Membrane surface patterning as a fouling mitigation strategy in liquid filtration: A review

© 2019 by the authors. Membrane fouling is seen as the main culprit that hinders the widespread of membrane application in liquid-based filtration. Therefore, fouling management is key for the successful implementation of membrane processes, and it is done across all magnitudes. For optimum operation, membrane developments and surface modifications have largely been reported, including membrane surface patterning. Membrane surface patterning involves structural modification of the membrane surface to induce secondary flow due to eddies, which mitigate foulant agglomeration and increase the effective surface area for improved permeance and antifouling properties. This paper reviews surface patterning approaches used for fouling mitigation in water and wastewater treatments. The focus is given on the pattern formation methods and their effect on overall process performances

Organic rankine cycle (ORC) system applications for solar energy: Recent technological advances

© 2019 by the authors. Organic Rankine Cycle (ORC) power generation systems may be used to utilize heat source with low pressure and low temperature such as solar energy. Many researchers have focused on different aspects ofORCpower generation systems, but none so far has focused on the patent landscape of ORC system applications. As such, the objective of this study is to identify published patents on ORC system applications, particularly for solar energy. Four (4) technologies were identified in ORC application for solar energy: parabolic dish, parabolic trough, solar tower, and linear Fresnel reflector. A methodical search and analysis of the patent landscape in ORC system applications for solar energy published between 2007-2018 was conducted using the Derwent Innovation patent database. From the approximately 51 million patents in the database from various countries and patent agencies, 3859 patents were initially identified to be related to ORC applications for solar energy. After further stringent selection processes, only 1100 patents were included in this review. From these 1100 patents, approximately 12% (130 patents) are associated with parabolic dishes, about 39% (428 patents) are associated with parabolic troughs, approximately 21% (237 patents) are associated with solar towers, and about 28% (305 patents) are associated with linear Fresnel reflectors. Published patents on solar tower technology are currently on an increasing trend, led by China. All of these patents were published in the past 11 years. From this study, further researches on ORC application are still ongoing, but ORC application for solar energy has the potential to advance; allowing the world to ease issues related to over-reliance on fossil fuel

Insight into the Sustainable Integration of Bio- and Petroleum Refineries for the Production of Fuels and Chemicals.

A petroleum refinery heavily depends on crude oil as its main feedstock to produce liquid fuels and chemicals. In the long term, this unyielding dependency is threatened by the depletion of the crude oil reserve. However, in the short term, its price highly fluctuates due to various factors, such as regional and global security instability causing additional complexity on refinery production planning. The petroleum refining industries are also drawing criticism and pressure due to their direct and indirect impacts on the environment. The exhaust gas emission of automobiles apart from the industrial and power plant emission has been viewed as the cause of global warming. In this sense, there is a need for a feasible, sustainable, and environmentally friendly generation process of fuels and chemicals. The attention turns to the utilization of biomass as a potential feedstock to produce substitutes for petroleum-derived fuels and building blocks for biochemicals. Biomass is abundant and currently is still low in utilization. The biorefinery, a facility to convert biomass into biofuels and biochemicals, is still lacking in competitiveness to a petroleum refinery. An attractive solution that addresses both is by the integration of bio- and petroleum refineries. In this context, the right decision making in the process selection and technologies can lower the investment and operational costs and assure optimum yield. Process optimization based on mathematical programming has been extensively used to conduct techno-economic and sustainability analysis for bio-, petroleum, and the integration of both refineries. This paper provides insights into the context of crude oil and biomass as potential refinery feedstocks. The current optimization status of either bio- or petroleum refineries and their integration is reviewed with the focus on the methods to solve the multi-objective optimization problems. Internal and external uncertain parameters are important aspects in process optimization. The nature of these uncertain parameters and their representation methods in process optimization are also discussed

Development of a novel corrugated polyvinylidene difluoride membrane via improved imprinting technique for membrane distillation

© 2019 by the authors. Membrane distillation (MD) is an attractive technology for desalination, mainly because its performance that is almost independent of feed solute concentration as opposed to the reverse osmosis process. However, its widespread application is still limited by the low water flux, low wetting resistance and high scaling vulnerability. This study focuses on addressing those limitations by developing a novel corrugated polyvinylidene difluoride (PVDF) membrane via an improved imprinting technique for MD. Corrugations on the membrane surface are designed to offer an effective surface area and at the same time act as a turbulence promoter to induce hydrodynamic by reducing temperature polarization. Results show that imprinting of spacer could help to induce surface corrugation. Pore defect could be minimized by employing a dual layer membrane. In short term run experiment, the corrugated membrane shows a flux of 23.1 Lm-2h-1 and a salt rejection of > 99%, higher than the referenced flat membrane (flux of 18.0 Lm-2h_asuf and similar rejection). The flux advantage can be ascribed by the larger effective surface area of the membrane coupled with larger pore size. The flux advantage could be maintained in the long-term operation of 50 h at a value of 8.6 Lm-2h-1. However, the flux performance slightly deteriorates over time mainly due to wetting and scaling. An attempt to overcome this limitation should be a focus of the future study, especially by exploring the role of cross-flow velocity in combination with the corrugated surface in inducing local mixing and enhancing system performance

Sustainability assessment of xylitol production from empty fruit bunch

Empty fruit bunch (EFB), one of the wastes from palm oil production, can be utilized into fuels and chemicals. The aim of this paper is to find the optimum capacity to produce xylitol from EFB. The optimum capacity was found by simultaneously considering its profitability, hazard potential and environmental performances. The process was developed and simulated using Aspen Plus to analyze its technical challenges and economic performances, covering net present values, internal rate of returns and payback period. On the other hand, hazard identification and ranking (HIRA) was used to evaluate its safety performances, while Simapro V.8.5.2 was used to assess the environmental impact via a life cycle assessment (LCA). The results show that the high consumption of steam in chemical hydrogenation causes the main contribution of Global warming potential (GWP) by 62%. This acid pre-treatment is also considered the most toxic part of the process while the hydrogenation of xylitol is the most hazardous part based on fire and explosion perspectives. Then, multi-objective optimization using Genetic Algorithm (GA) was performed in Matlab to find the optimum capacity. The methodology and result of this work lay the foundation of future works in utilizing

Progress in development of nanostructured manganese oxide as catalyst for oxygen reduction and evolution reaction

The rise in energy consumption is largely driven by the growth of population. The supply of energy to meet that demand can be fulfilled by slowly introducing energy from renewable re-sources. The fluctuating nature of the renewable energy production (i.e., affected by weather such as wind, sun light, etc.), necessitates the increasing demand in developing electricity storage systems. Reliable energy storage system will also play immense roles to support activities related to the internet of things. In the past decades, metal‐air batteries have attracted great attention and interest for their high theoretical capacity, environmental friendliness, and their low cost. However, one of the main challenges faced in metal‐air batteries is the slow rate of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) that affects the charging and the discharging performance. Various types of nanostructure manganese oxide with high specific surface area and excel-lent catalytic properties have been synthesized and studied. This review provides a discussion of the recent developments of the nanostructure manganese oxide and their performance in oxygen reduction and oxygen evolution reactions in alkaline media. It includes the experimental work in the nanostructure of manganese oxide, but also the fundamental understanding of ORR and OER. A brief discussion on electrocatalyst kinetics including the measurement and criteria for the ORR and the OER is also included. Finally, recently reported nanostructure manganese oxide catalysts are also discussed

Critical Evaluation of the Determination Methods for Transparent Exopolymer Particles, Agents of Membrane Fouling

© Taylor & Francis Group, LLC. Since the development of the first method to quantify transparent exopolymer particles in 1993, a number of alternative methods have been developed to improve the original method. Some of these alternative methods deviate firmly from the original method. In many cases, different methods determine a different fraction of the material present in the same investigated sample. This makes comparison between results of studies very difficult or even impossible. Better categorizing of transparent exopolymer particles could be useful to keep a clear view on which fraction is measured and how this fraction relates to the ones measured in other studies.status: publishe

A PVC-silica mixed-matrix membrane (MMM) as novel type of membrane bioreactor (MBR) membrane

© 2015 Elsevier B.V. A highly porous mixed matrix membrane (MMM), made from polyvinyl chloride (PVC) and silica, commonly used as separator in lead acid batteries, is screened here in a first feasibility study as a potential novel type of MBR membrane to treat synthetic wastewater encouraged by: (i) its high chemical and thermal stability and (ii) its high porosity. Its performance was compared with two commercial flat-sheet MBR membranes, a chlorinated PE and a PVDF membrane, in terms of hydraulic performance and membrane fouling. The COD removals of the three membranes were similar. The critical flux measurement also showed the potential of the MMM, being 18. LMH compared to 21. LMH for the commercial membranes. However, both short and long-term filtration tests showed that the MMM suffers from a severe irreversible fouling attributed to the blocking of the large pore mouths, which could not be removed via the applied chemical cleaning with NaOCl. Nevertheless, in a long-term test, despite the occurrence of pore blocking, other types of fouling exist to a much lesser extent in the MMM which maintains its performance comparable with the two commercial membranes.publisher: Elsevier articletitle: A PVC–silica mixed-matrix membrane (MMM) as novel type of membrane bioreactor (MBR) membrane journaltitle: Journal of Membrane Science articlelink: http://dx.doi.org/10.1016/j.memsci.2015.05.074 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved.status: publishe

Decreasing membrane fouling during Chlorella vulgaris broth filtration via membrane development and coagulant assisted filtration

© 2015 Elsevier B.V. Membrane filtration has been reported as an interesting low-cost technique for microalgae harvesting, either in a separated process or in a coupled process as in a membrane photobioreactor. However, the filtration performance can still be improved if the membrane fouling problem could be properly managed. In this study, the improvement of the filterability of a Chlorella vulgaris broth is investigated via both membrane development and via coagulant dosing before filtration. For the membrane development (via the process of phase inversion), four basic membrane preparation parameters were studied, namely polymer concentration, time gap between casting and coagulation, addition of water as a non-solvent into the casting dope solution and the addition of polyvinylpyrrolidone as an additive to a polyvinylidene fluoride/N,N-dimethylformamide system. For coagulation, FeCl3 and chitosan were tested using a polycarbonate 0.1μm membrane. Later, three new membranes were tested against two commercial membranes with and without coagulant dosing. The performance of the membrane was evaluated using the improved flux stepping filtration method and using a simple dead-end filtration for the coagulation/filtration study, respectively. Results show that the membrane properties and the filterability could be well manipulated by using the four phase inversion parameters. Both coagulants increased the filterability of the broth. When applied to the optimized membranes and the two commercial membranes, dosing 10ppm chitosan in the C. vulgaris broth had inconclusive effects. It improved filterability for most of them but imposed negative effect for the rest, which suggests that the coagulant type and dosing of a membrane filtration system should be optimized per membrane.status: publishe