Ion Exchange Membrane Bioreactor Research Articles

Performance evaluation of pilot scale ion exchange membrane bioreactor for nitrate removal from secondary effluent

Eutrophication, driven by excessive nutrient concentrations in water bodies, is a critical global environmental issue affecting water quality, ecosystems, and human health. Discharging nutrient-rich secondary effluents from municipal wastewater treatment plants exacerbates this problem. This study aimed to assess the effectiveness of a pilot-scale Ion Exchange Membrane Bioreactor (IEMB) in removing nitrate from secondary treated effluent. The process involved Donnan dialysis (DD) followed by heterotrophic denitrification in an anoxic fixed bed bioreactor (FBBR). DD process demonstrated an efficiency of over 75 % when nitrate was externally spiked in the secondary treated effluent and over 90 % without spiking, reaching final concentrations below 5.65 mg NO3–N/L and 1.1 mg NO3–N/L, respectively. Furthermore, denitrification in FBBR was greater than 95 % at C/N ratio of 1.8–2 provided in the form of glycerol at an HRT of 2 h when nitrate was not spiked externally. Though sulphate accumulation occurred in the receiver (bio-side) during DD, denitrification outperformed sulphate reduction, as confirmed by the favourable oxidation-reduction potential (ORP) readings (−50 to −200 mV) in the FBBR reactor. Optimal conditions for nitrate removal, considering chemical and energy consumption, resulted in a cost of $0.237 per cubic meter of treated secondary effluent during continuous operation. A life cycle assessment (LCA) was also conducted to understand the environmental impacts of the IEMB. In light of these findings, IEMB showed a promising potential for tertiary wastewater treatment, providing an economical and sustainable solution for nutrient removal and indirect potable reuse of treated wastewater.

Effective removal of nitrate in water by continuous-flow electro-dialysis ion exchange membrane bioreactor (CF-EDIMB): Performance optimization and microbial analysis

The use of nitrogen fertilizer has been causing nitrate pollution in groundwater, and there is an urgent need for efficient approach to remove nitrate from groundwater. In our job, a novel continuous-flow electrodialysis ion exchange membrane bioreactor system (CF-EDIMB) was set up to remove nitrate (NO3−) from water for the first time. Nitrate removal was positively dependent on water chamber HRT and voltage; voltage had significant effect on the water chamber effluent pH; acetate utilization efficiency was closely correlated with acetate dosage. The optimal conditions forecasted through response surface method (RSM) were given as follows: water chamber HRT was 20 h, biological chamber HRT was 24 h, voltage was 6.65 V and acetate dosage was 454.99 mg/L, dedicating to nitrate removal of 81.90% (83.70% in prediction), water chamber effluent pH of 7.10 (7.00 in prediction) and acetate utilization efficiency of 92.87% (96.51% in prediction). Meanwhile, microorganisms are crucial for nitrate removal, and the microbial community was not sensitive to the variation of acetate dosage. The microbial analysis results indicated that when CF-EDIMB system was operated for 20 d, the sulfate-reducing bacteria Sediminibacterium appeared in the biological chamber, and the effluent sulfate concentration of biological chamber was decreased. During the whole operation, Thauera was the dominant genus. Denitrifying functional genes nirS presented a better expression than the gene narG, and there was no accumulation of nitrite.

Construction of continuous-flow electrodialysis ion-exchange membrane bioreactor for effective removal of nitrate and perchlorate: Modelling and impact analysis of environmental variables

A novel continuous-flow electrodialysis ion-exchange membrane bioreactor (EDIMB) was firstly established for the simultaneous and effective removal of nitrate (NO3−) and perchlorate (ClO4−) in water. The optimum operation conditions predicted by response surface method (RSM) were water-compartment HRT of 20 h, bio-compartment HRT of 15.5 h, voltage of 10 V and acetate dosage of 444.88 mg/L, contributing to NO3− and ClO4− removal of 93.13% and 92.81%, acetate utilization efficiency of 98.49% and total current efficiency of 60.93%, without secondary pollution caused by the residual carbon (the total organic carbon TOC in effluent < 2.4 mg/L). Herein, the removal of pollutants was positively correlated with water-compartment HRT and operation voltage, acetate utilization was negatively related with acetate dosage, and the total current efficiency was negatively with water-compartment HRT and operating voltage. The final effluent pH of system decreased with the increase of voltage, and basically remained neutral. Meanwhile, the biological reduction in bio-compartment could reduce the resistance of pollutant transmembrane migration, and thus enhance ion migration. Microorganisms were the key elements for pollutant migration, and water-compartment HRT and acetate dosage were the significant factors for succession of microbial community structures. Thauera, Azospir, Mesorhizobium and Curvibacte were the main denitrifying bacteria/ perchlorate reducing bacteria.

An investigation on the ion exchange membrane bioreactor with a spiral wound contactor for nitrate removal from contaminated groundwater

In the present study, we report the first operation of a pilot scale ion exchange membrane bioreactor (IEMB). It treated 1–2 m3/d of water contaminated with nitrate. IEMB was made up of anion exchange membrane spiral module integrated with a fixed bed bioreactor (FBBR), a novel configuration for an IEMB system. Nitrate elimination was accomplished through Donnan dialysis using chloride as counter ion followed by heterotrophic denitrification in an anoxic FBBR employing glycerol as electron donor and carbon source. The performance of IEMB revealed an excellent nitrate removal at the selected operating conditions, successfully eliminating a nitrate loading rate of 5.0 kg NO3−/m3/d and producing 30 ± 5 mg/L nitrate in the effluent at steady state. Anion exchange membrane being non-selective also transferred a significant concentration of sulphate from the feed-side to the bio-side leading to sulphate accumulation in FBBR. As a result, denitrification performance was affected due to the activation of sulphate reducing bacteria leading to the upset of FBBR. Batch experimental study aiming to screen the effect of nitrate to sulphate ratio on denitrification, demonstrated the possible occurrence of sulphate reduction at [nitrate]/[sulphate] < 0.2, exhibiting a highly negative oxidation reduction potential (ORP) value (−450 mV). This signifies that a minimum [nitrate]/[sulphate] > 0.2 is required as to suppress sulphate reduction phenomenon during denitrification. IEMB calibration for denitrification using glycerol as a carbon source revealed that 100 % stoichiometric donor/acceptor (C/N) ratio was suitable for producing sufficient nitrate biodegradation and acceptable ORP value (~−220 mV). Present work established promising application prospects of IEMB comprising nitrate selective membrane module for the treatment of high nitrate wastewater with a treatment capacity of 1.5 m3/d at optimized operating conditions.

Electrodialysis ion-exchange membrane bioreactor (EDIMB) to remove nitrate from water: Optimization of operating conditions and kinetics analysis

Nitrate pollution has become a worldwide problem. In this study, we remove nitrate from water by electrodialysis ion-exchange membrane bioreactor (EDIMB) and enabling simultaneous nitrate enrichment and denitrification. In this reactor, nitrate migrated from the water chamber to the biological chamber via electrodialysis and was degraded by microorganisms. The effects of voltage and biomass concentration on the reactor performance were examined, and the kinetics data of the water chamber and biological chamber were fitted. The experimental results showed that the migration of nitrate in the water chamber conformed to the first-order model, and the constructed zero-Michaelis-Menten model described changes in nitrate concentration in the biological chamber. Furthermore, when the inflow nitrate concentration was 40 mg N/L, 5 V was the best voltage, and 3.00 g VSS/L was the best biomass concentration. The nitrate removal rate in the water chamber was 98.94%, and there was no accumulation of nitrate or nitrite in the biological chamber. Compared with traditional ED processes, the nitrate removal efficiency was 8.86% higher, and the current efficiency was 22.14% higher. The total organic carbon (TOC) of the water chamber was only 1.43 mg C/L, which proves that the structure of the EDIMB confined the denitrifying bacteria and organic carbon donors in the biological chamber and avoided secondary pollution in the water chamber. Microbial community analysis showed that Thauera (66.06%) was the dominant bacterium in the EDIMB system, and Azoarcus (9.81%) was a minor denitrifying genus.

Nitrate removal from drinking water using different reactor/membrane types: A comprehensive review

Nitrate is considered one of the key contaminants in drinking water sources, particularly groundwater. This could be a result of excessive human activities. Numerous studies have been successfully developed and are still developing eco-friendly and cost-effective treatment techniques for highly efficient nitrate removal from drinking water. Although most of the nitrate removal techniques are physically and chemically based, for example, ion exchange and reverse osmosis, biological treatment is an equally potent approach applied in full scale through autotrophic and heterotrophic denitrification. However, many studies are trying to reduce some of the disadvantages of the biological treatment, such as the need for further treatment for microbial or organic carbon removal. This paper addresses some of the conventional nitrate removal approaches and reviews the biological denitrification processes, highlighting the advantages and disadvantages of the following methods: (i) conventional nitrate removal techniques, (ii) biological denitrification via bioreactor membrane techniques, (iii) membrane bioreactor (MBR), (iv) membrane biofilm-reactor (MBfR), (v) ion exchange membrane bioreactor (IEMBR), and (vi) biofilm-electrode reactor (BER).

Nitrate Removal by Donnan Dialysis and Anion-Exchange Membrane Bioreactor Using Upcycled End-of-Life Reverse Osmosis Membranes.

This work explores the application of Reverse Osmosis (RO) upcycled membranes, as Anion Exchange Membranes (AEMs) in Donnan Dialysis (DD) and related processes, such as the Ion Exchange Membrane Bioreactor (IEMB), for the removal of nitrate from contaminated water, to meet drinking water standards. Such upcycled membranes might be manufactured at a lower price than commercial AEMs, while their utilization reinforces the commitment to a circular economy transition. In an effort to gain a better understanding of such AEMs, confocal µ-Raman spectroscopy was employed, to assess the distribution of the ion-exchange sites through the thickness of the prepared membranes, and 2D fluorescence spectroscopy, to evaluate alterations in the membranes caused by fouling and chemical cleaning The best performing membrane reached a 56% average nitrate removal within 24 h in the DD and IEMB systems, with the latter furthermore allowing for simultaneous elimination of the pollutant by biological denitrification, thus avoiding its discharge into the environment. Overall, this work validates the technical feasibility of using RO upcycled AEMs in DD and IEMB processes for nitrate removal. This membrane recycling concept might also find applications for the removal and/or recovery of other target negatively charged species.

Efficient nitrate and perchlorate removal from aqueous solution via a novel electro-dialysis ion-exchange membrane bioreactor

The performance of a novel Electro-dialysis ion-exchange membrane bioreactor (EDIMB) for simultaneous removal of perchlorate and nitrate from aqueous solution was studied. EDIMB combines electrodialysis (ED) with bioreduction to remove contaminants while avoiding secondary contamination of organic matter and microorganisms. The removal process of pollutants in water compartment and bio-compartment can be well simulated by the First-order kinetic model and the established Zero-Michaelis-Menten model. Furthermore, compared with ED (VSS = 0.00 g/L), when the microbial concentration was 3.00 g/L, the total current efficiency was increased by 43.5% in first 60 min. The biological reaction takes place in the bio-compartment, which reduces the resistance of pollutant transmembrane migration and promotes ion migration. Microorganisms played a promoting role in the process of pollutant migration. High-throughput sequencing analysis of microorganisms showed that Thauera and Macellibacteroides were the main denitrifying and perchlorate-reducing bacteria.

Improved two-reactor system with sulfonated membranes in wastewater treatment

The ion exchange membrane bioreactor with two-reactor system has gained attention because it has been known to be beneficial to the simultaneous removal of organic and nitrogen. However, this system has a disadvantage for accumulation of nitrate in nitrification due to low diffusivity of nitrate through a cation exchange membrane. To resolve this problem, this study proposed a unique membrane bioreactor system bounded sulfonate membrane to be applied for simultaneous removal of organic and nitrogen in wastewater. The unique membrane bioreactor system consists of two reactors called reactors A and B. The reactor A was maintained in anoxic condition while the reactor B was operated in aerobic condition during the operation period. In ammonium migration experiment, the ammonium migration rates were determined by measuring ammonium concentrations in reactor A. As a result of the measurement, the maximum mass fluxes at the initial ammonia levels of 500, 1000, 1500, and 2000 mg N/L resulted in 1.03, 2.06, 2.98, and 3.87 mg/m2• s, respectively. Those high fluxes indicated that the unique membrane bioreactor exhibited high ion diffusivity. The mass fluxes of ammonia nitrogen in this system were strongly correlated to the initial concentrations of ammonia. The nitrate produced in the reactor B by biological nitrification was effectively migrated to the reactor A, and then the migrated nitrate in the reactor A was converted to nitrogen gas by denitrifying bacteria. As a result, almost complete nitrogen removal efficiency was achieved as 99% in the batch system. Further interestingly, no severe nitrate accumulation problem was observed in reactor B in the unique membrane bioreactor, although such a problem commonly exists in the conventional cation exchange membrane bioreactor system. It is expected that this unique membrane system can be operated with low operation costs and high removal efficiencies of ammonia nitrogen.

Compact wastewater treatment process based on abiotic nitrogen management achieved high-rate and facile pollutants removal

Chemically enhanced primary treatment (CEPT), ammonium ion exchange and regeneration (AIR) and membrane bioreactor (MBR) were coupled as CAIRM to treat domestic wastewater compactly and efficiently. CAIRM achieved efficient removal of chemical oxygen demand, ammonia nitrogen, total nitrogen (TN) and total phosphorus with total hydraulic retention time of 4.6 h, and obtained 2.3 ± 0.9 mg/L TN in the effluent. CEPT removed phosphate and impurities and prevented AIR from pollution. AIR maintained excellent nitrogen removal with a slight decrease in the exchange capacity of ion exchangers. MBR polished the effluent from AIR, and the larger particle size and better dewaterability of sludge mitigated the membrane fouling. Many heterotrophic genera, such as Rhodobacter and Defluviimonas, were enriched in the oligotrophic MBR. This study demonstrates the viability and stability of CAIRM in efficient wastewater treatment, which will address critical challenges in insufficient nitrogen removal and high land occupancy of current processes.

Concurrent microbial reduction of high concentrations of nitrate and perchlorate in an ion exchange membrane bioreactor.

We investigated effective simultaneous removal of high loads of nitrate and perchlorate from synthetic groundwater using an ion exchange membrane bioreactor (IEMB). The aim of this research was to characterize both transport aspects and biodegradation mechanisms involved in the treatment process of high loads of the two anions. Biodegradation process was proven to be efficient with over 99% efficiency of both perchlorate and nitrate, regardless of their load. The maximum biodegradation rates were 18.3 (mmol m(-2) h(-1) ) and 5.5 (mmol m(-2) h(-1) ) for nitrate and perchlorate, respectively. The presence of a biofilm on the bio-side of the membrane only slightly increased the nitrate and perchlorate transmembrane flux as compared to the measured flux during a Donnan dialysis experiment where there is no biodegradation of perchlorate and nitrate in the bio-compartment. The nitrate flux in presence of a biofilm was 18.3 (±1.9) (mmole m(-2) h(-1) ), while without the biofilm, the flux was 16.9 (±1.5) (mmole m(-2) h(-1) ) for the same feed inlet nitrate concentration of 4 mM. The perchlorate transmembrane flux increased similarly by an average of 5%. Samples of membrane biofilm and suspended bacteria from the bio-reactor were analyzed for diversity and abundance of the perchlorate and nitrate reducing bacteria. Klebsiella oxytoca, known as a glycerol fermenter, accounted for 70% of the suspended bacteria. In contrast, perchlorate and nitrate reducing bacteria predominated in the biofilm present on the membrane. These results are consistent with our proposed two stage biodegradation mechanism where glycerol is first fermented in the suspended phase of the bio-reactor and the fermentation products drive perchlorate and nitrate bio-reduction in the biofilm attached to the membrane. These results suggest that the niche exclusion of microbial populations in between the reactor and membrane is controlled by the fluxes of the electron donors and acceptors. Such a mechanism has important implications for controlling the bio-reduction reaction in the IEMB when using glycerol as a carbon source and allowing treating a complex contamination of high concentrations of perchlorate and nitrating in groundwater and successfully biodegrading them to non-hazardous components. Biotechnol. Bioeng. 2016;113: 1881-1891. © 2016 Wiley Periodicals, Inc.

Ion exchange membrane textile bioreactor as a new alternative for drinking water denitrification

This work enters in the optics of the denitrification of a polluted water by two membrane techniques, the Donnan dialysis (DD) and the ion exchange membrane bioreactor (IEMB), using a conventional barrier, composed by an anion exchange membrane (AEM), and a hybrid barrier, where the AEM is combined to an anion exchange textile (AET). The effects of the hydrodynamic factor and the nature of the carbon source on the transfer and the reduction of nitrate ions were studied. The study results obtained through the DD showed the effectiveness of the hybrid barrier in the recovery and concentration of nitrate ions. This was also recorded during denitrification by the hybrid process, called the ion exchange membrane textile bioreactor (IEMTB), with a significant reduction of nitrates, compared to IEMB, due to the efficiency of the Pseudomonas aeruginosa biofilm formed at the surface of the AET. Here, the permselectivity of the membrane and the good bioreduction of the pollutants are no longer major conditions to the better performance of the process. The application of IEMTB in the denitrification of groundwater, having a nitrate concentration of 96.67ppm, shows a total reduction of nitrate ions without changing the quality of the water. Indeed, the analysis of the recovered water, or yet the treated water, shows the absence of the bacterium by-products and concentrations in the nitrates and nitrites which are, respectively, equal to 0.02±0.01 ppm, and inferiors to the detection limit (<0.02 ppm).

Mercury removal from water streams through the ion exchange membrane bioreactor concept

Mercury is a highly toxic heavy metal that causes human health problems and environmental contamination. In this study, an ion exchange membrane bioreactor (IEMB) process was developed to achieve Hg(II) removal from drinking water and industrial effluents. Hg(II) transport through a cation exchange membrane was coupled with its bioreduction to Hg0 in order to achieve Hg removal from concentrated streams, with minimal production of contaminated by-products observed. This study involves (1) membrane selection, (2) demonstration of process effectiveness for removing Hg from drinking water to below the 1ppb recommended limit, and (3) process application for treatment of concentrated water streams, where >98% of the Hg was removed, and the throughput of contaminated water was optimised through membrane pre-treatment. The IEMB process represents a novel mercury treatment technology with minimal generation of contaminated waste, thereby reducing the overall environmental impact of the process.

Ion exchange membrane bioreactor for treating groundwater contaminated with high perchlorate concentrations

Perchlorate contamination of groundwater is a worldwide concern. The most cost efficient treatment for high concentrations is biological treatment. In order to improve and increase the acceptance of this treatment, there is a need to reduce the contact between micro organisms in the treatment unit and the final effluent. An ion exchange membrane bioreactor (IEMB), in which treated water is separated from the bioreactor, was suggested for this purpose. In this study, the IEMB's performance was studied at a concentration as high as 250mgL−1 that were never studied before. In the bioreactor, glycerol was used as a low cost and nontoxic carbon and energy source for the reduction of perchlorate to chloride. We found that high perchlorate concentrations in the feed rendered the anion exchange membrane significantly less permeable to perchlorate. However, the presence of bacteria in the bio-compartment significantly increased the flux through the membrane by more than 25% in comparison to pure Donnan dialysis. In addition, the results suggested minimal secondary contamination (<3mgCL−1) of the treated water with the optimum feed of carbon substrate. Our results show that IEMB can efficiently treat groundwater contaminated with perchlorate as high as 250mgL−1.

Validation of the ion-exchange membrane bioreactor concept in a plate-and-frame module configuration

The ion exchange membrane bioreactor (IEMB) is a particular case of a membrane-supported biofilm reactor, in which oxy-anions, used as electron acceptors by an anoxic mixed microbial culture, are removed from a polluted water stream through an anion-exchange membrane. The opposite side of this membrane is used for the development of a biofilm, contacting a biocompartment, to which nutrients and chloride are fed as a source of “driving” counter-ion. The applicability of a plate-and-frame IEMB module configuration, consisting of a series of membranes, for the treatment of drinking water contaminated with nitrate and perchlorate, was evaluated. Permeation of carbon source across the membrane to the treated water stream was avoided by a dedicated start-up procedure involving a gradual increase of ethanol feeding to the IEMB biocompartment. It was demonstrated that the biocompartment pH must be controlled not only to guarantee a complete perchlorate removal, but also to avoid precipitation of struvite on the membrane surface, which provokes membrane scaling and decreases the availability of nutrients for the biofilm. Under these conditions, the IEMB was successfully operated maintaining both nitrate and perchlorate concentrations in the treated water below their recommended levels for drinking water supplies.

Kinetics of nitrate and perchlorate removal and biofilm stratification in an ion exchange membrane bioreactor

The biological degradation of nitrate and perchlorate was investigated in an ion exchange membrane bioreactor (IEMB) using a mixed anoxic microbial culture and ethanol as the carbon source. In this process, a membrane-supported biofilm reduces nitrate and perchlorate delivered through an anion exchange membrane from a polluted water stream, containing 60 mg/L of NO3− and 100 μg/L of ClO4−. Under ammonia limiting conditions, the perchlorate reduction rate decreased by 10%, whereas the nitrate reduction rate was unaffected. Though nitrate and perchlorate accumulated in the bioreactor, their concentrations in the treated water (2.8 ± 0.5 mg/L of NO3− and 7.0 ± 0.8 μg/L of ClO4−, respectively) were always below the drinking water regulatory levels, due to Donnan dialysis control of the ionic transport in the system.Kinetic parameters determined for the mixed microbial culture in suspension showed that the nitrate reduction rate was 35 times higher than the maximum perchlorate reduction rate. It was found that perchlorate reduction was inhibited by nitrate, since after nitrate depletion perchlorate reduction rate increased by 77%. The biofilm developed in the IEMB was cryosectioned and the microbial population was analyzed by fluorescence in situ hybridization (FISH). The results obtained seem to indicate that the kinetic advantage of nitrate reduction favored accumulation of denitrifiers near the membrane, whereas per(chlorate) reducing bacteria were mainly positioned at the biofilm outer surface, contacting the biomedium. As a consequence of the biofilm stratification, the reduction of perchlorate and nitrate occur sequentially in space allowing for the removal of both ions in the IEMB.

Effect of Influent Concentration on Perchlorate Removal from Drinking Water in an Ion Exchange Membrane Bioreactor

Removal of perchlorate from drinking water in an ion exchange membrane bioreactor (IEMB) was investigated at different influent ClO4- concentrations when the hydraulic retention time was 5h. Except the 49th day and the 51st day, the effluent ClO4- concentrations met standard of the U.S. Environmental Protection Agency (USEPA) required 18µg/L. In the initial stages of the influent ClO4- concentration increase, the ClO4- concentration in the anaerobic bioreactor, the effluent Cl- concentration and the effluent electrical conductivity increased suddenly. As the operating time increased, the ClO4- concentration in the sludge supernatant kept below 10µg/L after steady operation; the effluent Cl- concentration declined slowly and finally stabilized at about 90 mg/L; the effluent electrical conductivity decreased gradually and finally stabilized at about 279µs/cm.

Treating Ground Water Contaminated with High Perchlorate Concentrations by an Ion Exchange Membrane Bioreactor

Treating Ground Water Contaminated with High Perchlorate Concentrations by an Ion Exchange Membrane Bioreactor

Multivariate statistical modelling of mass transfer in a membrane-supported biofilm reactor

The main objective of this work is to develop an overall mass transfer model applicable to a particular case of membrane supported biofilm, the ion-exchange membrane bioreactor (IEMB). A multivariate projection to latent structures (PLS) model of the anionic membrane transport in an IEMB was developed and analyzed to establish the mass transfer limiting variables for the removal of anionic pollutants (nitrate and perchlorate) from drinking water. The proposed PLS model accounts for the biological contribution to the mass transfer and predicts the anionic fluxes across the ion-exchange membrane with a prediction improvement of at least 50% when compared with a simplified mechanistic Donnan dialysis-based transport model. The PLS model allowed for predicting the transport of target anions using only operational physicochemical data, therefore, the use of several assumptions as in mechanistic model building was avoided as well as the need for biofilm characterization. To decrease the model complexity, several techniques which select the most informative predictors were also successfully used. The analyses of important predictors to each anionic transport model show that transport driving force related variables were the most important. Moreover, at least 30% of the model information is related with biocompartment bulk variables.

Multivariate analysis of the transport in an Ion Exchange Membrane Bioreactor for removal of anionic micropollutants from drinking water

The present study focuses on investigating the effects of biological compartment conditions on the transport of nitrate and perchlorate in an Ion Exchange Membrane Bioreactor (IEMB). In this hybrid process, the transport depends not only on the membrane properties but also on the biological compartment conditions. The experiments were planned according to the Plackett-Burman statistical design in order to cover a broader range of experimental conditions, under which a previously developed mechanistic transport model was not able to predict correctly the transport fluxes of the target pollutants. Using Principal Component Analysis, it was possible to identify not only the concentrations of target (nitrate and perchlorate) and of major driving counter-ion (chloride) but also those of some biomedium components (e.g. ammonia, ethanol and sulphate) as variables that affect the transport rate of micropollutants across the membrane. These conclusions are based on the loadings of the two first principal components that describe 84% of the data variance. The present study also revealed that the hydraulic retention time and the hydrodynamic conditions in the biocompartment have a minor contribution to the micropollutants transport. The results obtained are important for process optimization purposes.