FOULING IN FORWARD OSMOSIS MEMBRANE PROCESSES: CHRACTERIZATION, MECHANISMS, AND MITIGATION

As a potential solution to the increasingly severe global water crisis and energy shortage, forward osmosis (FO) membrane process has attracted growing attention in many applications such as desalination, water purification, wastewater reuse, food processing, and sustainable power generation. However, the advancement of the FO membrane process is greatly hampered by a long-standing problem of membrane fouling. Membrane fouling is caused by the accumulation of foreign substances on the surface or within pores of the membrane. Membrane performance, such as energy consumption, water flux, and effluent quality, can be severely deteriorated by fouling. Therefore, developing fouling-resistant membranes is key to more efficient use of FO membrane technologies. The objectives of this research are to fundamentally understand membrane fouling mechanisms at the molecular level and to develop novel antifouling materials for FO membrane process. Three major research tasks were performed in this study. The first task was to systematically characterize FO membrane fouling behavior by performing microscope-assisted online monitoring experiments to study the kinetics of fouling layer formation and flux decline. The second task was to combine nanoscale characterization experiments (e.g. interfacial force measurement by atomic force microscope, quartz crystal microbalance with dissipation) and molecular simulation to understand membrane fouling mechanisms. The third task was to develop novel membrane modification strategies by using hydrophilic materials, such as polydopamine and zeolite nanoparticles, to improve the membrane's antifouling properties in FO membrane process. Major research achievements are summarized below. (1) A microscope-assisted direct observation FO system was developed to provide critical information on the morphology and formation kinetics of fouling layer for various types of fouling, including organic fouling, scaling, biofouling, and combined fouling. (2) The successful combination of experimental characterization and molecular simulation gave insights into the role of membrane surface characteristics (such as functionality and charge) in FO membrane fouling, thus providing critical information to develop new antifouling FO membranes. (3) Polydopamine and zeolite nanoparticles were successfully grafted onto FO membrane surface. The surface modification proved to greatly increase membrane surface hydrophilicity and to reduce fouling propensity in FO membrane process

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An Integrated Approach for Assessing Aquatic Ecological Carrying Capacity: A Case Study of Wujin District in the Tai Lake Basin, China

Aquatic ecological carrying capacity is an effective method for analyzing sustainable development in regional water management. In this paper, an integrated approach is employed for assessing the aquatic ecological carrying capacity of Wujin District in the Tai Lake Basin, China. An indicator system is established considering social and economic development as well as ecological resilience perspectives. While calculating the ecological index, the normalized difference vegetation index (NDVI) is extracted from Moderate Resolution Imaging Spectroradiometer (MODIS) time-series images, followed by spatial and temporal analysis of vegetation cover. Finally, multi-index assessment of aquatic ecological carrying capacity is carried out for the period 2000 to 2008, including both static and dynamic variables. The results reveal that aquatic ecological carrying capacity presents a slight upward trend in the past decade and the intensity of human activities still exceeded the aquatic ecological carrying capacity in 2008. In terms of human activities, population has decreased, GDP has quadrupled, and fertilizer application and industrial wastewater discharge have declined greatly in the past decade. The indicators representing aquatic ecosystem conditions have the lowest scores, which are primarily attributed to the water eutrophication problem. Yet the terrestrial ecosystem is assessed to be in better condition since topographic backgrounds and landscape diversity are at higher levels. Based on the work carried out, it is suggested that pollutant emission be controlled to improve water quality and agricultural development around Ge Lake (the largest lake in Wujin District) be reduced

The Poverty Alleviation and Immigration Practice Model Effect Research in Liulin

Abstract By the way of field investigation and statistical analysis, I have carried on investigation to Liulin, migrant village and I have learnt something about migration forms, mainly interaction patterns of villages and towns aggregation model. This article mainly analyzes the work and the necessity of immigration for poverty alleviation and the actual effect of the two modes in Lilulin. Moreover, I put forward some suggestions to model improvement and hope that I can do some useful things to poverty reduction in Liulin. At the same time, it can provide favorable help for building a harmonious society

Plasma reforming of toluene as a model tar compound from biomass gasification: effect of CO2 and steam

AbstractIn this study, plasma reforming of toluene as a tar model compound from biomass gasification has been carried out using an AC gliding arc discharge reactor. The influence of steam and CO2 addition on the reforming of toluene has been evaluated. The results show that the highest toluene conversion (59.9%) was achieved when adding 3 vol% CO2 at a toluene concentration of 16.1 g/Nm3 and a specific energy input of 0.25 kWh/m3. Further increasing CO2 concentration to 12 vol% decreased the conversion of toluene. The presence of steam in the plasma CO2 reforming of toluene creates oxidative OH radicals which contribute to the enhanced conversion of toluene and energy efficiency of the plasma reforming process through stepwise oxidation of toluene and reaction intermediates. Hydrogen and C2H2 were identified as the major gas products in the plasma reforming of toluene without CO2 or steam, with a yield of 9.7% and 14.5%, respectively, while syngas was the primary products with a maximum yield of 58.3% (27.5% for H2 and 30.8% for CO) in the plasma reforming with the addition of 12 vol% CO2. The plausible reaction pathways and mechanism in the plasma reforming of toluene have been proposed through the combination of the analysis of gas and condensed products and spectroscopic diagnostics.</jats:p

Diversifying of Chemical Structure of Native Monascus Pigments

Red Yeast Rice, produced by solid state fermentation of Monascus species on rice, is a traditional food additive and traditional Chinese medicine. With the introduction of modern microbiology and biotechnology to the traditional edible filamentous fungi Monascus species, it has been revealed that the production of red colorant by fermentation of Monascus species involves the biosynthesis of orange Monascus pigments and further chemical modification of orange Monascus pigments into the corresponding derivates with various amine residues. Further study indicates that non-Monascus species also produce Monascus pigments as well as Monascus-like pigments. Based on the chemical modification of orange Monascus pigments, the diversification of native Monascus pigments, including commercial food additives of Red Monascus Pigments® and Yellow Monascus Pigments® in Chinese market, was reviewed. Furthermore, Monascus pigments as well as their derivates as enzyme inhibitors for anti-obesity, hyperlipidemia, and hyperglycemia was also summarized

Optimization of a New Phase Change Material Integrated Photovoltaic/Thermal Panel with The Active Cooling Technique Using Taguchi Method

This paper investigates the energy performances of a hybrid system composed of a phase change materials-ventilated Trombe wall (PCMs-VTW) and a photovoltaic/thermal panel integrated with phase change material (PV/T-PCM). Equivalent overall output energy (QE) was proposed for energy performance evaluation regarding different energy forms, diversified conversions and hybrid thermal storages. This study focuses on parameters&rsquo; optimization of the PV/T-PCM system and parameters in the PCMs-VTW are kept optimal. Based on the experimentally validated numerical modelling, nine trial experiments have been conducted following Taguchi L9 (34) standard orthogonal array. The higher the better concept was implemented and the optimal combination of operating parameters was thereafter identified by using signal-to-noise (S/N) ratio and Analysis of Variance (ANOVA) method. The results show that QE is highly dependent on the mass flow rate, followed by the diameter of active cooling water pipe. However, the inlet cooling water temperature and the thickness of PCM have limited influence on QE. The optimal combination of each factor was identified as B3A3C2D1 (mass flow rate of 1 kg/s, diameter of water pipe of 0.6 m, inlet cooling water temperature of 15 &deg;C and the thickness of PCM of 20 mm) with the highest QE of 20,700 kWh