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[EN] In this work, the influence of bisphenol A (BPA) on biological wastewater treatment was studied. For it, two sequencing batch reactors (SBRs) were operated for three months. Both SBRs were fed with synthetic wastewater (SW), adding 1 mg.L-1 of BPA into the feed of reactor SBR-BPA, while the other one operatedwithout BPA as a control reactor (SBR-B). In addition, batch experiments were performed with adapted and non-adapted activated sludge, simulating the reaction step of SBR-BPA, to determine the pathways for BPA removal. Results of batch experiments showed that adsorption and biodegradation were the only significant BPA removal routes. BPA removal by biodegradation was more efficient when adapted biomass was used in the tests (32.2% and 8.2% with adapted and non-adapted biomass, respectively), while BPA adsorption removal route was similar in both types of activated sludge (around 40%). Regarding the SBRs experiments, after 16 days no BPA concentration was detected in SBR-BPA effluent. In the adaptation process, SBR-BPA biomass was more sensitive to low temperatures resulting in higher effluent turbidity, COD and solublemicrobial products concentrations than in SBR-B. However, once temperature increased, adapted biomass from SBR-BPA presented higher activity than SBR-B biomass, showing higher values of sludge production, microbial hydrolytic enzymatic activities and specific dynamic respiration rate. The bacterial community study revealed the increase of abundance of Proteobacteria (especially Thiothrix species) and Actinobacteria (especially Nocardioides species) phyla at the expense of Bacteroidetes and Chloroflexi phyla in SBR-BPA during its operation.

[EN] During the secondary treatment of Wastewater Treatment Plants (WWTP) previous studies have reported that microplastics (MPs), which correspond to plastic fragments smaller than 5 mm, are mostly retained in the activated sludge. Since the sludge can be applied as a fertilizer in agricultural land, the presence of MPs in this matrix can lead to soil contamination. In this study, the application of ultrasounds at a frequency of 80 kHz was tested to remove polyethylene (PE) microspheres from activated sludge samples in order to reduce their concentration in this organic matrix. The application of ultrasounds at a power of 50 W and 8 min 45 sec promoted the removal of 48 ± 4% of MPs from the mixed liquor (2820 ± 51 mg/L of TSS). However, under the same operating conditions, 12 ± 4% of MPs were recovery from the concentrated mixed liquor (9395 ± 164 mg/L of TSS). For the concentrated sludge, a higher power and a longer sonication time (80 kHz; 90 W; 30 min) was necessary to improve the MP recovery. Under these conditions 38 ± 4% of MPs were removed from the sludge. This is the first study applying ultrasounds to remove MPs from activated sludge and the results indicate that ultrasonication can be a suitable instrument in minimizing the concentration of PE microspheres in activated sludge, and thereby minimizing soil contamination when biosolids are applied to agriculture.

[EN] The high presence of microplastics (MPs) in different sizes, materials and concentrations in the aquatic environment is a global concern due to their potential physically and chemically harm to aquatic organisms including mammals. Furthermore, the bioaccumulation of these compounds is leading to their ingestion by humans through the consumption of sea food and even through the terrestrial food chain. Even though conventional wastewater treatment plants are capable of eliminating more than 90% of the influent MPs, these systems are still the main source of MPs introduction in the environment due to the high volumes of effluents generated and returned to the environment. The amount of MPs dumped by WWTP is influenced by the configuration of the WWTP, population served and influent flow. Thus, the average of MP/L disposed vary widely depending on the region. In addition to MPs disposed in water bodies, more than 80% of these emerging contaminants, which enter the WWTP, are retained in biosolids that can be applied as fertilizers, representing a potential source of soil contamination. Due to the continuous disposal of MPs in the environment by effluent treatment systems and their polluting potential, separation and identification techniques have been assessed by several researchers, but unfortunately, there are no standard protocols for them. Aiming to provide insight about the relevance of studying the WWTP as source of MPs, this review summarizes the currently methodologies used to classify and identify them.

[EN] Although wastewater treatment plants can retain a high percentage of microplastics (MP) arriving at the facilities, no method for extracting and characterizing these microparticles has been still standardized in these units. This study investigated three protocols of chemical digestion, prior to analysis of microplastics, one directed to the effluents, using peroxidation, and two for activated sludge (peroxidation and Fenton). The samples (primary effluent, secondary effluent and activated sludge) were collected from a wastewater treatment plant (WWTP) located in Valencia (Spain). In addition, four common types of polymers (Low density polyethylene-LDPE, Polypropylene-PP, Polystyrene-PS and Polyethylene terephthalate-PET) were used to assess the influence of reagent exposure on microparticle integrity. Peroxidation was effective in treating the studied effluents (primary and secondary) and was also identified as the ideal protocol for activated sludge. The analysis showed that the use of H2O2 does not compromise the identification of the polymers evaluated by FTIR and also significantly reduced the concentration of suspended solids, resulting in an efficient visual separation of the microparticles. After been properly separated, the microparticles were characterized according to their size, colour and shape, and a fraction submitted to identification by mu-ATR-FTIR/ATR-FTIR. In all samples, a high presence of microfibers (MF) was observed, corresponding to more than 90% of the microparticles. However, in relation to secondary effluents, only 9% of these MF were identified as plastics, the remaining ones corresponded to cotton. The fragments found in the samples were classified as secondary in origin, and were mainly PE and PP, lower than 1 mm size.

[EN] The management of fermentation brines from the table olive processing is very complex due to its characteristics: high salinity and high organic matter concentration including phenolic compounds, which behave as slow degradable compounds when a biological process is performed. In this work, the management of these effluents by an osmotic membrane bioreactor has been assessed. This technique combines a biological reactor with forward osmosis membranes. For the study, a laboratory plant consisting of 1 L reactor and a forward osmosis module equipped with a membrane of 42 cm(2) of active surface has been used. Fermentation brine from table olive processing was fed to the system both as draw solution to set out the driving force for the membrane process and as a part of the feed to the reactor, mixing it with municipal wastewater. The experiments were carried out at a constant feed to microorganism ratio of 0.4 g COD.g SS-1.d(-1). Results indicated that the hypersaline effluent was able to produce the needed driving force by the process. Permeate fluxes ranged between 1 and 1.5 L.m(-2).h(-1) after the flux decay of the first operation days. Concerning the biological reaction, it has to be highlighted that phenols were eliminated after 24 days. Until that day, the biological process was jeopardized due to the quick increase of the conductivity in the reactor (ranging between 30 and 35 mS.cm(-1)), which was caused not only by the salinity of the influent but also by the reverse salt flux phenomenon. Soluble microbial products and extracted extracellular polymeric substances also increased in the reactor during the start-up.

[EN] The performance of an osmotic membrane bioreactor (OMBR) for treating tannery wastewater at laboratory scale has been evaluated in this study. The forward osmosis (FO) membrane tested was CTA-NW from HTI. As draw solution, actual waste water from an absorption column for ammonia separation, which consists mainly of ammonium sulphate was used. The study was focused on the salt reverse flux during the OMBR operation, membrane water flux, biomass characteristics and membrane fouling. Regarding membrane water flux change with the time, the measured values diminished from 3.44 to 0.72 LMH due to the membrane fouling and the salt accumulation in the biological reactor. The stable mixed liquor conductivity value at the end of the experiment was 29.8 mS·cm¿1. The chemical oxygen demand (COD) removal efficiencies were maintained near 80% until the first 50 days of operation, considering the soluble COD in the reactor instead of the COD in the membrane permeate for the performance calculation. Thence, COD removal efficiencies decreased progressively due to the accumulation of non degradable COD coming from the tannery wastewater. Concerning to the membrane fouling, FESEM/EDX analysis corroborated that organic fouling was predominant on the membrane active layer.

[EN] Reduction of sludge production is one of the most desired goals in the wastewater treatment plants operation. Alternatives like the enhancement of metabolism uncoupling or the increase of endogenous respiration by different chemicals have been reported in the bibliography. In this work, two folic acid concentrations (0.8 and 1.6mg L-1) added to a laboratory sequencing batch reactor were tested in order to assess the effect of this vitamin on the biological treatment. For this purpose, in addition to study sludge reduction and organic matter removal, an exhaustive biomass characterization including soluble microbial products, cellular viability, adenosine triphosphate (ATP), microbial hydrolytic enzymatic activities and bacterial community analysis have been performed. Results indicated that a concentration of 0.8 mg L-1 led to the greatest sludge reduction (44.7%), due to the increase of endogenous respiration. In the reactor with folic acid addition, higher soluble microbial products, enzymatic activities, cellular viability and lower cellular ATP was observed. Regarding the microbial community, folic acid addition did not affect nitrifying bacteria although it did reduce the abundance of denitrifying, increased the amount of filamentous bacteria (Caldilineacaeae and Haliscomenobacter) and enhanced Bacteriodetes and Chloroflexi phyla. A continuous addition of folic acid drove to biomass adaptation that caused a diminution of folic acid activity after 40 days.

[EN] A complete study about the effects of 3,3',4',5-tetrachlorosalicylanilide (TCS) on organic matter elimination performance, sludge production and on the microbial community of a biological wastewater treatment process has been performed. For this purpose two sequencing batch reactors (SBR) worked in parallel for 43 days with 0.8 mg.L-1 of TCS (SBR-1) and without this metabolic uncoupler (SBR-2). Results indicated that 63.3% of sludge reduction was achieved in SBR-1. However, COD removal efficiency was maintained in similar values in both reactors (89.1% and 92.1% in SBR-1 and SBR-2, respectively). The exhaustive mixed liquor characterization led to know deeply the action mechanism of TCS. In this way, a 69% of adenosine triphosphate (ATP) reduction was observed in SBR-1 in comparison with values measured in SBR-2. On the contrary, an increase in soluble microbial products (SMP) and DNA concentrations occurred as a consequence of TCS addition. Thus, it could be concluded that sludge reduction due to TCS addition was due to both uncoupling effect and cellular lysis. Also, increase in all microbial hydrolytic enzymatic activities measured was observed, which explained the stable performance achieved in SBR-1 despite to the results explained above. It should be highlighted that this uncoupler should not be used in biological treatments that require nitrogen elimination because nitrifying bacteria were affected by its addition (Nitrosomonas and Nitrospira). Finally, the 16S rRNA gene amplicon sequencing informed that an important reduction of bacterial diversity resulted in SBR-1 due to TCS addition. (C) 2019 Elsevier B.V. All rights reserved.

[EN] In this work, six identical laboratory SBRs treating simulated wastewater were operated in parallel studying the effect of three food-to-microorganisms ratio (F/M ratio; 0.20, 0.35 and 0.50 kg COD¿kg MLSS-1¿d-1), two hydraulic retention times (HRT; 24 and 16 h) and two values of number of cycles per day (3 and 6). Influence of these operational parameters on the SMPs production and reactor performance, were studied. Results indicated that the highest F/M ratio, HRT and cycles/day produced 72.7% more of SMP. In a second experimental series, biological process yielding the maximal and the minimal SMPs production were replicated and both mixed liquors (ML) and treated effluents were ultrafiltrated. The flux decay in the conditions of minimum and maximum SMPs production were 52% and 72%, when the SBRs effluents were ultrafiltrated while no significant differences in the ultrafiltration of ML were found. In terms of permeability recovery, this was lower for the case of the ML (73% and 49% of initial permeability recovered for effluent and ML ultrafiltration, respectively).

[EN] The membrane process of ultrafiltration (UF) has been investigated as a pretreatment previous to the further recovery and concentration of phenolic compounds from residual table olives fermentation brines. Two UF membranes were tested: a permanently hydrophilic polyethersulfone (PES) membrane with a molecular weight cut-off (MWCO) of 30 kDa and a PES membrane with a MWCO of 5 kDa. Transmembrane pressure and crossflow velocity were varied from 1 to 3 bar and from 2.2 to 3.7 m s(-1), respectively. The best membrane in terms of permeate flux and selectivity was that with MWCO of 5 kDa and the best operating conditions were transmembrane pressure of 3 bar and crossflow velocity of 2.2 m s(-1). In these conditions permeate flux was 21.6 L h(-1).m(-2), while the rejection of COD and phenolic compounds were 50.0% and 21.9%, respectively and the removal of colour and turbidity was almost complete. In addition, an alkaline cleaning protocol was proposed, which was effective to restore the initial permeability of the selected membrane. (C) 2018 Elsevier Ltd. All rights reserved.

[EN] The fermentation brines from table olive processing (FTOP) are hypersaline effluents (conductivities higher than 75 mS·cm-1) with high organic matter concentrations (COD around 10 g·L-1), which also include phenolic compounds (between 700 and 1500 mg TY·L-1). In this work, an integrated process for the FTOP reuse as brine in the table olive processing has been evaluated. This integrated process consisted of a biological treatment followed by a membrane system, which included ultrafiltration (UF) plus nanofiltration (NF). The biological treatment was carried out by 6 L laboratory sequencing batch reactor (SBR). UF and NF were performed in laboratory plants for flat membranes of 0.0125 and 0.0072 m2, respectively. Each stream generated during the FTOP treatment (SBR effluent, and UF and NF permeates) were evaluated. The SBR eliminated around 80% of COD and 71% of total phenols concentration. In the final NF permeate the COD concentration was lower than 125 mg·L-1; while the turbidity, colour and phenolic compounds, were completely removed.

[EN] Osmotic membrane bioreactor (OMBR) is an emerging membrane process which has gained interest in the recent years because of the low energy consumption and the high effluent quality. The osmotic membrane bioreactor combines a forward osmosis (FO) membrane and a biological treatment. However, salt reverse flux is the main problem because of the negative effect of the salt concentration increase in the reactor on the microbial activity. This is the reason why the study of a suitable draw solution (DS) is very important in the overall performance of the reactor. This study compares the process performance using two draw solutions: a 53 g L-1 NaCI solution and a real waste water solution (waste water from an absorption column consisting mainly of SO42- and NH4-N with concentrations of 153 g L-1 and 19 g L-1, respectively). The comparison is focused on the salt reverse flux during the reactor operation, the mixed liquor characteristics, the membrane fouling and the overall performance. The results indicated that the industrial wastewater showed a higher salt reverse flux, but also a less severe fouling and a higher the osmotic pressure difference in comparison with the NaCl solution. In terms of chemical oxygen demand (COD) removal efficiencies, both draw solutions attained values higher than 80%, though the efficiency was slightly lower when the industrial effluent was used as DS. This was related to the higher conductivity reached in the bioreactor when the industrial effluent was used as draw solution. In spite of it, the use of this industrial effluent as draw solution is strongly recommended because of the high permeate fluxes yielded, the low membrane fouling and the lack of necessity of regenerating the draw solution. (C) 2017 Elsevier B.V. All rights reserved.

[EN] Sludge production in wastewater treatment plants is nowadays a big concern due to the high produced amounts and their characteristics. Consequently, the study of techniques that reduce the sludge generation in wastewater treatment plants is becoming of great importanceIn this work, four laboratory sequencing batch reactors (SBRs), which treated municipal wastewater, were operated to study the effect of adding the metabolic uncoupler 3,30,40,5-tetrachlorosalicylanilide (TCS) on the sludge reduction, the SBRs performance and the microbial hydrolytic enzymatic activities (MHEA).

[EN] In this work, the fouling mechanisms that dominate the ultrafiltration of residual brines from table olive packing plant wastewaters were investigated. For that purpose, Hermia's models adapted to crossflow filtration, resistance-in-series model and a model combining intermediate blocking and cake formation mechanisms were fitted to the experimental data. Tests were performed with a 5 kDa polyethersulfone membrane at transmembrane pressures between 1 and 3 bar and crossflow velocities between 2.2 and 3.7 m s(-1). Results demonstrated that the resistance-in-series model was the most accurate to predict permeate flux evolution with time. The predominant fouling mechanism was cake formation followed by intermediate blocking/adsorption. The fouling resistances that were determined by means of the resistance in series model were tested using a well-established mathematical model proposed by Mondal and De that also combines both fouling phenomena (intermediate pore blocking and cake formation). Results demonstrated that the predicted resistances are consistent with those determined by Mondal and De's model. (C) 2016 Elsevier Ltd. All rights reserved.

Nowadays cost reduction is a very important issue in wastewater treatment plants. One way, is to minimize the sludge production. Microorganisms break down the organic matter into inorganic compounds through catabolism. Uncoupling metabolism is a method which promote catabolism reactions instead of anabolism ones, where adenosine triphosphate synthesis is inhibited. In this work, the influence of the addition of para-nitrophenol and a commercial reagent to a sequencing batch reactor (SBR) on sludge production and process performance has been analyzed. Three laboratory SBRs were operated in parallel to compare the effect of the addition of both reagents with a control reactor. SBRs were fed with synthetic wastewater and were operated with the same conditions. Results showed that sludge production was slightly reduced for the tested para-nitrophenol concentrations (20 and 25 mg/L) and for a LODOred dose of 1 mL/day. Biological process performance was not influenced and high COD removals were achieved. (C) 2016 Elsevier Ltd. All rights reserved.

One of the main operational problems in membrane bioreactors (MBRs) is membrane fouling. It can be stated that extracellular polymeric substances (EPSs) analysis is of paramount importance for membrane fouling prediction and subsequently to enhance the performance of the MBR process. In this way, the standardization of EPS separation and their analytical procedures is a non-solved problem that plays an important role in order to be able of comparing data of pilot and full-scale bioreactors. Prior to unveil this fact, it is necessary to assure the accuracy of the analyzed data. In this paper, the Standard Addition Method (SAM) is applied with the aim of studying eventual interferences by other mixed liquor substances or by reagents used in the extraction procedures on the analytical methods for determining proteins and carbohydrates and as a consequence, to improve the data accuracy and reliability. For that, several extraction protocols were applied and compared in order to obtain the EPS from the activated sludge. Moreover, DNA was measured and viability tests were carried out to evaluate cell lysis extent. BCA and Lowry methods were used to quantify proteins, meanwhile Dubois and Anthrone were applied for carbohydrates. Results showed that Triton X-100 achieved the highest extraction values in terms of proteins (81.64 ± 12.9 mg BSA/g VSS) and carbohydrates (10.3 ± 1.4 mg Glucose/g VSS) concentrations linked to lower DNA values (4.9 ± 0.8 mg DNA/g VSS). In addition, epifluorescence microscope images showed the high extent of the extraction achieved. For this protocol, BCA and Dubois analytical methods were chosen since SAM found out interferences with Anthrone and Lowry, and consequently, they were recommended for data comparison in MBR plants, and for fouling prediction.

Ultrafiltration and nanofiltration processes were used to treat synthetic reactive dyes aqueous solutions and a raw textile effluent supplied from rinsing baths of Spanish textile industry. The influence of the reactive dyes molecular weights and the effect of the used membranes types and cut-offs were investigated with regard to the permeate flux at different transmembrane pressures (2 7 bar for UF and 4 15 bar or NF). The extent of colour retention, COD and conductivity was determined in order to monitor the membrane's separation efficiencies aiming at waste water treatment, water reuse and chemical usage minimisation. High COD retentions (80 100%) were achieved using UF and NF processes. Good conductivity rates (80%) and high COD and colour retention rates (>90%) were obtained for both NF 200 and NF 270 membranes for all studied dyes solutions. An improvement of the rinsing wastewater quality was obtained using UF and NF processes.

Costs reduction in the activated sludge process in municipal wastewater treatment plants (MWWTPs) has nowadays become of paramount important due to the current economic situation. One of the saving measures that are being currently studied is the reduction of sludge production. In this work, the influence of the addition of chlorine dioxide to a sequencing batch reactor (SBR) on the sludge production and on the process performance has been studied. After preliminary jar-tests to select the ClO2 concentration range to be studied, two series of experiences were carried out. In the first series of experiments two laboratory SBRs were operated in parallel to test the effect of three different ClO2 doses. In the second one, three laboratory SBRs were operated in parallel to go on studying the influence of the chlorine dioxide addition on the SBRs performance and to compare two different dosing strategies (directly to the reactor and mixing the oxidant with a part of the sludge in a separated tank). SBRs treated simulated municipal wastewater and they were operated with the same operating strategy. Results showed that doses of 5 and 10 mg ClO2/gTSS entailed severe deterioration of the biological process, meanwhile the dose of 2 mg ClO2/gTSS hardly decreased the COD removal performance, implying a reduction of sludge production of 20.2%. An increase of the dose up to 2.5 mg ClO2/gTSS increased the reduction of the sludge production up to 43.4%, when the oxidant was added directly to the reactor in the anoxic reaction phase.

One of the main drawbacks for the application of membranes technologies to the treatment of textile effluents is the fouling. Fouling phenomenon causes a flux decline and reduces the quality of the treated water. Previous studies have pointed at dyes that remain in the water after rinse processes, as one of the fouling agents. In this study several UF and NF membranes were tested using three synthetic reactive dyes solutions as feed streams. The influence of applied transmembrane pressure (TMP) on normalised flux, color, COD and salt retentions was studied. The extent of fouling phenomenon was evaluated in terms of filtration resistance (R s/R t ratio) and normalized flux also with TMP. The obtained results showed that R s/R t for NF and 1kDa membranes were not nearly affected by TMP, except for 10kDa one. In these cases R s/R t ratio was lower than 0.5 showing a negligible fouling phenomenon. Similar tendency was observed with the normalized flux results. For the 10kDa one, the normalized flux decreased progressively with TMP reaching a total normalized flux reduction of 60%