Performance of reverse osmosis (RO) for water recovery from permeates of membrane bio-reactor (MBR)

In this study, permeate from a hollow fiber polyethylene (PE) membrane bio-reactor (MBR) system treating synthetic agricultural wastewater was fed into a cellulose acetate brackish water reverse osmosis (BWRO30 2540) membrane system; three different trans-membranes pressures (TMPs) of 1000, 2500, and 4000 kPa were selected to evaluate the system performance in terms of general operating parameters as well as the removal of chosen important potential fouling water quality parameters. The results showed that highest corrected permeate flux rate was at a TMP of 2500 kPa, whereas lowest recorded at a TMP of 4000 kPa. Similar situation prevailed in water recovery rate. But temperature corrected specific fluxes decreased as the applied TMPs increased. In all selected TMPs, more than 96% of salinity was removed. Permeate from MBR as feed to reverse osmosis required frequent chemical cleaning than the microfiltration/ultrafiltration (MF/UF) permeates and granular media filter (GMF) filtered in order to maintain the required rate of product water. One of the reasons for this frequent chemical cleaning is due to higher total organic carbon as well as total nitrogen (TN) in the MBR permeate. This result needs to be further evaluated through field trials.

Removal of ametryn through nanofiltration and reverse osmosis

 This study focused on the performance of nanofiltration (NF) and reverse osmosis (RO) in the removal of ametryn. Here, we investigated the effects of the applied pressure and ionic conditions on the removal of ametryn from water. It was found that the adsorption of ametryn onto NF membrane to decrease with the increase in ionic strength. Increased interaction between the NaCl electrolyte and the membrane surface is considered as the reason for the reduction in the adsorption. However, adsorption of ametryn onto the RO membrane did not show any trend. The removal of ametryn by NF and RO found to increase with the increase in the ionic strength. Retention of electrolyte salt (NaCl) on the membrane surface tends to decrease the membrane pore size which in turn increases the removal of ametryn at higher ionic strengths. It was found that up to 92% of ametryn could be removed using RO.

Acquisition of domain ontology from relational schemes based on reverse engineering

Acquisition of domain ontology from database has been of catholic concern. This paper, taking relational schemes as example, analyzes how to identify the information about the structure of relational schemes in legacy systems. Then, it presents twelve extraction rules, which facilitate the obtaining of terms and relations from the relational schemes. Finally, it uses the EER diagram to further obtain semantic information from relational schemes for refining ontology model. The development method of domain ontology based on reverse engineering is a supplement to forward engineering. The union of the two development methods is certainly beneficial for the designers of domain ontology. © 2009 IEEE.

Validation of a multiplex reverse transcription and pre-amplification method using TaqMan(®) MicroRNA assays.

Since the discovery of microRNAs (miRNAs), different approaches have been developed to label, amplify and quantify miRNAs. The TaqMan(®) technology, provided by Applied Biosystems (ABIs), uses a stem-loop reverse transcription primer system to reverse transcribe the RNA and amplify the cDNA. This method is widely used to identify global differences between the expression of 100s of miRNAs across comparative samples. This technique also allows the quantification of the expression of targeted miRNAs to validate observations determined by whole-genome screening or to analyze few specific miRNAs on a large number of samples. Here, we describe the validation of a method published by ABIs on their web site allowing to reverse transcribe and pre-amplify multiple miRNAs and snoRNAs simultaneously. The validation of this protocol was performed on human muscle and plasma samples. Fast and cost efficient, this method achieves an easy and convenient way to screen a relatively large number of miRNAs in parallel.

Water security through scarcity pricing and reverse osmosis: a system dynamics approach

Water supply and demand planning is often conducted independently of social and economic strategies. There are presently no comprehensive life-cycle approaches to modelling urban water balances that incorporate economic feedbacks, such as tariff adjustment, which can in turn create a financing capacity for investment responses to low reservoir levels. This paper addresses this gap, and presents a system dynamics model that augments the usual water utility representation of the physical linkages of water grids, by adding inter-connected feedback loops in tariff structures, demand levels and financing capacity. The model, applied in the south-east Queensland region in Australia, enables simulation of alternatives and analysis of stocks and flows around a grid or portfolio of bulk supplies including an increasing proportion of rain-independent desalination plants. Such rain-independent water production plants complement the rain-dependent sources in the region and can potentially offer indefinite water security at a price. The study also shows how an alternative temporary drought pricing regime not only defers costly bulk supply infrastructure but actually generates greater price stability than traditional pricing approaches. The model has implications for water supply planners seeking to pro-actively plan, justify and finance portfolios of rain-dependent and rain-independent bulk water supply infrastructure. Interestingly, the modelling showed that a temporary drought pricing regime not only lowers the frequency and severity of water insecurity events but also reduces the long-run marginal cost of water supply for the region when compared to traditional reactive planning approaches that focus on restrictions to affect demand in scarcity periods.

Resistance and resilience: Can the abrupt end of extreme drought reverse avifaunal collapse?

Aim: Climate change is expected to increase the frequency and intensity of extreme climatic events, such as severe droughts and intense rainfall periods. We explored how the avifauna of a highly modified region responded to a 13-year drought (the 'Big Dry'), followed by a two-year period of substantially higher than average rainfall (the 'Big Wet'). Location: Temperate woodlands in north central Victoria, Australia. Methods: We used two spatially extensive, long-term survey programmes, each of which was repeated three times: early and late in the Big Dry, and in the Big Wet. We compared species-specific changes in reporting rates between periods in both programmes to explore the resistance (the ability to persist during drought) and resilience (extent of recovery post-drought) of species to climate extremes. Results: There was a substantial decline in the reporting rates of 42-62% (depending on programme) of species between surveys conducted early and late in the Big Dry. In the Big Wet, there was some recovery, with 21-29% of species increasing substantially. However, more than half of species did not recover and 14-27% of species continued to decline in reporting rate compared with early on in the Big Dry. Species' responses were not strongly related to ecological traits. Species resistance to the drought was inversely related to resilience in the Big Wet for 20-35% of the species, while 76-78% of species with low resistance showed an overall decline across the study period. Conclusions: As declines occurred largely irrespective of ecological traits, this suggests a widespread mechanism is responsible. Species that declined the most during the Big Dry did not necessarily show the greatest recoveries. In already much modified regions, climate extremes such as extended drought will induce on-going changes in the biota. © 2014 John Wiley & Sons Ltd.