Activated Sludge Treatment Plant Research Articles

Physicochemical characterization of wastewater from the Niamey National Hospital (NNH) (Niger) and assessment of its impact on the environment

The Niamey National Hospital (NNH) is among the reference hospital in the Niamey region (Niger) to after the quality of care it offers to the population. However, these activities have a negative impact on the quality of the water of the river constituting one of the main sources of water supply for the population of Niamey and gardening activities. This study aims to determine the physicochemical quality of wastewater from the NNH activated sludge treatment plant and its impact on the environment. To carry out this study, twenty (20) wastewater samples were taken at the outlet of the NNH treatment station. The sampling lasted five (5) weeks to take into count fluctuations. The results obtained indicate that the average values of physicochemical parameters such as: the pH (6,91), temperature (27.825°C), conductivity (574.80 µS/cm) and certain heavy metals of this hospital are compliance with national and international standards for wastewater discharge. However, it was noted that the average values ​​obtained at the HNN for copper (1.982 mg/L); zinc (1.077 mg/L); in phosphorus (18.065 mg/L); DCO (808 mgO2/L) and DBO5 (442.5 mgO2/L) do not comply with national and international wastewater discharge standards. These abnormal levels must be treated before being released into the river.

Linking conventional activated sludge treatment plant performances for micropollutants removal to environmental risk and SimpleTreat model assessment

The attention to the contaminants of emerging concerns or micropollutants is continuously rising, also stimulated by the new initiatives at European level. The present study focuses on the removal of target micropollutants in a conventional activated sludge wastewater treatment plant which is the most common system and considered a source of micropollutants to the environment. The aims were to evaluate the removal efficiency of different stages of the wastewater treatment plant and to conduct the Environmental Risk Assessment on the final effluent. As indicated by the European’s guidelines on Environmental Risk Assessment, the SimpleTreat4.1 model was applied to this purpose: different values of the biodegradation constant, which represents the key factor for modelling, were applied, and the effects on the quality of prediction were evaluated. The evaluations were carried out thorough 3-year monitoring activity in a full-scale wastewater treatment plant on 10 micropollutants belonging to the classes of illicit drugs, pharmaceuticals and psychoactive. The model was found statistically not satisfactory for most of the investigated micropollutants. A better prediction was obtained when the biodegradation constant was calculated based on the full-scale data. Nonetheless, the results obtained in terms of risk were considered acceptable and comparable among each other.Graphical abstract

Dynamic alpha factor prediction with operating data - a machine learning approach to model oxygen transfer dynamics in activated sludge

Aeration is an energy-intensive process of aerobic biological wastewater treatment. An accurate model of oxygen transfer dynamics in activated sludge tanks would improve design and operation of aeration systems. Such a model should consider spatial and diurnal variation of α-factor as well as site-specific conditions that impact oxygen transfer. For this dynamic prediction a machine learning approach was used for the first time. The data-driven method was based on long-term ex-situ off-gas measurements with pilot-scale reactors (5.8 m height, 8.3 m3 vol) coupled to full-scale activated sludge tanks on the sites of two conventional and a two-stage activated sludge treatment plant. The ex-situ off-gas method allowed to quantify theoretical off-gas parameters in non-aerated zones and thus consider the whole activated sludge tank. We introduced the α0-factor to compare aerated and non-aerated zones under nonsteady-state conditions. Like the established α-factor for steady-state conditions, the α0-factor describes oxygen transfer inhibiting effects in activated sludge. α0-factor was lowest in upstream denitrification zones. This indicates an anoxic elimination of oxygen transfer inhibiting wastewater contaminants which improved oxygen transfer in subsequent aerobic zones. Random Forest models predicted α0-factor reliably in all examined activated sludge tanks even for stormwater events and seasonal variation. Model development only required online sensor data already available to operators. Our results suggest that machine learning models can dynamically predict α-factors in a variety of activated sludge processes, thus considering site-specific conditions in model training without manual calibration.

Microbiological aspects of the aeration tanks of an activated sludge treatment plant in dysfunction: Consequences on its treatment performance

The present study was conducted in a sewage treatment plant, called "El Kouwaer", located in the department of Mascara, North-West of Algeria. Mainly, the objective of this investigation is to evaluate the relevant settling and pollution parameters and to assess the proliferation level of filamentous microbial communities during the dysfunction period to further the effectiveness of the operative treatment. Sludge parameter values were estimated such us Settling Test, Diluted Sludge Volume Index (DSVI), and Total Suspended Solids (TSS) content to set up the sludge classification, the performance analysis of treatment was conducted by computing pollution indicators and removal efficiencies of organic pollution, as well as the Principal Component Analysis (PCA) of dysfunction parameters. The results showed that in aeration tanks 65% of samples represented a maximum Filament Index (FI) of 6. Diluted Sludge Volume Index (DSVI) was greater than 300 mg/L in 23% of samples. A high level of filamentous bacteria biodiversity was also noted during the assessment of the (FI) including Microthrix parvicella, Bogiotae, and Sphaerotilus natans. The effluent in the biological unit was characterized by BOD5/COD ratio of 0.17 and COD removal efficiency of 53.32%. Those results demonstrated that the sewage treatment plant is frequently affected by bulking problems. This study had confirmed the importance of continuous monitoring of different process parameters like Wastewater Biodegradability Index, Dissolved Oxygen, filamentous flora, and Dilute Sludge Volume Index (DSVI) to avoid irreversible damage at the level of a wastewater treatment plant.

Risk assessment of a municipal extended aeration activated sludge treatment plant using physico-chemical and in vitro bioassay analyses

The present study involves physico-chemical profiling and toxicity assessment of wastewater and sludge samples collected from subsequent treatment stages of extended aeration activated sludge (EAAS) process based municipal wastewater treatment plant (WWTP). Wastewater samples were collected from inlet, aeration tank, final settling tank and outlet, while sludge samples were collected from sludge bed. All the samples were tested for their physico-chemical properties using titrimetry, multi elemental analysis and Gas chromatography and Mass spectrometry (GC–MS)(in scan and SIM (selective ion monitoring) modes). Toxicity testing was done using in vitro bioassays viz., 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cytotoxicity, 7-ethoxyresorufin-O-deethylase (EROD) assay for dioxin-like behaviour and alkaline comet assay for genotoxicity, on human hepato-carcinoma HepG2 cell line. Post-treatment liquid samples showed 12 fold chemical oxygen demand (COD) reduction and met discharge standards for most of the tested parameters. However, detection of organic contaminants such as phenols, phthalates and polycyclic aromatic hydrocarbons (PAHs) and a correlated low toxicity reduction in liquid and sludge samples after treatment revealed the need for up-gradation of the existing testing and treatment technologies. • A multiplicity of organic contaminants detected in effluent and sludge. • 12 fold reduction in effluent chemical oxygen demand (COD) post-treatment. • Slight increase in toxicity of effluent and sludge observed after final clarifier stage. • Correlation observed in COD and the three bioassay results. • Combination of Physico-chemical and toxicity assessments more useful.

Robust Control of Nitrification Process in Activated Sludge Treatment Plant using Quantitative Feedback Theory

Robust Control of Nitrification Process in Activated Sludge Treatment Plant using Quantitative Feedback Theory

Protozoa reduction through secondary wastewater treatment in two water reclamation facilities

The State of Nevada, USA Administrative Code requires a 12-log enteric virus reduction/inactivation, 10-log Giardia cyst reduction, and 10-log Cryptosporidium oocyst reduction for Category A+ reclaimed water suitable for indirect potable reuse (IPR) based on raw wastewater to potable reuse water. Accurately demonstrating log10 reduction values (LRVs) through secondary biological treatment prior to an advanced water treatment train enables redundancy and resiliency for IPR projects while maintaining a high level of public confidence. LRVs for Cryptosporidium and Giardia resulting from secondary biological treatment are not fully established due to a wide range of performance variabilities resulting from different types of secondary biological treatment processes employed in water reclamation. A one-year investigation of two full-scale northern Nevada (e.g. ≤4 mgd; 1.5 × 107 L/day) water reclamation facilities (WRFs) was conducted to monitor Cryptosporidium oocysts and Giardia cysts in untreated wastewater and secondary effluent. This study aimed at establishing secondary treatment LRVs, monitor WRF performance and attempted to correlate performance to protozoan reduction. California's IPR regulations, in which Nevada IPR regulations were modeled after, were based on a maximum concentration of 5-logs (cysts/L) of Giardia and 4-logs (oocysts/L) of Cryptosporidium. The recovery-corrected Giardia and Cryptosporidium concentrations measured in untreated influent (20 samples each at each WRF) were below 5-log cysts/L at the 99th percentile (maximum 4.4-log cysts/L) and 4-log oocysts/L (maximum 2.7 log oocysts/L), respectively. Both secondary treatment WRFs produced secondary effluent that is consistently better than federal and the State of Nevada requirements and perform within an operating envelop for other secondary facilities. Given the results, it appears that a minimum conservative estimate for LRVs for well-operated secondary activated sludge treatment plants (at the 5th percentile) of 0.5 LRV credit for Cryptosporidium and 2.0 LRV for Giardia is warranted. These minimum LRVs are consistent with a conservative review of the available literature.

Dewatering, Stabilization, and Final Disposal of Waste Activated Sludge in Constructed Wetlands

Objective: This research aimed to assay the dehydration and stabilization of surplus biosolids from a wastewater activated sludge treatment plant, with sludge-treatment wetlands, at the Iguazú National Park (Misiones, Argentina). Materials and Methods: A 12-cell sludge-treatment reed beds (STRB) system was built and operated for four years. Afterwards, the accumulated sediments were analyzed for total solids (TS) concentration, volatile solids (VS) reduction, specific oxygen-uptake rate (SOUR), and heavy metals and pathogens concentrations. Results and Discussion: TS concentration increased from 0.55 % to 14.3 %, VS were reduced by 33.3 %, and SOUR lowered to 1.09 mg O2gTS-1 h-1. These figures and the final concentrations of heavy metals and pathogenic microorganisms (102 MPN E.coli.gTS-1) indicated a degree of stabilization and sanitation that allowed classifying these biosolids as Class A, according to the Argentine guidelines, National Resolution 410/18, and enabled their reuse for soil amendment in landscapes and other agronomic purposes. Conclusion: The technology tested showed good results applied under a tropical climate, with annual temperatures between 17 and 27 °C, rainfall of 1870 mm y-1, and planted with autochthonous vegetation. Furthermore, it allowed the reuse of 221 t (144 m3) of a harmless product in an environmentally sustainable way.

Nutrient recovery in wastewater treatment plants: Comparative assessment of different technological options for the metropolitan region of Buenos Aires

In the metropolitan region of Buenos Aires, the load of nutrients discharged to urban rivers and shores is producing a severe eutrophication problem in the estuary of La Plata River. That problem could be alleviated by recovering nitrogen (N) and phosphorus (P) through the production of fertilizer products in the existing activated sludge treatment plants. Four nutrient recovery options were considered: struvite precipitation in the centrate line; acidic leaching of the sludge followed by struvite precipitation of the centrate; Ion Exchange in the centrate line; and a combination of struvite precipitation in the centrate line plus an Ion Exchange unit to further polish the secondary effluent. Those options were compared with basis on their economic sustainability and their capacity to reduce the load of N and P discharged to the coastal waters and rivers. The economic assessment indicated that producing fertilizer products in the existing facilities, using the four considered options, would be unprofitable. In the best case, which is struvite precipitation in the centrate line, the potential revenues would only cover 38.5 % of the operational expenses. Environmental benefits could justify that cost, as in some urban rivers the load of P could be reduced by 42.5 % by struvite precipitation. Regarding the load of nutrients that is discharged to the estuary, the impact of the considered nutrient recovery options ranges from a decrease in 0.5 % N and 3.7 % P (struvite precipitation) to a decrease in 8.2 % N and 4.4 % P (combination of struvite precipitation + Ion Exchange).

Assessing impact of activated sludge treatment plant effluent on selected environmental factors: case study of Kerman wastewater treatment plant effluent

Assessing impact of activated sludge treatment plant effluent on selected environmental factors: case study of Kerman wastewater treatment plant effluent

Impact of Sewage Sludge Leaching on Soil Constituents and Quality

Activated sludge treatment plants generate large quantities of sludge each year, thereby posing a serious environmental problem. This study aims to experimentally assess the effect of rainwater on the leaching of sludge components. In this context, a percolation test was set up, and composed of PVC cylinders into which the solid substrate was introduced. Five modalities of the solid substrate were used: a sludge modality, a soil modality and three modalities with increasing percentage of sludge (1%, 5% and 25%) in the soil. The percolation water is collected during the rainy months in bottles placed below each column. Solid substrate samples were taken before the test and after one year. The physicochemical analysis of the percolation water showed an increase in the electrical conductivity, BOD5, COD, nitrogen compounds and phosphate compounds which were proportional to the percentage of sludge. The pH of the sewage sludge leachates varies from 7.61 to 7.98. Zinc and copper were the most mobilized metals. A year following the installation of the percolation test, electrical conductivity, total phosphorus (TP) and orthophosphate (PO4) contents decreased for the solid substrates using the five modalities. Furthermore, ammonium (NH4) and nitrates (NO3) levels decreased in soil mixed with 1 to 25% of sludge due to their leaching by rainwater. Collectively, these data show that the leachates through the soil mixed with sludge are stable and loaded with NO3, a plant nutrient that can contaminate the groundwater as well as the surface waters inducing their eutrophication. Furthermore, addition of sludge to the soil improves the levels of carbon, total nitrogen, TP and PO4 in the soil and thereby soil fertility. The addition of sludge, however, is not without soil contamination with heavy metals. Such soil contamination would cause pollution of surface and ground water. Reaching certain severity, it should call for the adoption of prompt measures for the protection of environment and human health.

Flocs in disguise? High granule abundance found in continuous-flow activated sludge treatment plants

To date, high performance of full-scale aerobic granular sludge (AGS) technology has been demonstrated on a global scale. Its further integration with existing continuous flow activated sludge (CFAS) treatment plants is the next logical step. All granular sludge reactors operated in sequencing batch reactors (SBR) mode with anaerobic feeding conditions select for growth of phosphorus and glycogen accumulating organisms (PAO and GAO, respectively), which are known to enhance sludge settling characteristics. Therefore, we hypothesized that AGS are commonly present at full-scale CFAS processes with enhanced biological phosphorus removal (EBPR) and low sludge volume index (SVI). This hypothesis was confirmed at 13 EBPR plants, where granules were found present (at plants where SVI was lower than 100 ml/g) with a strong correlation between high granule abundance and low SVI. A wide range of granule abundance was found among the plants, ranging from 0.5% to as high as 80%. Evaluations of the EBPR plant process configurations showed that high granule abundances may be related to selector design features such as high anaerobic food to mass (F/M) ratios, unmixed in-line fermentation, and high influent soluble COD fraction. Granules were also observed at a non-EBPR plant with an aerobic selector receiving high F/M feeds. Quantitative PCR and 16S rRNA gene sequencing analyses revealed higher relative gene abundance of Accumulibacter PAO and Competibacter GAO in the granules over flocs, as well as a correlation between granule abundance and some possible EPS producers such as Flavobacterium and Competibacter. Our results indicated that process configurations that select for slow-growing or EPS-producing heterotrophs play an important role for granule formation in full-scale CFAS systems as previously shown in SBR configurations.

Full-scale simultaneous partial nitrification, anammox, and denitrification process for treating swine wastewater.

A full-scale swine-wastewater activated sludge treatment plant that contains naturally enriched anammox biofilms was investigated for 2 years. Red biofilm in this system included Planctomycetes at a maximum of 62.5% of the total bacteria diversity, including Candidatus Jettenia and Candidatus Brocadia. The plant was operated with an influent containing 1,104 ± 513 mg/L biochemical oxygen demand (BOD) and 629 ± 198 mg/L total nitrogen (TN) (BOD/N of 1.78 ± 0.58) at a volumetric BOD loading rate of 0.32 ± 0.12 kg/m3/d. Notwithstanding drastically varying influent concentrations, BOD removal efficiency was stable at 95 ± 4%. However, TN removal fluctuated at 75 ± 14%. Dissolved oxygen (DO) concentrations in the aeration tank were 0.06-2.0 mg/L. DO concentration greatly affected nitrogen removal, e.g. when DO was lower than 0.3 mg/L, total inorganic nitrogen removal was 61 ± 14% (≤20 °C), 78 ± 16% (20-30 °C), and 75 ± 12% (≥30 °C), whereas at higher DO concentrations, removal rates were 47 ± 13%, 55 ± 16%, and 68%, respectively. As BOD concentration in the influent was limited compared to nitrogen concentration, nitrogen was likely removed by simultaneous nitrification, anammox, and denitrification (SNAD) under microaerobic conditions. Maintaining low DO concentrations would therefore be a simple method to improve nitrogen removal during SNAD processes for swine-wastewater treatment with fluctuating influent.

The impact of pesticides on the electrogenic activity of the sludge in microbial fuel cells

The influence of Gezagard herbicide (active ingredient – promethrin, 500 g/l) and fungicide Kolosal (active principle – tebuconazole 250 g/l) on the dynamics of electrical indicators of microbial fuel cells (MFC) with activated sludge treatment plants as a bioagent was studied. It was shown that the tested pollutants reduced the electrogenic activity of sludge in MFC when the content in wastewater was from 0.1 g/l. The studied toxicants in the indicated concentrations significantly inhibited the dehydrogenase activity of the sludge microorganisms and the total microbial number. At the same time, the Kolosal fungicide had a more pronounced negative effect on all the studied parameters than the Gezagard herbicide. There is a positive relationship between the results of evaluating the electrogenic activity of sludge and such classical methods of its analysis as dehydrogenase activity and the total microbial number. This suggests that the ability of the sludge to generate an electric current in MFC can be used as one of the parameters for assessing its physiological state. In addition, in the case of a mono-composition of pollutants, MFC with activated sludge can be used as a tool for the initial non-specific assessment of wastewater pollution by pesticides.

Process Design and Physicochemical Characterization of Extended Aeration Activated Sludge Treatment Plant: A Case Study

The discharge of untreated wastewater to the environment causes adverse environmental problems. In this regard, feasible wastewater treatment system must be designed and operated to reduce the pollutant load and to safeguard the public health. The efficiency of a sewage treatment plant located in a residential college in UiTM Sarawak Branch, Samarahan Campus was examined in terms of process design and physiochemical parameters. Physiochemical parameters included pH, temperature, turbidity, chemical oxygen demand (COD) and suspended solids (SS) from raw influent and treated effluent were investigated using the Standard Methods. Removal efficiency of these parameters was also determined to evaluate the performance of the plant. The findings revealed that overall performance of the plant was satisfactory. All physiochemical parameters of the treated effluent complied with the requirements of Standard B, Environmental Quality (Sewage) Regulations 2009 except SS. The lowest concentration of turbidity and COD in the effluent was reported in the second week of the sampling period. The findings obtained were due to the low influent loading during the semester break where the number of students resided in the college was very minimal. The removal efficiencies of turbidity and COD were found to be 65% and 83%, respectively. A non-compliance SS requires special attention to enhance the efficiency and to maintain the good operation of the system to meet the stipulated standards.

Estimating the impact of inhibitory substances on activated sludge denitrification process

Abstract Industrial wastewater frequently contains substances which inhibit activated sludge treatment processes. Inhibitory characteristics of different substances are usually evaluated based on testing the impact of respective substance on activated sludge nitrification or oxygen uptake rates. However, denitrification is always before aerobic processes in conventional activated sludge treatment plants and thereby more exposed to inhibitory compounds. There is no easily applicable and validated method available for determination of denitrification process efficiency and inhibition. In this study, a method for evaluation of inhibition on the activated sludge denitrification process was developed and validated using 3,5-dichlorophenol (3,5-DCP) as a model inhibitory compound and additionally controlled with real wastewater produced in the shale oil industry. Average IC50 value (5.5 ± 2.2 mg L−1) for 3,5-DCP showed that denitrifiers were less sensitive than nitrifiers (IC50 = 2.9 ± 0.7 mg L−1) and more sensitive than aerobic heterotrophs (IC50 = 7.2 ± 2.4 mg L−1). Methodological aspects like accumulation of nitrite nitrogen, acclimatization of biomass and technical issues were discussed. Achieved validation characteristics were similar with ISO Standards estimating activated sludge nitrification and oxygen uptake rates, which proves the reliability of the method: standard deviation, 95.4% confidence level, relative standard deviation were calculated to be 2.2 mg L−1, 1.2 … 9.8 mg L−1 and 39.2%, respectively.

Optimization of mesophilic anaerobic digestion of a conventional activated sludge plant for sustainability

Potential of nutrient recovery as struvite (NH4MgPO4·6H2O) with sole waste activated sludge (WAS) of a conventional activated sludge treatment plant has been investigated using computational modelling supported by laboratory experiments. Predicted key outcomes using Bio-Win modelling tool indicated that anaerobic digestion of WAS could produce a supernatant consisting of 300–420 mg/L ammonia , 100–200 mg/L phosphate and 12–30 mg/L magnesium and laboratory experiments confirmed that struvite can be precipitated using these nutrient concentrations. Study of sludge retention time (SRT 15–30 days) and temperature (34–38 °C) on the nutrient concentrations of digester supernatant revealed that ammonia and phosphate concentrations of supernatant increased with SRT and temperature. The removal efficiencies of magnesium and phosphate in struvite precipitation reactions were 91% and 50% respectively, indicating that magnesium addition is required for extra phosphate removal in the digester supernatant. It was found that a substantial excess ammoniac nitrogen would remain and need alternative method to remove and recover, if sustainability is to be achieved. The outcome of this study confirms that WAS from conventional wastewater treatment plants such as Loganholme can be successfully upgraded towards a nutrient recovery facility by optimizing anaerobic digester parameters. Modelling is a suitable first approach for planning and decision-making.

Is dissolved COD a suitable design parameter for ozone oxidation of organic micropollutants in wastewater?

Ozone oxidation of organic micropollutants in biologically treated wastewater was investigated in pilot-scale after a high- and a low loaded activated sludge process. Higher ozone doses were required to remove organic micropollutants in the effluent wastewater from the high loaded activated sludge process. Further comparison of the micropollutant removal was based on normalized ozone doses, expressed as g O3/g DOC and g O3/g soluble COD (sCOD). A clear difference was noted for the two effluents when the micropollutant removal was normalized by DOC. This difference disappeared almost completely when the removal was linked to ozone doses normalized by sCOD. The dose-response curves for the organic micropollutants were practically linear in the removal range up to 95%. A linear prediction model was developed and compared with literature values to test the transferability of the obtained results. Results from this comparison indicated that the slope of the dose-response functions could be used to predict the removal efficiency of organic micropollutants at a third plant with an average uncertainty of 10%. The modeled ozone requirements were then set in relation to the COD concentrations in the discharged water from approximately 90 Swedish activated sludge treatment plants with and without nitrogen removal. This comparison highlighted the need for a well-functioning biological treatment for an effective ozone oxidation of organic micropollutants. The results in this study suggest that soluble COD should be further explored for design and modeling of ozone oxidation of organic micropollutants in biologically treated wastewater.

Inhibiting effect of textile wastewater on the activity of sludge from the biological treatment process of the activated sludge plant.

Textile industry represents an important source of toxic substances rejected in environment. Indeed, effluent of these industries contains dyes and chemicals. They are rejected in environment without any treatment. The aim of this work is to evaluate ecotoxicological effect of industrial textile effluents on the sludge harvested from activated sludge treatment plant of Marrakech city (Morocco). For this, we are interested in determining the inhibition condition that corresponds to 50% decrease of bacterial activity in sludge. Obtained results showed that inhibition percentage of bacterial activity depends narrowly on contact time and on added effluent volume, until a limit concentration where there is no degradation of substratum. In fact, substratum degradation speed shows about 65 times decrease when 80% (v/v) of textile wastewater is added, in comparison with the controlled one. Consequently the inhibition constant (Ki) that corresponds to 50% of bacterial inhibition activity is estimated to 0.65 mg l−1 of dye. These studies confirm a real ecotoxicological risk of these effluents. Therefore, a treatment is mandatory before their rejection in environment.

Behavior of Micropollutants in Polishing Units that Combine Sorption and Biodegradation Mechanisms to Improve the Quality of Activated Sludge Effluent

The current study evaluated the removal of six micropollutants (estrone (E1); 17β-estradiol (E2); 17α-ethynylestradiol (EE2); ibuprofen (IBP), diclofenac (DCF), and paracetamol (PCT)) from the final effluent of an activated sludge domestic sewage treatment plant using polishing filters. Four polishing filters were assembled as columns and filled with a mixture of sand and vermiculite, sand and charcoal, sand and granulated activated carbon (9:1 by volume), and sand only. The column filters were placed near the outlet of a full-scale activated sludge treatment plant and were fed with a treated effluent containing from 4.71 to 28.93 ng L-1 of the target compounds at a hydraulic loading rate (HLR) of 50 m3 m−2 day−1. Samples were collected periodically from the influent (biologically treated sewage) and effluent of the four columns and analyzed for estrogens, anti-inflammatories, and analgesic compounds. Liquid samples were submitted to a solid phase extraction (SPE) and analyzed by gas chromatography coupled with mass spectrometry after their derivatization. Among the compounds found, diclofenac was distinguished by the high occurrence of detection in the samples (85%) and higher mean concentration (~ 17 ng L−1). High removal efficiency (> 90%) of the estrogens was observed in the polishing systems studied, while for the other targets, the removal efficiency varied from 10 to 30%. The concentration values of some compounds were low, probably due to rainfall during the sampling period.