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[EN] According to previous research, it has been proved that wastewater treatment plants (WWTPs) can retain more than 90 % of the MPs contained in wastewater. However, a significant fraction of the MPs removed in WWTPs is retained in the sludge floc and this may lead to an environmental issue since biosolids can be used as fertilizers. The purpose of this research was to evaluate how the presence of polyethylene (PE) could interfere with the activated sludge performance. For this, a sequencing batch reactor (SBR) was continuously fed during 93 days with synthetic sewage and PE microbeads. It was observed that 98 +/- 2% of the total amount of MPs that entered SBR was accumulated in the activated sludge. Despite the high accumulation of MPs in the sludge, the depuration performance of the reactor was not compromised. However, the presence of MPs decreased the richness (Chao1) and abundance-based coverage estimators (ACE) and diversity (Shannon) of the bacterial community on day 93. Based on the analysis of the diversity indices and the relative abundances of microbial taxa, it was concluded that MPs had selective effects on activated sludge microbial community. However, MPs did not affect the abundance of nitrifying and denitrifying bacteria in the sludge., Authors thank the Spanish Ministry of Science, Innovation and Universities for the financial support (Reference of the project: RTI2018-096916-B-I00)

Full-scale wastewater treatment facilities are not able to prevent microplastics (MPs) from discharging into natural waters and they are also associated with the land application of the sludge. This study evaluates the distribution of microfibers (MFs) in a lab-scale sequencing batch reactor (SBR) fed by synthetic wastewater (SW) for 93 days. The MFs were analyzed through optical microscopy in the mixed liquor (ML) and the effluent, and sulfuric acid digestion was applied to discriminate between natural and synthetic MFs (i.e., MPs). The results of the optical microscopy analyses were further validated through FTIR spectroscopy. A model describing the evolution over time of the MF concentration in the ML was created, accounting for the MFs entering the system through the SW and atmospheric deposition. The ratio between the MF concentration in the ML and the effluent was 1409 ± 781, demonstrating that MFs settle with the sludge. Consistently, in the ML, 64.9% of the recovered MFs were smaller than 1000 µm (average size 968 µm), while in the effluent, 76.1% of MFs were smaller than 1000 µm (average size 772 µm). Overall, 72% of MFs recovered from the ML were natural fibers and sulfuric acid digestion was successful in eliminating the natural MFs.

[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., Authors thank the Spanish Ministry of Science, Innovation and Universities for the financial support (Reference of the project: RTI2018096916BI00).

[EN] Management of wastewater is a major challenge nowadays, due to increasing water demand, growing population and more stringent regulations on water quality. Wastewaters from food conservation are especially difficult to treat, since they have high salinity and high organic matter concentration. The aim of this work is the treatment of the effluent from a table olive fermentation process (FTOP) with the aim of reusing it once the organic matter is separated. The process proposed in this work consists of the following membrane-based technologies: Ultrafiltration (UF) (UP005, Microdyn Nadir), Forward Osmosis (FO) (Osmen2521, Hydration Technology Innovation) and Nanofiltration (NF) (NF245, Dow). The FO process was implemented to reduce the salinity entering the NF process, using the FTOP as draw solution and, at the same time, to concentrate the centrate produced in the sludge treatment of a municipal wastewater treatment plant with the aim of obtaining a stream enriched in nutrients. The UF step achieved the elimination of 50% of the chemical oxygen demand of the FTOP. The UF permeate was pumped to the FO system reducing the volume of the anaerobically digested sludge centrate (ADSC) by a factor of 3 in 6.5 h. Finally, the ultrafiltrated FTOP diluted by FO was subjected to NF. The transmembrane pressure needed in the NF stage was 40% lower than that required if the ultrafiltration permeate was directly nanofiltered. By means of the integrated process, the concentration of organic matter and phenolic compounds in the FTOP decreased by 97%. Therefore, the proposed process was able to obtain a treated brine that could be reused in other processes and simultaneously to concentrate a stream, such as the ADSC., This research was funded by CDTI (Centre for Industrial and Technological Development) depending on the Spanish Ministry of Science and Innovation through the INNPRONTA program, grant number IPT-20111020.

This work was supported by the Spanish Ministerio de Economia y Competitividad. (CTM2014-54546-P).

[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] 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., This study was supported by the Spanish Ministry of Economy and Competitiveness through the project RTC-2015-3582-5-AR

[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., This study was supported by the Spanish Ministry of Economy and Competitiveness through the project RTC-2015-3582-5-AR.

[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)., This work was supported by the Spanish Ministerio de Economia y Competitividad (CTM2014-54546-P).

Chromium is one of the most important environmental concerns related to tanneries. The most often used process for hide tanning is chrome tanning. This implies the presence of chromium both in wastewaters and in leather wastes. Leather wastes have to be disposed in landfills what entails a considerable environmental impact and high cost. In this work, a study about the effect of a chrome-free tanning process using titanium salts instead, on the wastewater and on the solid wastes has been performed. In this way, a study of biodegradation of leather waste samples tanned with different tanned agents by composting together with food wastes is carried out in a laboratory composter. Results indicated that leather tanned with titanium salts met the required quality standards. Besides, the concentration of organic matter and salts in the tannery process wastewater was lower comparing with the chromium tanning agent. In the biodegradation study by composting, leather samples tanned with titanium were degraded, reducing around 10% the carbon content with the subsequent diminution of the C/N ratio. In addition, the size was reduced 41% in 45 days. However, leather sample tanned with oxazolidine was partially degraded in the composter; meanwhile chrome and vegetable tanned leather kept inalterable.

[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., This work was supported by the Ministry of Economy and Competitiveness (MINECO), Spain (grant no. CTM201454546-P-AR).

[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)., This work was supported by the Spanish Ministerio de Economia y Competitividad (CTM2014-54546-P).

[EN] Tannery wastewater has a high environmental impact due to its low biodegradability. Sequencing batch reactors (SBRs) are an established method for treating highly polluted wastewater. To minimize the hydraulic retention time (HRT) of the SBRs, various HRT values were tested and the best value was chosen according to the removal efficiency of the soluble chemical oxygen demand (COD). A series of experiments was then carried out with two cationic polyelectrolytes added to the system in two different modes to improve the effluent quality. Both modes were evaluated in terms of the soluble COD, suspended solid concentration, and turbidity of the final effluent. The results showed that reducing the HRT to two days did not diminish the COD removal efficiencies., This work was supported by the Universitat Politecnica de Valencia (Project Ref.: PAID-06-10-2269).

In the last years, biological treatment plants for the previously separated organic fraction from municipal solid wastes (OFMSW) have gained importance. In these processes a liquid effluent (liquid fraction from the digestate and leachate from composting piles), which has to be treated previously to its discharge, is produced. In this paper, the characteristics of the mixed liquor from two full-scale membrane bioreactors treating the effluents of two OFMSW treatment plants have been evaluated in view to study their influence on membrane fouling in terms of filterability. For that, the mixed liquor samples have been ultrafiltrated in an OF laboratory plant. Besides, the effect of the influent characteristics to MBRs and the values of the chemical and physical parameters of the mixed liquors on the filterability have been studied. Results showed that the filterability of the mixed liquor was strongly influenced by the soluble microbial products in the mixed liquors and the influent characteristics to MBR. Permeate flux of MBR mixed liquor treating the most polluted wastewater was considerable the lowest (around 20 L/m(2) h for some samples), what was explained by viscosity and soluble microbial products concentration higher than those measured in other MBR mixed liquor. (c) 2016 Elsevier Ltd. All rights reserved., This work was supported by the URBASER Company. Authors thank personnel of the full-scale MBR plants for providing samples.

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., Authors thank Fomento Agricola Castellonense S.A. (FACSA) for the support in the project.

More demanding legal regulations for the wastewater disposal and water scarcity make necessary wastewater reuse in the industry. In particular, textile industry generates large amounts of wastewater with a high concentration of pollutants. Even though present biological or physical-chemical treatments are broadly in place, the quality of the final effluent is not good enough to allow its direct reuse. Consequently, a complementary membrane process is required in order to improve wastewater characteristics. In this work, six NF membranes were tested at different volume concentration factors in order to select the most appropriate one. The main studied criteria were the permeate quality for its reuse in the textile processes and the minimum membrane fouling effect. The different results obtained for the tested membranes were explained by membrane characterization parameters as contact angle, roughness and size exclusion. Taking these factors into consideration, TFC-SR2 has shown the overall best results because of the high permeate flux and the minimum fouling (in terms of the normalised flux reduction).

Tanneries wastewaters are characterized by high organic matter and salt concentrations. Beamhouse operations, in particular unhairing, are the processes that provide the most concentrated effluents concerning the organic matter. Besides, the unhairing wastewater includes a high sulphides concentration. Thus, the separated management of the unhairing effluents has been considered in the last 20 years with the aim of their recycling and reuse. Ultrafiltration was a promising technique to separate the organic matter from the chemicals (lime and sulphides) that could be reused in the unhairing process. However, the membrane fouling has avoided its application at an industrial scale. The main aims of this paper are to study the influence of the reuse of the ultrafiltration permeate on the quality of the final leather and the comparison among different types of membrane cleaning. Ultrafiltration experiments, including cleaning procedures, were carried out in a module for plane membranes with 30 cm2 of active surface. Sodium dodecyl sulphate, two different enzymes and sodium hypochlorite were used as cleaning chemicals. In addition, the module configuration with only a plane membrane let the study of the effect of providing air from the permeate side. Laboratory drums with a 5 L maximum capacity were used for the permeate reuse and further hide samples processing in order to study the final quality of the leathers. Results showed that the final quality of the leather was not modified by using ultrafiltration permeate for the unhairing process. Concerning the membrane cleaning, the best results in terms of flux recovery were achieved with 1000 mg L−1 of sodium hypochlorite (92% of flux recovery) and with the air dosing from the permeate side. Flux recovery with enzymatic cleaning hardly reached an efficiency of 35%.

Textile industries are rated as the most polluting among all industrial sectors taking into account both wastewater volume and composition. In order to be able to reuse these effluents, membrane technologies have been proven as a viable alternative. However, these technologies show some drawbacks, such as the retentate stream management and the worsening of their performance due to membrane fouling. Therefore, effluents must be pre-treated in order to prevent fouling. Membrane technologies also provide some alternatives for these pre-treatments by means of the application of ceramic ultrafiltration among others. This work studies the performance of ceramic membranes by carrying out experiments with three commercial ceramic membranes with molecular weight cut-offs (MWCO) of 30, 50 and 150 kDa, respectively. Moreover, the effect of cross-flow velocity (CFV) was studied by performing the essays at different flow velocities of 3, 4 and 5 m/s. According to the obtained results, ceramic UF membranes proved to be a feasible pre-treatment alternative. Permeate flux increased as flow velocity was increased for most of the cases, owing to the fact that the cake layer formation was limited. Furthermore, flux decline along operating time was negligible for the higher flow velocities, whereas it was noticeable for the lowest flow velocity tested. For the lowest MWCO analyzed, lower cross-flow velocities were needed in order to limit the cake layer formation and reach the steady-state. This implies that, although fouling was significant for all the three molecular weight cut-off studied, it was much more noticeable when MWCO was increased. Slightly better results in terms of permeate quality were achieved as MWCO was lower. In addition, higher chemical oxygen demand (COD) and conductivity retention coefficients were obtained for the lowest cross-flow velocity. Turbidity and color removals seemed to be more influenced by water composition than CFV, with rejections higher than 99% and between 84 and 98%, respectively.

Wastewater reclamation and reuse are being widely implemented due to the lack of fresh water. When salinity is a limiting parameter to obtain the required water quality for agricultural uses, a desalination step is necessary to achieve it. Therefore, techniques such as nanofiltration (NF) or reverse osmosis (RO) can play an important role and have to be deeply studied in order to implement an economically feasible tertiary treatment. In this work, NF of a secondary effluent from a municipal wastewater treatment plant has been evaluated for increasing feed concentration in order to reach a final conversion of approximately 75%. Experiments were carried out with a laboratory plant containing a spiral wound membrane (DURASLICK-2540, General Electric) with an active area of 2.2m2. Tests were performed increasing volume concentration factors (VCFs) up to almost 4 and replicated three times to confirm the results statistically. After NF experiments an RO step of the retentate was carried out in order to concentrate the final brine. In NF experiments, for the highest VCF values, fluxes recommended for the membrane maker (17 Lm−2 h−1) were produced at a transmembrane pressure (TMP) of 3.2 bar. The TMP hardly increased with the VCF. NF membranes yielded a conductivity retention index around 42%, reaching nearly 99% for sulphate ions and only 23% for chloride ions.

Water scarcity makes industrial wastewater reuse necessary, especially in those industries characterized by both high water consumptions and extremely polluted effluents as textile industries. Membrane technologies are very efficient to treat industrial effluents for water reuse successfully, since their application entails important reductions in pollutant concentration. In the present work, a direct treatment of a textile industry effluent by means of a combination of ultrafiltration (UF) followed by a final nanofiltration (NF) stage is presented. Two different NF membranes were tested in order to compare their behaviors. For that, the influence of the feed water pH and transmembrane pressure (TMP) of the NF process were investigated. The UF results showed that the highest permeate fluxes were achieved at pH 11. Related to NF experiments, NF270 reached for the same operational conditions higher fluxes and salts rejection values than the Duraslick NF. No influence of pH was found for the permeate flux. However, the pH effect was manifest for the salts rejection. Although COD, color, and turbidity removals were high in all tests, Duraslick NF showed an average slightly better removal of COD and color. The results obtained confirm the viability of this treatment for water reuse in most of the different processes carried out in these kinds of industries.

Textile industry processes (dyeing, bleaching, printing and finishing) require a high-water consumption generating high amounts of wastewater. According to the literature, typically 200 and 500 L of water are needed to produce 1 kg of finished product [1]. This fact in combination with the current water scarcity makes necessary textile wastewater reuse. In this work, nanofiltration of biologically treated textile wastewater has been evaluated testing three nanofiltration membranes. It was studied that the influence of different volume concentration factors (VCF) on the permeate flux and salts and COD rejections. Nanofiltration experiments were carried out in a laboratory plant equipped with a pressure vessel containing one spiral wounded membrane element. The membranes tested were Ds-5 DK and DURASLICK from General Electric and Fluid System® TFC® SR®2 from KMS. For all membranes, the COD values in the permeate were negligible and flux reduction was not severe even for the maximum operating VCF (3). According to the permeate characteristics the main use of the treated water is for machinery washing processes and print implements.

Water scarcity is becoming a serious problem in the Mediterranean countries. To minimize negative effects, wastewater reclamation can be one of the possible solutions. Reverse osmosis (RO) is the process that ensures the highest water quality. Thus, the required quality goal can be reached adjusting the wastewater portion to be treated and the portion directed to the blending tank. In this work, a study with a low-pressure RO pilot plant was conducted in the laboratory. A spiral wound composite polyamide membrane (ESPA1-2540, Hydranautics) with an active area of 2.59 m2 was tested for increasing volume concentration factors (VFC). Thus, the membrane elements behaviour within a pressure vessel in a full-scale plant was simulated. The experiments were run three times to confirm statistically the results. These ones showed an almost constant permeate flux (17L m−2 h−1) while keeping the transmembrane pressure constant at 6.8 bar with a VCF of 2.5. Concerning the salt retention, it was observed a slightly reduction on increasing the VFC. However, the permeate conductivity was lower than 80 µS/cm in all cases.

One of the main environmental problems of tannery industries is due to the liquid effluents generated in their processes. It contains high amounts of organic matter, sulphates and chlorides. In fact, the wastewater stream that comes from the pickling process can reach nearly 75 mS/cm of conductivity. The present work is focused on the reclamation of pickling wastewater after applying a nanofiltration (NF) process. The retentate stream, with a high sulphates concentration, can be reused in pickling baths whereas the permeate stream, with a high chlorides concentration, can be pumped to the soaking drums. In this work a detailed study of the use of the NF permeate stream in the soaking process and its effect on the quality of the final leather is performed. At the same time, a reduction of the salt content in the final tannery effluent is accomplished. NF experiments with pickling wastewater were performed in a laboratory plant equipped with a pressure vessel that contains one spiral wound membrane element (Desal-5 DK from GE-OSMONICS) with an effective membrane area of 2.51 m 2 . The operating conditions of the experiments were a transmembrane pressure of 15 bar, 400 L h -1 of feed flow rate and a temperature of 25°C. It was studied the influence of the feed pH on the membrane performance (flux and salts rejection). The results showed that the maximum permeate flux was obtained at wastewater pH. The measured quality parameters of the final leathers soaked with NF permeates demonstrated that leathers did maintain the necessary quality for the final product.

Due to the water scarcity in Spain and in particular in the Mediterranean areas such as Valencian Region, water authorities have enhanced the wastewater reuse in the municipalities. Different treatments can be applied according to the aim of the wastewater reclamation. In this work different alternatives of tertiary treatment (conventional treatments and one treatment including ultrafiltration) were evaluated using two pilot plants (2 m 3 /h of capacity) located in the wastewater treatment plant of Quart-Benager in Valencia. Settling (with and without chemicals addition), conventional sand filtration, UV disinfection and ultrafiltration were the processes included in the different alternatives. Results showed that the most efficient conventional alternative consisting in settling + filtration + UV radiation and the treatment including ultrafiltration eliminated almost the 100% of the total coliforms. However COD removal was very much higher in the alternative including ultrafiltration (60%) in comparison with the other process combinations.

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., This work was supported by Universitat Politecnica de Valencia (Project reference: PAID-05-12).

Due to the high conductivity of the global wastewater from a tannery industry, wastewater reuse is only possible if a reverse osmosis process is implemented in the wastewater treatment. The supernatant of a physical-chemical treatment is still very polluted, containing high COD values between 3000 mg/l and 4000 mg/l and conductivities of nearly 20 ms/cm. In this work, a combination of filtration, ultrafiltration and reverse osmosis is evaluated as treatment for the physical-chemically treated wastewater. Filtration was carried out using microfilters as a previous stage to ultrafiltration process. Ultrafiltration tests were performed in a laboratory plant. Organic membranes from Orelis with different cut-offs were tested to optimize the rejection and the permeate flux. Finally, the reverse osmosis step was carried out using an ESPA-1 membrane from Hydranautics. Results showed high COD values in ultrafiltration permeates (between 2000 and 3000 mg/l). A polyethersulfone membrane with cut-off of 30 kD was chosen for the pre-treatment of the reverse osmosis membrane. Permeate fluxes of the reverse osmosis membrane reached 40 l/(m 2 h) at 30 bar. Though membrane fouling was not observed during RO experiments, an industrial scale plant should pay special attention to a probable flux decrease due to the scaling if a high conversion is aimed.

Tannery industries generate wastewater containing high sulphate concentrations as sulphates are salts widely used in the tanneries as auxiliary matter. Some residual floats from tanneries (pickling, chrome tanning and dyeing) contribute to the final sulphate discharge. In order to predict NF membrane behaviour after filtering different tannery floats, a simulated wastewater was made. The effect of conductivity on the permeate flux and on chloride and sulphate retention was studied. Experiments were carried out in a laboratory plant equipped with a spiral-wound module of 2.51 m2 of active surface. Chloride retention lower than 20% was measured, and the membrane permeate fluxes were around 18 L·m−2·h−1 for feed conductivities higher than 85 mS/cm.

Physical-chemical and biological processes are the most common methods for the textile effluents treatment. However, in many occasions the pollutants removal efficiency can be increased through the combination of these conventional methods with advanced ones. In this paper, initially the ozonation influence on the coagulation-flocculation process has been studied in textile wastewater from a dyeing, printing and finishing industry. Thus, several jar-tests were carried out using wastewater before and after an ozonation process, with reaction times of 30 and 60 min. It can be highlighted that a short time preozonation enhanced the coagulation process, achieving after sedimentation COD and turbidity reductions of 57% and 95%, respectively. After that, two different NF membranes were tested using as feeding stream the wastewater after the ozone and physical-chemical stages in order to reduce the water conductivity and COD. NF experiments were carried out in a laboratory plant containing a plane module with an effective area of 120 cm2. The membranes tested were Desal DK-5 from Osmonics and NF-90 from Dow Chemical. The results showed that the COD and conductivity of the nanofiltration permeates were around 100 mg/L and 0.5 mS/cm, respectively with NF-90 membrane.

The main environmental problem of textile industries is the high water consumption for their processes. Thus it is very important to reuse wastewater, especially in areas with a water scarcity such as Comunidad Valenciana (Spain). The goal of this work is wastewater reuse combining chemical neutralization, physicochemical treatment and membranes. Neutralization studies were conducted in order to select the most appropriate neutralizing agent in terms of conductivity of the neutralized wastewater. For the physicochemical treatment four coagulants from the Cibaâ Company (Mangasol 5389, Mangasol 6348, Zetag 7103 and Alcyl 955) were compared by carrying out jar tests using different concentrations and pH values. The experimental tests were made according to the statistics program Statgraphics. After that, nanofiltration experiments of the physicochemically treated wastewater were performed in a laboratory plant equipped with a pressure vessel containing one spiral-wound membrane element (A = 2.51 m2). The operating conditions were: transmembrane pressure of 20 bar, cross-flow velocity of 1.66 m/s and a temperature of 25°C. The membrane tested was the Desal DK2540 from Osmonics. Physicochemical experiments showed that the Zetag 7130 coagulant achieved higher reductions in COD and turbidity. In addition, the sludge volume was lower than 100 mL/L. NF experiments showed that permeates, COD and conductivity were around 100 mg/L and 1000 μS/cm, respectively, with a volume concentration factor of 2.5. As a result, the combination of physicochemical treatment and nanofiltration provided treated water with good enough quality to be reused in the industry.

Tannery industries generate wastewater containing high concentrations of sulfates. In the pickling process, the presence of sulfates is due to the sulfuric acid added for pH lowering, and chromium is used as Cr 2 (SO 4 ) 3 in the tanning process. Concentrations higher than 2000 mg/L are usual in tannery wastewater, and the legal standard is 1000 mg/L beginning in 2005 in Catalonia (Spain). In this work, an evaluation of sulfate concentrations in the different residual streams of a tannery was carried out. Then, the possibilities of treating the pickling and tanning wastewaters (a part of the acidic tannery wastewaters) were studied and nanofiltration experiments using Osmonics membranes (Desal DK-2540) were carried out in a laboratory plant equipped with a spiral-wound module with 2.51 m 2 of active surface. Sulfate retention of more than 90% was achieved, and permeate quality was good enough to be reused. Finally, different alternatives to concentrate management were discussed, including its reuse in the pickling process.

Water scarcity in Mediterranean areas such as Comunidad Valenciana (Spain) makes water reuse necessary in high water-consuming industries. Previous studies by our research group showed that nanofiltration (NF) membrane permeates could be reused in some processes of finishing, dyeing and printing in the textile industry. In this work, biologically treated textile wastewaters were subjected to ozonation as a pre-treatment stage to NF. The aim was to reduce organic matter in order to prevent membranes from fouling and to oxidize organic wastewater compounds that could damage the membrane material. NF experiments were carried out in a laboratory plant equipped with a pressure vessel containing one spiral-wound membrane element (2.51 m2 of active surface). With ozonation, wastewater COD was reduced up to three different levels (160, 135 and 82 mg/L). NF experiments with wastewaters of different organic matter concentrations were carried out studying the effect of increasing the feed concentration periodically. Conductivity retentions higher than 65% were achieved, with no significant flux decay observed during the experiments.

The main goal of this work was to study the feasibility of the combination of physico-chemical treatment with nanofiltration to reuse wastewater of a printing, dyeing and finishing textile industry. For the physico-chemical treatment two coagulants (one containing Al3+ and another containing Fe2+) were compared by carrying out jar-tests using different chemical concentrations and pH values. After that, nanofltration experiments with physico-chemically treated wastewater were performed at different operating pressures and cross-flow velocities. The results showed that the COD and conductivity of the nanofiltration permeates were lower than 100 mg/L and 1000 μS/cm respectively.

This work is focused on the treatment of a textile plant wastewater. The industry mainly manufactures socks, stockings and panties, and the water is treated in order to be reused. The wastewater was characterized and jar-tests experiments were carried out with different coagulants and flocculants, at different concentrations and pH in order to obtain clarified water that can be treated by means of ultrafiltration (UF) or nanofiltration (NF). The combination of the physico-chemical treatment and the nanofiltration leads to a COD removal of almost 100%.

Wastewater reclamation and reuse has become one of the most important environmental issues nowadays. Thus, municipal wastewater treatment plants are being upgraded converting conventional activated sludge processes into membrane bioreactors in order to improve the quality of the treated wastewater. However, operational costs increase because of higher energy consumption and membrane fouling. Wastewater composition is one of the factors affecting membrane fouling, though its influence is difficult to describe. In this work, a study about wastewater pretreatment and filterability has been carried out in view of achieving valuable information for a further implementation of a membrane bioreactor. Experiments were performed with samples of four municipal wastewater treatment plants taken from the plant influent, the biological process influent and the plant effluent. Filterability was evaluated by membrane filtration resistances using the resistance in series model. Resistances were measured with ultrafiltration tests performed with flat membranes. Results showed that suspended solids concentration was the most influential parameter on the total membrane resistance when pretreated wastewater is filtered. No statistical correlation between the membrane resistances of biological process influent and plant effluent was found.

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 for 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.

[EN] The use of large quantities of sulfuric acid and other sulfur-containing chemicals causes high sulfate concentrations in the wastewater of a tannery. The aim of this work was reducing the sulfate concentration in the final wastewater from a tannery. For that, firstly a study about the main sulfate sources in a tannery was carried out and the total sulfates load in the tannery wastewater was evaluated. Two measures for sulfates reduction were studied: the recycling of unhairing wastewater to the soaking drums and the reuse of the chromium sulfate from the tanning washing wastewater after its separation by nanofiltration (NF). The first measure proposed was studied experimentally in laboratory drums of 5 L of volume. Two series of experiments with different volumes of unhairing wastewater in the soaking bath were carried out. The quality of the final leather was evaluated by means of mechanical tests. NF experiments were carried out in a laboratory pilot plant with a spiral wounded membrane element. Concerning the results, the combination of 50% unhairing wastewater and 50% of fresh water was appropriate in order to obtain leather with an acceptable quality. Besides, it drove to a diminution of approximately 10% in the addition of sulfide in the unhairing. Related to the NF experiments, 97% of the sulfates were rejected by the membrane. The separated ions could be recycled to the tanning drums. The application of the two measures (firstly the recycling of the unhairing wastewater and secondly the NF of the tanning washing wastewater) drove to a reduction of 14.82 kg SO 4 -2 t -1 of raw hide. © 2010 Elsevier Ltd. All rights reserved.

Jar-test is a well-known tool for chemicals selection for physical–chemical wastewater treatment. Jar-test results show the treatment efficiency in terms of suspended matter and organic matter removal. However, in spite of having all these results, coagulant selection is not an easy task because one coagulant can remove efficiently the suspended solids but at the same time increase the conductivity or increase considerably the sludge production containing chemicals and toxic dyes. This makes the final selection of coagulants very dependent on the relative importance assigned to each measured parameter. In this paper, the use of multicriteria decision analysis (MCDA) is proposed to help on the selection of the coagulant and its concentration in the physical–chemical wastewater treatment, since textile wastewater contains hazardous substances. Therefore, starting from the parameters fixed by the jar-test results, these techniques will allow to weight these parameters, according to the judgements of wastewater experts, and to establish priorities among coagulants. Two well-known MCDA techniques have been used: analytic hierarchic process (AHP) and preference ranking organization method for enrichment evaluations (PROMETHEEs) and their results were compared. The method proposed has been applied to the particular case of textile wastewaters. The results obtained show that MCDA techniques are useful tools to select the chemicals for the physical-technical treatment.