Current World Environment

Introduction

Antibiotics are crucial medications which have been extensively employed to prevent infectious diseases, boost public health, and enhance the productivity of domestic and some low-cost animals.¹ Over 100,000 tonnes of antibiotics are utilized globally each year.² Studies have shown that nearly ninety percent of the medications would ultimately end up in different places by means of excretory waste.³ The antibiotic pollution in water primarily stems from the improper disposal of unused medications including antibiotics. They are often disposed of improperly, either flushed down toilets or washed down sinks, leading to direct contamination of water sources. Despite the advances in science and technology, both human health and ecosystems remain at risk as a result of this antibiotic pollution since it can cause bacteria to develop antibiotic resistance. Many countries are currently experiencing a severe water shortage as a result of climate change, excessive water use, and poor waste management systems. The breakdown of contaminants and the safe release and reuse of wastewater depend on cost-effective improvements to wastewater treatment processes. According to studies wastewaters from different sources have been found to contain varying amounts of antibiotics including hospital wastewater (0.1 - 157 mgL^-1), domestic wastewater (0.001 - 32 mgL^-1) and industrial wastewater (26 ng L^-1 - 31 mg L^-1).^4-6 The environment and human health are seriously threatened by the antibiotic pollution in water.⁷ Antibiotic removal from wastewater has therefore attracted increased global public attention and concern in recent years. Selecting the most effective treatment plan is essential for achieving the desired purification objectives since the water gets polluted and cleaning turns into necessary.^8,9

Currently, an array of technologies is used for the elimination of antibiotics from aquatic environments, employing biological, physical and chemical methods. To improve the rate of elimination of antibiotics from wastewater, physicochemical techniques have been developed up to this point. These include adsorption, flocculation, coagulation, ozonation, ion exchange, membrane filtration, electrochemical degradation and chemical oxidation.¹⁰ Furthermore, due to its distinctive benefits, such as their affordability and environmental friendliness, biological methods such as ligninolytic fungi, biochars, and microalgae are frequently suggested for elimination of antibiotics from wastewater.^11-13 Considering numerous advantages such as low cost, wastewater purification, CO₂ sequestration, and biomass production, microalgae-based technology has recently received significant attention among biological treatment techniques.¹⁴

Algae are mostly found in aquatic environments and serve as ecological indicators for pollutant removal, as they possess a limited growth cycle, high sensitivity to aquatic pollutants, and the ability to trigger stress response mechanisms. Techniques based on microalgae have become renowned for their economical ability to simultaneously restore nutrients and antibiotics.^15,16 Therefore, Microalgae-based biotechnology is regarded as an eco-friendly method of eliminating antibiotics from wastewater and enhancing wastewater quality.

Methodology

The review employed an approach to analyze the current state of microalgae-based technology for antibiotic removal from wastewater. The literature search was conducted using major academic databases (e.g., Scopus, Web of Science, PubMed, Google Scholar). Keywords include: ("microalgae" OR "cyanobacteria"); ("antibiotic" OR "antimicrobial"); ("wastewater treatment" OR "bioremediation" OR "phytoremediation") and ("removal" OR "degradation" OR "biosorption"). The search will be limited to peer-reviewed articles and reviews published in English, with a focus on the last 15 years to capture recent advancements. This methodology will ensure a rigorous, reproducible and insightful review.

Microalgae: Nature’s companion

Microalgae play a vital role in wastewater treatment as they can absorb nutrients, raise pH levels, and help phosphorous precipitation. They are potent source for bioremediation as they flourish in nitrogen and phosphate rich wastewater environments. The ability of several microalgal species, including Scenedesmus, Chlorella, Phormidium, Botryococcus, Limnospira, and Chlamydomonas, to bioremediate nutrients, heavy metals, emerging pollutants and pathogens associated with wastewater has been demonstrated.^17,18 Microalgae-based technology for treating antibiotics-contaminated wastewater is an environmental-friendly and cost-effective method. Studies have reported that Chlorella vulgaris can remove metronidazole (5 uM) with 100% removal efficiency through bioadsorption.¹⁹ The mechanisms used to eliminate antibiotics depend on the microalgae species and antibiotic properties, and each mechanism's efficacy differs.²⁰ Commercial research into the efficacy of microalgae has increased due to their ability to absorb nutrients and generate significant volumes of biomass. Microalgae require only limited space for growth and can survive under harsh conditions. Microalgae biomass can double within 13 hours of culture.^21,22 Chlorella sorokiniana was proven to be effective in eliminating painkillers.²³ A recent research investigation, reported the use of microalgaae Chromochloris zofingiensis for the removal of the antibiotic levofloxacin from waste water.²⁴ Table 1 shows the role of algae in the bioremediation of different classes of antibiotics and their mechanism of action.

Elimination of antibiotics by algal mechanism

Microalgae eliminate antibiotics primarily through biosorption, followed by bioaccumulation and biodegradation.^15,25,26 Certain types of antibiotics are destroyed by photo-oxidation and volatilization during microalgal growth.²⁷ But some studies reported that photodegradation and volatilization are unusual and generally considered to be irrelevant.²⁸ Micro algae technology comprises three unified processes- Bioadsorption, Bioaccumulation, Biodegradation. In bio adsorption antibiotics are rapidly and passively adsorbed onto the algal cell surface via physical and chemical interactions. In bioaccumulation the compounds slowly diffuse across the cell membrane into the algal interior and in biodegradation the substances gradually accumulate and are metabolized through bioaccumulation pathways.²⁹

Bioadsorption

Bioadsorption is a physico-chemical method used to remove antibiotics from wastewater directly.³⁰ It is a mass transfer mechanism through which a substance moves from the liquid phase and holds itself to the surface of a solid.  Since the sorbent is a biological substance that can bind and concentrate contaminants from water, biosorption is regarded as a passive process. The variety of components found in biomass and the spectrum of functional groups, which are influenced to differing degrees by physico-chemical processes, give biomaterials their structural complexity and diversity.³¹ Microalgae's cell wall is directly responsible for biosorption; its chemical composition is crucial during the process and controls the mechanism of occurrence in. By binding to extracellular polymetric substances (EPS) or components of their cell walls, algae can bioadsorb antibiotics.³² EPS is a mixture of biopolymers produced by microbes. It performs various structural and functional roles, including enhancing adsorption capacity, modifying surface properties, retaining enzymes, maintaining structural stability, and facilitating nutrient transport.³³ Antibiotics interact passively with negative-charged microalgal cellular membranes or discharges.³⁴ Increased area for contact per biomass unit is provided by smaller cell diameters, increasing the adsorbent surface area.³⁵ For instance Chlorella vulgaris can bioadsorb metronidazole (initial concentration 5 mM) with 100% removal efficiency.¹⁹ Additionally, it has been shown that nonliving microalgae biomass is a promising biosorbent material for antibiotic removal.

Bio adsorbent loading, initial adsorbate concentration, adsorption duration, pH, temperature, and excretions of extracellular polymeric substances are process parameters that affect the bioadsorption process.²⁷ Furthermore, antibiotic bioadsorption onto the biomass can be influenced by the medium's pH.³⁶ Antibiotics' aggregation, hydrophobicity, electrostatic attraction, and repulsion are all impacted by pH.³⁷ Increased lipophilicity lowers pKa, which in turn affects a substance's lipophilicity and protein-binding ability.^38,39 Deviations in temperature had a consequence on the rate at which antibiotics are absorbed by microalgal cells during bioadsorption.⁴⁰ The structure of the species and the surrounding environment have a significant impact on the potential of microalgae to adsorb substances.⁴¹ Hydrophilic materials have a lower affinity for bioadsorption and are able to endure longer in growth media.^27,42

Bioaccumulation

Bioaccumulation is a dynamic metabolic pathway for the uptake of antibiotics. It is a lively, intracellular process which demands an immense amount of energy.^43,44 Research indicates that antibiotics enter algal cells by passive diffusion.⁴⁵ Bioaccumulation is measured using a Bioconcentration factor, which is the ratio of the concentration of a contaminant adsorbent to the medium.⁴⁶ One of the difficulties with bioaccumulation is being aware that some compounds that have collected in the body might release reactive oxygen species. These free radicals may result in to oxidative destruction of biomolecules, cellular malfunction, and finally death of cells. They also have a crucial impact on cell metabolism.^42,47 The antibiotic sulfamethazine bioaccumulated in C. pyrenoidosa prior to being eliminated.⁴⁸ Levofloxacin was also removed by C. vulgaris by means of accumulation and subsequent intracellular biodegradation.⁴⁹

Biodegradation

One of the most effective techniques for eliminating pollutants from effluents is biodegradation. It involves the metabolic breakdown of complex substances into smaller.⁵⁰ Biodegradation is a method in which organic compounds break down by means of biotransformation resulting in metabolic intermediates.^42,51,52 The biodegradation of microalgae can occur in two chief ways. The one is metabolic degradation, in which antibiotics give microalgae a carbon source and act as electron donors or acceptors and the other is co-metabolism, in which enzymes reduce the antibiotics to produce non-toxic product compounds. Studies showed that the degradation potential of several algae, including C. vulgaris, Selenastrum capricornutum, Haematococcus pluvialis, and S. quadricauda against various antibiotics, biodegradation was the primary mechanism for antibiotic elimination.⁵³ Algal-based technologies break down antibiotics in three different ways: biodegradation, bioaccumulation, or both; relatively slow molecule transfer through algal cell walls; and rapid adsorption.²⁹

Table 1: Removal of antibiotics by various algal species and its mechanisms

Exploring microalgal integration for cleaner water

Microalgal integrations seem to be a promising wastewater treatment method due to their low cost, large biomass results in significant pollutant removal capacity, and ecological sustainability. Microalgae - bacteria–fungus symbioses offer a potent, integrated approach for treating antibiotic-laden wastewater. Together, these synergistic systems - leveraging biosorption, bioaccumulation, enzymatic biodegradation, and optimized harvesting -demonstrate a sustainable, high-efficiency route for antibiotic wastewater remediation.

Microalgae – bacteria consortium

Algae can employ heterotrophic metabolism or extracellular enzymes to entirely eliminate antibiotics. Additionally, they symbiotic interactions with bacteria.⁶⁵ Photosynthetically changing pH levels, or high oxygen formation can all indirectly enhance algae's capacity for biodegradation.⁴¹ Through photosynthetic processes, microalgae generate molecular oxygen, which aerobic bacteria use as an electron acceptor to break down organic pollutants. Microalgae can use the CO₂ released through bacterial mineralization as a carbon source for photosynthesis. Since antibiotics are made expressly to kill bacteria, microalgae are far more resistant to them than heterotrophic bacteria.  Using processes like biodegradation, volatilization, photodegradation and sorption, algae-bacteria consortium techniques can break down antibiotics in wastewater. Recent years have seen a lot of research on algal-bacterial systems due to their simple functioning, robustness, and improved removal efficiencies.⁶⁶

Studies demonstrated that the removal of ketoprofen was improved when Chlorella sp. was combined with a bacterial consortium.⁶⁷ Combined algal-bacterial systems showed a caffeine removal rate of over 99%, compared to a removal rate of only 17% in microalgal incubation alone.⁶⁸ Bacterial-algal synergy was crucial in the treatment of anthraquinone. Anthraquinone's molecular bonds could be broken by Chlorella, transforming it into intermediate molecules. The heterotrophic bacteria fully absorbed the intermediate molecules.⁶⁹ Both bacteria and algae may act as biosorbents in algae-bacteria consortia, and the EPS that the bacteria and algae produce provides vital sites for the biosorption of antibiotics.⁷⁰ For the degradation of cephalosporins, created a new algae-activated sludge mixed system that demonstrated an exceptional cefradine removal rate with green algae, achieving increased overall removal effectiveness worth 97.91%.³⁴ Algae–bacteria granular sludge reactors (ABGS) combining Scenedesmus or Chlorella with bacterial sludge have removed tetracycline and sulfadiazine at rates of ~79 % and ~94 %, respectively.¹³

Microalgae – fungal consortium

Compared to bacteria in biological wastewater purification, fungi have demonstrated encouraging results and offers several advantages. The microalgal-fungal system's mechanisms that support its exceptional wastewater remediation performance. When it comes to removing nutrients from wastewater, co-approach works better than traditional pure cultivation. Heterotrophic organisms like fungi employ metabolism to convert organic resources into carbon dioxide, whereas autotrophic microalgae use inorganic carbon sources as building blocks to accumulate biomass.⁷¹ In this manner, fungi can be fully supplied with oxygen from microalgal photosynthesis, which returns carbon dioxide to algal cells. Studies discovered that seven pharmaceuticals were removed using Aspergillus niger, Chlorella vulgaris, and bio-pellets made of both microorganisms.⁷² Systems combining Chlorella vulgaris and the fungus Clonostachys rosea showed antibiotic removal rates up to ~96 % for tetracycline, ~91 % for oxytetracycline, with moderate efficiency on quinolones and sulfonamides - especially when enhanced with plant hormones like gibberellins (50 mg/L).⁷³

Fungal wastewater remediation, according to Sankaran et al.⁷⁴ not only converts organic matter into valuable biochemicals and high-value fungal proteins (like lactic acids, amylase, and chitin), but, it also produces a sizable amount of dewaterable fungal biomass that can be consumed by people or utilized as animal feed. Moreover, fungi have a large number of extracellular enzymes and a high resistance to inhibitory substances, which facilitate the bioremediation of persistent substances. Additionally, it has been discovered that the removal of various pharmaceuticals from wastewater is improved by fungus-assisted algae harvesting.⁷⁵ Certain filamentous fungi have the ability to pelletize, which involves microalgal cells further illustrates the mechanisms by which algae-fungi consortia remove contaminants. It has been demonstrated that algae-fungus consortia can treat wastewater containing antibiotics. For example, biopellets made of Aspergillus niger and C. vulgaris have demonstrated a significant ability to remove ranitidine.⁷² Additionally, it has been discovered that the removal of various pharmaceuticals from wastewater is improved by fungus-assisted algae harvesting.⁷⁵Apart from their potential high removal rate, biopellets enable harvesting through sieve filtration or sedimentation, which drastically lowers treatment expenses. Adding fungi and algae to promote co-pelletization eliminates the need for additional energy or chemical inputs and could be a promising treatment approach.

Microalgae - genetic engineering

A desired trait can be introduced into a target organism through genetic engineering. Previously, this method was employed to develop engineered algae with enhanced metabolic activity and functionality.³⁴ Genetic engineering using engineered microbial strains or consortia has also been applied to enhance specific metabolic activities or to enrich microbes with particular functions.³⁴ It has been demonstrated that microalgal clones modified with functional enzyme genes, such as laccase, increase the stability of oxidoreductases, ensuring efficient bioremediation of contaminants.⁷⁶ Zhang et al. examined the ability of an enriched bacterial consortium to biodegrade chloramphenicol.⁷⁷ The use of targeted genome editing to modify microalgal strains and introduce functional genes into their genomes is growing in popularity.⁷⁸ For instance, when the linA gene from P. paucimobilis UT26 was introduced into Anabaena sp. PCC7120, lindane removal increased even in the absence of nitrate.⁷⁹ Microalgal ploidy, selection agent sensitivity, and cell wall composition and structure continue to be major barriers to microalgal genetic engineering.⁸⁰ Algal cell walls are very resistant to infiltration because of their complex heteropolymer composition.⁸¹ More research should be done on the utilization of microalgae and genetic engineering methods to expand their usage in wastewater bioremediation.

Microalgae – nanoparticles

Due to its better degradation efficiency, nanotechnology has replaced traditional methods for breakdown antibiotics in wastewater. Typical characteristics of nanomaterials include a high specific surface area, size-dependent characteristics, high reactivity, and a high degree of functionalization. Owing to these properties, nanomaterials can be effectively used for water purification and wastewater treatment.⁸² The synthesis of nanoparticles involves a variety of compounds that are produced by microalgae, including proteins, carbohydrates, lipids, nucleic acids, vitamins, and minerals.^83-85 According to some studies, nanofibers are the most effective supportive carriers for encapsulating and immobilizing microalgae. As a result, bio-integrated hybrid materials have been developed that are recyclable, more user-friendly, and more effective in eliminating pollutants.⁵⁵ Using processes like bioadsorption, biodegradation, and the application of novel technologies, microalgae which are frequently supplemented with nanoparticles have demonstrated encouraging efficacy in eliminating antibiotics from wastewater. It has been demonstrated that adding nanoparticles, particularly metal oxides, improves the effectiveness of antibiotic removal.⁸⁶

Factors affecting antibiotic removal by microalgae

pH affects cell surface charge and antibiotic ionization. For most species, a pH between 6 and 9 is ideal.⁸⁷ Higher temperatures (20–30°C) increase metabolic activity but may decrease thermolabile compound adsorption.⁸⁸ Intensity of Light play a vital role in biodegradation. Studies showed that degradation of B-lactam antibiotics is accelerated by UV light.55 Unbalanced ratios, such as a high N/P ratio, can inhibit microalgal growth. Studies revealed that for Chlorella C: N:P of 100:16:1 is optimal.⁸⁹ Regarding antibiotic Concentration, Fluoroquinolones and other lipophilic antibiotics (log Kow > 3) adsorb more effectively than hydrophilic ones.13 Species-Specific efficiency is crucial in determining the degradation efficiency. For example, Chlorella spp. and Scenedesmus spp. show high removal rates for tetracyclines and sulfonamides.⁹⁰ In algal-bacterial Synergy, bacteria enhance degradation through co-metabolism e.g., Pseudomonas spp. with Chlorella for sulfamethoxazole removal.⁹¹

Conclusion

Microalgal technology holds great potential for treating wastewater containing antibiotics since it can efficiently extract antibiotics and other pollutants from wastewater while additionally producing biomass that can be used for other purposes. Microalgae may effectively eliminate antibiotics from wastewater through a variety of mechanisms, including bioadsorption, biodegradation, and bioaccumulation. The process of bioadsorption by algal cells occurs when antibiotics are adsorbed onto organic substances produced by the cell or to components of the cell wall. The ability of living organisms to bioaccumulate depends on various chemical, physical, and biological processes. Through catalytic metabolic reduction, complexed substrates may be broken down into simpler molecules as part of biodegradation. This reduces the negative environmental effects of antibiotic pollution. An additional economic advantage is that the biomass produced during treatment can be utilized for various applications, such as biofuel production, animal feed, or fertilizer. Overall, microalgal technology shows great promise in addressing the problem of antibiotic contamination in wastewater and advancing environmentally sustainable water treatment methods.

Acknowledgement

The authors are grateful to Department of Biochemistry & Industrial Microbiology, Sree Ayyappa College, Eramallikkara, Chengannur, Alappuzha; Cashew Export promotion Council of India, Kollam; Gregorian Institute of Health Sciences, Kangazha, Kottayam and South Park Institute of Hotel Management, Anad, Trivandrum for providing the facilities, infrastructure and a favourable working environment that enabled the study.

Funding Sources

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Conflict of Interest

The authors do not have any conflict of interest.

Data Availability Statement

The data supporting in this review are derived from publicly available published studies, which are cited in the reference list of this manuscript. No new experimental data were generated or analysed in this study.

Ethics Statement

This research did not involve human participants, animal subjects, or any material that requires ethical approval.

Informed Consent Statement

This study did not involve human participants, and therefore, informed consent was not required.

Permission to Reproduce Material from Other Sources

Not Applicable

Author Contributions

Aswin L: Data collection, Writing the Original Draft

Lincy Davin: Review and Editing

Nitha B:  Visualization, Supervision and Final Editing of manuscript

Noha Laj: Data Collection

Harikrishnan: Data Collection

Reference

1. Zhang X., Zhao H., Du J., et al. Occurrence, removal, and risk assessment of antibiotics in 12 wastewater treatment plants from Dalian, China. Environ. Sci. Pollut. Res. 2017;24(19):16478-16487.  doi:10.1007/s11356-017-9296-7
   CrossRef
2. Danner M.C., Robertson A., Behrends V., Reiss J. Antibiotic pollution in surface fresh waters: Occurrence and effects. Sci. Total Environ. 2019; 664:793-804. doi: 10.1016/j.scitotenv.2019.01.406
   CrossRef
3. Wang N., Peng L., Gu Y., Liang C., Pott R.W.M., Xu Y. Insights into biodegradation of antibiotics during the biofilm-based wastewater treatment processes. J. Clean Prod. 2023; 393:136321. doi:10.1016/j.jclepro.2023.136321
   CrossRef
4. Parida V.K., Sikarwar D., Majumder A., Gupta A.K. An assessment of hospital wastewater and biomedical waste generation, existing legislations, risk assessment, treatment processes, and scenario during COVID-19. J. Environ. Manage. 2022; 308:114609. doi:10.1016/j.jenvman.2022.114609
   CrossRef
5. Verlicchi P., Aukidy M.A., Zambello E. Occurrence of pharmaceutical compounds in urban wastewater: Removal, mass load and environmental risk after a secondary treatment—A review. Sci. Total Environ. 2012; 429:123-155. doi:10.1016/ j.scitotenv. 2012.04.028
   CrossRef
6. Okeke E.S., Ezeorba T.P.C., Okoye C.O., et al. Environmental and health impact of unrecovered API from pharmaceutical manufacturing wastes: A review of contemporary treatment, recycling and management strategies. Sustain. Chem. Pharm. 2022;30:100865. doi:10.1016/j.scp.2022.100865
   CrossRef
7. Wang C., Liu X., Yang Y., Wang Z. Antibiotic and antibiotic resistance genes in freshwater aquaculture ponds in China: A meta-analysis and assessment. J. Clean Prod. 2021; 329:129719. doi:10.1016/j.jclepro.2021.129719
   CrossRef
8. Al-Tohamy R., Ali S.S., Li F., et al. A critical review on the treatment of dye-containing wastewater: Ecotoxicological and health concerns of textile dyes and possible remediation approaches for environmental safety. Ecotoxicol. Environ. Saf. 2022; 231:113160. doi:10.1016/j.ecoenv.2021.113160
   CrossRef
9. Basu S., Dutta A., Mukherjee S.K., Hossain S.T. Exploration of green technology for arsenic removal from groundwater by oxidation and adsorption using arsenic-oxidizing bacteria and metal nanoparticles. In: Elsevier eBooks.  2021:177-211. doi:10.1016/b978-0-12-822965-1.00009-x.
   CrossRef
10. Noor N.N.M., Kamaruzaman N.H., Al-Gheethi A., Mohamed R.M.S.R., Hossain M.D.S. Degradation of antibiotics in aquaculture wastewater by bio-nanoparticles: A critical review. Ain Shams Eng. J. 2022;14(7):101981. doi:10.1016/j.asej.2022.101981
    CrossRef
11. Rambabu K., Banat F., Pham Q.M., Ho S.H., Ren N.Q., Show P.L. Biological remediation of acid mine drainage: Review of past trends and current outlook. Environ. Sci. Ecotechnol. 2020; 2:100024. doi:10.1016/j.ese.2020.100024
    CrossRef
12. Russell J.N., Yost C.K. Alternative, environmentally conscious approaches for removing antibiotics from wastewater treatment systems. Chemosphere. 2020; 263:128177. doi:10.1016/j.chemosphere.2020.128177
    CrossRef
13. Li S., Show P.L., Ngo H.H., Ho S.H. Algae-mediated antibiotic wastewater treatment: A critical review. Environ. Sci. Ecotechnol. 2022; 9:100145. doi:10.1016/j.ese. 2022.100145
    CrossRef
14. Bhatt P., Bhandari G., Bhatt K, Simsek H. Microalgae-based removal of pollutants from wastewaters: Occurrence, toxicity and circular economy. Chemosphere. 2022; 306:135576. doi:10.1016/j.chemosphere.2022.135576
    CrossRef
15. Leng L., Wei L., Xiong Q., et al. Use of microalgae based technology for the removal of antibiotics from wastewater: A review. Chemosphere. 2019; 238:124680. doi:10.1016/j.chemosphere.2019.124680
    CrossRef
16. Qv M., Dai D., Liu D., et al. Towards advanced nutrient removal by microalgae-bacteria symbiosis system for wastewater treatment. Bioresour. Technol. 2023; 370: 128574. doi:10.1016/j.biortech.2022.128574
    CrossRef
17. López-Sánchez A., Silva-Gálvez A.L., Aguilar-Juárez Ó., et al. Microalgae-based livestock wastewater treatment (MbWT) as a circular bioeconomy approach: Enhancement of biomass productivity, pollutant removal and high-value compound production. J. Environ. Manage. 2022; 308:114612. doi:10.1016/j.jenvman. 2022.114612.
    CrossRef
18. Ahmad I., Abdullah N., Koji I., Yuzir A., Mohamad S.E. Potential of microalgae in bioremediation of wastewater. Bull. Chem. React. Eng. Catal. 2021;16(2):413-429. doi:10.9767/bcrec.16.2.10616.413-429
    CrossRef
19. Hena S., Gutierrez L., Croué J.P. Removal of metronidazole from aqueous media by C. vulgaris. J. Hazard Mater. 2019; 384:121400. doi:10.1016/j.jhazmat.2019.121400
    CrossRef
20. Maryjoseph S., Ketheesan B. Microalgae based wastewater treatment for the removal of emerging contaminants: A review of challenges and opportunities. Case Studies in Chem. Environ. Eng. 2020; 2:100046. doi:10.1016/j.cscee.2020.100046
    CrossRef
21. Mohsenpour S.F., Hennige S., Willoughby N., Adeloye A., Gutierrez T. Integrating micro-algae into wastewater treatment: A review. Sci. Total Environ. 2020; 752:142168. doi:10.1016/j.scitotenv.2020.142168
    CrossRef
22. Aron N.S.M., Khoo K.S., Chew K.W., Veeramuthu A., Chang J.S., Show P.L. Microalgae cultivation in wastewater and potential processing strategies using solvent and membrane separation technologies. J. Water Process Eng. 2020; 39:101701. doi:10.1016/j.jwpe.2020.101701
    CrossRef
23. De Wilt A., Butkovskyi A., Tuantet K., et al. Micropollutant removal in an algal treatment system fed with source separated wastewater streams. J. Hazard Mater. 2015; 304:84-92. doi:10.1016/j.jhazmat.2015.10.033
    CrossRef
24. Peng J., He Y.Y., Zhang Z.Y., et al. Removal of levofloxacin by an oleaginous microalgae Chromochloris zofingiensis in the heterotrophic mode of cultivation: Removal performance and mechanism. J. Hazard Mater. 2021; 425:128036. doi:10.1016/j.jhazmat.2021.128036
    CrossRef
25. Hena S., Gutierrez L., Croué J.P. Removal of pharmaceutical and personal care products (PPCPs) from wastewater using microalgae: A review. J Hazard Mater. 2020; 403:124041. doi:10.1016/j.jhazmat.2020.124041
    CrossRef
26. Xiong J.Q., Kurade M.B., Jeon BH. Can Microalgae Remove Pharmaceutical Contaminants from Water? Trends Biotechnol. 2017; 36(1):30-44. doi:10.1016/j .tibtech.2017.09.003
    CrossRef
27. Sutherland D.L., Ralph P.J. Microalgal bioremediation of emerging contaminants - Opportunities and challenges. Water Res. 2019; 164:114921. doi:10.1016/j. watres.2019.114921
    CrossRef
28. Nguyen H.T., Yoon Y., Ngo H.H., Jang A. The application of microalgae in removing organic micropollutants in wastewater. Crit. Rev. Environ. Sci. Technol. 2020; 51(12):1187-1220. doi:10.1080/10643389.2020.1753633
    CrossRef
29. Yu Y., Zhou Y., Wang Z., Torres O.L., Guo R., Chen J. Investigation of the removal mechanism of antibiotic ceftazidime by green algae and subsequent microbic impact assessment. Sci. Rep. 2017; 7(1). doi:10.1038/s41598-017-04128-3
    CrossRef
30. Fomina M., Gadd G.M. Biosorption: current perspectives on concept, definition and application. Bioresour. Technol. 2014; 160:3-14. doi:10.1016/j.biortech.2013.12.102
    CrossRef
31. Feng H., Sun C., Zhang C., et al. Bioconversion of mature landfill leachate into biohydrogen and volatile fatty acids via microalgal photosynthesis together with dark fermentation. Energy Convers. Manag. 2021; 252:115035. doi:10.1016/j.enconman. 2021.115035
    CrossRef
32. Wang L., Li Y., Wang L., et al. Responses of biofilm microorganisms from moving bed biofilm reactor to antibiotics exposure: Protective role of extracellular polymeric substances. Bioresour. Technol. 2018; 254:268-277. doi:10.1016/j.biortech.2018.01. 063
    CrossRef
33. Wu Y., Li T., Yang L. Mechanisms of removing pollutants from aqueous solutions by microorganisms and their aggregates: A review. Bioresour. Technol. 2011; 107:10-18. doi:10.1016/j.biortech.2011.12.088
    CrossRef
34. Xiong Q., Hu L.X., Liu Y.S., Zhao J.L., He L.Y., Ying G.G. Microalgae-based technology for antibiotics removal: From mechanisms to application of innovational hybrid systems. Environ. Int. 2021; 155:106594. doi:10.1016/j.envint.2021.106594
    CrossRef
35. Mathew B.B., Jaishankar M., Biju V.G., Beeregowda N.K.N. Role of bioadsorbents in reducing toxic metals. J. Toxicol. 2016; 2016:1-13. doi:10.1155/2016/4369604
    CrossRef
36. Daneshvar E., Zarrinmehr M.J., Hashtjin A.M., Farhadian O., Bhatnagar A. Versatile applications of freshwater and marine water microalgae in dairy wastewater treatment, lipid extraction and tetracycline biosorption. Bioresour. Technol. 2018; 268:523-530. doi:10.1016/j.biortech.2018.08.032
    CrossRef
37. Zambrano J., García-Encina P.A., Hernández F., Botero-Coy A.M., Jiménez J.J., Irusta-Mata R. Removal of a mixture of veterinary medicinal products by adsorption onto a Scenedesmus almeriensis microalgae-bacteria consortium. J. Water Process Eng. 2021; 43:102226. doi:10.1016/j.jwpe.2021.102226
    CrossRef
38. Besha A.T., Liu Y., Fang C., Bekele D.N., Naidu R. Assessing the interactions between micropollutants and nanoparticles in engineered and natural aquatic environments. Crit. Rev. Environ. Sci. Technol. 2019; 50(2):135-215. doi:10.1080/ 10643389.2019.1629799
    CrossRef
39. Chen S., Zhang W., Li J., et al. Ecotoxicological effects of sulfonamides and fluoroquinolones and their removal by a green alga (Chlorella vulgaris) and a cyanobacterium (Chrysosporum ovalisporum). Environ. Pollut. 2020; 263:114554. doi:10.1016/j.envpol.2020.114554
    CrossRef
40. Zeraatkar A.K., Ahmadzadeh H., Talebi A.F., Moheimani N.R., McHenry M.P. Potential use of algae for heavy metal bioremediation, a critical review. J. Environ. Manage. 2016;181:817-831. doi:10.1016/j.jenvman.2016.06.059
    CrossRef
41. Norvill Z.N., Shilton A., Guieysse B. Emerging contaminant degradation and removal in algal wastewater treatment ponds: Identifying the research gaps. J. Hazard Mater. 2016; 313:291-309. doi:10.1016/j.jhazmat.2016.03.085
    CrossRef
42. Xiong J.Q., Kim S.J., Kurade M.B., et al. Combined effects of sulfamethazine and sulfamethoxazole on a freshwater microalga, Scenedesmus obliquus: toxicity, biodegradation, and metabolic fate. J. Hazard. Mater. 2018; 370:138-146. doi:10.1016/j.jhazmat.2018.07.049
    CrossRef
43. Bai X., Acharya K. Algae-mediated removal of selected pharmaceutical and personal care products (PPCPs) from Lake Mead water. Sci. Total Environ. 2017; 581-582:734-740. doi:10.1016/j.scitotenv.2016.12.192
    CrossRef
44. Davis T.A., Volesky B., Mucci A. A review of the biochemistry of heavy metal biosorption by brown algae. Water Res. 2003; 37(18):4311-4330. doi:10.1016/s0043-1354(03)00293-8
    CrossRef
45. Song C., Wei Y., Qiu Y., Qi Y., Li Y., Kitamura Y. Biodegradability and mechanism of florfenicol via Chlorella sp. UTEX1602 and L38: Experimental study. Bioresour. Technol. 2018; 272:529-534. doi:10.1016/j.biortech.2018.10.080
    CrossRef
46. Gobas F.A., Burkhard L.P., Doucette W.J., et al. Review of existing terrestrial bioaccumulation models and terrestrial bioaccumulation modeling needs for organic chemicals. Integr. Environ. Assess. Manag. 2015;12(1):123-134. doi:10.1002/ieam. 1690
    CrossRef
47. Priyadharshini S.D., Babu P.S., Manikandan S., Subbaiya R., Govarthanan M., Karmegam N. Phycoremediation of wastewater for pollutant removal: A green approach to environmental protection and long-term remediation. Environ. Pollut. 2021; 290:117989. doi:10.1016/j.envpol.2021.117989
    CrossRef
48. Sun M., Lin H., Guo W., Zhao F., Li J. Bioaccumulation and biodegradation of sulfamethazine in Chlorella pyrenoidosa. J. Ocean Univ. China. 2017; 16(6):1167-1174. doi:10.1007/s11802-017-3367-8
    CrossRef
49. Xiong J.Q., Kurade M.B., Jeon B.H. Biodegradation of levofloxacin by an acclimated freshwater microalga, Chlorella vulgaris. Chem. Eng. J. 2016; 313:1251-1257. doi:10.1016/j.cej.2016.11.017
    CrossRef
50. Fu X., Wang H., Bai Y., et al. Systematic degradation mechanism and pathways analysis of the immobilized bacteria: Permeability and biodegradation, kinetic and molecular simulation. Environ. Sci. Ecotechnol. 2020; 2:100028. doi:10.1016/j.ese. 2020.100028
    CrossRef
51. Xiong Q., Liu Y.S., Hu L.X., et al. Co-metabolism of sulfamethoxazole by a freshwater microalga Chlorella pyrenoidosa. Water Res. 2020; 175:115656. doi:10.1016/j.watres.2020.115656
    CrossRef
52. Achermann S., Bianco V., Mansfeldt C.B., et al. Biotransformation of sulfonamide antibiotics in activated sludge: The formation of Pterin-Conjugates leads to sustained risk. Environ. Sci. Technol. 2018; 52(11):6265-6274. doi:10.1021/acs.est.7b06716
    CrossRef
53. Kiki C., Rashid A., Wang Y., et al. Dissipation of antibiotics by microalgae: Kinetics, identification of transformation products and pathways. J. Hazard. Mater. 2019; 387:121985. doi:10.1016/j.jhazmat.2019.121985
    CrossRef
54. Liu Y., Guan Y., Gao B., Yue Q. Antioxidant responses and degradation of two antibiotic contaminants in Microcystis aeruginosa. Ecotoxicol. Environ. Saf. 2012;86:23-30. doi:10.1016/j.ecoenv.2012.09.004
    CrossRef
55. Ghosh I., Banerjee P. Removal of antibiotics by algae: Elucidating the removal mechanisms, treatment systems and Post-Treatment antibiotic resistance. Afr. J. Biomed. Res. Published online October 12, 2024:790-804. doi:10.53555/ajbr. v27i3.2936
    CrossRef
56. Angulo E., Bula L., Mercado I., Montaño A., Cubillán N. Bioremediation of Cephalexin with non-living Chlorella sp., biomass after lipid extraction. Bioresour. Technol. 2018;257:17-22. doi:10.1016/j.biortech.2018.02.079
    CrossRef
57. Guo R., Chen J. Application of alga-activated sludge combined system (AASCS) as a novel treatment to remove cephalosporins. Chem. Eng. J. 2014;260:550-556. doi:10.1016/j.cej.2014.09.053
    CrossRef
58. Xie P., Chen C., Zhang C., Su G., Ren N., Ho S.H. Revealing the role of adsorption in ciprofloxacin and sulfadiazine elimination routes in microalgae. Water Res. 2020;172:115475. doi:10.1016/j.watres.2020.115475
    CrossRef
59. Garcia-Rodríguez A., Matamoros V., Fontàs C., Salvadó V. The influence of light exposure, water quality and vegetation on the removal of sulfonamides and tetracyclines: A laboratory-scale study. Chemosphere. 2012;90(8):2297-2302. doi:10.1016/j.chemosphere.2012.09.092
    CrossRef
60. Xie P., Ho S.H., Peng J., et al. Dual purpose microalgae-based biorefinery for treating pharmaceuticals and personal care products (PPCPs) residues and biodiesel production. Sci. Total Environ. 2019;688:253-261. doi:10.1016/j.scitotenv. 2019.06.062
    CrossRef
61. Bai X., Acharya K. Removal of trimethoprim, sulfamethoxazole, and triclosan by the green alga Nannochloris sp. J. Hazard Mater. 2016;315:70-75. doi:10.1016/j.jhazmat. 2016.04.067
    CrossRef
62. Li J., Min Z., Li W., Xu L., Han J., Li P. Interactive effects of roxithromycin and freshwater microalgae, Chlorella pyrenoidosa: Toxicity and removal mechanism. Ecotoxicol Environ Saf. 2020;191:110156. doi:10.1016/j.ecoenv.2019.110156
    CrossRef
63. Grimes K.L., Dunphy L.J., Loudermilk E.M., et al. Evaluating the efficacy of an algae-based treatment to mitigate elicitation of antibiotic resistance. Chemosphere. 2019;237:124421. doi:10.1016/j.chemosphere.2019.124421
    CrossRef
64. Zhang J., Fu D., Wu J. Photodegradation of Norfloxacin in aqueous solution containing algae. J. Environ. Sci. 2012;24(4):743-749. doi:10.1016/s1001-0742(11) 60814-0
    CrossRef
65. Zhang C., Li S., Ho S.H. Converting nitrogen and phosphorus wastewater into bioenergy using microalgae-bacteria consortia: A critical review. Bioresour. Technol. 2021; 342:126056. doi:10.1016/j.biortech.2021.126056
    CrossRef
66. Oruganti R.K., Katam K., Show P.L., Gadhamshetty V., Upadhyayula V.K.K., Bhattacharyya D. A comprehensive review on the use of algal-bacterial systems for wastewater treatment with emphasis on nutrient and micropollutant removal. Bioengineered. 2022;13(4):10412-10453. doi:10.1080/21655979.2022.2056823
    CrossRef
67. Ismail M.M., Essam T.M., Ragab Y.M, Mourad F.E. Biodegradation of ketoprofen using a microalgal–bacterial consortium. Biotechnol. Lett. 2016;38(9):1493-1502. doi:10.1007/s10529-016-2145-9.
    CrossRef
68. Matamoros V., Uggetti E., García J., Bayona J.M. Assessment of the mechanisms involved in the removal of emerging contaminants by microalgae from wastewater: a laboratory scale study. J. Hazard Mater. 2015; 301:197-205. doi:10.1016/j.jhazmat. 2015.08.050.
    CrossRef
69. Li Y., Cao P., Wang S., Xu X. Research on the treatment mechanism of anthraquinone dye wastewater by algal-bacterial symbiotic system. Bioresour. Technol. 2022; 347:126691. doi:10.1016/j.biortech.2022.126691
    CrossRef
70. Wang Y., Liu J., Kang D., Wu C., Wu Y. Removal of pharmaceuticals and personal care products from wastewater using algae-based technologies: a review. Rev. Environ. Sci. Biotechnol. 2017; 16(4):717-735. doi:10.1007/s11157-017-9446-x
    CrossRef
71. Abinandan S., Subashchandrabose S.R., Venkateswarlu K., Megharaj M. Microalgae–bacteria biofilms: a sustainable synergistic approach in remediation of acid mine drainage. Appl. Microbiol. Biotechnol. 2017; 102(3):1131-1144. doi:10.1007/s00253-017-8693-7
    CrossRef
72. Bodin H., Daneshvar A., Gros M., Hultberg M. Effects of biopellets composed of microalgae and fungi on pharmaceuticals present at environmentally relevant levels in water. Ecol. Eng. 2016; 91:169-172. doi:10.1016/j.ecoleng.2016.02.007
    CrossRef
73. Liu J., Wang Z., Zhao C., Lu B., Zhao Y. Phytohormone gibberellins treatment enhances multiple antibiotics removal efficiency of different bacteria-microalgae-fungi symbionts. Bioresource Technology. 2023;394:130182. doi:10.1016/j. biortech.2023.130182
    CrossRef
74. Sankaran S., Khanal S.K., Jasti N., Jin B., Pometto A.L., Van Leeuwen J.H. Use of filamentous fungi for wastewater treatment and production of high value fungal byproducts: a review. Crit. Rev. Environ. Sci. Technol. 2010; 40(5):400-449. doi:10.1080/10643380802278943
    CrossRef
75. Hultberg M., Bodin H. Effects of fungal-assisted algal harvesting through biopellet formation on pesticides in water. Biodegradation. 2018; 29(6):557-565. doi:10.1007/ s10532-018-9852-y
    CrossRef
76. Subashchandrabose S.R., Ramakrishnan B., Megharaj M., Venkateswarlu K., Naidu R. Mixotrophic cyanobacteria and microalgae as distinctive biological agents for organic pollutant degradation. Environ. Int. 2012; 51:59-72. doi:10.1016/j.envint. 2012.10.007
    CrossRef
77. Zhang J., Gan W., Zhao R., et al. Chloramphenicol biodegradation by enriched bacterial consortia and isolated strain Sphingomonas sp. CL5.1: The reconstruction of a novel biodegradation pathway. Water Res. 2020;187:116397. doi:10.1016/j .watres.2020.116397
    CrossRef
78. Khatiwada B., Sunna A., Nevalainen H. Molecular tools and applications of Euglena gracilis: From biorefineries to bioremediation. Biotechnol. Bioeng. 2020; 117(12):3952-3967.  doi:10.1002/bit.27516
    CrossRef
79. Kuritz T., Bocanera L.V., Rivera N.S. Dechlorination of lindane by the cyanobacterium Anabaena sp. strain PCC7120 depends on the function of the nir operon. J. Bacteriol. 1997;179(10):3368-3370.doi:10.1128/jb.179.10.3368-3370. 1997.
    CrossRef
80. Mosey M., Douchi D., Knoshaug E.P., Laurens L.M.L. Methodological review of genetic engineering approaches for non-model algae. Algal Res. 2021; 54:102221. doi:10.1016/j.algal.2021.102221
    CrossRef
81. Scholz M.J., Weiss T.L., Jinkerson R.E., et al. Ultrastructure and Composition of the Nannochloropsis gaditana Cell Wall. Eukaryot. Cell. 2014; 13(11):1450-1464. doi:10.1128/ec.00183-14
    CrossRef
82. Vasistha S, Khanra A., Rai M.P. Influence of microalgae-ZnO nanoparticle association on sewage wastewater towards efficient nutrient removal and improved biodiesel application: An integrated approach. J. Water Proc. Eng. 2020; 39:101711. doi:10.1016/j.jwpe.2020.101711
    CrossRef
83. Soru S., Malavasi V., Caboni P., Concas A., Cao G. Behavior of the extremophile green alga Coccomyxa melkonianii SCCA 048 in terms of lipids production and morphology at different pH values. Extremophiles. 2018; 23(1):79-89. doi:10.1007/ s00792-018-1062-3
    CrossRef
84. Soru S., Malavasi V., Concas A., Caboni P., Cao G. A novel investigation of the growth and lipid production of the extremophile microalga Coccomyxa melkonianii SCCA 048 under the effect of different cultivation conditions: Experiments and modeling. Chem. Eng. J. 2018; 377:120589. doi:10.1016/j.cej.2018.12.049
    CrossRef
85. Tsvetanova F., Yankov D. Bioactive Compounds from Red Microalgae with Therapeutic and Nutritional Value. Microorganisms. 2022; 10(11):2290. doi:10.3390/ microorganisms10112290
    CrossRef
86. El-Aswar E.I., Ramadan H., Elkik H., Taha A.G. A comprehensive review on preparation, functionalization and recent applications of nanofiber membranes in wastewater treatment. J. Environ. Manag. 2021;301:113908. doi:10.1016/j.jenvman. 2021.113908
    CrossRef
87. Hashmi M.Z., Habib A., Hasnain A. Removal of antibiotics from wastewater using nanoparticles-based technology: a review. J. Umm. Al-Qura University App. Sci. Published online August 10, 2024. doi:10.1007/s43994-024-00183-5.
    CrossRef
88. Kundu P., Dutta N., Bhattacharya S. Application of microalgae in wastewater treatment with special reference to emerging contaminants: a step towards sustainability. FrontAnal Sci. 2024; 4. doi:10.3389/frans.2024.1513153
    CrossRef
89. Plöhn M., Spain O., Sirin S., et al. Wastewater treatment by microalgae. Physiol Plant. 2021;173(2):568-578. doi:10.1111/ppl.13427.
    CrossRef
90. Singh A., Singh P., Kashyap J., et al. Mitigating antibiotic pollution in wastewater by harnessing the potential of microalgae-based bioremediation technologies. Vegetos. Published online September 27, 2024. doi:10.1007/s42535-024-01035-7.
    CrossRef
91. Pereira A., De Morais E.G., Silva L., et al. Pharmaceuticals Removal from Wastewater with Microalgae: A Pilot Study. Appl. Sci. 2023;13(11):6414. doi:10.3390/app13116414.
    CrossRef