Fouling in reverse osmosis (RO) membrane in water recovery from secondary effluent : a review

Reverse osmosis (RO) is the most preferable process for water recovery from secondary effluent (SE) because of its higher rejection of impurities with lower associated cost and higher quality of product. Fouling still is a major challenge during the water recovery due to higher contaminant loadings in SE and high rejection capability of this membrane. The presence of suspended solids, colloidal and organic matters, and high level of biological activities in SE further elevate fouling potentiality. This review was performed to identify major foulants causing hindrance in sustainable application of reverse osmosis and to present available pre-treatment options for these foulants. There are four fouling types present in RO namely; bio-fouling, inorganic/scaling, organic, and particulate fouling. Among them; bio-fouling is less understood but dominant since the pre-treatment options are not well developed. Other fouling mechanisms have been overcome by well developed pre-treatments. The major foulants for RO are dissolved and macromolecular organic substances, sparingly soluble inorganic compounds, colloidal and suspended particles, and micro-organisms. Some of these potential fouling water quality parameters (PFWQPs) are interrelated with each others such as electrical conductivity is a surrogate measure of total dissolved solids with established stable relationship. Most of these PFWQPs such as total suspended solids, turbidity, chemical oxygen demand can be removed by conventional pre-treatment; some such as colloidal particles and micro-organisms by modern options and even others such as endocrine disrupting compounds, pharmaceutical and personal care products are still challenging for current pre-treatments. These foulants need to be identified properly to integrate appropriate pre-treatments for minimizing fouling potentiality to increase water recovery at minimal costs.

Sex-related differences in the organismal and cellular stress response in juvenile salmon exposed to treated bleached kraft mill effluent

Exposure of fish to stressors can elicit biochemical and organismal changes at multiple levels of biological organization collectively known as stress responses. The organismal (plasma glucose and cortisol levels) and cellular (hepatic hsp70) stress responses in fish have been studied in several species, but little is known about sex-related differences in these responses. In this study, we exposed sexually immature juvenile chinook salmon (Oncorhynchus tshawytscha) to bleached kraft mill effluent (BKME: 0%, 1%, and 10% v/v) for 30 days and then measured components of their organismal and cellular stress responses. Males exposed to 1% BKME had higher levels of plasma glucose than females. Plasma cortisol levels were unaffected in females exposed to BKME, but males exposed to 10% BKME had significantly higher levels of plasma cortisol relative to non-exposed males. While exposure to BKME did not affect hsp70 levels in males, females exposed to 1% BKME had higher levels of hsp70 relative to non-exposed and 10% BKME groups. Within any given treatment, females had higher levels of hsp70 relative to males. This study demonstrates that sex-related differences exist in commonly used indicators of stress in fish, and points out the importance of considering the sex of the fish in stress research.

Constructed wetland for treating aquaculture and industrial effluent

This project was a practical assessment of the giant reed Arundo donax in comparison with the common reed, Phragmites autralis, in gravel substrate-based horizontal subsurface flow constructed wetlands designed to treat agro-industrial effluent. Results indicated, the planted CWs were more effective at removing nutrients than the unplanted conrol CWs with A.donax produce larger amounts of biomass than P. australis planted CWs.

Use of ultraviolet C (UVC) radiation to inactivate infectious hematopoietic necrosis virus (IHNV) and viral haemorrhagic septicaemia virus (VHSV) in fish processing plant effluent

We determined the stability of infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV) suspended in either fish processing plant effluent blood water (EBW) or culture media and examined the effectiveness of UVC radiation to inactivate IHNV and VHSV suspended in both solutions. Without exposure to UVC, IHNV and VHSV were maintained in 4°C blood water for up to 48 hours without significant reduction in virus titer. However when exposed to UVC radiation using a low pressure mercury vapour lamp collimated beam, IHNV and VHSV were inactivated, and the efficacy of UVC radiation was dependent upon the solution and virus type being treated. A 3-log reduction for VHSV and IHNV in culture media was achieved at 3.28 and 3.84 mJ cm-2, respectively. The UV dose needed for a 3-log reduction of VHSV in EBW was 3.82 mJ cm-2. However, exposure of IHNV in EBW to the maximum UVC dose tested (4.0 mJ cm-2) only led to a 2.26-log-reduction. Factors such as particle size, and possible association of viruses with suspended EBW particulate, were not investigated in this study, but may have contributed to the difference in UVC effectiveness. Future work should emphasize improved filtration methods prior to UV treatment of processing plant EBW at an industrial scale.

Do financial reforms improve the performance of financial holding companies? The case of Taiwan

We examine the performance of financial holding companies (FHCs) in Taiwan after the financial reform that removes the separation of banking, securities, insurance, and other financial services. Using data envelopment analysis, we find that FHCs fail to improve technical efficiencies in the post-reform era. They also do not outperform independent commercial banks after the financial reform. Lower technical efficiency caused by excess operating expenses appears to be the primary source of inefficiency. While scale efficiency may improve as FHCs grow larger, the benefits are marginal and insufficient to offset the potential costs of organizational diseconomies. Our findings suggest that increasing the size and scope of financial activities alone do not necessarily improve the performance of financial firms.

Comparison of fouling mechanisms in low-pressure membrane (MF/UF) filtration of secondary effluent

Membrane filtration in municipal wastewater treatment is being increasingly used to improve the quality of water and increase the productivity of existing plants. However, membrane fouling encountered in reclamation of municipal wastewater represents serious design and operational concern. There are several fouling models which are being developed and used as a powerful tool to increase the understanding of the fouling mechanisms and its key characteristics that influence the design of optimal process and operating conditions. This study investigates and compares the fouling mechanisms of three different types of polymeric and ceramic ultrafiltration (UF) and microfiltration (MF) membranes in the recovery of water from secondary effluent. The result demonstrated that ceramic UF membrane produced very high quality of water compared to polymeric UF and ceramic MF membranes. Out of four fouling models used to fit the experimental flux data, cake filtration and pore narrowing and complete pore blocking models predicted the initial fluxes of polymeric UF membrane more accurately. On the other hand, the cake filtration and pore narrowing models predicted the performance of ceramic UF membrane. Whereas, pore narrowing model predicted the performance of ceramic MF membrane more precisely compared to other three models. Further, the application of unified membrane fouling index (UMFI) was used to assess the fouling potential of the membranes. Good agreement between UMFI and other models was found. © 2013 Copyright Balaban Desalination Publications.

Does banks’ dual holding affect bank lending and firms’ investment decisions? Evidence from China

This study investigates the effect of banks’ dual holding on bank lending and firms’ investment decisions using a sample of listed firms in China. We find that dual holding leads to easier access to bank loans, a result that is more pronounced for non-state-owned enterprises (non-SOEs) than SOEs. We also find that dual holding distorts banks’ lending decisions and harms the investment efficiency for SOEs, while resulting in optimal lending decisions and enhanced investment efficiency for non-SOEs. For non-SOEs, further analysis suggests that optimal lending decisions and efficient investment can be achieved for firms with higher ownership concentration, and firms in which the family and foreign investors are the controlling shareholders. We argue that, in emerging markets, whether a bank plays a monitoring role by directly holding the debt and equity claims of companies relies heavily on whether the potential collusion between firm executives and bank managers can be averted, which in turn is determined by the firms’ governance framework and ownership structure.

Noisy neighbours at the frog pond: effects of invasive cane toads on the calling behaviour of native Australian frogs

Invasive species can disrupt the communication systems that native biota use for reproductive interactions. In tropical Australia, invasive cane toads (Rhinella marina) breed in many of the same waterbodies that are used by native frogs, and males of both the invader and the native taxa rely on vocal signals to attract mates. We conducted playback experiments to test the hypothesis that calls of toads may influence the calling behaviour of frogs (Limnodynastes convexiusculus and Litoria rothii). Male L. convexiusculus adjusted their calling rate and the variance in inter-call interval in response to a variety of sounds, including the calls of cane toads as well as those of other native frog species, and other anthropogenic noise, whereas L. rothii did not. Within the stimulus periods of playbacks, male L. convexiusculus called more intensely during long silent gaps than during calling blocks. Thus, males of one frog species reduced their calling rate, possibly to minimise energy expenditure during periods of acoustic interference generated by cane toads. In spite of such modifications, the number of overlapping calls (within stimulus periods) did not differ significantly from that expected by chance. In natural conditions, the calls of cane toads are continuous rather than episodic, leaving fewer gaps of silence that male frogs could exploit. Future work could usefully quantify the magnitude of temporal (e.g. diel and seasonal) and spatial overlap between calling by toads and by frogs and the impact of call-structure shifts on the ability of male frogs to attract receptive females.

An alternative (partial) justification for the holding in Kirk

In Kirk v Industrial Court (NSW), the High Court determined that, based on“accepted doctrine at the time of Federation”, s 73 of the Constitutionentrenched the jurisdiction of the State Supreme Courts to review thedecisions of State decision-makers on the grounds of jurisdictional error. In anearlier article, the author argued that this reasoning was seriously flawed. Thisarticle propounds an alternative, partial justification for the holding in Kirk,based on features inherent in the text and structure of Ch III of the Constitutionat Federation and the preservation of those features in the face of thepost-Federation dismantling of the imperial legal system. It argues that animplication can be inserted into s 73 which entrenches the jurisdiction of theState Supreme Courts to review the decisions of “Lower State Courts”, but not“State Administrators”.