The effect of NOM characteristics and membrane type on microfiltration performance

Efforts to understand and predict the role of different organic fractions in the fouling of low-pressure membranes are presented. Preliminary experiments with an experimental apparatus that incorporates automatic backwashing and filtration over several days has shown that microfiltration of the hydrophilic fractions leads to rapid flux decline and the formation of a cake or gel layer, while the hydrophobic fractions show a steady flux decline and no obvious formation of a gel or cake layer. The addition of calcium to the weakly hydrophobic acid (WHA) fraction led to the formation of a gel layer from associations between components of the WHA. The dominant foulants were found to be the neutral and charged hydrophilic compounds, with hydrophobic and small pore size membranes being the most readily fouled. The findings suggest that surface analyses such as FTIR will preferentially identify hydrophilic compounds as the main foulants, as these components form a gel layer on the surface while the hydrophobic compounds adsorb within the membrane pores. Furthermore, coagulation pre-treatment is also likely to reduce fouling by reducing pore constriction rather than the formation of a gel layer, as coagulants remove the hydrophobic compounds to a large extent and very little of the hydrophilic neutral components

Ultrasound enhancement of microfiltration performance for natural organic matter removal

Sonication of water at 1500 W power prior to microfiltration showed that short sonication times (60 s) gave a reduced flux decline. It is suggested that a less potent, smaller molecular form of the natural organic matter (NOM) was produced by sonication. Longer sonication times diminished this beneficial effect. This may be due to the formation of aggregates or compounds that are more readily adsorbed on the membrane. Where the sonication was preceded by an alum treatment, the flux loss showed a regular decrease with longer sonication times. It is suggested that the effects of sonication on the alum flocs and on the flocs; NOM interactions may play a critical role in regulating the flux. Where sand was present on sonication at 800 and 1400 W, the cavitational energy was focussed on adsorbed organic material, resulting in more efficient destruction and the formation of compounds that counteracted the flux enhancement

Effect of membrane character and solution chemistry on microfiltration performance

To help understand and predict the role of natural organic matter (NOM) in the fouling of low-pressure membranes, experiments were carried out with an apparatus that incorporates automatic backwashing and long filtration runs. Three hollow fibre membranes of varying character were included in the study, and the filtration of two different surface waters was compared. The hydrophilic membrane had greater flux recovery after backwashing than the hydrophobic membranes, but the efficiency of backwashing decreased at extended filtration times. NOM concentration of these waters (7.9 and 9.1 mg/L) had little effect on the flux of the membranes at extended filtration times, as backwashing of the membrane restored the flux to similar values regardless of the NOM concentration. The solution pH also had little effect at extended filtration times. The backwashing efficiency of the hydrophilic membrane was dramatically different for the two waters, and the presence of colloid NOM alone could not explain these differences. It is proposed that colloidal NOM forms a filter cake on the surface of the membranes and that small molecular weight organics that have an adsorption peak at 220 nm but not 254 nm were responsible for “gluing” the colloids to the membrane surface. Alum coagulation improved membrane performance in all instances, and this was suggested to be because coagulation reduced the concentration of “glue” that holds the organic colloids to the membrane surface

Comparaciones indirectas en los informes de evaluación de medicamentos en la web del grupo GENESIS de la SEFH

An active comparator was present in 95% of the 337 analysed reports; 50% included a direct comparative study vs comparator. In 114 reports (34%), an IC was used; 69% of the ICs were made by the report author. Most ICs were narrative and none were adjusted. An IC could have been made in an additional 16% of the cases and possibly in 24% more. Conclusions: Most evaluated drugs have an active comparator but studies comparing them directly are not as common. ICs could be included in more reports along with quality control criteria. © 2011 SEFH. Publishe

Measuring poly(acrylamide) flocculants in fresh water using inter-polymer complex formation

YesA novel detection method for poly(acrylamide) flocculants was developed using interpolymer complexation between flocculants and a probe (poly(acrylic acid-co-acenaphthylene)). This detection method was tested in fresh water situations and found to be robust against a range of contaminants; additionally it was capable of detecting levels of flocculant dosing below 1 mg l−1. This method is remarkably fast and requires little sample modification compared to existing methods of detection

Effect of algal flocculation on dissolved organic matters using cationic starch modified soils

Modified soils are being increasingly used as geo-engineering materials for the sedimentation removal of cyanobacterial blooms. However, when organic flocculants were used as soil modifiers, little is known about the potential impacts of these materials on the treated water. This study investigated dissolved organic matters in the bloom water after algal removal using cationic starch modified soils (CS-MS). Results showed that the dissolved organic carbon (DOC) could be decreased by CS-MS flocculation and the use of higher charge density CS yielded a greater DOC reduction. When CS with the charge density of 0.052, 0.102 and 0.293 meq/g were used, dissolved organic carbon (DOC) was decreased from 3.4 to 3.0, 2.3 and 1.7 mg/L, respectively. The excitation-emission matrix fluorescence spectroscopy and UV254 analysis indicated that CS-MS exhibits an ability to remove some soluble organics, which contributed to the DOC reduction. However, the use of low charge density CS posed a potential risk of DOC increase due to the high CS loading for effective algal removal. When CS with the charge density of 0.044 meq/g was used, DOC was increased from 3.4 to 3.9 mg/L. This study suggested that by optimizing charge density of CS, the use of organic MS-CS flocculants can achieve the sedimentation removal of cyanobacterial cells without increasing the content of dissolved organic matters in bloom waters. For the settled organic matters, other measures (e.g., capping treatments using oxygen loaded materials) should be jointly applied after algal flocculation

Secretive yet accountable: Formal and informal accountability in the Australian Intelligence Community

This research explores different types of accountability within the Australian Intelligence Community (AIC), including democratic, constitutional, learning and reputational accountability. Accountability practices in the intelligence sector and the relationship between accountability and official secrecy are not well understood. Yet the work, practices and impacts of Australia's intelligence agencies have been increasingly significant and visible as these secretive organisations have grown and emerged from the shadows. Accountability can be conceptualised as an important social process that involves interactions between two or more parties. With this lens, this research brings together theory and empirical data to explore who in the AIC has been accountable to whom, for what, why and when. This approach offers new insights into formal and informal accountability practices through the experiences of intelligence agencies, officers and overseers, and builds on existing studies of both accountability and national security. To address gaps in knowledge this research catalogues scholarly concepts of accountability, explores the relevance of these concepts to accountability in the AIC, and documents the development of AIC accountability processes and structures over time. Drawing and analysing data from 32 elite interviews, official documents and media reporting, interpretive case study research is used to explore accountability across three case studies. Case studies focus on three intelligence agencies: the Australian Security Intelligence Organisation and its evolving powers in the 2000s and 2010s, the involvement of the Australian Signals Directorate in the 2001 'Tampa affair', and the experiences of the then Office of National Assessments in the lead-up to and aftermath of the 2003 Iraq war. Types of accountability, approaches to transparency, impacts of secrecy and other potential factors in accountability are considered across cases. Control is explored as a significant but distinct counterpart to accountability. Intelligence agencies are not immune to typical or more unusual accountability challenges. But this research shows how both formal and informal types of accountability can occur. It shows how accountability can be hindered by secrecy and more common factors such as account-holders' mandates, resources and influence. The individual practices and perceptions of account-givers and account-holders are also influential due to the secrecy which surrounds intelligence. In the end, strong albeit varying types of accountability are evident, with domestic intelligence collections receiving particular scrutiny, foreign intelligence collections later attention, and less oversight of intelligence assessment functions

Natural coagulates for wastewater treatment; a review for application and mechanism

The increase of water demand and wastewater generation is among the global concerns in the world. The less effective management of water sources leads to serious consequences, the direct disposal of untreated wastewater is associated with the environmental pollution, elimination of aquatic life and the spread of deadly epidemics. The flocculation process is one of the most important stages in water and wastewater treatment plants, wherein this phase the plankton, colloidal particles, and pollutants are precipitated and removed. Two major types of coagulants are used in the flocculation process included the chemical and natural coagulants. Many studies have been performed to optimize the flocculation process while most of these studies have confirmed the hazardous effects of chemical coagulants utilization on the ecosystem. This chapter reviews a summary of the coagulation/flocculation processes using natural coagulants as well as reviews one of the most effective natural methods of water and wastewater treatment