A focus on fouling of nanofiltration membranes in the treatment of two-phase olive mill wastewater by boundary flux and pore blocking theories

The implementation of membranes in water and wastewater treatment processes has significantly increased in the last decades. However, membrane fouling leads to increased expenses if not properly examined and considered, and this is especially problematic in wastewater treatments. For this reason, fouling minimization represents the key factor to make those processes feasible. The use of NF membranes is especially problematic regarding fouling problems. In first place, adequate fouling inhibition methods should be designed upstream the membrane operation, in order to make the downstream membrane processes for wastewater treatment technically and economically feasible. In the present work, fouling build-up on a nanofiltration (NF) membrane during the treatment of olive mill wastewater coming from Spain (OMW-S) is addressed by the boundary flux theory, and the results were compared and complemented by using the pore blocking models. Fouling mechanisms are important to fully understand what is happening between the membrane and the effluent, to take the adequate decisions with respect to the design of the membrane plant and set-up of optimized operating conditions. The goal is to operate membranes modules by avoiding irreversible fouling for a long period of time, that is, several years of service lifetime. Thereafter, the operating parameters should be carefully chosen to avoid working beyond the conditions that the selected membrane can stand for the specific feedstream. The followed strategy allows the operation of the membranes system in a controlled framework that permits the stable operation of the plant. Moreover, the required membrane area is minimized and the constancy of the permeate productivity is also narrowed by following the proposed methodology

In Vitro Antitumor and Anti-Inflammatory Activities of Allium-Derived Compounds Propyl Propane Thiosulfonate (PTSO) and Propyl Propane Thiosulfinate (PTS)

Increasing rates of cancer incidence and the side-effects of current chemotherapeutic treatments have led to the research on novel anticancer products based on dietary compounds. The use of Allium metabolites and extracts has been proposed to reduce the proliferation of tumor cells by several mechanisms. In this study, we have shown the in vitro anti-proliferative and antiinflammatory effect of two onion-derived metabolites propyl propane thiosulfinate (PTS) and propyl propane thiosulfonate (PTSO) on several human tumor lines (MCF-7, T-84, A-549, HT-29, Panc-1, Jurkat, PC-3, SW-837, and T1-73). We observed that this effect was related to their ability to induce apoptosis regulated by oxidative stress. In addition, both compounds were also able to reduce the levels of some pro-inflammatory cytokines, such as IL-8, IL-6, and IL-17. Therefore, PTS and PTSO may have a promising role in cancer prevention and/or treatmentMISIONES-CDTI program (CDTI, Centre for the Development of Industrial Technology; CULTUREDMEAT Project)Junta de Andalucia PI19/01058Instituto de Salud Carlos III MIG-2020101European CommissionInstituto de Salud Carlos III CTS 164 IFI21/0003

Optimization study of the fouling build-up on a RO membrane for pretrated olive mill wastewater purification

Even though membranes are considered in many aspects a mature technology, a range of features are still in development and under investigation. Regarding this, the main handicap of this technology is inevitably membrane fouling. Fouling issues have investigated by many research groups in the last years to convince investors to implement membranes as substitutes of a range of unit operations at industrial scale. In the wastewater treatment field, this is especially problematic, given the low economic value of the product, that is, treated water. On another hand, the management of the effluents generated by olive oil industries, olive mill wastewaters (OMW), is a task of global concern not anymore constrained to a specific region. These wastewaters represent an ever-increasing problem still unresolved. The present work was aimed for the modelling and optimization of a reverse osmosis (RO) membrane operation for the purification of pretreated olive mill wastewater, with a focus on the dynamic fouling development minimization on the selected membrane as a function of the set-up of the operating conditions. For this goal, beforehand a factorial design was implemented for the optimization of the RO treatment of the OMW stream. The results gathered were thereafter interpreted by means of the response surface methodology. A significant impact was noted to be driven by the operating pressure and the tangential velocity on the fouling rate on the RO membrane. The response surfaces withdrawn from the experimental data support the previous results, and the optimised parameters - ambient temperature range (24 - 25 °C), moderate operating pressure (25 - 30 bar) and turbulent tangential flow (3.1 - 3.5 m s -1 ) - were found to provide a stable permeate flux of 32.3 - 38.5 L h -1 m -2 . These results reveal the proposed process could be operated successfully at ambient temperature conditions and medium operating pressure, boosting the economic efficiency of the RO purification of this effluent. Finally, the parametric quality standards stablished to reuse the purified effluent for irrigation purposes were checked and found to be satisfactory

Analysis of fouling resistances under dynamic filtration of pretreated olive mill wastewater on a loose reverse osmosis membrane

In this work, a loose reverse osmosis (RO) membrane (Osmonics AK model), capable of offering beforehand higher fluxes under lower operating pressure than typical tight reverse osmosis membranes but still offering similar rejection, was used for the final purification of olive mill wastewater. However, the output that a membrane may offer when it is virgin and readily used will change in time due to membrane fouling. If not properly considered, the advantages that a chosen membrane may offer in contrast with others would quickly and often irreversibly vanish, with the consequences in terms of capital expenses that this will represent. One approach to meet the investor's needs to trust membrane technology is to guarantee that fouling will be inhibited as much as possible, but to overcome the loss of performance that fouling carries engineers overdesign the membrane plants by using too wide safety margins that trigger the costs sensibly. Since the mechanisms by which fouling phenomena are triggered are always complex, the osmotic-pressure resistances-in-series model can be a simple but reliable model to describe the membrane response and predict its performance in time. In this context, the normalized fouling measured on the examined RO membrane was found to be minimum in the operating pressure range between 5 and 8 bar (0.65-0.98, respectively), and it decreased down to 0.51 upon increasing the crossflow up to 5.09 m s-1, avoiding irreversible fouling. Moreover, significantly minor fouling (0.33) was attained at the lowest temperature, regularly experienced during the olive oil production campaign. On another hand, the rejection towards organic solutes was maintained above 97%

Multiple emulsions as a tool to microencapsulate bioactive compounds with controlled release

En esta conferencia se abordarán conceptos generales relacionados con las emulsiones múltiples, sistemas dispersos complejos en los que la fase dispersa es una emulsión, y están caracterizados por tener una baja estabilidad termodinámica. Cada uno de los glóbulos en estos sistemas contiene uno o más compartimentos de una fase, la cual está separada de una fase químicamente similar, a través de una membrana o película de una fase diferente e inmiscible; es por ello que también suele dárseles el nombre de membranas dobles. Los dos tipos más comunes de estos sistemas son las emulsiones de agua–aceite–agua (W1/O/W2) y aceite–agua–aceite (O1/W/O1). Las emulsiones múltiples W1/O/W2 tienen un gran potencial de aplicación en la industria farmacéutica, cosmética, agrícola, alimentaria y ambiental; pues pueden ser usadas como medios de separación de sustancias contaminantes, encapsulación y liberación controlada de productos probióticos, en la protección oxidativa de sabores y encapsulación de fármacos o para generar nuevos alimentos de bajo contenido calórico. También existen trabajos de la implementación de estos sistemas en la elaboración de películas y/o recubrimientos comestibles. Sin embargo, la inherente inestabilidad de las emulsiones W1/O/W2 que se asocia a la complejidad estructural de estos sistemas sigue limitando su aplicación, por lo que abordaremos las nuevas estrategias de estabilización que están resultando exitosas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Comparison of the performance of two reverse osmosis membranes for the final purification of olive mill wastewater

Two quite different reverse osmosis (RO) polymeric membranes were examined for the final purification of olive mill wastewater from two-phase olive mills (OMW2): the first one is a thin-film composite (TFC) membrane consisting of polyamide active layer on polysulfone ultrafiltration support, whereas the other one is a low-pressure membrane made of asymmetric polyamide. A net operating pressure (PTM) of 25 bar was found as the target for the TFC membrane, whereas for the asymmetric one a PTM of 8 bar was chosen, given that similar flux decay but still significant productivity was observed by increasing the PTM for this membrane. These results are confirmed by the fouling index (b) values calculated for each membrane. Complete removal of suspended solids, phenolic compounds and iron was achieved by both membranes. Otherwise, the asymmetric membrane ensured slightly higher organic matter (COD) and electroconductivity (EC) reduction, leading to a COD concentration in the permeate stream equal to 3.7 mg L-1 and 1.4 mg L-1 (TFC vs. asymmetric), whereas the EC values were 97.0 and 31.0 μs cm-1, respectively. This would permit reusing the purified effluent provided by both membranes in the production process and close the loop at industrial scale. Moreover, the asymmetric membrane provides a steady-state flux value of the same order of that yielded by the TFC membrane upon more than three times less PTM (14.9 L h-1m-2 at PTM = 8 bar vs. 15.2 L h-1m-2 at PTM = 25 bar), implying a reduction of the specific energy consumption above 50 %, from 0.30 ? m-3 for the TFC membrane to 0.14? m-3 for the asymmetric one. Copyright © 2015, AIDIC Servizi S.r.l

Analysis of the Flux Performance of Different RO/NF Membranes in the Treatment of Agroindustrial Wastewater by Means of the Boundary Flux Theory

Dynamic membrane system behaviour must be adequately addressed to avoid process unfeasibility. The lack of proper analysis will mean relying on erroneous permeate flux values in the system design, which will lead to quick and/or steady high fouling rates. In this paper, the authors present additional data supporting the boundary flux theory as a helpful tool for membrane engineers to carefully avoid process failures. By fitting the dynamic permeate flux data to the boundary flux model, it was possible to calculate the fouling index for the three selected membranes (one nanofiltration (NF) and two reverse osmosis (RO) ones). The dynamic flux given by the low-pressure RO membrane did not follow sub-boundary operating conditions, since a sharp flux loss was measured throughout the whole operating cycle, pinpointing that supra-boundary flux conditions were governing the system. This was supported by the calculated value of the fouling parameter, which resulted to be in the order of ten times higher for this membrane. However, the values of !0 for the SC-RO and DK-NF ones, supported by the very low value of the sub-boundary fouling parameter α (0.002 and 0.007 L.h-1.m-2.bar-2, respectively), ensure nearly boundary operating conditions for these membranes.The Spanish Ministry of Economy and Competitiveness is acknowledged for having funded the project CTM2014-61105-JIN: “Design and development of an integral process for revalorization and treatment of the effluents from olive oil industry”

Optimization of polymeric nanofiltration performance for olive-oil-washing wastewater phenols recovery and reclamation

The core of the present work was to model and optimize an environmentally friendly nanofiltration (NF) treatment process for two-phase olive-oil-washing wastewater (OOWW) valorization throughout the concentration and recovery of its phenolic fraction and the obtention of a purified permeate stream. For this objective, a factorial design was used for the optimization of the process. Results were interpreted by means of the response surface methodology. A statistical multifactorial analysis was performed in order to quantify all the potential complex conjugated effects of the input parameters in the NF process. The process was subsequently modelled by means of a second-grade quadratic fitting model equation. Finally, the parametric quality standards that permit to reuse the purified stream for irrigation, recycling or even discharge in-site reuse purposes were checked. To the author's knowledge, no previous work on the optimization and statistical modelling of membrane processes for OOWW purification and valorization can be found up to the present. The optimized parameters for the proposed OOWW purification process – operating pressure of 26.5 bar, tangential velocity 32.7 m s−1, system temperature 35 °C and pH of 3.7 – ensured high and stable membrane flux (106.2 L h−1 m−2). The obtained optimized data are very relevant for the feasible scale-up of the proposed process in the mills, since the NF membrane (TFC polyamide/polysulfone, MWCO 300 Da) was highly efficient at ambient temperature conditions and raw effluent pH. The optimized conditions provided a permeate stream that could be reused for irrigation purposes and a retantate stream concentrated in volume up to 6.5 times, with a total phenolic content of minimum 1315.7 mg/L.Spanish Ministry of Economy and Competitiveness is acknowledged for having funded the project CTM2014-61105-JIN ‘Design and development of an integral process for revalorization and treatment of the effluents from olive oil industry’, as well as the University of Granada

Optimization and modeling of two-phase olive-oil washing wastewater integral treatment and phenolic compounds recovery by novel weak-base ion exchange resins

In light of the Circular Economy concept, recently emerged as a need for sustainable production, olive oil industry should be concerned to transform the whole process into environmentally friendly, which necessarily implies the treatment of the wastewater by-produced in olive mills. In this work, concentration and recovery of high-added value phenolic compounds from two-phase olive-oil washing wastewater (OOWW) and parallel effluent treatment by a ‘green process’ based on novel weak-base ion exchange (IE) resins was addressed. The key operating input factors of the resin process for the treatment and valorization of OOWW were studied, optimized and further modelled. A Box-Behnken design was implemented and the obtained data were analyzed by ANOVA and interpreted by RSM methodology. The process was ulteriorly modelled by a second-grade quadratic fitting equation comprising the significant operating variables. The optimization of the IE process performance (20.3 °C, pH0 6.7 and 114 g/L Mresin) ensured up to 92.5% recovery of total phenols concentration. Moreover, the purified stream presented good quality (56.6–83.7 mg L−1 total phenols), following standard recommendations by the FAO. The obtained information would be of key importance for the scale-up of the proposed IE operation. Both the treatment and revalorization of OOWW would help implement a definite sustainable production process of olive-oil.Spanish Ministry of Economy and Competitiveness is acknowledged for having funded the project CTM2014-61105-JIN ‘Design and development of an integral process for revalorization and treatment of the effluents from olive oil industry’, as well as the University of Granada

On the effect of ph and operating conditions on nanofiltration of two-phase olive mill wastewater

In the present work, a thin-film composite polymeric nanofiltration (NF) membrane is examined for the tertiary treatment of secondary-treated two-phase olive mill wastewater (OMW2-ST). Overcoming the deleterious fouling phenomena persistently encountered in membrane processes managing wastewater streams was indeed pursued. With this purpose, the point of zero charge (PZC) of the membrane was determined as a key for the operating conditions. This will determine the intensity of the electrostatic interactions between the organic and inorganic solutes present in the OMW2-ST stream and the active surface of the NF membrane, further to the steric effects. Working above the point of zero charge (pH > 5.8) of the membrane ensured highsteady-state permeate productivity (59.6 L h-1m-2), also economically sustainable in time owed to minimizationof the permeate flux decay (5.5 %). Moreover, these conditions also provided high feed recovery (90%) and significant rejection efficiencies for the electroconductivity (58.1%) and organic matter (76.1%). This led to a purified permeate stream exiting the NF membrane operation exhibiting average EC and COD values equal to1.4 mS cm-1 and 45 mg L-1. This permits complying with the water quality parameters established by different regulations for discharge public waterways and irrigation purposes