Membrane fouling during fertiliser drawn forward osmosis desalination using brackish groundwater

University of Technology, Sydney. Faculty of Engineering and Information Technology.Freshwater has become a scarce resource in many parts of the world and has been recognised as a critical global issue. By far, agriculture is the largest consumer of global freshwater, reaching a proportion that exceeds 70% of the total water consumption, mainly in the form of irrigation. In 2006, 54% of the total water use in Australia related to the irrigation of farms and pastures although the figure was much higher in previous years. Due to the rapid growth in the world‘s population, water demand for agriculture will keep increasing to meet the corresponding food demands. Creating new water sources can reduce pressure on the existing fresh water resources. Hence, desalination can play a key role in creating a new water sources because saline water sources exist in abundance. However, current desalination technologies are energy and cost intensive and this can have negative impacts on the environment and natural resources. Forward osmosis (FO) has been recognised as one of the most promising low energy processes for desalination. The FO process, as an alternative to conventional desalination techniques, has attracted much attention in recent years. The driving force in the FO process is generated by the osmotic pressure difference between the feed water and the concentrated draw solution (DS). Where a natural source of high concentration DS is available, FO can be highly attractive due to its significantly lower energy demand for pumping. Fertiliser drawn forward osmosis (FDFO) desalination has been recently studied as one of the most practical applications of FO for irrigation. The study indicated that most commercially available fertilisers can be used as osmotic draw solutes. This led to the idea of applying FO technology in agriculture where the diluted fertiliser DS containing desalinated water can be used directly for fertigation (fertilised irrigation) instead of further subjecting it to a separation process. Despite the many benefits of membrane technologies, the unavoidable issue of membrane fouling during membrane filtration remains a problem. Membrane fouling is a process where solute or particles deposit onto a membrane surface or into membrane pores. Membrane fouling causes a reduction in the permeate yield and a decrease in the quality of water produced, which leads to an increase in the operational and capital costs of the entire membrane filtration process. It is generally accepted that fouling reduces the performance of membrane. When the fouling occurs, a thick gel layer and cake layer are formed on and in the membrane, causing the permeate flux to decline and increasing the operational costs due to the need for higher energy, cleaning frequency and/or the reduced life of the membrane. Mechanisms of fouling in pressure-driven membrane processes have been investigated extensively. By contrast, only a few studies have so far targeted membrane fouling during the FO process. This study investigates the influence of various factors affecting the water flux behavior and membrane fouling during the desalination of brackish groundwater by FDFO process. The major factors responsible for the performance of FDFO water flux behavior are thoroughly investigated and their implications to the overall process were discussed. The major factors assessed include membrane properties, DS properties and FS properties. The influences of all these factors have been measured in terms of water flux decline. A membrane autopsy has also been conducted to identify the inorganic scaling that forms on the membrane surface. Foulants have been analysed using Scanning Electron Microscopy (SEM), energy dispersive spectroscopy (EDS) and X-Ray Diffraction (XRD). Six commercially available fertilisers (Potassium chloride, potassium nitrate, ammonium sulphate, monoammonium phosphate or MAP, diammonium phosphate or DAP, calcium nitrate) have been selected as DS to observe the effects of different fertilisers in water flux behavior during the FDFO process. DAP, having one of the highest osmotic pressures amongst the six selected fertiliser solutions has been found to produce unexpected water flux behavior with severe flux decline during the FDFO desalination of brackish ground water (BGW). The XRD results indicate that the scales formed on the membrane surface during FDFO process using DAP as DS are mainly composed of magnesium phosphate (MgHPO₄) and magnesium ammonium phosphate (MgNH₄PO₄.6H₂O) or struvite. These insoluble compounds are formed because of the reverse diffusion of DAP towards the feed during the osmotic process which then reacts with the magnesium ions present in the FS. This study shows that, the selection of fertiliser as DS is important for several reasons. Fertilisers that generate higher water flux at lower concentrations are preferable as these can contribute to significant cost savings in terms of both capital and operational costs. The other important characteristic of DS is that, it should have lower membrane scaling and fouling potential. Fertilisers that produce steady water flux and lower membrane scaling and fouling during long-term operation are preferable for FDFO application. This work also seeks to show that besides the selection of suitable fertiliser as DS during the long term FDFO process, the selection of an appropriate membrane for the selected fertiliser is also essential. The interaction between fertiliser properties and membrane characteristics has a significant influence in water flux behavior. As in real situations, varied types of foulants always coexist in natural waters. In addition to inorganic scaling by super saturation of calcium and sulfate ions, which are common in brackish groundwater, organic fouling is also possible due to prevalent natural organic matters. Therefore, alginate, albumin (BSA), and humic acid (HA) have been chosen as model organic foulants to study the effect of combined fouling in water flux behavior during the long term operation of the FDFO desalination process. 60 mg/l alginate has been found to aggravate inorganic scaling leading to a decrease in water flux of more than 30%. Physical cleaning with cross-flow rates similar to normal FDFO process has been adopted to evaluate the effectiveness of restoring the membrane flux after inorganic scaling. The flux recovery is about 80-97% depending on the type of the DS. However, when the cross-flow rate is increased, the water flux is restored almost in full, irrespective of the type of DS and DS concentration used

Security and Privacy Issues in IoT Healthcare Application for Disabled Users in Developing Economies

In this paper, we explore the security and privacy issues of Internet of Things (IoT) healthcare applications for special needs users. IoT enables health-related organizations to lift important data from diverse sources in real-time and this helps in precise decision-making. The transformation of the health sector, required enhancement and efficiency of protective systems, thereby reducing data vulnerability and hence, providing opportunities for secure patient data, particularly, for special needs patients. A quantitative method for purposive sampling technique was adopted and eighty-eight respondents provided the process of how the IoT technology was utilised. Data findings indicated that IoT monitoring devices have the detective ability for a person with special needs living alone with problems related to vital signs of diseases or disabilities. Personal patient health records are integrated into the e-health Centre via IoT technologies. For data privacy, security, and confidentiality, patients' records are kept on Personal Health Record Systems (PHRS). The research revealed suspected breaches of information due to cyber-attacks on the probability of false data errors in the PHRS, leading to special needs personal data leakage

Effect of synthetic juvenoid hormone (pyriproxyfen) on the larval stages and survival rates of fresh water prawn (Macrobrachium rosenbergii)

Possible effects of a synthetic juvenoid hormone (Pyriproxyfen) on larval development, metamorphosis and survival of a crustacean octopod, Macrobrachium rosenbergii, was studied. Although Pyriproxyfen is well known as an effective pest control product, our knowledge about its effects on crustacean metamorphosis, especially on larval stages is yet little. Macrobrachium rosenbergii is a suitable invertebrate species in the neurobiological and endocrinological researches. The species has II larval stages with obvious morphological features for every stage. In this study, larvae of the species were treated with 0.01, 0.05 and 0.1 ppm of Pyriproxyfen against a group of control for which xylene was used. In the first day of exposure to the Pyriproxyfen, all larvae were in the 1st larval stage. We studied the larval stages in samples obtained in different days and percentage of survival in the end of metamorphosis for treatment and control groups. The results showed that all concentrations of Pyriproxyfen significantly caused a delayed larval development and metamorphosis. Furthermore, the post larval survival rates of all treatment groups were less than control. These results suggest that synthetic juvenoid hormone retards the larval morphological development in Macrobrachium rosenbergii, and decreases the survival of the species

A minimal HIV-AIDS infection model with general incidence rate and application to Morocco data

We study the global dynamics of a SICA infection model with general incidence rate. The proposed model is calibrated with cumulative cases of infection by HIV-AIDS in Morocco from 1986 to 2015. We first prove that our model is biologically and mathematically well-posed. Stability analysis of different steady states is performed and threshold parameters are identified where the model exhibits clearance of infection or maintenance of a chronic infection. Furthermore, we examine the robustness of the model to some parameter values by examining the sensitivity of the basic reproduction number. Finally, using numerical simulations with real data from Morocco, we show that the model predicts well such reality.Comment: This is a preprint of a paper whose final and definite form is with 'Statistics Opt. Inform. Comput.', Vol. 7, No 2 (2019). See [http://www.IAPress.org]. Submitted 16/Sept/2018; Revised 10 & 15/Dec/2018; Accepted 15/Dec/201

Investigation of pilot-scale 8040 FO membrane module under different operating conditions for brackish water desalination

© 2014, © 2014 Balaban Desalination Publications. All rights reserved. Two spiral wound forward osmosis membrane modules with different spacer designs (corrugated spacer [CS] and medium spacer [MS]) were investigated for the fertilizer-drawn forward osmosis (FO) desalination of brackish groundwater (BGW) at a pilot-scale level. This study mainly focused on examining the influence of various operating conditions such as feed flow rate, total dissolved solids (TDS) concentration of the BGW feed, and draw solution (DS) concentrations using ammonium sulfate ((NH4)2SO4, SOA) on the performance of two membrane modules. The feed flow rate played a positive role in the average water flux of the pilot-scale FO membrane module due to enhanced mass transfer coefficient across the membrane surface. Feed TDS and DS concentrations also played a significant role in both FO membrane modules because they are directly related to the osmotic driving force and membrane fouling tendency. CS module performed slightly better than MS module during all experiments due to probably enhanced mass transfer and lower fouling propensity associated with the CS. Besides, CS spacer provides larger channel space that can accommodate larger volumes of DS, and hence, could maintain higher DS concentration. However, the extent of dilution for the CS module is slightly lower

Fuzzy Efficiency Measure with Fuzzy Production Possibility Set

The existing data envelopment analysis (DEA) models for measuring the relative efficiencies of a set of decision making units (DMUs) using various inputs to produce various outputs are limited to crisp data. The notion of fuzziness has been introduced to deal with imprecise data. Fuzzy DEA models are made more powerful for applications. This paper develops the measure of efficiencies in input oriented of DMUs by envelopment form in fuzzy production possibility set (FPPS) with constant return to scale

The effect of direct and indirect education on attitudes of parents of children with attention-deficit/hyperactivity disorder towards medication treatments

Background and aims: Attention-deficit/hyperactivity disorder (ADHD) is one of the most common childhood behavioral disorders causing hyperactivity, attention deficit and education decline among children. Regarding the importance of medication treatment, this study was performed to compare the effect of two methods (Direct and Indirect) of education of parents of children with ADHD on their attitudes about medication, treatment satisfaction and medication compliance. Methods: In this clinical trial study, eighty parents of children with ADHD, referred to child psychiatry clinic in Shahrekord were randomly assigned to direct and indirect education groups. The first group (direct education) was attended in groups four sessions. The second group was given education booklet with the same content. Participants were evaluated before and one month after education in terms of their attitudes to medication, treatment satisfaction and treatment compliance. Results: 61 parents of 81 participants continued the study. After intervention, the mean scores of attitudes about medication and satisfaction with treatment were significantly improved in the direct education group (P0.05). Both groups had significantly increased treatment compliance one month after education (P<0.001). Change of mean score attitudes to medication consumption at the end of the periods was significantly different in direct group compared to indirect education group (P<0.01). Conclusion: Direct education was more effective than indirect education on improvement of attitudes towards medication and increase in treatment satisfaction, and both methods resulted in increased medication compliance. Regarding the importance of medication treatment in this disorder, using results of this study can have significant influence on function of children with this disorder in family and school environment

Asymmetric Information in Iranian's Health Insurance Market: Testing of Adverse Selection and Moral Hazard

BACKGROUND: Asymmetric information is one of the most important issues in insurance market which occurred due to inherent characteristics of one of the agents involved in insurance contracts; hence its management requires designing appropriate policies. This phenomenon can lead to the failure of insurance market via its two consequences, namely, adverse selection and moral hazard. OBJECTIVE: This study was aimed to evaluate the status of asymmetric information in Iran's health insurance market with respect to the demand for outpatient services. MATERIALS/PATIENTS AND METHODS: This research is a cross sectional study conducted on households living in Iran. The data of the research was extracted from the information on household's budget survey collected by the Statistical Center of Iran in 2012. In this study, the Generalized Method of Moment model was used and the status of adverse selection and moral hazard was evaluated through calculating the latent health status of individuals in each insurance category. To analyze the data, Excel, Eviews and stata11 software were used. RESULTS: The estimation of parameters of the utility function of the demand for outpatient services (visit, medicine, and Para-clinical services) showed that households were more risk averse in the use of outpatient care than other goods and services. After estimating the health status of households based on their health insurance categories, the results showed that rural-insured people had the best health status and people with supplementary insurance had the worst health status. In addition, the comparison of the conditional distribution of latent health status approved the phenomenon of adverse selection in all insurance groups, with the exception of rural insurance. Moreover, calculation of the elasticity of medical expenses to reimbursement rate confirmed the existence of moral hazard phenomenon. CONCLUSIONS: Due to the existence of the phenomena of adverse selection and moral hazard in most of health insurances categories, policymakers need to adjust contracts so that to reduce these phenomena. Given the importance of financing, the presence of such problems can lead to less coverage of health insurance provided by insurers, loss of contracts with health care institutions and service providers, and lower quality of health services