Current research progress in the biological removal of emerging contaminants from the water environment Open Access

Recent studies have focused on emerging contaminants (ECs) in wastewater because they possess severe hazards to health and wildlife (Gianico et al. 2021; Werkneh et al. 2022). The revolutionized development of technologies and resources has caused the manufacture of more compounds and chemicals, which increases the number of chemicals recognized as potential threats to living things (Deb et al. 2020). This growing count of shady chemicals poses a potential threat to living things and the environment (Werkneh et al. 2022). Waste water treatment plants (WWTPs) and sewage include pharmaceuticals, personal care products (PPCPs), surfactants, and a variety of industrial chemicals that are not metabolized and are considered to be endocrine disruptors (EDs). These present difficulties for the designers of upcoming treatment plants and associated eradication methodologies (Rotta et al. 2021). The issues accompanying these ECs are examined here to feature the difficulties in addressing the issues (Liu et al. 2019).

The first issue is the lack of restricting regulations, particularly for pharmaceuticals, by-products, and new compounds, in the wastewater treatment plant (Maryjoseph & Ketheesan 2020). Advancements in technology and industry exceeded conventional methods. Biological treatment technologies such as membrane bioreactors (MBRs), biofilm reactors (BFRs), and activated sludge process (ASP) are used to remove ECs (Aoudj et al. 2019). These systems can be created to focus on a narrow range of contaminants or a variety of contaminants (Bilal et al. 2019). In comparison to conventional techniques, biological treatment has a number of advantages for removing developing pollutants from wastewater (Nika et al. 2022). It is economical, energy-efficient, and environmentally friendly. It is also easy to incorporate into wastewater treatment plants that are already in operation. According to Ramakrishnan et al. (2015), biological treatment generally shows promise as a remedy for the issues caused by recently discovered toxins in wastewater. It can protect the environment and public health while raising the standard for wastewater treatment. Micro-range poisons and other unregulated or newly discovered substances were not being monitored or barely any safeguards were being taken to keep them out of water sources (Khan et al. 2022).

To achieve a comprehensive and effective removal of ECs by wastewater treatment plants, extensive research and improvement are thus needed, together with techno-economic acceptability evaluations of the treatment processes (Thuptimdang et al. 2021). Several ECs, especially pesticides and medicines, were shown to be considerably eliminated by a hybrid method using ozonation and activated carbon (AC) (Tong et al. 2022). Nanotechnology may be an effective strategy despite the paucity of thorough studies because nanomaterial-integrated technologies have shown promise in eliminating various toxins from wastewater (Pereira et al. 2015).

The treatment of emerging pollutants in wastewater has received a lot of attention because of potential risks to human health and the environment. Traditional wastewater treatment technologies often become inadequate in successfully eliminating these contaminants. This study explores the most recent trends and breakthroughs in biological treatment methods, highlighting their potential to overcome the limits of traditional treatments. This comprehensive research emphasises creative methods and hybrid strategies for removing emerging pollutants by using novel biosorbents, activated sludge processes, constructed wetlands (CWs), and membrane bioreactors. This paper also discusses future perspectives and potential developments in biological wastewater treatment, with the goal of promoting sustainable and effective environmental management systems.

ECs are substances that exist naturally or artificially, or microbes that are not properly monitored have the ability to spread throughout the environment and produce known or suspected harmful environmental and/or human health impacts (Petrie et al. 2015). Personal care products (PCPs), pharmaceuticals, surfactants, pesticides, and industrial chemicals have been found in municipal wastewater, groundwater, surface water, food sources, and drinking water on a regular basis. They also comprise EDs, hormones, analgesics, antibiotics, and various other pharmaceuticals such as anti-diabetic, anti-inflammatory, and anti-epileptic medications (Stefanakis & Becker 2016).

Reclaimed water is now more frequently used for irrigation as a result of population growth and diminishing freshwater supplies. Reclaimed water has a number of organic pollutants that have been considered to be emerging hazards, which is the main problem. Some of these might lead to cancer and harm nearby water and soil sources (Bayabil et al. 2022). Nutrients, suspended and dissolved particles, heavy metals, and solids are the most typical contaminants. The usage of chemicals as well as chemical fertilizers, such as those based on arsenic (As), as well as anthropogenic activities like mining and the dumping of industrial waste have all been listed as contributors to the rising levels of ECs in ecosystems (Gwenzi et al. 2018). Since conventional techniques of wastewater treatments (WWTs) like sedimentation, coagulation, Filtration, ASP and Chemical Precipitation are ineffective and expensive to entirely eliminate ECs, wastewater has also been described as a source of ECs (Yan et al. 2010). Pesticides, pharma, drugs of abuse (including legal and illegal drugs), surfactants, cosmetics, chemicals, personal care items, industrial mixtures and toiletries, food packaging, food products, rare elements, microplastics, metalloids, pathogens, and nanomaterials are just a hardly any of the numerous items and substances on the list (Rout et al. 2021). In addition to domestic wastewater and commercial emissions, the majority of these contaminants also exist in surface water and groundwater, which therefore affects potable water and food supplies (Morin-Crini et al. 2021). A completely hydrophobic alkyl chain which is fluorinated is joined to a hydrophilic group to form perfluorinated compounds (PFCs), that have been made since the late 1940s (Kannan & Subramanian 2015). The most important representative PFCs are perfluorooctanoic (PFOA), perfluoro octane sulfonate (PFOS), and salts which are broadly used in firefighting foams, lube, detergent products and metal spray plating, varnishes, inks, encasing formulations (for furniture, walls, flooring, and food packing), oils, and oil and water repellents for paper, leather, and textile PFCs have excellent light, heat, and chemical resistance and are difficult for microorganisms to break down. As a result, PFCs are thought to be persistent, bio-accumulative, and perhaps dangerous to both people and animals (Lei et al. 2015).

PPCPs fall within the category of ECs. PPCPs reach the water system through human and animal excretions as well as effluent from pharmaceutical manufacturing facilities. Once PPCPs are present in water, it can be very difficult to efficiently remove them (Beadle 2021). The primary sources of pharmacological contamination are either patients or animals under medications intended for human usage or veterinary usage (Ghelli 2021). The WWTP discharge, leaching through soil, surface runoff, or discharge to the blue water bodies are the two main ways that medicines and their toxins infiltrate aquatic nature (Stuart et al. 2012). The aquatic ecosystem's bioaccumulation of PPCPs is found to disrupt human hormonal equilibrium, leading to a number of unfavorable consequences such as lower fertility, reproductive deficits, and significantly increased testosterone and breast cancer risk (Shahid et al. 2021). One of the main global environmental issues is the documented occurrence of trace metal pollution in water bodies in developing nations. The trace metals can settle on the fine sediment or be held in the water column as they make their way into aquatic environments (Sivaranjanee & Kumar 2021). Aquatic creatures are impacted by trace metals biologically through the processes of accumulation and magnification (Srikanth et al. 2019).

Pharmaceutically active chemicals (PhACs) are a significant class of new environmental pollutants that have drawn growing attention from the scientific community worldwide (Samal et al. 2022). Naproxen, ciprofloxacin, Ibuprofen, atenolol, diclofenac, azithromycin, ketoprofen and were examples of ECs (Saidulu et al. 2021). Since there are over 3,000 distinct PhACs utilized in human medications (such as anti-inflammatory and analgesics medications, lipid regulators, β-blockers, and antibiotics), ingestion is the primary way they enter the aquatic environment after being excreted and disposed of through wastewater (Rathi & Kumar 2021). The enhanced polarity of drug metabolites can be predicted to make them bioactive and much more persistent. In addition, during sewage treatment in WWTPs, conjugates of raw material may cleave back again into the original medicament (Petrovic et al. 2008).

Pesticides, which are a diverse group of substances with various physicochemical properties, are applied in agricultural settings to control or inhibit the rise of undesirable weeds, insects, and microbes like fungi and bacteria (Egea-Corbacho et al. 2019). They enter the aquatic environment by discharge from the application premises, and depending on the chemical's solubility, these compounds may persist in soil, living organisms, or sediments (Khan et al. 2022).

In developing nations like India, where there is a higher degree of acute risk, insecticides are used more frequently than herbicides, which have a lower level of toxic effect than insecticides (Gani & Kazmi 2017).

Pesticides, cosmetics, dioxins, PCPs, pharmaceuticals, alkyl phenolic compounds, and polycyclic aromatic hydrocarbons (PAHs) are common sources of ECs (Omi et al. 2022). Because of the rapid advancement of the industries, the pollutants have been found in dangerous quantities in groundwater, wastewater, and blue water (Yap et al. 2019). Waters include a varied spectrum of individual organic pollutants in addition to considerable volumes of complex high polymer organic substances, which often dominate the overall organic load, and various kinds of collective pollutants that consist of mineral oils, total lipids, and detergents (Noguera-Oviedo & Aga 2016). The type and quantities of organic pollutants have expanded significantly during the previous few decades. A large percentage of these compounds are found in detergents and PCPs, medicines, plasticizers, fire retardants, and other items (Kümmerer 2011).

Nanomaterials, pesticides, industrial compounds, pharmaceuticals, PCPs, water treatment (WT) by-products, fragrances, surfactants and fire retardants, and nicotine and caffeine are samples for ECs. Numerous of these are small minute pure substances that potable water treatments are not effective in eliminating these substances (Stuart et al. 2012). ECs have been found in practically every country's ecosystem, making them a worldwide concern, even if the actual source in many instances cannot be established. There is a scant understanding of the fate and movement of ECs in the surroundings, in addition to their toxicological effect (Naidu et al. 2016). However, ECs, whether natural or manufactured, have been linked to a range of harmful health and environmental impacts. Pharmaceutical compounds, for example, that are meant to elicit a biological reaction in a certain organism can cause the same effect in non-specific species after extended exposure to even trace levels of those substances (Khan et al. 2022). Even at low doses, antibiotics such as penicillin can create resistance in bacteria along with other microbes. Streptococcus pneumoniae, for instance, is classed as ‘penicillin-non-susceptible’ under the World Health Organization's (WHO's) list of priority infections to help prioritize research and development (R&D) of novel and effective antibiotic therapies.

Caffeine, theobromine, and stimulants, theophylline, have also been found in significant amounts in both effluent and incoming waters, in particular in some Mediterranean river basins where WWTP effluents account for a high percentage of total river flow, especially during drought periods (Lopera et al. 2019). Wetting agents, dispersants, Sulfonated azo dyes, pesticides, optical brighteners, concrete plasticizers, pharmaceuticals, ion-exchange resins, and leveling agents are all made from aryl sulfonates (Renau-Pruñonosa et al. 2020). Asbestos, red phosphorus, magnesium hydroxide, aluminum hydroxide, various hydrates, antimony trioxide, and boron substances, mainly borates, are utilized as fire retardants (Kümmerer 2011).

E-waste, Nanomaterials, and commonly existing radioactive materials (NORMs) have been given the least attention in the Middle East and North Africa (MENA). The MENA region has almost no experimentation on the elimination of nanoparticles from water systems (Singh et al. 2020a, 2020b). Previous regional assessments, on the other hand, have revealed an interest in the implementation of nanotechnologies in desalination operations. As a result, attempts to prevent nanomaterial pollution of water sources are becoming increasingly important (Ouda et al. 2021). The immune system's function during the instantaneous post-natal period is especially sensitive, according to the European Food Safety Authority's (EFSA) recommendations on risk analysis for chemicals in baby food, and exposure to immunized toxicants can result in long-lasting impacts on the body's immune system that persist or show up only after the exposure, however, might happen at lower levels than adult being exposed (Nobile et al. 2020).

For the safety and health of the people, the presence of developing or newly discovered contaminants in our water sources extends to be a concern. The standard WT facilities that are currently in place were not developed to handle these ECs. These are currently posing a threat to our water supply system (Mandaric et al. 2015). Due to the lack of strict regulations that are unique to these contaminants, the present effluent treatment systems are ineffective in removing these varieties of classes of emerging pollutants. Unwanted chemicals are being released into the marine habitat, either purposefully or inadvertently, that have an influence on every organism (Bolong et al. 2009). In recent years, ECs such as pesticides and their lifestyle compounds, metabolic products, industrial products, food additives and wastes, and nanomaterials have become an issue for the surroundings (Gomes et al. 2017).

Health impacts include cancer, reproductive issues, altered brain development, and allergies are the ones that grab the public's attention. Accordingly, the following substances become the ‘culprits’ at the top of any list of newly developing contaminants: possibly harmful compounds (Smital 2008). Several investigations have concentrated on the existence of organic pollutants on the Llobregat River, which serves as the primary drinking water supply for Barcelona and its surrounding areas and has been shown to have a diverse spectrum of contaminants (González et al. 2012).

TCS, TCC, fluoroquinolones, carbamazepine, TBT, and PFCs are not significantly removed; moreover, data on such compounds is still limited (Stasinakis 2012). Metabolomics applications include studying the economic and environmental consequences of various environmental concerns such as personal hygiene products, medicine and nanoparticles, pesticides, and alterations in naturally found compounds in the surroundings with an emphasis on plant communities (Matich et al. 2019). Recent research has brought attention to their potential toxicity, including oxidative stress, cytotoxicity, genotoxicity, and protein alterations, raising significant concern about their adverse effects on humans and aquatic environments (Farkas et al. 2010). Chemical pollution from ECs is a problem in the Noco River, even at high altitudes (Lencioni et al. 2020). Aside from that, WWTPs are ineffective at removing ECs and their microbial metabolites. As a result, these ECs will be unfavorably released into bodies of water in the future (Saidulu et al. 2021).

In surface and groundwater, numerous chemicals from various classifications, including hormones and pharmaceuticals, illegal narcotics, personal care items, pesticides, PFCs, artificial sweeteners, UV filters, and disinfection by-products (DBPs), have been found recently (Riva et al. 2018). Potentiometry, Voltammetry, electrochemical impedance spectroscopy (EIS)-based electrochemical methods, amperometry, surface-enhanced Raman spectroscopy (SERS), colorimetry, fluorescence spectroscopy-based optical techniques, and fluorescence probes are some alternate ways for EC detection. These methods are superior to conventional methods in a number of ways, including minimal sample volume, high sensitivity, exclusion of solid phase extraction, portability, selectivity, speed, reproducibility, reduced cost, and the capability to detect ECs (Manivannan et al. 2022). Although selenium is a vital trace element for humans, its bioaccumulation potential makes its discharge at large concentrations a serious hazard for aquatic and terrestrial ecosystems (Fawell & Ong 2012). Among the largest causes of selenium discharged into the environment are mining and the processing of metals and minerals (Etteieb et al. 2020).

These chemicals are not monitored regularly in the surroundings. Some developing contaminants may have been released into the surroundings over a period of time, but they could not have been detected until the advancement of modern identification techniques. Currently, EPs are not a part of international routine surveillance systems (Chen et al. 2022a, 2022b). Understanding the incidence and destiny of EPs necessitates the monitoring, identification, and measurement of EPs as well as the products changed in various environmental divisions. This is extremely difficult for various reasons: There are already around 700 possible EPs (and corresponding transformation items) known in Europe. Their importance shifts throughout time because of modifications to (agro)chemical production, use, and disposal, as well as emerging knowledge on their incidence, fate, and risks. Some EPs, such as pyrethroids, hormones, and some organophosphorus insecticides, have such little influence on aquatic life that analytical procedures with low detection limits are required (Taheran et al. 2018). Improved ultra-sensitive instrumental methods (such as newer development LC-/MS/MS, GC-APCI-MS/MS) have become accessible in traditional approaches focusing on specific EPs, although they have so far hardly been used for regular monitoring. Utilization of such mechanisms would improve opportunities for simultaneous measurement of several EPs, simplify sample preparation, and/or greatly increase detection sensitivity for EPs with certain PNECs (Prajapati et al. 2023).

The employment of such instruments would be beneficial for the quantitative identification of targeted contaminants in soil, particulate matter, water, and biota, notwithstanding their higher cost. To replace or supplement existing focused methods, general chemicals screening methods rely on deep scan mass spectrometry (MS) with chromatography have gained popularity recently (Geissen et al. 2015). Due to its high sensitivity, non-destructive nature, and ability to simultaneously monitor many analytes with various optical properties, optical sensors have indeed been utilized as effective analytical tools in a variety of disciplines, from the chemical and medical industries to environmental monitoring. The main idea behind optical sensors is to use a light beam to excite the electrons in specially created molecules, then measure the resulting changes in optical properties to make a detection. A transducer and a recognition element often make up optical sensors. Typically, to interact with the target analyte through an enzymatic process, recognition elements such as enzymes, antibodies, customixed receptors, and/or bifunctional surfaces are utilized (Ryu et al. 2021). The application of deep scan and high-resolution MS with liquid chromatography (LC) to detect specific toxins – often the reaction products or degradation of the origin contaminant – or to increase the selectivity of analytes, has become one of the most popular trends in recent years. For decades, gas chromatography (GC) was previously employed in a similar way with full scan and high-resolution MS, enabling the identification of numerous environmental pollutants (Richardson 2009). Table 2 gives information about the various monitoring and detecting techniques and their operating conditions.

For the sake of assessing the elimination of developing pollutants in drainage water, advanced oxidation processes (AOPs) relying upon ozone treatment, supported by ultrasounds, were studied at a pilot plant scale (Ibáñez et al. 2013). Based on the large collection of various physicochemical characteristics of the contaminants evaluated, two distinct analytical procedures were used to analyze the samples obtained from water sources. Liquid–liquid extraction (LLE) with hexane was the specimen treatment method used for the separation and prior enrichment of non-polar and semipolar evaporative chemicals. This was subsequently followed by a GC/MS study (Robles-Molina et al. 2014).

The following are some instances of biosorbents that can be utilized for adsorption such as Peat moss, a naturally occurring substance, has a broad variety of contaminants it may absorb, is highly porous and manufactured from charcoal, AC is a powerful absorbent for organic contaminants (Chaukura et al. 2016). A byproduct of the rice industry called rice husk can be used to filter heavy metals out of water and Algae can be cultivated especially for their capability to eliminate impurities from the water (Yaashikaa et al. 2021).

Additionally, biosorbents can be utilized in the bioremediation (BR) procedure, which uses microorganisms to degrade contaminants. This procedure involves the addition of microorganisms to polluted water or soil, which then naturally eat the toxins as a food supply. Through procedures including oxidation, reduction, and hydrolysis, they can degrade contaminants (dos Santos Cardoso & Vitali 2021). Utilizing bacteria that can break down PAHs, a class of contaminants found in crude oil or other fossil fuels, is one example of using biosorbents in BR. The PAHs can be consumed by these bacteria, which then convert them into less dangerous substances. In BR, biosorbents can also be utilized to support microorganisms; for instance, bacteria can immobilize on a biosorbent material like alginate beads (Singh et al. 2020a, 2020b). Immobilizing biosorbents entails securing the biosorbent substance to a support, such as a filter or a column, to enable repeated use. The removal of contaminants from huge quantities of liquid, such as wastewater, is possible with this technique (Ahmad & Zaidi 2020). The biosorbent substance is initially attached to a support, like a filter or a column, in the procedure. After passing through the support, where the pollutants are absorbed by the biosorbent material, the treated water is discharged. The biosorbent substance can then be taken off the support and utilized again. Entrapment is a method for immobilizing biosorbents in which the biosorbent is contained within a matrix made of alginate beads, cellulose fibers, or polymeric gels. This makes it simple to remove the biosorbent from the liquid once it is contaminated to saturation. Covalent binding is a method for immobilizing biosorbents that is also available (Velkova et al. 2018).

Air pollution can be removed using biosorbents called biofilters. Filters with a layer of biosorbent material can be used for this. Pollutants are adsorbed to the biosorbent material as air passes through the filter. Algae, peat moss, and AC are among biosorbents that can be utilized as biofilters. Chromium and copper, among other metals that are heavy, could be eliminated from wastewater using biofilters. In order to eliminate the metals that are heavy, the polluted water is passed through a filter that has a layer of biosorbent material, such as microorganisms or plant-based materials. The plant-based substances or microbes can be immobilized on a substrate, such as a column or beads, allowing for repeated use (Jacinto et al. 2009).

When it comes to eliminating contaminants from water and the air, biosorbents have a number of advantages over conventional techniques, including high adsorption capacity because biosorbents are efficient in removing pollutants from huge amounts of water or air because they are distinguished by a high capacity for adsorption for pollutants, selectivity because biosorbents have the ability to selectively remove pollutants, they can concentrate on a particular type of pollutant while leaving other elements of the water or air unaffected, environmental friendly because biosorbents do not release any toxic by-products because they are created from natural resources like microbes or plant fibers, cost-effective because biosorbents can be utilized in a smaller area and are frequently less expensive than conventional treatment procedures and Reusability because biosorbents can be used repeatedly, the cost of therapy as a whole may be decreased (Moghadas et al. 2022).

Depending on the type of biosorbent and the particular heavy metal being removed, different biosorbents have varying degrees of efficacy in removing heavy metals. It has also been discovered that plant-based biosorbents, such as agricultural waste, are efficient at removing metals that are heavy from water. Research has shown that metals that are heavy like cadmium, zinc, and lead may be eliminated from the water by over 70% using rice straws and banana peels. A popular type of biosorbent utilized to eliminate metals that are heavy from the water is AC; it can degrade 99% of metals that are heavy like lead and copper. It is crucial to remember that parameters like temperature, and pH, and when there are additional pollutants in water can all have an impact on how effective biosorbents are. Biosorbents can be highly effective at removing heavy metals from water (Qin et al. 2020). Bacterial biosorbents are microorganisms like bacteria and algae that can absorb or bioaccumulate contaminants like heavy metals from water and air. These bacteria may successfully remove contaminants from the environment by binding them to their cell surfaces or to the internal structures of their cells. They are vulnerable to microbial deterioration and need particular circumstances to operate at their best (Wang 2009; Wang & Chen 2009).

Organic contaminants discharged into the environment by wastewater discharges have the potential to remain in the ecosystem, bioaccumulate in the food chain, infiltrate drinking water production, and damage human health and our surroundings. Conventional activated sludge (CAS) treatment procedures are usually intended to eliminate or reduce the levels of pathogens and bulk organic loads, but not to remove trace organic residues (Buttiglieri & Knepper 2008). The elimination of the traditional contaminants, particularly macro-contaminants (i.e., organic carbon, suspended solids, phosphorus, and nitrogen), was the focus of the WWT process. These contaminants were removed using renowned biochemical mechanisms like aerobic biodegradation of organic carbon using bacteria that are heterotrophic, denitrification (DNP)/nitrification (NP) for the removal of nitrogen employing a mixture of bacteria that are heterotrophic (for DNP) and nitrifiers (NP), and dephosphatation for the removal of phosphorus using phosphorus-accumulating microbes capable of absorbing dissolved phosphorus from sewage and storing it in granulates (Koumaki et al. 2021).

Sulfamethoxazole, trimethoprim, diclofenac, carbamazepine, methyl 3,5-dichloro-4-hydroxybenzoate, and triclosan were selected as the most often identified emerging organic micropollutants (EMOPs) in WWTPs effluent to adapt to AS and improve EMOP biodegradation. Sulfamethoxazole, trimethoprim, methyl 3,5-dichloro-4-hydroxybenzoate, triclosan, and diclofenac elimination were greatly enhanced by acclimated AS, whereas carbamazepine degradation was only modestly improved. The dispersal of 6 EMOPs across the sludge and water phases demonstrated that biodegradation was important in their elimination (Wang & Wang 2018). While being challenged by various micropollutants, gravity-driven membranes (GDMs) can effectively remove the water effluents with pathogenic microbes in rural areas (MPs). For the first time, this study researched the removal of sulfamethoxazole in GDM, and pre-adding acclimated AS was proposed to stimulate MP extraction (Chen et al. 2022a, 2022b). Some integrated systems of CWs and waste stabilization settings demonstrated promising biosorptive elimination of beta blockers and pharma products. Integrated systems that combine the AS process with physical processes like reverse osmosis (RO), ultra filtration (UF), and γ radiations are thought to be the most affordable and effective at removing trace organic pollutants (Dhangar & Kumar 2020). Traditional sewage treatment methods have demonstrated low elimination efficiency for ECs. As a result, more effective treatment mechanisms must be reported. According to the present research, an Integrated Fixed-Film Activated Sludge Process (IFAS) could be an option.

The elimination of the eight ECs in a traditional sequencing batch reactor (SBR)-based sewage treatment plant was compared to the deterioration of the eight ECs in domestic sewage during the steady-state conversion of a pilot IFAS plant (Ali et al. 2022). Ibuprofen and caffeine degraded up to 100% when treated separately at 30 mg/L concentrations, while metronidazole degraded between the region of 12–27%. They inhibited the NP process, whereas metronidazole inhibited the metabolic processes of microbes that denitrate. Biological treatments of synthetic waste water that contains all three substances (at conc of 10 mg/L) are shown in 100% ibuprofen and caffeine degradation, and 56% metronidazole degradation. Total eliminating nitrogen was decreased from 53 to 22% because both processes were impacted. (Kanafin et al. 2021).

AS was utilized in this study to adsorb perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in investigating their sorption behavior and potential absorption mechanisms in WWTPs in a solution of water. (Zhou et al. 2010). Based on the extensive literature on the subject, the techniques of micropollutant elimination are summarized and MBR working conditions. The dominant removal processes have been identified as micropollutant adsorption and ensuring decay, and they are affected by operational factors such pH, redox conditions, temperature, solid retention period and biomass content (Besha et al. 2017).

AS systems and oxidation ponds are two common conventional WWT methods that are frequently replaced with CWs because they are more affordable and environmentally beneficial (Scholz & Lee 2005). Microorganisms and plants clean the water before it is released into the environment or used again. SSF wetlands are frequently utilized to treat hazardous or high-strength wastewater (Garcia et al. 2010). Surface flow (SF) CWs, greywater, stormwater, and wastewater are usually treated in these wetlands. They are made up of a marsh or shallow pond where water flows (Kadlec 1995). Low-strength wastewater is treated in FWS wetlands (Su et al. 2009). Vertical flow constructed wetlands (VF) where Stormwater and wastewater are often treated in these wetlands. Low-strength wastewater is also frequently treated using VF wetlands (Kumar & Singh 2017). Hybrid wetlands (HWs) are more effective than conventional treatment systems and can be custom-tailored to the site circumstances and pollutant loads. They save money, require little upkeep, and take up little room (Maine et al. 2019).

As part of maintenance, it may be necessary to clear away trash and extra plants, keep an eye on water flow and level, and make any adjustments to the water supply (Jones-Lepp et al. 2012). In order to make sure that the wetland is successfully eliminating pollutants and surplus nutrients, it is also crucial to routinely evaluate the water quality (Carty et al. 2008). In order to offer a vast microorganisms' available surface area and plants for growth and purify the water, CWs use a range of media, including dirt, gravel, or sand medium help filter and eliminate impurities from the water while also acting as a habitat for microbes and plants. The type of pollutants to be treated and the unique site conditions will determine the medium utilized in a built wetland (Saeed et al. 2012).

CWs have a number of benefits, such as reduced maintenance requirements, high treatment effectiveness, improved habitat, and decreased water pollution. They are a good alternative for treating a variety of water sources since they may be customized to meet particular site circumstances and pollution loads (Stefanakis 2020). While the extra fertilizer supply might promote plant development and, thus, net nutrient uptake, the increasing loading of ions and other harmful compounds progressively converts the ecosystem into one made up of species more tolerant of pollution. In addition to nutrients, alterations in pH and salinity are examples of chemical changes that also impact the biotic community (Gopal 1999). They might also need routine upkeep and supervision, and some pollutants, such as heavy metals, might not be amenable to treatment (Huang et al. 2013). They can be tailored to fit particular site circumstances and pollutant loads (Verlicchi & Zambello 2014).

MBR is a suspended growth-activated sewage treatment that uses microporous membranes to separate particles from liquids rather than secondary clarifiers. It offers a major improvement in effluent quality through the creation of an effluent that is effectively pure and displays an outstanding degree of operational reliability (Radjenović et al. 2008). They can also be used to treat landfill leachate and recycle and reuse treated water. Wastewater contaminants such as organic matter, nitrogen, and phosphorus compounds are broken down by microorganisms. These bacteria feed on the contaminants, decomposing them into less complex substances like carbon dioxide and water. An MBR system typically uses bacteria, fungi, and protozoa as its microorganisms (Ji et al. 2020). During filtration, the flux decreases as it does in most membrane filtration procedures. The primary cause of this is membrane fouling. The main challenge in managing membrane fouling in an MBR is controlling it. The hydrodynamic situations, membrane form, module layout, and the presence of higher molecular weight compounds – which can be generated by microbial growth or added to the sludge bulking process – all have a substantial impact on the fouling of the membrane. Poly-electrolytes are one example of such a chemical. The technique of cross-flow filtration is appropriate for the continuous separation of activated sludge with high MLSS concentrations. It is possible to achieve a stable flow by managing the cake layer creation with shear pressures (Melin et al. 2006). Membrane performance (fouling) varies with loading rates and is dependent on the effluent quality of the biofilm reactor (HRT) (Leiknes & Ødegaard 2007).

The bioreactor and membranes module each execute a specific task: (i) the bioreactor uses appropriate microorganisms to biologically degrade organic pollution; (ii) the membrane module separates organisms from the treated wastewater; (iii) the membranes operate as a barrier for all suspended solids, allowing for the creation of permeate that is free of bacteria, viruses, and suspended debris in addition to enabling the recycling of AS into the bioreactor (Marrot et al. 2004). Although they are frequently found in wastewater, they can also be introduced to the system as seed sludge or AS (Roy & Saha 2021).

Additionally, the contaminants with molecular weights greater than the molecular weight cut-off of the barriers are preserved due to the sieving function of the membrane, bringing them into touch with the microorganisms responsible for their total destruction inside the MBR (Goswami et al. 2018). Aerobic treatment at large loadings and the more modern hydrogenation of oxyanions like nitrate, which is suitable for treatments by all three configurations, appear to be the main uses of MBR in biotreatment (Judd 2008). If not for membrane depreciation cost, operating costs are related to personnel expenditures (10–30%), sludge disposal (5–15%), chemical consumption (10–30%), energy consumption (40–60%), and others (5–20%) (Xiao et al. 2019).

The degree of EC adsorption on the membrane surface and their subsequent biodegradation are determined by the bond that exists between the ECs & the outermost layer of the membrane. (Sengupta et al. 2021) Industrial effluent treatment: MBRs are used to handle a variety of industrial effluents, including those generated during the production of semiconductors, medicines, and food and beverage products. Recycling and reuse in which MBRs are capable of treating and recycling wastewater for non-potable purposes like irrigation, process industries water, and flushing toilets (Chyoshi et al. 2022). MBRs could be used in combination with RO (Al-Asheh et al. 2021). In order to treat wastewater, an MBR system can employ a number of removal techniques: Filtration using membrane, Denitrogenation and NP, removing phosphorus, removing heavy metal Disinfection, and biological treatment (Bhattacharyya et al. 2022). MBRs have some disadvantages, including hefty upfront costs and ongoing expenses, upkeep requirements, the risk of membrane fouling, and the demand for a regular, high-quality feed in order to avoid membrane clogging (Gkotsis et al. 2014).

Biodegradation is a process in which microorganisms degrade organic contaminants. Another fast and environmentally benign process is biodegradation to treat ECs. Microorganisms such as algae, fungi, and bacteria have the capability to eliminate various contaminants (Gan et al. 2022). In the process known as phytoremediation, plants are employed to remove pollutants from water. Plants can absorb and store contaminants in their tissues, and later these contaminants can be harvested and disposed of safely (Rai 2018). Electrochemical oxidation is an advanced treatment method that involves the use of electrical energy to oxidize contaminants. Electrochemical oxidation can be employed for treating a variety of ECs (Rodríguez-Narváez et al. 2021). Nanoparticles can be perhaps used as a treatment method to eliminate ECs from water. Nanoparticles including iron oxide and titanium dioxide can adsorb and degrade contaminants (Vicente-Martínez et al. 2020). AOPs involve utilizing chemical reactions to remove unwanted chemicals from water. AOPs can be employed for treating a variety of ECs, including PPCPs and pesticides (Wang et al. 2023). Enzymes are naturally occurring proteins that can be used to break down organic contaminants. Enzyme treatment is a practical and eco-friendly way to treat ECs. Enzymes such as peroxidases, dehalogenases and laccases can degrade various contaminants (Ouyang et al. 2022). Microbial fuel cells (MFCs) are a novel technology which uses microbes to generate electricity while also removing contaminants from water. MFCs can be used to treat a wide variety of ECs, including PPCPs and pesticides (Kumar et al. 2019). Biofiltration (BF) is a process in which microorganisms are used to remove contaminants from air or water. BF can be claimed to treat a wide variety of ECs, consisting of volatile organic compounds (VOCs) and nitrogen oxides (NOx). Biofilters can be designed to suit specific treatment needs and can be combined with other treatment methods for increased efficiency (Thuptimdang et al. 2021).

Technologies for removing new pollutants have made tremendous strides in recent years. ECs are compounds that have recently been recognized as having the potential to be detrimental to both human health and the environment and are not subject to regulation by environmental agencies (Petrovic 2003; McBean 2019).

Using sophisticated oxidation reactions, such as ozone and UV radiation, to convert developing pollutants into less hazardous chemicals is one significant innovation in removal technology. AC and graphene are two examples of adsorption materials that are being used increasingly in technology to purge water and air of impurities (Morin-Crini et al. 2022).

Moreover, researchers have created nanoparticles that can adhere to toxins and eliminate them from water sources, demonstrating the promise of nanotechnology in the elimination of new pollutants (Gondi et al. 2022). The catalytic sulfate radical-based AOPs are the ones that use affordable materials for proper and efficient remediation of ECs pollution (cSR-AOP) (Rivera-Utrilla et al. 2013). The core of this technique is the creation of SR (SO4•). SR is preferred because it has higher selectivity (in contrast to the hydroxyl radical (HR)), resulting in decreased secondary reactions (Parida et al. 2021). While several studies have shown that SR is effective, its formation is premised on the activation of peroxydisulfate (PDS) or peroxymonosulfate (PMS) or sulfite with flame, high pH, UV radiation, or a catalyst. The heterogeneous catalytic activation technique, which uses carbon-based substances, transition metals and their oxides as catalysts, and natural minerals, offers potential benefits like high pore sizes, considerable specific surface area, and extremely low activation temperatures (Yusuf et al. 2022). Catalytic AOPs, for example, have emerged as feasible options, but their application is constrained by the shortcomings of conventional catalysts (Ahmed et al. 2017). To address this problem, new materials with enhanced textural qualities have been created, demonstrating how Their capacity as a catalyst is impacted by their porosity and chemical makeup. This article discusses the most current developments in very porous catalysts and how to use them to successfully nano-remediate contaminated environmental matrices (González-González et al. 2022).

For the purpose of the elimination of dyes from water, silica along with silica-based composite nanoparticles are being investigated extensively. The excellent effectiveness of silica nanoparticles in eliminating dyes from water is due to the presence of exterior silanols that can intricate dyes, the simplicity of grafting extra features for better complexation, the potential for grafting photocatalysts to accelerate dye degradation, along excellent chemical stability (Jadhav et al. 2019). The electro-Fenton (EF) is a highly effective electrochemical AOP. Over the past three decades, its growth as a safe and efficient method for managing ECs has increased (da Silva Vilar et al. 2021). Despite the fact that the use of traditional EF has been proved to be a It has some limitations for industrial-scale development while being a strong method for the effective degradation/mineralization of hazardous and/or persistent organic contaminants. The present research has concentrated on increasing its productiveness (Nidheesh et al. 2023). The applicability of in silico methods as well as the computational framework, toxicity assessment, and the potential for decomposing complex resistant substances have all been adapted to predictive BR procedures to remove pollutants (Singh et al. 2021).

Conventional filtration techniques cannot remove ECs, and interest in adopting nanomembrane-based filtration is developing (Dolar et al. 2012). No special equipment is required to manipulate nanomembrane-based filtration. According to various research findings, better removal of ECs was achieved with filtering based on nanomembranes. Additionally, new advances have been studied and put into practice at different levels, and these developments are anticipated to continue (Tiruneh Adugna 2023). Environmental and health concerns would be there if there were a lot of toxins in the environment. Recent years have seen the development of photocatalytic technologies, which use sunshine to eliminate impurities. The primary goal of researchers is to create high-performance photocatalysts (Liang et al. 2019).

There is a growing need to look into PPCP elimination technologies on a deeper and more comprehensive level (Kumar et al. 2023). It begins by summarizing the types, attributes, and dangers of PPCPs to human health and the environment. The process of adsorption, among many other approaches for eliminating PPCPs from solutions of water, is then thoroughly discussed (Liu et al. 2022). Dyeing wastewater is harmful and cancer-causing to aquatic settings as well as humans. Adsorption technology has been widely utilized for decades to eliminate dyes from watery solutions because it is a simple and effective method. Many scientists have tried to locate or develop different dye adsorption materials (Zhou et al. 2019).

The electrocoagulation (ECoag) method has shown promise as an economical and environmentally responsible way to remove a variety of contaminants from a variety of water sources (Lima 2018). Numerous significant factors, including reactor geometry, pH, current density operating period, agitation speed and electrode gap have an impact on how well the EC method performs. The ECoag technology has some drawbacks, including the use of energy and electrodes in the passivation procedure in addition to its wider application (Al-Raad & Hanafiah 2021).

While they are also frequently referred to as ‘composites,’ ‘hybrid materials’ are difficult to define because this term is typically used to describe materials made by combining various components. A hybrid material, according to the IUPAC definition, is the outcome of a close-knit combination of inorganic as well as organic substances, or both of them, that traverse on a scale smaller than 1 m. On the other hand, different descriptions of hybrid materials are employed, and many classifications based on various criteria are being proposed (Rigoletto et al. 2022). Many treatment methods, such as physical, chemical, and biological methods, have been developed to remove a variety of ECs. Hybrid solutions have regularly been proven to be more effective, despite the fact that no one technique can now successfully eliminate ECs. A hybrid ozonation-AC method was found to be notably successful in eliminating some ECs, particularly pesticides and pharmaceuticals (Ahmed et al. 2021). Hybrid microbial electrochemical technologies (HMETs) are being used for the BR of ECs and toxic metals. An in-depth clarification and classification of in situ BR techniques and detailed explanations of individual technologies are provided (Ghangrekar et al. 2020).

The degradation of ECs from WWTP effluents using biological-based, chemical-based, and hybrid-based techniques. An MBR, AS, and aeration processes between a variety of biological processes are more effective at reducing endocrine-disrupting chemicals (EDCs). AS processes can effectively reduce PCPs, EDCs, and surfactants. Pesticides and pharmaceuticals were reduced effectively by biological AC (Ghernaout & Elboughdiri 2019). Because of the adverse impact on people's health and ecosystems, alternative technologies for adequate WWT are being developed. The Physical, chemical hybrid or biological technologies for treating EPs produce intriguing outcomes because they will improve the productivity of WWTPs. This mixture of biological/ adsorption systems may offer novel possibilities (García et al. 2021). A look at such hybrid systems that combine chemical, physical and biological methods to remove ECs from wastewater quickly and efficiently. Most of the hybrid systems used biological-based treatments first, followed by physical-based or chemical-based treatments (Rodriguez-Narvaez et al. 2017).

A suite of ECs such as PCPs, pesticides, EDCs and beta blockers were effectively removed using a hybrid system of MBRs followed by membrane filtrations (MFs). Some mixed systems of CWs and waste stabilization pools demonstrated removal through biosorption of PCPS and beta blockers (Dhangar & Kumar 2020). In terms of efficiency, cost-effectiveness, low energy consumption, and nanomaterial recovery, hybrid bionanotechnology is the best alternative to conventional treatment techniques (Paliya et al. 2023). In the area of chemical water analysis, we discuss some of our experiences using the integrated linear ion trap (LTQ) and FT Orbitrap mass spectrometer (Hogenboom et al. 2009). A brief examination of the combination photocatalytic membranes for the treatment of wastewaters containing POP: photocatalysis and membrane technology (Subramaniam et al. 2022). Adsorption is a crucial and adaptable remediation approach that has been utilized for many years to eliminate harmful components from water-based materials among all other ways of water purification (Alipoori et al. 2021). In a hybrid CWs comprised of several CW configurations: (i) unsaturated vertical subsurface flow (VF), (ii) free water surface (FWS) wetlands, (iii)partial saturated vertical subsurface flow (VF sat) saturated horizontal flow (HF), and (iv)saturated horizontal flow (HF), the elimination of conventional water quality parameters, emerging organic contaminants (EOCs), and fluorescence signature has been investigated (Sgroi et al. 2017). The PVA/gluten-integrated nanofibers that were created will be used as cost-effective adsorbents for metal nanoparticle recovery from aqueous environments (Dhandayuthapani et al. 2014).

Learning about ECs is becoming increasingly important to minimize the damage in the future and enable new monitoring techniques in the environment, which will help to enhance the relevant legislation. ECs in aquatic settings have received concern in recent decades because of their potential for both sudden and ongoing toxicity. Chemicals classified as ECs have a likelihood to produce undesirable ecological and (or) societal impacts that are not often examined throughout their surroundings (and are mostly neglected). A rising percentage of these are being built by industry and cannot be discovered in the surroundings naturally.

In general, three types of ECs can be distinguished depending on their frequency: (1) PPCPs; (2) PFASs; and (3) EDCs. They might dive into aquatic settings by farming. WT and refurbish using BF systems that use biologically enhanced activated carbon (BAC). Both treatment of toxins and biofilm formation have been addressed, as well as the operational elements impacting the outcome of the BAC system. Because adsorption and biodegradation govern contaminant removal by BAC, the link between the two procedures and the treatment strategies is looked at recent ECs such nitrates and deregulated DBPs and their precursors, including PFASs, micron-sized particles plasticizers, and plastic particles have been extracted by BAC, according to reports.

A lot of work has been put into finding fresh approaches for sample identification, quantification, and efficiency or bettering the remediation activities. More inventive methods for WT remediation can be developed, thanks to the rising interest in biotech and ecologic engineering. It has been discussed how to manage EC assessment and oversight over an extended period of time. It is possible to find bacteria that can break down ECs in cemeteries and their runoff by using genetic approaches. The waste water from landfills is thought to be a substantial isolated source of contaminating things, severely jeopardizing the natural systems and resources in the area. As an outcome, it is critical to keep an eye on the presence of harmful substances and create effective cleanup procedures; to do this, the desired level, of suspicious and non-target testing needs to be performed. Recent works that detail the chemical makeup of wellheads and sewage from landfills. Enzymes, particularly oxidoreductases, are a class of green biocatalysts with extraordinary potential for catalyzing without the use of any extra cofactors besides the readily available H₂O₂, the oxidizing or elimination of various substances or chemical impurities in soils and streams.

Further research is needed in the future to advance the integrated technique's advancement and incorporate HC with technologies like electrochemical approaches. This type of process acceleration might result in ‘organic pollutants conversion’ or improved quality of water. These studies focus on the utilization of solar energy that are shown as a desirable way to reduce operational expenses. If a full-scale reactor is considered, when used to power integrated processes, renewable energy sources like solar PV would also lower the associated expenses. The effectiveness of the discussion of the kinetics and characteristics involved by decomposition during WWT includes physicochemical features as well as the coefficient of sorption and constants of biodegradation. The most popular sampling and monitoring methodologies are scrutinized.

New investigation techniques are suggested for upcoming monitoring studies as well as the necessities for analytical study are indicated. More research is needed on biodegradation-assisted BR because of the fate of ECs in microalgal cells and the usage of algal biomasses can be selectively removed from a huge variety of species of extreme microalgae. In-depth research is required to characterize the effluent quality of wastewater after a microalgal biomass system. For instance, studies of the life cycle are necessary to determine the efficacy of EC BR supported by microalgae. Recent developments in biotech and ecology have led to the widespread adoption of genetically modified bacteria with a high capacity to remove environmental toxins in the domains of environmental restoration, making BR more effective and environmentally friendly. When released into fresh water, plastic particles serve as long-lasting substrates that can be colonized quickly. A preliminary study focuses on determining the composition of biological communities attached to microplastics understanding how microorganisms affect microplastics distribution and fate and determining whether the shape of microplastics affects community diversity. Because conventional WWT does not remove EDCs efficiently. Through mutualistic connections, soil bacteria are thought to have positive effects on plant health.

On the other hand, microbes are vulnerable to pollution, and in such polluted soils, microbial population decline, both in terms of variety and biomass, is widespread. A slight alteration in the physicochemical-biological characteristics of rhizosphere soils can have a substantial effect on how plants and microbes interact. Furthermore, isolating and characterizing suitable beneficial microorganisms connected with plants takes time. Sludge use in agriculture has a proven record of environmental acceptance and agricultural benefits. Sewage sludge might serve as a sustainable supply of phosphorus because tetra phosphorus and phosphate ions are two of the 20 key raw materials (CRM) for the EU, according to the European Commission's ‘Report on Critical Raw Materials for the EU’ published in 2017.

Fields to focus on in the future for improving biological treatment of ECs from wastewater such as Microbial BR where the modified microbes speed up the biodegradation of new pollutants is one potential field of research. These altered microbes can be engineered to break down particular pollutants and can boost the effectiveness of the BR procedure. AOPs might be combined with biological treatment to develop the removal of developing pollutants. Reactive oxygen species are used by AOPs to convert pollutants into safe molecules. Nanotechnology integration incorporating nanotechnology into biological therapy systems, the effectiveness and performance of the healing technique can be increased. For instance, nanoparticles can improve the biodegradation of microorganisms by enhancing the adsorption of pollutants onto them. Biological treatment system layout and functionality might be enhanced via means of artificial intelligence and machine learning. Prediction accuracy may be increased with these technologies, which will boost efficiency and save costs. Biological treatment systems' carbon footprints can be decreased by using sources of renewable energy including solar and wind energy. The financial impact of these systems can also be increased by integrating renewable energy sources.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.