ABSTRACT
The presence of 17α-ethinylestradiol (EE2) in water bodies and its potential risks to human health and the environment have been frequently described in the literature, in addition to its limited removal in conventional wastewater treatment plants. Many studies have evaluated this removal by advanced processes, including photodegradation and membrane separation. A significant number of studies also assess the economic analysis of these technologies. However, few works articulate both perspectives: the specificity involved in estrogen removal and economic analysis. Given this gap, this work evaluates the synergies involved in the integration of reverse osmosis (RO) and advanced oxidative processes by UV/H2O2 (AOP) in the post-treatment of membrane bioreactor (MBR) effluents. To this end, the integrated plant possibilities were represented through a superstructure that integrated EE2 removal and cost models of each process. The use of a Hook and Jeeves optimizer considering these processes standard operating conditions made it possible to determine the percentage of stream division for each equipment and even the absence of any of these in an integrated plant with lower cost and EE2 concentration output below the recommended limit by the European Union (0.035 ng.L-1). For EE2 feed content up to 3 ng.L-1, the lowest cost configuration is to route 20% of the MBR effluent to the AOP, 30% to the RO, and the remainder to a final mixer. For concentrations above 15 ng.L-1, the sufficient and lowest cost configuration is the MBR-RO-AOP series. Intermediate values have a more advantageous integrated process configuration with the parallel and series configurations combined, with a stream distribution dependent on the feed concentration. Moreover, a parameter sensitivity analysis was performed, clarifying paths for design improvements and acting as a systematic guide for future work in this area. This analysis highlights that EE2 removal is more sensitive to temperature (1.04%), feed substrate concentration (-1.18%), solid retention time in the MBR (0.32%), and irradiance in AOP (-0.46%). Investment costs also proved to be decisive in the composition of the total cost, enhancing the relevance of the maturation process of these technologies in light of simple changes in operating parameters.
Subject(s)
Water Pollutants, Chemical , Water Purification , Bioreactors , Cost-Benefit Analysis , Ethinyl Estradiol/analysis , Humans , Hydrogen Peroxide , Membranes, Artificial , Osmosis , Waste Disposal, Fluid , Water Pollutants, Chemical/analysisABSTRACT
Synthetic hormone 17α-ethinylestradiol (EE2) is not completely removed by conventional wastewater treatment plants and therefore is often detected in surface and groundwater, sludge and sediments. Due to its persistence in the environment and its estrogenic potential, a high removal of EE2 from wastewaters before its disposal has become a concern from an environmental point of view, particularly when considering urban reuse applications. This work investigated the application of advanced processes to treat synthetic municipal wastewater containing EE2 after treatment in a membrane bioreactor (MBR). Two advanced processes were assessed: the first is advanced oxidation process (AOP), using hydrogen peroxide (H2O2) and ultraviolet (UV) light (route MBR-AOP) and the second, reverse osmosis (RO), in this case using UV/H2O2 to treat the retentate from RO (route MBR-RO). EE2 concentration in final effluent was one order of magnitude lower in route MBR-AOP than in route MBR-RO. Implications for disposal or water reuse were discussed considering the importance of other water quality parameters as well. Economic estimates for CAPEX, OPEX and total cost were made. The introduction of the oxidative step (UV/H2O2) after MBR caused an increase in the total cost of US$ 0.39/m3. In turn, route MBR-RO increased the total process cost by US$ 0.86/m3, showing that reduction of volume to be treated by UV/H2O2 in this route did not offset the cost associated with the acquisition and operation of RO. The total cost was estimated at US$ 2.47/m3 for MBR-AOP and US$ 2.94/m3 for MBR-RO for a design flow of 10 m³/h.
Subject(s)
Water Pollutants, Chemical , Water Purification , Bioreactors , Ethinyl Estradiol , Hydrogen Peroxide , Membranes, Artificial , Osmosis , Waste Disposal, Fluid , WastewaterABSTRACT
This work explored the use of ozonation and photoperoxidation before the microfiltration process to reduce fouling. Produced water was synthesized with salt, viscosifier, and surfactant. The additives influence on membrane fouling was evaluated. Photoperoxidation process led to an overall better performance than ozonation in terms of oil removal and fouling reduction. The maximum oil removal efficiency was 86%, obtained for emulsions with salt after 2 h of treatment (COD: H2O2 ratio 1:1, UV dose of 965 J/m2). The inclusion of chemical additives impaired the oxidative power of hydroxyl radicals leading to a moderate oil removal; however, they were still able to reduce membrane fouling, mainly in oil/water emulsions with viscosifier. Higher salt concentration promoted fouling resistance and also benefited the permeate quality. Cross-flow microfiltration process integrated with photoperoxidation was able to improve the permeate flux from 84 to 182 L/m2.h after 3 h of exposure to UV radiation, resulting in a permeate with less than 10 mg/L of oil content. Graphical abstract.
Subject(s)
Hydrogen Peroxide , Water Purification , Filtration , Membranes, Artificial , Oxidation-Reduction , WaterABSTRACT
RESUMO Água do mar é comumente utilizada como fluido de injeção em plataformas offshore na recuperação secundária do petróleo. Porém, a presença de sulfato causa diversos inconvenientes, como a formação de precipitados, que podem se depositar em diversas partes da plataforma de produção. Atualmente, a dessulfatação é realizada em unidades removedoras de sulfato (URS) por processo de nanofiltração (NF), cujas amostras precisam ser pré-tratadas, usualmente em filtros cartuchos. Os sólidos suspensos e os microrganismos que não foram retidos pelo sistema de filtração podem depositar sobre a superfície das membranas de NF, diminuindo a produtividade do sistema e reduzindo o tempo de vida das membranas. O processo de microfiltração (MF) pode ser utilizado como pré-tratamento alternativo e possibilitaria a remoção desses elementos. Neste estudo, foi desenvolvido um processo combinado de MF e NF para a dessulfatação da água do mar, visando a sua injeção em reservatórios de petróleo. Módulos de permeação contendo membranas de poli(imida) no formato de fibras ocas foram utilizados na construção de um sistema piloto de MF integrado a um sistema piloto de NF similar aos já atualmente utilizados nas plataformas. O desempenho dos sistemas foi avaliado por meio do acompanhamento da permeabilidade de ambos durante a filtração da água do mar. Parâmetros como grau de recuperação de água, frequência e eficiência de procedimentos de retrolavagem e limpeza química também foram estudados. Os resultados demonstraram que o pré-tratamento da água do mar por MF é uma alternativa eficaz para a dessulfatação por NF.
ABSTRACT Seawater is commonly used in offshore platforms as an injection fluid in secondary oil recovery. However, the sulfate found in seawater has been the cause of many inconveniences, such as the formation of precipitates, which can settle in various parts of the production platform. Nowadays, nanofiltration (NF) is used in sulfate removal units for seawater desulfation, where cartridge filters are commonly used for seawater pretreatment. Suspended solids and microorganisms that have not been retained by the filtration system may deposit on the surface of NF membranes, decreasing system productivity and reducing membrane life. The microfiltration (MF) process can be used as an alternative pretreatment and would allow the removal of these elements. In this study, a combined process of MF and NF for seawater desulfation was developed for injection into oil reservoirs. Permeation modules containing hollow fiber shaped poly (imide) membranes were used in the construction of an MF pilot system, integrated with an NF pilot system similar to those already used on platforms. The performance of the systems was evaluated by monitoring the permeability of both during seawater filtration. Parameters such as degree of water recovery, frequency, and efficiency of backwash procedures and chemical cleaning were also studied. The results showed that MF seawater pretreatment is an effective alternative for NF desulfation.
ABSTRACT
RESUMO O objetivo deste trabalho foi discutir os principais parâmetros de controle de um sistema de membranas de microfiltração para remoção de óleo de efluentes com base em ensaios experimentais. Os ensaios utilizaram efluentes sintéticos com diâmetros de gotas de óleo entre 4 e 8 µm. As membranas usadas foram do tipo fibra oca com módulo submerso. Foram testados os seguintes parâmetros: concentrações de óleos e graxas na alimentação das membranas (O&Gam) entre 100 e 260 mg.L-1; taxas de recuperação de água (Rec) de 0,75 e 0,90; e pressões através das membranas (Δp) de -0,20 e -0,30 bar. Os resultados mostraram que as membranas produzem um permeado com uma qualidade boa a ponto de possibilitar o seu reúso em atividades industriais diversas. Foi também observado que a elevação da O&Gam e da Rec acentuam o declínio de fluxo com o tempo e que a elevação da Δp aumenta o valor do fluxo no tempo de seis horas.
ABSTRACT The aim of this paper is to discuss the main control parameters of a microfiltration membranes system for oil removal from effluent on experimental bases. The experiments were conducted by using synthetic effluent with oil droplets diameter ranging from 4 to 8 microns. The membranes used were hollow fiber-type which were assembled in a submerged module. The following parameters were tested: Oil and grease concentration in the feed stream (O&Gf ) of 100 and 200 mg.L-1, Water recovery rates (WRR) of 0.75 and 0.90, and Transmembrane pressure (TMP) of -0.20 and -0.30 bar. The results showed that the membranes produced a permeate with a good quality to the point of enabling their reuse in several industrial activities. It was also observed that the elevation of O&Gf and WRR increase the flux decline over time and that the increase of TMP increases the flow value in time of 6 hours.
ABSTRACT
Poly(lactic acid) (PLA)-containing nerve guidance conduits (NGCs) are currently being investigated for nerve repair as an alternative to autograft, which leads to permanent functional impairment in the territory innervated by the removed nerve. Combination of polymers modifies the physical properties of the conduits, altering their nerve-guidance properties. Conduits made from PLA-only or combined with other polymers have been used successfully for nerve repair, but their efficiency has not been compared. We compared the morphological and functional outcomes of peripheral nerve repair by using NGCs made of poly(lactic acid) and combined or not with polycaprolactone (PLA/PCL) or polyvinylpyrrolidone (PLA/PVP). To assess the functional recovery, we employed a mechanical hyperalgesia analysis, sciatic functional index (SFI), and electroneuromyography. The mechanical hyperalgesia analysis showed that the PLA group improved more rapidly than the PLA/PVP and PLA/PCL groups; similarly, in the electroneuromyography assay, the PLA group exhibited higher amplitude than the PLA/PCL and PLA/PVP groups. However, the SFI improvement rates did not differ among the groups. Morphologically, the PLA group showed more vascularization, while the nerve fiber regeneration did not differ among the groups. In conclusion, the PLA-only conduits were superior to the other NGCs tested for nerve repair.
ABSTRACT
BACKGROUND: Membrane separation is an established technological process, and since 1980s, it has been used commercially at large industrial plants worldwide. Water and wastewater disinfection is one of the applications of membrane technologies, but fouling and biofouling are still a challenge for the sector. The use of silver nanoparticles in membranes has attracted research interest because of their biocidal action. METHODS: This technology foresight study investigates the academic literature and patenting activity to map out the technological progress and difficulties in the area. RESULTS: One hundred and sixty-seven articles on the subject published between 2005 and 2017 were retrieved, and it was found that the greatest number of publications were undertaken in 2016. A wide range of materials being used to make membranes and institutions involved in researching this technology were identified. Fifty-nine patents of relevance were also retrieved, with 2011 and 2013 seeing the highest number of patent applications filed. CONCLUSION: The countries with the most academic output and priority patents are the United States and China, but no institution stands out from the others in this area.
ABSTRACT
Polymeric biomaterials are often used for stimulating nerve regeneration. Among different conduits, poly(lactide acid) - PLA polymer is considered to be a good substrate due to its biocompatibility and resorbable characteristics. This polymer is an aliphatic polyester which has been mostly used in biomedical application. It is an organic compound with low allergenic potential, low toxicity, high biocompatibility and predictable kinetics of degradation. In this study we fabricated and evaluated a PLA microporous hollow fiber as a conduit for its ability to bridge a nerve gap in a mouse sciatic nerve injury model. The PLA conduit was prepared from a polymer solution, throughout extrusion technique. The left sciatic nerve of C57BL/6 mouse was transected and the nerve stumps were placed into a resorbable PLA (PLA group) or a PCL conduit (PCL group), n=5 each group. We have also used another group in which the nerves were repaired by autograft (autograft group, n=5). Motor function was analyzed according to sciatic functional index (SFI). After 56days, the regenerated nerves were processed for light and electron microscopy and morphometric analyses were performed. A quantitative analysis of regenerated nerves showed significant increase in the number of myelinated fibers and blood vessels in animals that received PLA conduit. The PLA group exhibited better overall tissue organization compared to other groups. Presenting well-organized bundles, many regenerating clusters composed of preserved nerve fibers surrounded by layers of compacted perineurium-like cells. Also the SFI revealed a significant improvement in functional recovery. This work suggests that PLA conduits are suitable substrate for cell survival and it provides an effective strategy to be used to support axonal growth becoming a potential alternative to autograft.
Subject(s)
Nerve Regeneration , Polyesters/chemistry , Sciatic Nerve/physiopathology , Tissue Scaffolds/chemistry , Animals , Cell Survival , Cells, Cultured , Evaluation Studies as Topic , Implants, Experimental , Male , Mice, Inbred C57BL , Peripheral Nerve Injuries/therapy , Recovery of Function , Schwann Cells/physiology , Schwann Cells/ultrastructureABSTRACT
O tratamento de efluentes com coalescedor de leito consiste em induzir o aumento das gotas de óleo, pela passagem da emulsão por um leito poroso, para que elas possam, posteriormente, flotar por processo de separação gravitacional. O objetivo deste artigo foi apresentar considerações técnicas e experimentais sobre o uso do coalescedor de leito granular, com leito constituído por resinas de trocas catiônicas, visando o pré-tratamento de óleo emulsionado em efluentes líquidos. Os testes ocorreram em uma unidade em escala de bancada alimentada com emulsão óleo em água (O/A) com um teor de óleos e graxas (TOG) entre 200 e 400 mg.L-1 e diâmetro de gotas entre 3 a 8 μm. As velocidades do fluido (v) testadas foram entre 4,4 e 17,4 m.h-1. A altura do leito do coalescedor foi fixada em 5 cm. Os parâmetros usados para avaliar a eficiência dos testes foram eficiência de remoção de óleo (%E), pressão diferencial através do leito (Δp) e permeabilidade do leito (ko). Os resultados mostraram que o processo operou em estado estacionário e que os valores de TOG testados influenciaram no processo, bem como as velocidades do fluido, cuja elevação reduziu a eficiência significativamente. Os valores aproximados de %E obtidos foram 50 e 20-30%, para valores de v de 4,4 e 17,4 m.h-1, respectivamente.
The wastewater treatment with a bed coalescer consists of inducing the increase of oil droplets by passing the emulsion through a porous bed, so they can flote by gravitational separation process. The objective of this paper is to present technical and experimental considerations on the use of a granular bed coalescer, with a bed made of cationic exchange resins, for pre-treatment of emulsified oil from oily wastewater. Tests were conducted on a bench scale unit, which was fed with oil in water emulsion with oil and grease concentration (O & G) between 200 and 400 mg.L-1 and oil droplet diameter between 3 and 8 μm. The fluid velocities (v) tested were between 4.4 and 17.4 m.h-1. The coalescer bed height was fixed at 5 cm. The parameters used for assessing the tests efficiency were oil removal efficiency percentage (%E), differential pressure across the bed and, bed permeability. Results showed that the process operates in a steady-state condition and that the influent O&G affected the process efficiency, as well as the fluid velocities which reduced the efficiency significantly, with its increasing. The %E values obtained were between 50 and 20-30% to v between 4.4 and 17.4 m.h-1, respectively.
ABSTRACT
O gerenciamento da água produzida (AP) de petróleo se constitui em um enorme desafio para as empresas petrolíferas. As alternativas usualmente adotadas para o seu destino são o descarte, injeção e o reúso. Em todos os casos é necessário tratamento da AP, a fim de evitar danos ao meio ambiente e às instalações de produção ou a fim de permitir o seu reúso sem causar prejuízos aos processos nos quais a AP será utilizada. Os processos de separação por membranas (PSM) têm se mostrado capazes de tratar efluentes que apresentam elevados teores de óleo em emulsão e de partículas com tamanhos médios e pequenos, competindo, assim, com tecnologias de tratamento mais complexas, tais como flotação. O objetivo deste artigo foi apresentar uma revisão sobre o tratamento de AP utilizando os PSM discutindo os principais aspectos da AP e os aspectos conceituais dos PSM, com ênfase para sua aplicação para remoção de óleo da AP.
The management of oil produced water (PW) constitutes a major challenge to oil companies. The options usually adopted for PW are disposal, injection and reuse. In all cases, a PW treatment is required in order to avoid damages to the environment and to production facilities or to allow its reuse without causing damage to processes in which the PW is used. The membrane separation processes (MSP) has been shown to be capable of treating effluent with high content of emulsified oil and with medium and small sizes particle, competing well with more complex treatment technologies such as flotation. The aim of this paper was to present a review of the PW treatment by MSP, discussing the main aspects of the PW and the conceptual aspects of the MSP, with emphasis on their application for removal of oil from the PW.
ABSTRACT
Rhamnolipids have been pointed out as promising biosurfactants. The most studied microorganisms for the aerobic production of these molecules are the bacteria of the genus Pseudomonas. The aim of this work was to produce a rhamnolipid-type biosurfactant in a bench-scale bioreactor by one strain of Pseudomonas aeruginosa isolated from oil environments. To study the microorganism growth and production dependency on oxygen, a nondispersive oxygenation device was developed, and a programmable logic controller (PLC) was used to set the dissolved oxygen (DO) concentration. Using the data stored in a computer and the predetermined characteristics of the oxygenation device, it was possible to evaluate the oxygen uptake rate (OUR) and the specific OUR (SOUR) of this microorganism. These rates, obtained for some different DO concentrations, were then compared to the bacterial growth, to the carbon source consumption, and to the rhamnolipid and other virulence factors production. The SOUR presented an initial value of about 60.0 mgO(2)/g(DW) h. Then, when the exponential growth phase begins, there is a rise in this rate. After that, the SOUR reduces to about 20.0 mgO(2)/g(DW) h. The carbon source consumption is linear during the whole process.
