Project Publications

Hybrid semi-batch/batch reverse osmosis (HSBRO) for use in zero liquid
discharge (ZLD) applications. 

Ebrahim Hosseinipour, Somayeh Karimi, Stephan Barbe, Kiho Park, Philip A. Davies 

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This study aimed to quantify the effect of membrane surface porosity on particulate fouling predicted by the MFIUF method at constant flux. Firstly, the surface porosity of polyethersulfone UF membranes (5–100 kDa) was determined using ultra-high resolution SEM. Thereafter, the MFI-UF was measured using suspensions of polystyrene particles (75 nm), which were pre-washed to remove surfactant and particle fractions smaller than the pores of MFI-UF membranes, thus ensuring complete retention of particles during MFI-UF measurements. Consequently, the MFI-UF values of washed polystyrene particle suspensions were independent of the pore size and depended only on the surface porosity of MFI-UF membrane. The results showed that the membrane surface porosity decreased with MWCO from 10.5% (100 kDa) to 0.6% (5 kDa), and consequently the MFI-UF increased from 3700 to 8700 s/L 2,, respectively. This increase in MFI-UF was attributed to the non-uniform distribution of membrane pores, which is exacerbated as surface porosity decreases. Consequently, preliminary correction factors of 0.4–1.0 were proposed for MFI-UF measured with UF membranes in the range 5–100 kDa.  Finally, the surface porosity correction was applied to predict particulate fouling in a full-scale RO plant. However, additional research is required to establish correction factors for different types of feed water. 

Improving MFI-UF constant flux to more accurately predict particulate fouling in RO systems: Quantifying the effect of membrane surface porosity 
Mohanad Abunada, Nirajan Dhakal, William Z. Andyar, Pamela Ajok, Herman Smit, Noreddine Ghaffour, Jan C. Schippers, Maria D. Kennedy 

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This study aimed to quantify the effect of membrane surface porosity on particulate fouling predicted by the MFIUF method at constant flux. Firstly, the surface porosity of polyethersulfone UF membranes (5–100 kDa) was determined using ultra-high resolution SEM. Thereafter, the MFI-UF was measured using suspensions of polystyrene particles (75 nm), which were pre-washed to remove surfactant and particle fractions smaller than the pores of MFI-UF membranes, thus ensuring complete retention of particles during MFI-UF measurements. Consequently, the MFI-UF values of washed polystyrene particle suspensions were independent of the pore size and depended only on the surface porosity of MFI-UF membrane. The results showed that the membrane surface porosity decreased with MWCO from 10.5% (100 kDa) to 0.6% (5 kDa), and consequently the MFI-UF increased from 3700 to 8700 s/L 2,, respectively. This increase in MFI-UF was attributed to the non-uniform distribution of membrane pores, which is exacerbated as surface porosity decreases. Consequently, preliminary correction factors of 0.4–1.0 were proposed for MFI-UF measured with UF membranes in the range 5–100 kDa.  Finally, the surface porosity correction was applied to predict particulate fouling in a full-scale RO plant. However, additional research is required to establish correction factors for different types of feed water. 

Effect of Salinity and Nitrogen Fertilization Levels on Growth Parameters of Sarcocornia fruticosa, Salicornia brachiata, and
Arthrocnemum macrostachyum 

Tesfaye Asmare Sisay, Zhadyrassyn Nurbekova, Dinara Oshanova, Arvind Kumar Dubey  , Kusum Khatri, Varsha Mudgal, Anurag Mudgal, Amir Neori, Muki Shpigel, Rajeev Kumar Srivastava, Luísa Margarida Batista Custódi , Dominic Standing and Moshe Sagi  

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This study aimed to quantify the effect of membrane surface porosity on particulate fouling predicted by the MFIUF method at constant flux. Firstly, the surface porosity of polyethersulfone UF membranes (5–100 kDa) was determined using ultra-high resolution SEM. Thereafter, the MFI-UF was measured using suspensions of polystyrene particles (75 nm), which were pre-washed to remove surfactant and particle fractions smaller than the pores of MFI-UF membranes, thus ensuring complete retention of particles during MFI-UF measurements. Consequently, the MFI-UF values of washed polystyrene particle suspensions were independent of the pore size and depended only on the surface porosity of MFI-UF membrane. The results showed that the membrane surface porosity decreased with MWCO from 10.5% (100 kDa) to 0.6% (5 kDa), and consequently the MFI-UF increased from 3700 to 8700 s/L 2,, respectively. This increase in MFI-UF was attributed to the non-uniform distribution of membrane pores, which is exacerbated as surface porosity decreases. Consequently, preliminary correction factors of 0.4–1.0 were proposed for MFI-UF measured with UF membranes in the range 5–100 kDa.  Finally, the surface porosity correction was applied to predict particulate fouling in a full-scale RO plant. However, additional research is required to establish correction factors for different types of feed water. 

A free-piston batch reverse osmosis (RO) system for brackish water desalination: Experimental study and model validation
Ebrahim Hosseinipour, Kiho Park, Liam Burlace, Tim Naughton & Philip A. Davies

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Batch RO is designed to achieve high energy efficiency and high recovery in desalination. However, so far
relatively few experiments on batch RO have been reported. Here we present an extensive experimental study of a single-acting, free-piston batch RO system using an 8-inch spiral wound membrane. The system was tested in the laboratory with brackish feed water containing up to 5 g/L NaCl. The objective was to quantify system performance in terms of Specific Energy Consumption (SEC), recovery, rejection, and output. Sensitivity to permeate flux and recirculation flow rate was also investigated. Performance was compared against the predictions of a theoretical model that accounts for salt retention, concentration polarization, and longitudinal concentration gradient in the RO module. For the first time, osmotic backflow was measured and incorporated into the model. For feed concentrations ranging from 1 to 5 g/L and recovery of 0.8, hydraulic SEC was measured in the range 0.22–0.48 kWh/m3 and electrical SEC in the range 0.48–0.83 kWh/m3. With improvements to the membrane permeability from 4.4 to 8 LMH/bar, selection of more efficient pumps, and reduction of valve friction losses, the model predicts that hydraulic SEC will be lowered to 0.14–0.39 kWh/m3

A compact hybrid batch/semi-batch reverse osmosis (HBSRO) system for high-recovery, low-energy desalination

Kiho Park & Philip A. Davies

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Batch reverse osmosis (RO) is  a  promising approach to  high-recovery desalination. It  has  low  energy consumption, but system size increases sharply with recovery because of the need for a large work exchange vessel. In this study, we propose a compact hybrid batch/semi-batch reverse osmosis (HBSRO) system incorporating aspects of each approach. HBSRO works in three phases, i.e. semi-batch pressurisation phase, batch pressurisation phase, and finally purge-and-refill phase. We analyse ideal and practical cases of HBSRO to gain understanding about the specific energy consumption (SEC) and size of the system. In the ideal analysis, HBSRO can halve the size of work exchange vessel while incurring just a 5% energy penalty compared to batch RO at all recoveries. In the practical case, accounting for nonidealities, HBSRO has lower SEC than batch RO at recovery over 0.9, because a smaller volume of work exchange vessel minimises the energy penalty of the purge-and-refill phase in HBSRO. The reduced volume not only makes HBSRO more practical, but also improves energy-efficiency through reduced losses. Thus, our  study highlights that  HBSRO is  highly flexible, achieving high recovery, compact size, and low SEC – advantages that are  especially important in  minimal or  zero liquid discharge applications. 

Design, modelling and Optimisation of a batch reverse osmosis desalination system

Kiho Park, Liam Burlace, Nirajan Dhakal, Anurag Mudgal, Neil A. Stewart           & Philip A. Davies

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Batch RO is a concept for achieving the minimum possible energy consumption in desalination, even at high recoveries. We present a batch RO design that operates cyclically in two alternating phases. The system uses a free piston, housed in a pressure vessel, to transfer pressure from the feed fluid to the recirculating fluid. No complete design procedure for this configuration currently exists. To fill this gap, we present a systematic model based on justified assumptions. The specific energy consumption (SEC) is broken down into contributions from the feed pump, recirculating pump, and auxiliary loads. The calculation of feed pump SEC includes three non-ideal correction factors: concentration polarisation, longitudinal concentration gradient, and salt retention. The model requires only the solution of explicit algebraic equations, without need of specialised numerical techniques, and is implemented in a simple 3-step procedure. The model is applied to an example involving desalination of brackish water using an 8-inch spiral-wound RO module. The design parameters are explored and optimised in a sensitivity analysis. The results show that the optimised batch RO at 80% recovery can produce fresh water with low-energy consumption, achieving 2nd law efficiency of 33.2% compared to 10–15% for conventional brackish water RO.

Design and optimization of electrodialysis process parameters for brackish water treatment
Dipak Ankoliya, Anurag Mudgal, Manish Kumar Sinha, Philip Davies, Edxon Licon, Rubén Rodríguez Alegre, Vivek Patel & Jatin Patel

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Effect of flow velocity and cell-pair thickness in electrodialysis (ED) is studied. The production cost includes pump energy, while the size of the system is considered as an output variable. The performance of ED system depends on three categories of process parameters namely water quality data, stack configuration and flow characteristic inside the stack. The design of ED system is complex due to interrelation among the system variables so the design calculation chronology steps are developed with flow-chart for the fix feed salinity of groundwater and salt removal rate. The effect of recovery ratio on capital and energy cost is studied and found unidirectional. Sparingly soluble salt present in feed decides the upper limit and obtained 70–75% recovery rate based on the feedwater quality. The optimum value of the linear flow velocity and cell-pair thickness can be obtained by the trade-off among capital cost, stack energy cost and pumping energy cost. Simultaneous effect of both the variable on minimizing the total cost gives the narrow working range of flow velocity 15–17 cm/s and 0.4–0.8 mm thickness. The minimum production cost of 0.08 USD/m3 is obtained at 16 cm/s velocity and 0.5 mm thickness.