The role of ozone combined with UVC/H2O2 process for the tertiary treatment of a real slaughterhouse wastewater.

The main goal of this work is to evaluate the usage of ozone (O3) as a pre-treatment or simultaneously combined with UVC/H2O2 process for the polishing stage treatment of real bio-treated slaughterhouse wastewater. Two different treatment strategies were tested: i) pre-ozonation of the wastewater followed by an UVC/H2O2 process (two-step treatment); ii) simultaneous application of O3/UVC/H2O2 combined process (one-step treatment). For the two-step strategy, the pre-treatment with 30 mg O3/min for 10 min reduces significantly total suspended solids (TSS), turbidity and colour, reducing light filtering effects and increasing the efficiency of the following UVC/H2O2 process. In turn, the one-step treatment strategy (O3/UVC/H2O2) allows a more efficient use of injected O3 by reducing the amount of O3 required (from 273 to 189 mg O3/Leffluent) to achieve similar mineralization levels. The real bio-treated slaughterhouse wastewater treated by O3/UVC/H2O2 process achieved final colour values of 20 Pt/Co, TSS of 35 mg/L and COD of 61 mg O2/L, allowing its direct discharge into water compartments according to European Council Directive 91/271/EEC.

Integration of Fenton's reaction based processes and cation exchange processes in textile wastewater treatment as a strategy for water reuse.

The remediation of a real textile wastewater aiming its reuse in the textile industry was carried out by integrating two processes: (i) a chemical or electrochemical advanced oxidation process (AOP or EAOP) based on Fenton's reaction for organics degradation, and (ii) a cation exchange process using marine macroalgae for removal of the iron acting in the Fenton's reaction based processes. Four AOPs/EAOPs at acidic pH 2.8 were tested: Fenton, photo-Fenton with ultraviolet A (UVA) radiation (PF/UVA), electro-Fenton (EF) and photoelectro-Fenton with UVA radiation (PEF/UVA). These processes provided very high color removals. After a running time of 45 min, the color removals were 68-95% for the Fenton process, 76-94% for the EF process, 80-98% for the PF/UVA process and 85-100% for the PEF/UVA process. In contrast, the mineralization was negligible for all the processes, indicating the generation/presence of persistent colorless compounds. The PF process was selected as first treatment stage due to its ability for color removal and related lower costs. A set of six marine macroalgae (Gracilaria caudata, Gracilaria cervicornis, Ascophyllum nodosum, Fucus spiralis, Laminaria hyperborea and Pelvetia canaliculata) were tested for iron uptake. Laminaria hyperborea showed the highest ion exchange capacity and affinity for iron species. Its application allowed the removal of all the iron acting in the PF process (3.4 mg/L). The textile wastewater resulting from the application of PF process followed by cation exchange with Laminaria hyperborea was successfully reused in scouring, bleaching and dyeing processes.

Application of a micro-meso-structured reactor (NETmix) to promote photochemical UVC/H2O2 processes - oxidation of As(iii) to As(v).

A micro-meso-structured reactor (NETmix) was used for the first time to promote photochemical UVC/H2O2 processes. The NETmix photoreactor consists of a network of chambers and channels, where the liquid flows, sealed with a quartz slab with high UVC transparency. Due to the small size of channels and chambers, the NETmix presents a uniform irradiance through the entire reactor depth, short molecular diffusion distances and large specific interfacial areas, maximizing the pollutant/oxidant contact. In this study, the NETmix photoreactor was evaluated for As(iii) oxidation to As(v) using a photochemical UVC/H2O2 system. The effect of the UVC lamp power (4, 6 or 11 W), the number of UVC lamps (2 or 3 lamps) and the UVC lamp layout (parallel or perpendicular to the flow direction) was evaluated, in order to ensure uniform irradiation of the entire reaction mixture. The optimum H2O2 concentration for each light distribution system was also evaluated. At the best configuration, 3 lamps of 11 W positioned parallel to the flow direction, total As(iii) oxidation ([As(iii)]0 = 1.33 × 10-2 mM) was achieved in 15 min with an absorbed photon flux density of 1.9 × 10-1 einstein per m3 per s. Significant differences were highlighted between the photon flux actually received in the photoreactor and the radiant power emitted by the lamp. A kinetic model able to represent the As(iii) oxidation employing UVC radiation and H2O2 in a micro-meso-structured reactor was presented. The photochemical space time yield (PSTY) values obtained for the micro-meso-structured reactor are higher than for conventional batch reactors, showing that the NETmix technology can be a good solution for application in photochemical processes.

Brown marine macroalgae as natural cation exchangers for toxic metal removal from industrial wastewaters: A review.

The discharge of inadequately treated or untreated industrial wastewaters has greatly contributed to the release of contaminants into the environment, including toxic metals. Toxic metals are persistent and bioaccumulative, being their removal from wastewaters prior to release into water bodies of great concern. Literature reports the use of brown marine macroalgae for toxic metals removal from aqueous solutions as an economic and eco-friendly technique, even when applied to diluted solutions. Minor attention has been given to the application of this technique in the treatment of real wastewaters, which present a complex composition that can compromise the biosorption performance. Therefore, the main goal of this comprehensive review is to critically outline studies that: (i) applied brown marine macroalgae as natural cation exchanger for toxic metals removal from real and complex matrices; (ii) optimised the biosorption process in a fixed-bed column, which was further scaled-up to pilot plants. An overview of toxic metals sources, chemistry and toxicity, which are relevant aspects to understand and develop treatment techniques, is initially presented. The problem of water resources pollution by toxic metals and more specifically the participation of metal finishing industries in the environmental contamination are issues also covered. The current and potential decontamination methods are presented including a discussion of their advantages and drawbacks. The literature on biosorption was reviewed in detail, considering especially the ion exchange properties of cell wall constituents, such as alginate and fucoidan, and their role in metal sequestration. Besides that, a detailed description of biosorption process design, especially in continuous mode, and the application of mechanistic models is addressed.

Strategies to reduce mass and photons transfer limitations in heterogeneous photocatalytic processes: Hexavalent chromium reduction studies.

The current work presents different approaches to overcome mass and photon transfer limitations in heterogeneous photocatalytic processes applied to the reduction of hexavalent chromium to its trivalent form in the presence of a sacrificial agent. Two reactor designs were tested, a monolithic tubular photoreactor (MTP) and a micro-meso-structured photoreactor (NETmix), both presenting a high catalyst surface area per reaction liquid volume. In order to reduce photon transfer limitations, the tubular photoreactor was packed with transparent cellulose acetate monolithic structures (CAM) coated with the catalyst by a dip-coating method. For the NETmix reactor, a thin film of photocatalyst was uniformly deposited on the front glass slab (GS) or on the network of channels and chambers imprinted in the back stainless steel slab (SSS) using a spray system. The reaction rate for the NETmix photoreactor was evaluated for two illumination sources, solar light or UVA-LEDs, using the NETmix with the front glass slab or/and back stainless steel slab coated with TiO2-P25. The reusability of the photocatalytic films on the NETmix walls was also evaluated for three consecutive cycles using fresh Cr(VI) solutions. The catalyst reactivity in combination with the NETmix-SSS photoreactor is almost 70 times superior to one obtained with the MTP.

Nitrogen Removal from Landfill Leachate by Microalgae.

Landfill leachates result from the degradation of solid residues in sanitary landfills, thus presenting a high variability in terms of composition. Normally, these effluents are characterized by high ammoniacal-nitrogen (N-NH4⁺) concentrations, high chemical oxygen demands and low phosphorus concentrations. The development of effective treatment strategies becomes difficult, posing a serious problem to the environment. Phycoremediation appears to be a suitable alternative for the treatment of landfill leachates. In this study, the potential of Chlorella vulgaris for biomass production and nutrients (mainly nitrogen and phosphorus) removal from different compositions of a landfill leachate was evaluated. Since microalgae also require phosphorus for their growth, different loads of this nutrient were evaluated, giving the following N:P ratios: 12:1, 23:1 and 35:1. The results have shown that C. vulgaris was able to grow in the different leachate compositions assessed. However, microalgal growth was higher in the cultures presenting the lowest N-NH4⁺ concentration. In terms of nutrients uptake, an effective removal of N-NH4⁺ and phosphorus was observed in all the experiments, especially in those supplied with phosphorus. Nevertheless, N-NO3- removal was considered almost negligible. These promising results constitute important findings in the development of a bioremediation technology for the treatment of landfill leachates.

Multidrug-resistant Enterobacteriaceae from indoor air of an urban wastewater treatment plant.

Wastewater treatment plants (WWTPs) have been recognized as sources of bioaerosols that may act as vehicles for dissemination of pathogens and multidrug-resistant (MDR) bacteria. The occurrence of MDR Enterobacteriaceae in indoor air of an urban WWTP was investigated. A possible airborne contamination with extended-spectrum beta-lactamase (ESBL) and carbapenemase-producing Enterobacteriaceae was also explored. Fourteen of 39 Enterobacteriaceae isolates were MDR. These isolates were found at all sampling sites, mainly at the secondary sedimentation settings. The highest levels of resistance were detected in three different species: Enterobacter cloacae, Escherichia coli, and Citrobacter freundii. Furthermore, one of the airborne E. coli isolates was phenotypically characterized as an ESBL producer. Additionally, five isolates showed non-susceptibility to at least one carbapenem tested. The presence of genes encoding relevant beta-lactamase types in these ESBL-producing and carbapenem-resistant Enterobacteriaceae isolates was investigated by PCR. Results showed amplification for bla CTX-M and bla OXA. These findings are relevant both in terms of occupational/public health and of environmental dissemination of MDR bacteria.

Insights into solar photo-Fenton reaction parameters in the oxidation of a sanitary landfill leachate at lab-scale.

This work evaluates the effect of the main photo-Fenton (PF) reaction variables on the treatment of a sanitary landfill leachate collected at the outlet of a leachate treatment plant, which includes aerated lagooning followed by aerated activated sludge and a final coagulation-flocculation step. The PF experiments were performed in a lab-scale compound parabolic collector (CPC) photoreactor using artificial solar radiation. The photocatalytic reaction rate was determined while varying the total dissolved iron concentration (20-100 mg Fe(2+)/L), solution pH (2.0-3.6), operating temperature (10-50 °C), type of acid used for acidification (H2SO4, HCl and H2SO4 + HCl) and UV irradiance (22-68 W/m(2)). This work also tries to elucidate the role of ferric hydroxides, ferric sulphate and ferric chloride species, by taking advantage of ferric speciation diagrams, in the efficiency of the PF reaction when applied to leachate oxidation. The molar fraction of the most photoactive ferric species, FeOH(2+), was linearly correlated with the PF pseudo-first order kinetic constants obtained at different solution pH and temperature values. Ferric ion speciation diagrams also showed that the presence of high amounts of chloride ions negatively affected the PF reaction, due to the decrease of ferric ions solubility and scavenging of hydroxyl radicals for chlorine radical formation. The increment of the PF reaction rates with temperature was mainly associated with the increase of the molar fraction of FeOH(2+). The optimal parameters for the photo-Fenton reaction were: pH = 2.8 (acidification agent: H2SO4); T = 30 °C; [Fe(2+)] = 60 mg/L and UV irradiance = 44 WUV/m(2), achieving 72% mineralization after 25 kJUV/L of accumulated UV energy and 149 mM of H2O2 consumed.

Enhancement of a solar photo-Fenton reaction with ferric-organic ligands for the treatment of acrylic-textile dyeing wastewater.

Literature describes a kinetic mineralization profile for most of acrylic-textile dyeing wastewaters using a photo-Fenton reaction characterized by a slow degradation process and high reactants consumption. This work tries to elucidate that the slow decay on DOC concentration is associated with the formation of stable complexes between Fe(3+) and textile auxiliary products, limiting the photoreduction of Fe(3+). This work also evaluates the enhancement of a solar photo-Fenton reaction through the use of different ferric-organic ligands applied to the treatment of a simulated acrylic-textile dyeing wastewater, as a pre-oxidation step to enhance its biodegradability. The photo-Fenton reaction was negatively affected by two dyeing auxiliary products: i) Sera(®) Tard A-AS, a surfactant mainly composed of alkyl dimethyl benzyl ammonium chloride and ii) Sera(®) Sperse M-IW, a dispersing agent composed of polyglycol solvents. The catalytic activity of the organic ligands toward the ferrous-catalysed system followed this order: Fe(III)-Oxalate > Fe(III)-Citrate > Fe(III)-EDDS, and all were better than the traditional photo-Fenton reaction. Different design parameters such as iron concentration, pH, temperature, flow conditions, UV irradiance and H2O2 addition strategy and dose were evaluated. The ferrioxalate induced photo-Fenton process presented the best results, achieving 87% mineralization after 9.3 kJUV L(-1) and allowing to work until near neutral pH values. As expected, the biodegradability of the textile wastewater was significantly enhanced during the photo-Fenton treatment, achieving a value of 73%, consuming 32.4 mM of H2O2 and 5.7 kJUV L(-1).

Biodegradability and toxicity assessment of a real textile wastewater effluent treated by an optimized electrocoagulation process.

In this work, the application of an iron electrode-based electrocoagulation (EC) process on the treatment of a real textile wastewater (RTW) was investigated. In order to perform an efficient integration of the EC process with a biological oxidation one, an enhancement in the biodegradability and low toxicity of final compounds was sought. Optimal values of EC reactor operation parameters (pH, current density and electrolysis time) were achieved by applying a full factorial 3(3) experimental design. Biodegradability and toxicity assays were performed on treated RTW samples obtained at the optimal values of: pH of the solution (7.0), current density (142.9 A m(-2)) and different electrolysis times. As response variables for the biodegradability and toxicity assessment, the Zahn-Wellens test (Dt), the ratio values of dissolved organic carbon (DOC) relative to low-molecular-weight carboxylates anions (LMCA) and lethal concentration 50 (LC50) were used. According to the Dt, the DOC/LMCA ratio and LC50, an electrolysis time of 15 min along with the optimal values of pH and current density were suggested as suitable for a next stage of treatment based on a biological oxidation process.

Ozonation using a stainless-steel membrane contactor: Gas-liquid mass transfer and pharmaceuticals removal from secondary-treated municipal wastewater.

A tubular porous stainless steel membrane contactor was characterized in terms of ozone-water mass transport, as well as its application in removing 23 pharmaceuticals (PhACs) detected in the secondary-treated municipal wastewater, under continuous mode operation. The volumetric mass transfer coefficient (KLa) was evaluated based on liquid flow rate, gas flow rate, and ozone gas concentration. The KLa values were substantially improved with an increment in liquid flow rate (1.6 times from 30 to 70 dm3 h-1) and gas flow rate (3.6 times from 0.30 to 0.85 Ndm3 min-1) due to the improved mixing in the gas-liquid interface. For the lowest liquid flow rate (30 dm3 h-1), the water phase boundary layer (82%) exhibited the major ozone transfer resistance, but it became almost comparable with membrane resistance for the highest liquid flow rate (70 dm3 h-1). Additionally, the influence of the specific ozone dose (0.39, 0.53, and 0.69 g O3 g DOC-1) and ozone inlet gas concentration ( [Formula: see text]  = 27, 80, and 134 g Nm-3) were investigated in the elimination of 23 PhACs found in secondary-treated municipal wastewater. An ozone dose of 0.69 g O3 g DOC-1 and residence time of 60 s resulted in the removal of 12 out of the 23 compounds over 80%, while 17 compounds were abated above 60%. The elimination of PhACs was strongly correlated with kinetic reaction constants values with ozone and hydroxyl radicals (kO3 and kHO•), leading to a characteristic elimination pattern for each group of contaminants. This study demonstrates the high potential of membrane contactors as an appealing alternative for ozone-driven wastewater treatment.

Continuous UV-C/H2O2 and UV-C/Chlorine applied to municipal secondary effluent and nanofiltration retentate: Removal of contaminants of emerging concern, ecotoxicity, and reuse potential.

As global effects of water scarcity raise concerns and environmental regulations evolve, contemporary wastewater treatment plants (WWTPs) face the challenge of effectively removing a diverse range of contaminants of emerging concern (CECs) from municipal effluents. This study focuses on the assessment of advanced oxidation processes (AOPs), specifically UV-C/H2O2 and UV-C/Chlorine, for the removal of 14 target CECs in municipal secondary effluent (MSE, spiked with 10 µg L-1 of each CEC) or in the subsequent MSE nanofiltration retentate (NFR, no spiking). Phototreatments were carried out in continuous mode operation, with a hydraulic retention time of 3.4 min, using a tube-in-tube membrane photoreactor. For both wastewater matrices, UV-C photolysis (3.3 kJ L-1) exhibited high efficacy in removing CECs susceptible to photolysis, although lower treatment performance was observed for NFR. In MSE, adding 10 mg L-1 of H2O2 or Cl2 enhanced treatment efficiency, with UV-C/H2O2 outperforming UV-C/Chlorine. Both UV-C/AOPs eliminated the chronic toxicity of MSE toward Chlorella vulgaris. In the NFR, not only was the degradation of target CECs diminished, but chronic toxicity to C. vulgaris persisted after both UV-C/AOPs, with UV-C/Chlorine increasing toxicity due to potential toxic by-products. Nanofiltration permeate (NFP) exhibited low CECs and microbial content. A single chlorine addition effectively controlled Escherichia coli regrowth for 3 days, proving NFP potential for safe reuse in crop irrigation (<1 CFU/100 mL for E. coli; <1 mg L-1 for free chlorine). These findings provide valuable insights into the applications and limitations of UV-C/H2O2 and UV-C/Chlorine for distinct wastewater treatment scenarios.

Water quality in Minho/Miño River (Portugal/Spain).

Minho River, also called Miño (in Spain), extends to about 300 km from Spain to Portugal. The source of the river lies in Spain and in the last 75 km, the river defines the border between Portugal and Spain. Under the scope of a cooperation project between North Portugal and Galicia region of Spain, titled: "Valorization of the natural resources of the Minho/Miño drainage basin", seven water-sampling campaigns were carried out during the last 2 years in Minho River basin. Seven sampling sites were selected along the international stretch, and five were chosen in the main Portuguese and Spanish tributaries of Minho River. Water quality based on the physicochemical and microbial parameters was assessed. According to the Portuguese legislation for surface waters, the international section of Minho River presents a reasonably good water quality (BOD5 <5 mg/L, TNK <2 mg/L, and total phosphorous <1 mg P/L). Valença and Louro were found to be the most polluted sampling sites and Louro the most polluted tributary (maximum values observed: TSS = 26 mg/L, BOD5 = 6.6 mg O2/L, COD = 20.8 mg O2/L, total nitrogen = 9.9 mg N/L; minimum value observed: OD = 1.3 mg O2/L). A one-dimensional stream water quality model QUAL2Kw was calibrated using data measured in field surveys along the international stretch of Minho River. QUAL2Kw was also used to predict the impact of flow conditions, discharges, and tributaries on the water quality of international stretch of Minho River, essential to establish proposals for management and planning of Minho River Basin.

Assessment of indoor airborne contamination in a wastewater treatment plant.

The main objective of this work was to quantify and characterize the major indoor air contaminants present in different stages of a municipal WWTP, including microorganisms (bacteria and fungi), carbon dioxide, carbon monoxide, hydrogen sulfide ammonia, formaldehyde, and volatile organic compounds (VOCs). In general, the total bacteria concentration was found to vary from 60 to >52,560 colony-forming units (CFU)/m(3), and the total fungi concentration ranged from 369 to 14,068 CFU/m(3). Generally, Gram-positive bacteria were observed in higher number than Gram-negative bacteria. CO(2) concentration ranged from 251 to 9,710 ppm, and CO concentration was either not detected or presented a level of 1 ppm. H(2)S concentration ranged from 0.1 to 6.0 ppm. NH(3) concentration was <2 ppm in most samples. Formaldehyde was <0.01 ppm at all sampling sites. The total VOC concentration ranged from 36 to 1,724 µg/m(3). Among the VOCs, toluene presented the highest concentration. Results point to indoor/outdoor ratios higher than one. In general, the highest levels of airborne contaminants were detected at the primary treatment (SEDIPAC 3D), secondary sedimentation, and sludge dehydration. At most sampling sites, the concentrations of airborne contaminants were below the occupational exposure limits (OELs) for all the campaigns. However, a few contaminants were above OELs in some sampling sites.

Cork barriers for the remediation of soils polluted with lindane.

The in-situ removal of lindane from spiked soil was studied using cork barriers combined with electrokinetic and ohmic heating soil remediation processes. Both vertical and horizontal cork barriers have been evaluated to retain pollutants mobilized by electro-osmotic flow or volatilized by ohmic heating. Moreover, the addition of surfactant solutions in electrolyte wells has been evaluated to promote the dragging of lindane by electrokinetic fluxes. Results indicated that the drag of lindane by liquid flows is not as important as expected, opposite to what happened with the dragging by gaseous flows. The retention of gaseous lindane was also confirmed in adsorption tests carried out in a column packed with cork granules. The addition of surfactant had a very limited effect on the mobility of lindane, and dragging of this species to the electrode wells or to a permeable reactive barrier. On the contrary, the reactivity of lindane during the electrochemical treatments is relevant due to the electrokinetic basic front promoting the in-situ conversion of lindane into less chlorinated pollutants.

Influence of oxygen vacancies, surface composition, and crystallite size on the photoelectrochemical oxidation activity of C,N-codoped TiO2 for cefadroxil abatement along with O3.

This study aims the development of photoelectrodes to be incorporated in a photoelectrocatalytic ozonation (PECO) process for tertiary treatment of urban wastewaters, targeting the removal of contaminants of emerging concern (CEC). PECO tests were performed using urban wastewater after secondary treatment fortified with Cefadroxil (CFX, C16H17N3O5S), as target model CEC. Three Nitrogen and Carbon doped TiO2 (CN-TiO2) electrodes were synthesized by anodizing at 50, 70, and 90 V, and calcined. These materials were characterized by X-Ray diffraction and Rietveld refinement, Scanning Electron Microscopy, Diffuse Reflectance Spectroscopy, X-ray photoelectron spectroscopy, chronoamperometry, and electrochemical impedance spectroscopy, to correlate defects with photoactivity. All photoanodes considerably reduced their main bandgaps by the incorporation of C and N species, to enable absorption capacities in the UV region using a Xe lamp. The lowest oxygen vacancy content and largest crystallite size were found for CN-TiO2-70, favoring the reduction of bulk defects that could act as recombination of charge carriers. Therefore, oxygen vacancies affect more the TiO2 photoactivity compared to the crystallite size or the light absorption capacity, confirming that a lower content of vacancies in the material bulk and surface doping significantly influence the activity as detected by Rietveld refinement, DRS, and XPS. The electrochemical techniques confirm that the highest photocurrent was obtained for CN-TiO2-70, whence this photoanode was chosen to carry out the CFX degradation. A point defect model simulating Nyquist plot reveals that the photoactivity depends on the speed to diffuse oxygen vacancies through the TiO2 coating. All abatement processes were followed by high-performance liquid chromatography, and Total Organic Carbon (TOC). At neutral and alkaline conditions, CFX is eliminated to levels below the analytical detection limit after 90 min of treatment (TOC removals of 87 and 91%, respectively), indicating that the coupling between the CN-TiO2-70 photocatalyst and ozone is effective in eliminating the contaminant due to parallel routes forming •OH species. Lower CFX degradation observed at acidic pH (TOC removal of 70%) is assigned to the difficulty of oxidizing protonated CFX species.

Ozone membrane contactor for tertiary treatment of urban wastewater: Chemical, microbial and toxicological assessment.

A membrane ozone contactor, operated under continuous mode, was applied to promote the tertiary treatment of urban wastewater (UWW), targeting the removal of contaminants of emerging concern (CECs), bacterial disinfection, and toxicity reduction. This system relies on the homogeneous radial distribution of ozone (O3) in the reaction zone by "titration" through a microfiltration borosilicate tubular membrane, while the UWW swirls around the membrane and drags the O3 microbubbles generated in the membrane shell-side. The membrane is coated with titanium dioxide (TiO2-P25) and radiation can be externally supplied via four UV lamps. The ozonation tests were carried out with secondary-treated UWW collected in different seasons (winter and summer) and spiked with a mix of 19 CECs (10 µg L-1 each). For an O3 dose of 18 g m-3, the best performance was obtained by increasing the O3 concentration (maximum [O3]G,inlet of 200 g Nm-3) and decreasing the gas flow rate (minimum QG of 0.15 Ndm3 min-1), providing the highest ozone transfer yield (88 %) and, thus higher specific ozone dose (g O3 per g dissolved organic carbon). Under these conditions, removals >80 % or concentrations below the limit of quantification were obtained for up to 13 of the 19 CECs and reductions up to 5 log units for total heterotrophs and below the limit of detection for enterobacteria and enterococci. Tests including a UVC dose of 0.10 kJ L-1 enhanced disinfection ability but had no impact on CECs oxidation. After ozonation, the abundance of antibiotic resistant bacteria was reduced but not eliminated, and microbial regrowth after 3-day storage was observed. No toxic effect was detected on zebrafish embryos using a dilution factor of 4 for the ozonized UWW and when granular activated carbon adsorption was subsequently applied the dilution factor decreased to 2.

Water quality in Lis river, Portugal.

In the past 30 years, the Lis river basin has been subjected to constant ecological disasters mainly due to piggery untreated wastewater discharges. The aim of this study was to evaluate the effect of existing domestic, agricultural, and industrial activities on the water quality, and to propose a watershed plan to protect and manage surface water resources within the Lis river basin. For this purpose, 16 monitoring stations have been strategically selected along the Lis river stretch and its main tributaries to evaluate the water quality in six different sampling periods (2003­2006). All samples were characterized in terms of organic material, nutrients, chlorophyll, and pathogenic bacteria. Generally, the Lis river presents poor water quality, according to environmental quality standards for surface water, principally in terms of dissolved oxygen, biochemical oxygen demand, total nitrogen, and fecal coliform, which can be associated mainly with the contamination source from pig-breeding farms.

Ultrafiltration ceramic membrane as oxidant-catalyst/water contactor to promote sulfate radical AOPs: a case study on 17ß-estradiol and 17α-ethinylestradiol removal.

This work highlights the performance of an ultrafiltration ceramic membrane as photocatalyst support and oxidant-catalyst/water contactor to promote sulfate radical advanced oxidation processes (SR-AOPs). Peroxydisulfate (PDS) activation mechanisms include photolysis (UVC irradiation) and chemical electron transfer (TiO2-P25 photocatalysis). The photoreactor is composed of an outer quartz tube (the "window"-radiation entrance to the reactor) and an inner tubular ceramic ultrafiltration membrane, where the catalyst particles (TiO2-P25) are immobilized on the membrane shell-side. PDS stock solution is fed by the lumen side of the membrane, delivering the oxidant to the catalyst particles and to the annular reaction zone (ARZ), being the catalyst and PDS activated by UV light. The design facilitates controlled radial slip of PDS into the catalyst surface and to concurrent water to be treated, flowing with a helix trajectory in the ARZ. Under continuous mode operation, with an UV fluence of 45 mJ cm-2 (residence time of 4.6 s), the UVC/PDS/TiO2 system showed the best removal efficiency for two specific endocrine disrupting chemicals, 17ß-estradiol (E2) and 17α-ethinylestradiol (EE2), spiked (100 µg L-1 each) in demineralized water and urban wastewater after secondary treatment.

Industrial steel waste recovery pathway: Production of innovative supported catalyst and its application on hexavalent chromium reduction studies.

Mill scale is the metallurgical waste produced by the rolling mill in the steel hot rolling process. This hazardous waste is mainly composed of oxide iron, such as hematite, magnetite and wustite. It may have a different and alternative final destination by becoming a catalyst for wastewater treatment. In this work, the catalytic potential of mill scale (MS) from a steel plant was evaluated for hexavalent chromium reduction from synthetic and real matrices under slurry conditions (MS particles dispersed in the solution) or immobilized in Raschig rings. Experiments were conducted in an annular photoreactor irradiated by UVA light. Raschig rings were coated with MS by electrostatic link with polyethylene-grafted-maleic anhydride copolymer (PEGMA) film, and further packed in the annular zone of the UV photoreactor. SEM, XRD and FTIR analysis showed a homogeneous film of MS firmly attached on Raschig rings surface. In this way, the iron-rich industrial steel waste acted as both source of iron and photocatalyst, allowing the reduction of Cr(VI) to Cr(III) in the bulk solution and MS surface, respectively, in the presence of tartaric acid as hole and hydroxyl scavenger and Fe-complexing agent. The Raschig rings (248 g) coated with MS (23 g) achieved total Cr(VI) reduction (below detection limit) after 45 min of reaction (k = 2.0 × 10-2 mg L-1 min- 1) under UVA radiation, considering the following initial conditions: [Cr(VI)]0 = 10 mg L-1, [tartaric acid]0/[Cr(VI)]0 molar ratio = 6:1, pH = 3.0, T = 25 °C. The same system was tested for the treatment of a real effluent from a galvanic industry containing 6 mg L-1 of Cr(VI). Using the same tartaric acid/Cr(VI) molar ratio (6:1) and pH 3.0, the Cr(VI) present in the effluent was totally reduced (below detection limit) in 360 min (k = 1.93 × 10-2 mg L- 1 min- 1), showing similar kinetic behavior as the process with the synthetic matrix. In all experiments, the concentrations of dissolved iron (Fe(II) and Fe(total)) were below the disposal limit established by Brazilian legislation, and total chromium removal was achieved by Cr(III) precipitation after the photocatalytic reaction.