not-yet-known not-yet-known not-yet-known unknown Abbreviations : ECs: Emerging contaminant EPS: Emerging Pollutants MPs: Micro Pollutants TrOCs: Trace Organic Compounds CEC: Contaminants of Emerging Concern USGS: US Geological Survey ARGs: Antibiotic Resistant Genes DDT: dichlorodiphenyltrichloroethane PCBs: polychlorinated biphenyls RQ: risk quotient PNEC: predicted no-effect concentrations PEC: predicted concentrations of ECs EDCs: Endocrine Disrupting Chemicals NSAIDs: Non-steroidal anti-inflammatory drugs AOPs advanced oxidation procedures WWTPs: wastewater treatment plants PhACS: pharmaceutically active compounds POPs: persistent organic pollutants REEs: Rare Earth Elements PCPs: Personal Care Products PFAS: per- and polyfluoroalkyl substances COPD: chronic obstructive pulmonary disease PBDEs: polybrominated diphenyl ethers PFAS: per- and polyfluoroalkyl substances UNEP: United Nations Environment Programme WHO: world health organization EPA: Environmental Protection Agency SDWA: Safe Drinking Water Act CWA: Clean Water Act REACH: Registration, evaluation, Authorisation and restriction of chemicals NPDES: National Pollutant Discharge Elimination System WFD: Water Framework Directive EAWAG: Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz EQS: environmental quality standards CLRTAP: Convention on Long-Range Transboundary Air Pollution COD: Chemical oxygen demand BOD: Biochemical oxygen demand DOC: Dissolved organic carbon AOX: Adsorbable organic halides TOC: Total Organic Carbon LC: Liquid Chromatography GS: Gas Chromatography UHPLC: ultra-high-overall performance Liquid Chromatography QTOF: Quadrupole Time of flight mass spectrometry UPC2: ultra-performance Convergence Chromatography FTIR: Fourier- transform infrared spectrometry NMR: Nuclear Magnetic Resonance MBRs: Membrane bioreactors SBRs: Sequencing batch reactors DBDE: decabromodiphenyl ether WSPs: waste stabilization ponds CWs: Constructed Wetlands AD: Anaerobic Digestion AnMBR: Anaerobic membrane bioreactor SMX: sulfamethoxazole CIP: Ciprofloxacin HRT: hydraulic retention time SRT: stable retention time SSA: specific surface area HTC: Hydrothermal Carbonization PAHs: polycyclic aromatic hydrocarbons AOP: Advanced oxidation processes SPEF: Solar Photo electro-Fenton EfOM: effluent organic matter RO: Reverse osmosis NF: Nanofiltration NMs: Nanomaterials Introduction The global intake of water has doubled during the last few years (van Vliet et al., 2017). This augmented demand, pushed by way of agricultural, household, industrial and transportation uses, coupled with the influences of weather alternate, is speedily contributing to water scarcity (Yap et al., 2019). Simultaneously, human actions which include mining and the release of toxic metal effluents from battery production, steel mills and electricity generation have considerably deteriorated water quality, raising many environmental issues (Bala et al., 2022). In response to these challenging situations, there is a developing awareness on studies and improvement of water treatment technology geared toward enhancing water reuse and improving the quality of treated effluent (Ahmed et al., 2021). A critical aspect of this trouble is the presence of numerous newly recognized contaminants in aquatic environments, that have grown to be a global subject. These contaminants, predominantly natural, are typically found in trace concentrations ranging from parts per trillion (ppt or ng/L) to parts per billion (ppb or μg/L). They are cited variously as ”emerging pollutants (EPs),””emerging contaminants (ECs),” ”trace organic compounds (TrOCs)” ”micropollutants (MPs)” or ”contaminants of emerging concern (CEC)” through distinctive research groups. (Rout et al., 2021). The US Geological Survey (USGS) defines emerging contaminants (ECs) as any substance, synthetic or naturally occurring or organic, present in the environment that is  not normally monitored but has the potential to cause adverse effects on the environment and /or human health” (USGS, 2017) .This definition extends to microbial contaminants, inclusive of antibiotic resistant genes (ARGs) and microorganism mediated with the aid of antibacterial drugs, which can be particularly defined as emerging microbial contaminants (Rout et al., 2021). The presence of chemical contaminants inside the environment is not a new concern ; it dates back to over 2000 years to the exploitation of lead mines by the Romans and Greeks, marking lead as one of the oldest global contaminants (Sauvé and Desrosiers, 2014). Over time, the scope of contaminants has developed from conventional pollutants to consist of present day materials inclusive of personal care products, pharmaceuticals and nanomaterials. The awareness of emerging contaminants started with Rachel Carson’s seminal 1962 book, Silent Spring, which highlighted the environmental hazards associated with massive use of dichlorodiphenyltrichloroethane (DDT) (Carson, 2002; Sauvé and Desrosiers, 2014). These days, ECs, along with personal care products, pharmaceuticals, cosmetics and X-ray contrast media are detected in surface water, ground water and wastewater. These contaminants enter the surroundings via leaky septic systems and sewage pipes, infiltrate groundwater, traverse wastewater treatment canters and in the long run discharge into receiving rivers (Kumar et al., 2022). Current studies have recognized a wide variety of chemical contaminants in surface and groundwater, which include pesticides, hormones, pharmaceuticals, illicit capsules, , non-public care products, artificial sweeteners, disinfection by products ,UV filters, perfluorinated compounds, and different commercial chemical substances, commonly observed in concentrations starting from ng/L to g/L (Riva et al., 2018). Amongst these emerging contaminants (ECs), predominant pollution includes dichlorodiphenyltrichloroethane (DDT) carbamates, chloroacetanilides, polychlorinated biphenyls (PCBs), triazines and organophosphates (Shahid et al., 2021). The growing presence of emerging contaminants (ECs) in aquatic environments is raising significant alarm because of the possible combined effects they may produce (Rout et al., 2021). To evaluate the chance associated with ECs, the risk quotient (RQ) is calculated via evaluating the expected environmental concentrations (percent) with the predicted no-effect concentrations (PNEC). The RQ (risk quotient) cost is determined using the equation RQ = PEC/PNEC, in which PEC represents the predicted concentrations of ECs in the surroundings, anticipated from literature on environmental concentration, transport, fate and persistence. PNEC reflects the sensitivity of specific organisms, indicating the concentrations of ECs at which no destructive consequences are expected (Peake et al., 2016). Emerging contaminants (ECs) with their hydrophobic properties, can bioaccumulate in organisms, causing endocrine disruption and antimicrobial resistance (Rodríguez-Narváez et al., 2017). Endocrine-disrupting chemical substances (EDCs) are connected with severe health issues, including cancer and reproductive troubles. Personal care products as well as pharmaceuticals consisting of antibiotics, NSAIDs (Non-steroidal anti-inflammatory drugs), and cosmetics in addition exacerbate these worries by impacting reproductive fitness and increasing antimicrobial resistance (Ahmed et al., 2021). Heavy metals, piling up in organs in brain and liver, cause significant health consequences and degrade soil quality by inhibiting plant development and nutrient absorption (Bala et al.,2022). Technologies for EC elimination include natural attenuation techniques like dilution and biodegradation, conventional procedures such as membrane filtration and activated carbon adsorption, and superior procedures like advanced oxidation procedures (AOPs), which might be powerful in treating urban wastewater (Rout et al., 2021; Ahmed et al., 2021). An in-depth review of emerging contaminant (EC) elimination strategies is currently missing. Therefore, this paper pursuits to provide a systematic review of the current treatment technologies used for EC elimination in wastewater treatment plants (WWTPs). It begins with an outline of the sources, types, and distribution of ECs in the surroundings, and discusses their health and environmental impacts, together with present guidelines to manage these contaminants. The paper discusses cutting-edge technology for the identity, measurement, and removal of ECs, such as organic, physical, and chemical methods. Moreover, it gives steering for future research and improvement to enhance techniques for greater effective EC removal from wastewater. Emerging contaminants: Source, types and Distribution Contaminants are categorized as ’emerging’ when they originate from new sources, choose alternative pathways for human exposure, or contain novel treatment methodologies (Gogoi et al., 2018). Till lately, lots of these contaminants had been both unidentified or were not considered as pollutants, but they have now emerged as environmental threats (Shahid et al., 2021). Their behaviour in the environment is complex and is primarily determined by their physicochemical properties, which can be affected by the surrounding conditions, either in a complementary or opposing manner (Lopez-Doval ´ et al., 2017; Mohapatra et al., 2021a). The endurance and excessive mobility of numerous chemical and microbial agents make contributions to their class as non-degradable, long-range contaminants, that are now detected even in areas wherein they have never been utilized, transported by the movement of air and water (Rasheed et al., 2019). To understand the destiny and delivery of emerging contaminants (ECs), it’s far critical to first become aware of their sources. Table 1 suggests the listing of emerging contaminants from various resources and categories. Pharmaceuticals provide a relevant example, with an estimated global average consumption of 15 grams per person annually. However, in developed countries, this number can be considerably higher, reaching as much as 150 grams per capita Due to the unfinished metabolism of pharmaceuticals in both human and animals, over 50% of these compounds are excreted via faeces and urine, eventually entering wastewater treatment plants (WWTPs) through the sewer system. Regardless of the improvement of alternative wastewater remedy technologies, which include membrane bioreactors coupled with advanced oxidation processes or nanotechnologies, these strategies remain in large part on the laboratory scale and are tough to enforce in industrial-scale WWTPs because of their prohibitive prices. Consequently, conventional WWTPs often fail to completely get rid of ECs, ensuing in the detection of excessive levels of these contaminants in effluents.(Tong et al., 2022) Contaminants of emerging concern have been detected across various stages of the hydrological cycle, including groundwater, surface waters, and the effluents of wastewater treatment plant (Kumar et al.,2022) These contaminants include a wide array of products often used in day to day life, including antibiotics, hormones, pesticides and pharmaceuticals. An overview of the source and types of emerging contaminants is given in the Fig. 1 . The sources of ECs can be extensively categorized into two classes: point sources and non-point (diffuse) sources. Point sources are characterized through the direct discharge of vast quantities of pollution and include sectors like agriculture, prescription drugs, aquaculture, cosmetics, mining, cattle farming, landfill sites, and food processing centres. In contrast, non-factor sources, or diffuse assets, are normally related to the discharge of contaminants over a wide area and include agricultural runoff, urban stormwater, and atmospheric deposition (D.J. Lapworth et al., 2012). Emerging contaminants (ECs) embody a large variety of substances that may be categorised based on their physical and chemical characteristics into organic, inorganic and particulate contaminants along with their subtypes. Those sources make contributions to the release of various ECs, including pharmaceutically active compounds (PhACs), persistent organic pollutants (POPs), uncommon earth factors (REEs), endocrine-disrupting chemical substances (EDCs), personal care products (PCPs), insecticides, preservatives, and antibiotic-resistant, pathogenic microorganisms (Rout et al., 2021;Gwenzi et al., 2018). Fig. 2 indicates the pathways and distribution of emerging contaminants. Pesticides, which are a chief source of ECs in aquatic environments, are further classified as fungicides, herbicides, or pesticides. A study, identified 150 pesticides and their metabolic intermediates in 58 surfcae water and groundwater samples, underscoring their pervasive presence and environmental impact (Shahid et al., 2021). Fernandez et al. (2017) investigated the effect of weather conditions on the tiers of emerging contaminants (ECs) and discovered notable variability. Their study highlighted that severe rainstorms and high flood activities notably affect the presence and distribution of ECs in groundwater, mainly in areas in which the drainage systems are designed to acquire and integrate rainwater runoff, home sewage, and industrial wastewater. Among the substantial list of ECs detected in environmental samples, about 70% are personal care products (PCPs) and pharmaceutically active compounds (PhACs) while the remaining 30% are agricultural and industrial compounds . As an instance, more than 200 PhACs had been globally discovered in river waters with ciprofloxacin, an antibiotic, detected at concentrations up to 6 mg/L (Rout et al., 2021). Jones et al. (2001) founded environmental concentrations of various pharmaceuticals which includes antidepressants, lipid regulators, hormones, analgesics and chemotherapy pills ranging from 0.04 to 6.3 μg/L. Additionally, high-usage chemical substances like sunscreen dealers and preservatives are often reported at concentrations exceeding 1000 ng/L (Petrie et al., 2015) Health and Environmental effects of Emerging Contaminants Emerging contaminants (ECs) pose significant danger to human health, even at trace levels, ordinarily because of their ability to bioaccumulate and persist in the environment. Endocrine disrupting chemicals (EDCs) are a prime issue, as human exposure mainly happens through the ingestion of contaminated food and liquids, leading to biomagnification, especially in species on the pinnacle of the meals chain. Pharmaceuticals, because of their water solubility and steadiness in biological systems, are hard to dissociate in aqueous solutions and may penetrate biochemical barriers, thereby persisting in the human body. Antibiotics utilized in food processing make contributions to health dangers through antimicrobial resistance. The hydrophobic nature of some ECs permits them to bioaccumulate in lipid- rich tissues, disrupting endocrine structures and contributing to cardiovascular and neurological damage, as visible with several pesticides and PFAS (per- and polyfluoroalkyl substances), that are related with cancer and other serious health issues. Moreover, industrial pollutants, in particular minute particles, pose a giant risk to respiratory health, increasing the danger of asthma and chronic obstructive pulmonary disease (COPD) (Li et al., 2024 ; Kumar et al., 2022). Latest advances in environmental chemistry have diagnosed several chemicals of emerging concern (CECs), which include PBDEs (polybrominated diphenyl ethers) and PFAS (per- and polyfluoroalkyl substances), which can be now detected in faraway areas like the Arctic. These contaminants, often bypassing sewage treatment plants, are located in groundwater, lakes and streams. Pharmaceuticals were shown to disrupt reproductive behaviours in aquatic species, whereas industrial by-products enhance mortality, threatening species sustainability. Long- term encounter to ECs may additionally lead to manipulations in the gene sequence, genetic range reduction and reducing population adaptability (Reid et al., 2019). The accumulation of pharmacologically active compounds in non-target species increases critical issues, with ecotoxicological research displaying massive influences on green algae, daphnids and zebrafish. Improving techniques to eliminate these ECs is important for protecting flora and fauna and maintaining ecosystem health and resilience. (Li et al., 2024 ; Kumar et al., 2022). Various studies have documented the ecological influences of rare earth elements (REEs) on vegetation, soil organisms as well as on both aquatic and terrestrial animals . REEs have been shown to interfere with the uptake of critical nutrients, mainly calcium (Ca), because of their similar ionic radii. This interference can disrupt various physiological processes in plants, consisting of root growth, cell wall formation, photosynthesis, and flowering (Gwenzi et al., 2018). Moreover, agricultural runoff, that’s regularly enriched with nutrients and pollution, exacerbates disruptions in ecosystem nutrient cycles, leading to eutrophication. This procedure, characterised by premature aging of aquatic ecosystems, leading to oxygen depletion and unrestrained algal blooms which adversely influences aquatic existence. Furthermore, microplastics, by posing ingestion risks to wildlife and disrupting habitats, were implicated in changing soil nutrient dynamics by means of decreasing nutrient leaching. Current studies shows that these microplastics may additionally contribute to changes in soil health and environment functions (Li et al., 2024). Regulations Related to Emerging Contaminants The United international locations environment software (UNEP) and the world health organization (WHO) spearhead worldwide efforts to control ECs, offering recommendations and guidelines. Rules on ECs differ throughout countrywide and global stages, reflecting evolving awareness of their influences (Puri et al., 2023). Within the United States of America, the Environmental Protection Agency (EPA) enforces guidelines under the Safe Drinking Water Act (SDWA) and the Clean Water Act (CWA), with the National Pollutant Discharge Elimination System (NPDES) playing a crucial position in controlling water contaminants (Elrod, 2022). The European Union implements key regulations incorporating REACH (Registration, evaluation, Authorisation and restriction of chemicals) and the Water Framework Directive (WFD). REACH mandates the registration and evaluation of chemicals, at the same time as the WFD ambitions to attain ’good status’ for water bodies (Brack et al., 2017; Dulio et al., 2018). International locations which include Australia and Japan emphasize rigorous monitoring and manage of pollutants, inclusive of pharmaceuticals and persistent organic pollutants (Jose et al., 2020). The EAWAG (Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz) Institute in Switzerland has proposed environmental quality standards (EQS) for numerous ECs, which includes hormones and pharmaceuticals. Regardless of these efforts, some documents, which includes those from the European Commission (2011), awareness on lowering the use of EDCs in cosmetics food additives and consumer products, but do not provide specific guidelines for maximum allowable concentrations in consuming water, wastewater, or the environment. Worldwide treaties, including the CLRTAP (Convention on Long-Range Transboundary Air Pollution) Protocol and the Stockholm convention, play a pivotal position in the global reduction of persistent organic pollutants via coordinated efforts (Crini et al., 2022) Techniques for Identifying and Measuring Emerging Contaminants There is a substantial emphasis at the development of swift and reactive analytical strategies for the efficient monitoring and resolution of a vast spectrum of ECs (Agüera et al., 2013). Latest advancements have brought about the advent and implementation of numerous analytical techniques specifically designed for the detection and quantification of numerous ECs in surface water, wastewater and groundwater. The assessment of contamination concentration in water bodies entails diverse parameters, including chemical oxygen demand (COD), biological oxygen demand (BOD), Dissolved organic Carbon (DOC), adsorbable organic halides (AOX) and total organic Carbon (TOC) (Khan et al., 2019). Analytical techniques including chromatographic strategies and mass spectrometry, consisting of liquid chromatography (LC) and gas chromatography (GC), are instrumental in detecting low-stage contaminants and analysing volatile and semi-volatile natural compounds. Advanced techniques, including ultra-high-overall performance Liquid Chromatography (UHPLC),Quadrupole Time of flight mass spectrometry (QTOF) and ultra-performance Convergence Chromatography (UPC2) are increasingly hired for precise evaluation. Fourier- transform infrared spectrometry (FTIR) and Nuclear Magnetic Resonance (NMR) are vital for identifying organic contaminant structures and concentrations. Moreover, novel biosensor technologies are being developed for rapid on-site detection. . Different methods consist of immunoanalytical techniques (e.g., ELISA), capillary electrophoresis and microbiological assays. Although capillary electrophoresis is less sensitive than liquid chromatography. Immunoanalytical techniques are antibody-dependent, and microbiological assays range primarily based on pattern nature. (Li et al., 2024 ; Buchberger, 2011) Remediation Technologies for Emerging Contaminants ECs can be eliminated from water using diverse strategies, consisting of physical, chemical, organic, and hybrid procedures. Before discharging the treated water into the environment, these techniques are usually hired in water treatment plant to produce potable water or in industrial-scale water treatment processes (Ahmed et al., 2021). The elimination efficiency of ECs varies widely primarily based on their stability, physicochemical properties, treatment technology, and working/atmospheric conditions. Table 2 gives the overview of treatment strategies for emerging Contaminants. Wastewater treatment plants (WWTPs) generally appoint primary, secondary, and occasionally tertiary remedy steps. Primary treatment, designed to put off suspended and colloidal solids, additionally removes a few ECs via sorption onto primary sludge. Secondary treatment specializes in eliminating organics and nutrients via biological degradation, where ECs go through biodegradation, sorption, dispersion, dilution, photodegradation, and volatilization. Biotransformation, biodegradation, and sorption are the dominant mechanisms. Tertiary treatment, aimed at removing nutrients, suspended solids, and pathogens, notably complements EC removal, especially for recalcitrant compounds by strategies like ozonation and traditional oxidation (Luo et al., 2014 ; Barbosa et al., 2016 ; Rout et al., 2016 ; Ahmed et al., 2017). Biological Treatment Biological treatment eliminates ECs through various biological organisms or methods, aiming to efficiently manage the decomposition of waste products (Grandclement et al.,2017). This approach is favoured because of its cost-effectiveness as compared to chemical or physical remedies (Samer, 2015). It is predicated on natural cellular techniques and includes organisms which include nematodes and bacteria to break down organic wastes (Mani et al., 2020). Commonly carried out during the secondary or tertiary degrees of treatment, biological treatment makes a speciality of vast contaminant elimination via biodegradation. (Ahmed et al., 2021). Aerobic and anaerobic methods are the two types of biological treatments. Aerobic Processes Biological treatment strategies for emerging contaminants (ECs) include activated sludge processes, membrane bioreactors (MBRs), and sequencing batch reactors (SBRs). Aerobic conditions commonly provide better elimination efficiencies for endocrine-disrupting chemical compounds (EDCs) compared to anaerobic situations. Ni et al. (2014) evaluated the adoption of aerobic granular sludge for the removal of numerous decabromodiphenyl ether (DBDE) congeners. Their study revealed that while BDE-209 was resistant to degradation, lower congeners such as BDE-15 were successfully degraded into BDE-3 and diphenyl ether. MBRs, especially, were diagnosed as extra powerful than conventional activated sludge systems in eliminating toxic compounds which can be otherwise immune to degradation [Barrios-Estrada et al., 2018]. Tolboom et al. (2019) highlighted the capability of algae-based bioreactors for the partial or whole elimination of pharmaceutical-based ECs from wastewater. Moreover, natural processes such as waste stabilization ponds (WSPs) and constructed wetlands (CWs) have proven massive effectiveness. WSPs attain excessive removal quotes for most personal care products and pharmaceuticals, though they are much less effective for sure compounds like carbamazepine. Constructed wetlands frequently match or surpass the removal efficiencies of conventional wastewater treatment plants(WWTPs), making them a promising option for the secondary treatment of pharmaceuticals (Anindita Gogoi et al., 2018). Anaerobic Processes Anaerobic digestion (AD) is an energy-efficient technique that converts biodegradable organic mass into biogas, generating fewer biosolids and reducing organic matter (Batstone and Virdis, 2014). Despite the fact that AD removes synthetic endocrine-disrupting chemicals (EDCs) and pharmaceuticals like ibuprofen and naproxen, less proficient for hydrophilic and toxic emerging contaminants (ECs) (Phan et al., 2018). The anaerobic membrane bioreactor (AnMBR) has emerged as a promising alternative, with its EC elimination efficiency in large part depending on the hydrophobicity and biodegradability of the contaminants (Wijekoon et al., 2015). Carneiro et al. (2020) established the elimination of sulfamethoxazole (SMX) and ciprofloxacin (CIP) the use of methanogenic sludge in anaerobic packed bed and structured mattress biofilm reactors, emphasizing the significance of hydraulic retention time (HRT) and organic loading rate of their degradation. Additionally, Dutta et al. (2014) accomplished 86–100% elimination efficiency for 20 ECs, which include tylosin, ciprofloxacin and ibuprofen, with the usage of an anaerobic fluidized membrane bioreactor device. This device, while incorporated with a microalgae post treatment technique, enhanced the elimination rates up to 90% for EDCs like 4 nonylphenol technical nonylphenol, 4 tert-octylphenol and bisphenol A (Abargues et al.,2018). The achievement of EC elimination in AnMBR structures is prompted via elements which include pH, temperature, stable retention time (SRT), salinity, wastewater composition, HRT and membrane fouling, underscoring the need for cautious optimization of these operational parameters to maximize elimination performance. Physico-chemical Treatment Activated Carbon Adsorption Activated carbon is an inexpensive material used commonly for the removal of ECs, due to its high specific surface area (SSA), high porosity and adsorptive properties (Rizzo et al., 2019). Contaminants convert from aqueous/liquid phase to solid (Rodriguez-Narvaez et al., 2017). Particle size, mineral content, surface area, and pore diameter affect AC efficiency (Luo et al et al., 2014). AC can remove dyes, heavy metals and some organic compounds. Micro-grain AC removed 50 to sulfamethoxazole (56–83%), ciprofloxacin (75–95%), oxazepam (74–91%), diclofenac (71–97%) and atenolol (92–97%). Furthermore, removed 50–90% of pesticides, artificial sweeteners, benzotriazole, alkylphenols, bisphenol A, and personal care products (triclocarban and parabens) (Mailler et al., 2016). Delgado et al. (2019) reported AC to remove recalcitrant emerging pollutants, such as Carbamazepine and sildenafil citrate with greater than 85% efficiency. Carabineiro et al. (2011) had shown ciprofloxacin can be removed instantly under detection limit value. Entia et all. (2024) shown Rhodamine-B, a dye possessing many health risks was removed with 98.87 ± 0.84% efficiency. Although AC is effective, its production is energy intensive, and the disposal of saturated adsorbents still remains a challenge (Rodriguez-Narvaez et al., 2017).