross-Sectional Study.

Although there is an established connection between diet and mental health, the relationship between diet and dental anxiety has not been examined yet. The purpose of this study was to fill this gap by assessing the association between diet quality, mental distress, and dental anxiety. The data was collected through an anonymous Google Forms survey. The survey consisted of a modified version of the validated Food-Mood Questionnaire and the Modified Dental Anxiety Scale with questions about demographics, dental health, and dental health anxieties. Data collection was performed over seven months, from April to October 2021. Data were analyzed using Pearson's correlation coefficient in SPSS version 25.0 and STATA 17 for sample size calculation, data processing and regression analyses. A total of 506 responses were collected. Our data verified that diet quality modulates dental anxiety. Women exhibited a stronger link with dental anxiety than men (p < 0.01). Consumption of sugary foods was associated with different attributes of dental anxiety (p < 0.01). Low-quality energy-dense foods and dairy were associated with dental anxiety, whereas caffeine, meat, nuts, and green leafy vegetables produced a negative correlation. This cross-sectional study provides proof of concept that dietary patterns are potentially associated with dental anxiety.

How does social support relate to emotional availability for learning during COVID-19? A multi-group structural equation model of university students from the U.S. and Israel.

Given the social and emotional tolls of the COVID-19 pandemic on college and university students, many students have become academically disengaged during the pandemic. Although some colleges and universities have the capacity to promote social support for their students, research has yet to comprehensively demonstrate the relationship between social support and academic engagement. To fill this gap, we leverage survey results from four universities across the United States and Israel. Through multi-group structural equation modelling, we explore (a) how perceived social support relates to being emotionally unavailable for learning, (b) how this relationship is partially explained through coping and COVID-19 concerns, and (c) how these relationships can differ across countries. We find that students who perceived higher levels of social support had lower rates of being emotionally unavailable for learning. Part of this relationship occurred through greater rates of coping and, subsequently, fewer concerns about the pandemic. We also noticed significant differences in these relationships between countries. We conclude with a discussion of study implications for higher education policies and practices.

Acute acalculous cholecystitis as a rare gastroenterological association of COVID-19: a case series and systematic review.

Background and Aim: Acute acalculous cholecystitis (AAC) is an acute inflammatory disease of the gallbladder in the absence of cholecystolithiasis. It is a serious clinicopathologic entity, with a high mortality rate of 30-50%. A number of etiologies have been identified that can potentially trigger AAC. However, clinical evidence on its occurrence following COVID-19 remains scarce. We aim to evaluate the association between COVID-19 and AAC. Methods: We report our clinical experience based on 3 patients who were diagnosed with AAC secondary to COVID-19. A systematic review of the MEDLINE, Google Scholar, Scopus, and Embase databases was conducted for English-only studies. The latest search date was December 20, 2022. Specific search terms were used regarding AAC and COVID-19, with all associated permutations. Articles that fulfilled the inclusion criteria were screened, and 23 studies were selected for a quantitative analysis. Results: A total of 31 case reports (level of clinical evidence: IV) of AAC related to COVID-19 were included. The mean age of patients was 64.7 ± 14.8 years, with a male-to-female ratio of 2.1:1. Major clinical presentations included fever 18 (58.0%), abdominal pain 16 (51.6%), and cough 6 (19.3%). Hypertension 17 (54.8%), diabetes mellitus 5 (16.1%), and cardiac disease 5 (16.1%) were among the common comorbid conditions. COVID-19 pneumonia was encountered before, after, or concurrently with AAC in 17 (54.8%), 10 (32.2%), and 4 (12.9%) patients, respectively. Coagulopathy was noted in 9 (29.0%) patients. Imaging studies for AAC included computed tomography scan and ultrasonography in 21 (67.7%) and 8 (25.8%) cases, respectively. Based on the Tokyo Guidelines 2018 criteria for severity, 22 (70.9%) had grade II and 9 (29.0%) patients had grade I cholecystitis. Treatment included surgical intervention in 17 (54.8%), conservative management alone in 8 (25.8%), and percutaneous transhepatic gallbladder drainage in 6 (19.3%) patients. Clinical recovery was achieved in 29 (93.5%) patients. Gallbladder perforation was encountered as a sequela in 4 (12.9%) patients. The mortality rate in patients with AAC following COVID-19 was 6.5%. Conclusions: We report AAC as an uncommon but important gastroenterological complication following COVID-19. Clinicians should remain vigilant for COVID-19 as a possible trigger of AAC. Early diagnosis and appropriate treatment can potentially save patients from morbidity and mortality. Relevance for Patients: AAC can occur in association with COVID-19. If left undiagnosed, it may adversely impact the clinical course and outcomes of patients. Therefore, it should be considered among the differential diagnoses of the right upper abdominal pain in these patients. Gangrenous cholecystitis can often be encountered in this setting, necessitating an aggressive treatment approach. Our results point out the clinical importance of raising awareness about this biliary complication of COVID-19, which will aid in early diagnosis and appropriate clinical management.

Young Adults at the National Epicenter of the COVID-19 Outbreak: Understanding the Impact and Future Challenges of Social Distancing on Mental Health Outcomes.

OBJECTIVES: To understand the role and future implications of social distancing on mental health and substance use in young adults between the ages of 18 and 35 living in high-disease-prevalent areas of New York. METHODS: Participants completed a self-administered online survey through Qualtrics. RESULTS: 43.9% of the sample met criteria for moderate or severe anxiety, and 53.1% of the sample met criteria for moderate to severe depression. 76.1% of the sample experienced both anxiety and depressive symptoms. Despite this, the rates of lifetime mental health diagnoses, treatment, and access to mental health services were low. Rates of depression and anxiety differed across socio-demographic variables (gender, income, sexuality, education, and insurance status). Experiencing severe symptoms of the COVID-19 virus, poor coping skills, loneliness, increased alcohol use, and sleep disturbances were linked to higher rates of depression, anxiety, or both. CONCLUSION: As the first epicenter of COVID-19 in the United States, New York represents an important location for prevention researchers to learn about how COVID-19 affected a diverse population of young adults. It is essential that researchers and practitioners proactively develop early and appropriate interventions to address the ongoing mental health crisis and also plan for future crises.

Intersecting Race and Gender Across Hardships and Mental Health During COVID-19: A Moderated-Mediation Model of Graduate Students at Two Universities.

While the effects of the pandemic on the mental health of college students can vary across race and gender, few studies have explored the role of hardships and university assistance in these disparities, as well as how these disparities can manifest themselves differently across intersections of race and gender. We address this gap by using unique survey data (n = 417) from two large graduate schools of social work, public health, and social policy in the United States. Using multi-group structural equation modeling, we explore how material hardships, academic hardships, and university assistance needed mediates the relationship between race and mental health, including depression and anxiety. We also explore how gender moderates these relationships. We find that Black students are directly related to material hardships and-through these hardships-indirectly related to increased depression, indicating mediation. However, material hardships did not mediate the relationship between race and anxiety. Furthermore, while academic hardships mediated the relationships between race and depression, as well as race and anxiety, these relationships were only significant for females, indicating moderated-mediation. Moreover, although university assistance needed mediated the relationship between race and depression for females only, university assistance needed mediated the relationship between race and anxiety for both males and females. We close with implications for policy and practice.

Characterization of a newly isolated self-flocculating microalga Bracteacoccus pseudominor BERC09 and its evaluation as a candidate for a multiproduct algal biorefinery.

Microalgae have the highest capability to fix the atmospheric carbon and wastewater-derived nutrients to produce high-value bioproducts including lipids and carotenoids. However, their lower titers and single-product-oriented biomass processing have made the overall process expensive. Hence, increased metabolite titer and processing of the biomass for more than one product are required to ensure the commercial robustness of the algal biorefinery. In this study, a newly isolated algal strain was identified as Bracteacoccus pseudominor BERC09 through phylogenetic analysis based on the 18S rRNA gene sequence. Basic characterization of the strain revealed its promising potential to produce carotenoids and lipids. The lipids and carotenoid biosynthesis pathways of BERC09 were further triggered by manipulating the abiotic factors including nitrogen sources (NaNO3, KNO3, NH4Cl, Urea), nitrogen concentrations (0.06-0.36 gL-1), light intensity (150 µmolm-2s-1 to 300 µmolm-2s-1), and light quality (white and blue). Resultantly, 300 µmolm-2s-1 of blue light yielded 0.768 gL-1 of biomass, 8.4 mgg-1 of carotenoids, and 390 mgg-1 of lipids, and supplementation of 0.36 gL-1 of KNO3 further improved metabolism and yielded 0.814 gL-1 of biomass, 11.86 mgg-1 of carotenoids, and 424 mgg-1 of lipids. Overall, the optimal combination of light and nitrogen concurrently improved biomass, carotenoids, and lipids by 3.5-fold, 6-fold, and 4-fold than control, respectively. Besides, the excellent glycoproteins-based self-flocculation ability of the strain rendered an easier harvesting via gravity sedimentation. Hence, this biomass can be processed in a cascading fashion to use this strain as a candidate for a multiproduct biorefinery to achieve commercial robustness and environmental sustainability.

A Longitudinal Examination of the Association Between Loss of Control and Loneliness Among Older Adults Diagnosed with Cancer.

Objectives: The objective of this paper is to examine whether feeling a loss of control over one's life is associated with an increased risk for loneliness among those diagnosed with cancer. Method: We draw on data from the Health and Retirement Study to identify three baseline and follow-up cohorts of cancer survivors age 50 and older. Ordinary least squared regression is used to examine predictors for future loneliness. Results: Upon adjusting for other known predictors of loneliness, feelings of loss of control was significantly predictive of loneliness among 4-year cancer survivors. Discussion: Social workers and other health care practitioners should seek to provide evidence-based interventions to reduce the risk for loneliness for cancer survivors feeling a loss of control.

Advances in pretreatment technology for handling the palm oil mill effluent: Challenges and prospects.

The palm oil mill effluent (POME) from palm milling oil activities is discharged into various water bodies which poses several environmental problems including turbidity, increases COD and BOD, adds oil and grease, increases total nitrogen, and other pollutants. Therefore, it requires effective treatment to remove the pollutants before disposal. The objective was to critically discuss the performance of POME pretreatments along with their limitations. To offer a coverage on the present less efficient technologies, the opportunities and challenges of advanced pretreatments that combine magnetic materials and natural composites as adsorbents are comprehensively reviewed here. Moreover, potential of various magnetic materials for POME pretreatment has been described. Several existing pretreatment methods such as physical pretreatments, chemical pretreatments, coagulation-flocculation, and adsorption can remove pollutant content from POME with certain limitations and the use of magnetic composite adsorbents can enhance the treatment efficiency.

An Evaluation-Focused Framework for Visualization Recommendation Algorithms.

Although we have seen a proliferation of algorithms for recommending visualizations, these algorithms are rarely compared with one another, making it difficult to ascertain which algorithm is best for a given visual analysis scenario. Though several formal frameworks have been proposed in response, we believe this issue persists because visualization recommendation algorithms are inadequately specified from an evaluation perspective. In this paper, we propose an evaluation-focused framework to contextualize and compare a broad range of visualization recommendation algorithms. We present the structure of our framework, where algorithms are specified using three components: (1) a graph representing the full space of possible visualization designs, (2) the method used to traverse the graph for potential candidates for recommendation, and (3) an oracle used to rank candidate designs. To demonstrate how our framework guides the formal comparison of algorithmic performance, we not only theoretically compare five existing representative recommendation algorithms, but also empirically compare four new algorithms generated based on our findings from the theoretical comparison. Our results show that these algorithms behave similarly in terms of user performance, highlighting the need for more rigorous formal comparisons of recommendation algorithms to further clarify their benefits in various analysis scenarios.

National Utilization, Survival, and Costs Analysis of Treatment Options for Stage I Non-Small Cell Lung Cancer: A SEER-Medicare Database Analysis.

RATIONALE AND OBJECTIVES: To compare utilization, outcomes, and costs of surgery, radiation therapy, and percutaneous ablation for the treatment of stage I non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Using 2006-2016 Medicare-linked Surveillance, Epidemiology, and End Results (SEER) databases, stage I NSCLC patients who underwent surgery, radiotherapy, or percutaneous ablation were identified using relevant billing codes. National utilization rates were determined. Overall survival for treatment arms were compared using log-rank test and Cox-proportional hazard modeling. Mean direct costs for each treatment strategy during the first year after diagnosis were compared using Analysis of Variance. RESULTS: A total of 15,847 Stage I NSCLC patients were identified; mean age at diagnosis was 75.5 years (minimum age = 66 years) and 59.2% were female. A total of 10,732 patients (67.7%) underwent only surgery, 5013 (31.6%) only radiotherapy, and 102 (0.6%) only ablation. Utilization of surgery and ablation decreased while radiotherapy utilization increased from 2007 to 2015 (p < 0.0001). Compared to the ablation group, overall survival was greater for the surgery group (HR: 0.7, 95% CI of HR: 0.6-0.9, p = 0.0047) and lower for the radiotherapy group (HR: 1.4, 95% CI of HR: 1.1-1.8, p = 0.002). The mean first year cost of therapy for ablation = $11,976) was significantly less (p < 0.05) than for radiotherapy ($15,447) and surgery ($22,669). CONCLUSION: In Medicare patients with stage I NSCLC, the utilization of radiation therapy has increased and surgery has declined, while utilization of percutaneous ablation has remained uniformly low. Although overall survival is best for surgery, then ablation, and then radiation therapy, first year treatment costs are lowest for ablation.

Untargeted metabolomics of the alkaliphilic cyanobacterium Plectonema terebrans elucidated novel stress-responsive metabolic modulations.

Alkaliphilic cyanobacteria are suitable candidates to study the effect of alkaline wastewater cultivation on molecular metabolic responses. In the present study, the impact of wastewater, alkalinity, and alkaline wastewater cultivation was studied on the biomass production, biochemical composition, and the alkalinity responsive molecular mechanism through metabolomics. The results suggested a 1.29 to 1.44-fold higher biomass production along with improved lipid, carbohydrate, and pigment production under alkaline wastewater cultivation. The metabolomics analysis showed 1.2-fold and 5.54-fold increase in the indole-acetic acid and phytoene biosynthesis which contributed to overall enhanced cell differentiation and photo-protectiveness. Furthermore, lower levels of Ribulose-1,5-bisphosphate (RuBP), and higher levels of 2-phosphoglycerate and 3-phosphoglycerate suggested the efficient fixation of CO2 into biomass, and storage compounds including polysaccharides, lipids, and sterols. Interestingly, except L-histidine and L-phenylalanine, all the metabolites related to protein biosynthesis were downregulated in response to wastewater and alkaline wastewater cultivation. The cells protected themselves from alkalinity and nutrient stress by improving the biosynthesis of sterols, non-toxic antioxidants, and osmo-protectants. Alkaline wastewater cultivation regulated the activation of carbon concentration mechanism (CCM), glycolysis, fatty-acid biosynthesis, and shikimate pathway. The data revealed the importance of alkaline wastewater cultivation for improved CO2 fixation, wastewater treatment, and producing valuable bioproducts including phytoene, Lyso PC 18:0, and sterols. These metabolic pathways could be future targets of metabolic engineering for improving biomass and metabolite production. SIGNIFICANCE: Alkalinity is an imperative factor, responsible for the contamination control and biochemical regulation in cyanobactera, especially during the wastewater cultivation. Currently, understanding of alkaline wastewater responsive molecular mechanism is lacking and most of the studies are focused on transcriptomics of model organisms for this purpose. In this study, untargeted metabolomics was employed to analyze the impact of wastewater and alkaline wastewater on the growth, CO2 assimilation, nutrient uptake, and associated metabolic modulations of the alkaliphilic cyanobacterium Plectonema terebrans BERC10. Results unveiled that alkaline wastewater cultivation regulated the activation of carbon concentration mechanism (CCM), glycolysis, fatty-acid biosynthesis, and shikimate pathway. It indicated the feasibility of alkaline wastewater as promising low-cost media for cyanobacterium cultivation. The identified stress-responsive pathways could be future genetic targets for strain improvement.

Correction to: Intersecting Race and Gender Across Hardships and Mental Health During COVID 19: A Moderated Mediation Model of Graduate Students at Two Universities.

[This corrects the article DOI: 10.1007/s12552-022-09379-y.].

Alcohol Use Cravings as a Mediator Between Associated Risk Factors on Increased Alcohol Use among Youth Adults in New York During the COVID-19 Pandemic.

The sudden increase in alcohol use in the young adult population during the COVID-19 pandemic may be partially explained by social isolation and stress due to restricted stay-at-home orders. The goal of this study was to assess specific psychological factors (e.g., anxiety, depressive symptoms, sleep disturbances, and alcohol cravings) and COVID-19 diagnoses and their association with increased alcohol use and misuse during the COVID-19 pandemic among New York residents 18-35 years of age. Survey data were collected via Qualtrics between July 2020-October 2020. Path analyses tests were employed to test alcohol use cravings as a mediator. Among the total sample (N=575), mean age was 27.94±4.12; a majority were White non-Hispanic (66%), female (55%) and had completed a 4-year college or university degree (n = 249; 43.5%). Results revealed that alcohol use cravings was a significant mediator between sleep disturbances, having a COVID-19 diagnoses, and having mental health symptoms on increased alcohol use. Our findings underscore the importance of providing alcohol use prevention and treatment resources in this unprecedented COVID-19 era. Policymakers, public health professionals, and clinicians have a significant role in curbing the COVID-19-induced substance use epidemic.

Advances in developing metabolically engineered microbial platforms to produce fourth-generation biofuels and high-value biochemicals.

Producing bio-based chemicals is imperative to establish an eco-friendly circular bioeconomy. However, the compromised titer of these biochemicals hampers their commercial implementation. Advances in genetic engineering tools have enabled researchers to develop robust strains producing desired titers of the next-generation biofuels and biochemicals. The native and non-native pathways have been extensively engineered in various host strains via pathway reconstruction and metabolic flux redirection of lipid metabolism and central carbon metabolism to produce myriad biomolecules including alcohols, isoprenoids, hydrocarbons, fatty-acids, and their derivatives. This review has briefly covered the research efforts made during the previous decade to produce advanced biofuels and biochemicals through engineered microbial platforms along with the engineering approaches employed. The efficiency of the various techniques along with their shortcomings is also covered to provide a comprehensive overview of the progress and future directions to achieve higher titer of fourth-generation biofuels and biochemicals while keeping environmental sustainability intact.

Impact of wastewater cultivation on pollutant removal, biomass production, metabolite biosynthesis, and carbon dioxide fixation of newly isolated cyanobacteria in a multiproduct biorefinery paradigm.

The impact of wastewater cultivation was studied on pollutant removal, biomass production, and biosynthesis of high-value metabolites by newly isolated cyanobacteria namely Acaryochloris marina BERC03, Oscillatoria sp. BERC04, and Pleurocapsa sp. BERC06. During cultivation in urabn wastewater, its pH used to adjust from pH 8.0 to 11, offering contamination-free cultivation, and flotation-based easy harvesting. Besides, wastewater cultivation improved biomass production by 1.3-fold when compared to control along with 3.54-4.2 gL-1 of CO2 fixation, concomitantly removing suspended organic matter, total nitrogen, and phosphorus by 100%, 53%, and 88%, respectively. Biomass accumulated 26-36% carbohydrates, 15-28% proteins, 38-43% lipids, and 6.3-9.5% phycobilins, where phycobilin yield was improved by 1.6-fold when compared to control. Lipids extracted from the pigment-free biomass were trans-esterified to biodiesel where pigment extraction showed no negative impact on quality of the biodiesel. These strains demonstrated the potential to become feedstock of an integrated biorefinery using urban wastewater as low-cost growth media.

Recombinant Protein Production in Microalgae: Emerging Trends.

In recent years, microalgae have emerged as an alternative platform for large-scale production of recombinant proteins for different commercial applications. As a production platform, it has several advantages, including rapid growth, easily scale up and ability to grow with or without the external carbon source. Genetic transformation of several species has been established. Of these, Chlamydomonas reinhardtii has become significantly attractive for its potential to express foreign proteins inexpensively. All its three genomes - nuclear, mitochondrial and chloroplastic - have been sequenced. As a result, a wealth of information about its genetic machinery, protein expression mechanism (transcription, translation and post-translational modifications) is available. Over the years, various molecular tools have been developed for the manipulation of all these genomes. Various studies show that the transformation of the chloroplast genome has several advantages over nuclear transformation from the biopharming point of view. According to a recent survey, over 100 recombinant proteins have been expressed in algal chloroplasts. However, the expression levels achieved in the algal chloroplast genome are generally lower compared to the chloroplasts of higher plants. Work is therefore needed to make the algal chloroplast transformation commercially competitive. In this review, we discuss some examples from the algal research, which could play their role in making algal chloroplast commercially successful.

Microalgal flocculation: Global research progress and prospects for algal biorefinery.

Microalgal research has made significant progress due to versatile and high-value industrial applications of microalgal biomass or its derivatives. However, to explore their full potential and to achieve commercial robustness, microalgal biorefinery needs cost-effective technologies to produce, harvest, and process the microalgal biomass on large scale as higher production and harvesting cost is one of the key hindrances in the commercialization of algae-based products. Among several other algal biomass harvesting technologies, self-flocculation seems to be an attractive, low-cost, and eco-friendly harvesting technology. This review covers various flocculation-based methods that have been employed to harvest microalgal biomass with a special emphasis on self-flocculation in microalgae. Moreover, genetic engineering approaches to induce self-flocculation in non-flocculating microalgae along with the factors affecting self-flocculation and recent research trends have also been discussed. It is concluded that self-flocculation is the most desired approach for the energy- and environment-efficient harvesting of microalgal biomass. However, its poorly understood genetic basis needs to be deciphered through detailed studies to harness its potential for the algal biorefinery.

Cultivating microalgae in wastewater for biomass production, pollutant removal, and atmospheric carbon mitigation; a review.

Water shortage is one of the leading global problems along with the depletion of energy resources and environmental deterioration. Recent industrialization, global mobility, and increasing population have adversely affected the freshwater resources. The wastewater sources are categorized as domestic, agricultural and industrial effluents and their disposal into water bodies poses a harmful impact on human and animal health due to the presence of higher amounts of nitrogen, phosphorus, sulfur, heavy metals and other organic/inorganic pollutants. Several conventional treatment methods have been employed, but none of those can be termed as a universal method due to their high cost, less efficiency, and non-environment friendly nature. Alternatively, wastewater treatment using microalgae (phycoremediation) offers several advantages over chemical-based treatment methods. Microalgae cultivation using wastewater offers the highest atmospheric carbon fixation rate (1.83 kg CO2/kg of biomass) and fastest biomass productivity (40-50% higher than terrestrial crops) among all terrestrial bio-remediators with concomitant pollutant removal (80-100%). Moreover, the algal biomass may contain high-value metabolites including omega-3-fatty acids, pigments, amino acids, and high sugar content. Hence, after extraction of high-value compounds, residual biomass can be either directly converted to energy through thermochemical transformation or can be used to produce biofuels through biological fermentation or transesterification. This review highlights the recent advances in microalgal biotechnology to establish a biorefinery approach to treat wastewater. The articulation of wastewater treatment facilities with microalgal biorefinery, the use of microalgal consortia, the possible merits, and demerits of phycoremediation are also discussed. The impact of wastewater-derived nutrient stress and its exploitation to modify the algal metabolite content in view of future concerns of cost-benefit ratios of algal biorefineries is also highlighted.