Darren Oatley-Radcliffe

Swansea University | SWAN · College of Engineering

The ever-increasing demand for phosphorus fertilisers for securing global food production, coupled with finite phosphate rock reserves, is one of the emerging problems in the world. Indeed, phosphate rock is listed as an EU critical raw material, triggering attention to find an alternative source to substitute the use of this limited resource. Chee...

Cultivating microalgae requires a nitrogen and phosphorous feed source. Anaerobic digestion waste (digestate) provides a cheap sustainable feedstock for these materials. Previous studies have successfully demonstrated the feasibility of nutrient recovery and subsequent algae growth. There is now a need to fully characterise digestate filtration to...

Human activities produce waste. In autotrophic mode, microalgae consume these waste materials, as growth nutrients, along with sunlight to create more biomass and O2. This process is known as photosynthesis, and microalgae are the fastest photosynthetic organism on the planet. Moreover, they are not land-based and do not compete for arable land. Th...

Chemical functionalization with super hydrophilic substituents (e.g. cysteic acid) has been shown to increase the flux of fresh water and brine through membranes. As a consequence, lower trans-membrane pressures are required, reducing the cost (due to the use of low-pressure pumps and polymer plumbing). The super hydrophilic nature of the membrane...

Abstract Current trends of livestock expansion and associated mass production of manure bring a net import of nutrients that have led to a significant excess in many areas. The implementation of an efficient and more economical technology solution to recover and re-use nutrients from raw or digested wastes is essential and will reduce the need for...

Groundwater contamination by chlorinated hydrocarbons represents a particularly difficult separation to achieve and very little is published on the subject. In this paper, we explore the potential for the removal of chlorinated volatile and non-volatile organics from a site in Bedfordshire UK. The compounds of interest include trichloroethylene (TC...

Digestate produced from the anaerobic digestion of food and farm waste is primarily returned to land as a biofertiliser for crops, with its potential to generate value through alternative processing methods at present under explored. In this work, valorisation of a digestate resulting from the treatment of kitchen and food waste was investigated, u...

Successful characterization of membranes is of paramount importance for the development and improvement of novel membranes and membrane processes. The characterisation of membrane charge is key to understanding charge interactions between the process stream and the membrane and is typically represented by the surface zeta potential. In a previous p...

Abandoned mines cause serious environmental damage to their surroundings with considerable impacts on freshwater ecosystems. These impacts occur mainly due to the uncontrolled discharge of polluted effluents, which may contain high concentrations of heavy metals. Currently, no real solution exists for this important environmental problem, leaving a...

Anaerobic Digester (AD) waste, known as digestate (spent anaerobically digested effluents) of agricultural origin, was collected for a feasibility study on the use of membrane filtration to fractionate phosphate and ammonia from digestate into nutrient streams. The digestate was pre-treated to remove bulk solids and then filtered using diafiltratio...

The removal of oil from water is of increasing importance in many industries, such as oil and gas, petrochemical and food industries, because of the large volumes of oily wastewater they produce. The aim of this work is to evaluate and compare the performance of ferrous and aluminium sulfate coagulations and to compare between sand filter, coagulat...

This chapter addresses aspects of fresh clean water from a variety of perspectives: economic, geographic, and technological (production). Types of water filters are discussed, along with the materials from which they are made. In-depth details of reverse osmosis systems, including plant layouts, are presented. The chapter concludes with a section o...

In this paper we investigate the potential for using suspension crystallisation for the production of clean drinking water from a seawater source. The experimental results show that the produced water from the suspension crystallisation plant not only meets water quality standards but is comparable in ionic composition to premier bottled water from...

A novel hybrid membrane-adsorption process has been developed for the production of clean water supplies. A 0.2 μm ceramic membrane has been functionalised to produce a super-hydrophilic surface on the microfiltration membrane capable of maintaining flux with little or no fouling under normal operating conditions. The adsorbent used is a supported...

The environmental impact of shale oil and gas production by hydraulic fracturing (fracking) is of increasing concern. The biggest potential source of environmental contamination is flowback and produced water, which is highly contaminated with hydrocarbons, bacteria and particulates, meaning that traditional membranes are readily fouled. We show th...

Nanofiltration technology has come a long way since first inception in the late 1980s. Research activity in this area covers a great many topics and the aim of this review is to quantify the level interest in each of these areas. The number of annual publications directly related to nanofiltration technology has been harvested from ScienceDirect si...

Casting of a novel polyetherimide-sulfonated poly (ether ether ketone) membrane onto a non-woven support layer to improve mechanical strength and robustness of the resulting membrane is studied. The resultant membrane performance is optimised by considering the phase inversion parameters of polymer concentration, casting thickness, casting speed, e...

The typical characteristics of membranes can be estimated directly from experimental data. To successfully characterize membranes using such techniques a representative model of the membrane process must be used that is simple enough for solution yet detailed enough to capture the key characteristics required. Two cases have been considered where t...

The use of atomic force microscopy (AFM) has been increasingly used in recent years in academic research labs to probe the surface morphology and physical properties of a wide range of surfaces at high resolution, including surfaces pertinent to water treatment processes, particularly polymer membranes. The AFM at its heart is based around a very s...

Membrane Characterization provides a valuable source of information on how membranes are characterized, an extremely limited field that is confined to only brief descriptions in various technical papers available online. For the first time, readers will be able to understand the importance of membrane characterization, the techniques required, and...

The mass transfer processes involved in transporting materials from the bulk feed solution through the membrane to form a permeate stream is discussed. The complex microhydrodynamics and interfacial events occurring at the membrane surface and within the membrane itself are outlined. A description of concentration polarization at the membrane surfa...

Membrane processes are advanced filtration processes that utilize the separation properties of finely porous polymeric or inorganic films. Membrane separations are used in a wide range of industrial processes to separate biological macromolecules, colloids, ions, solvents, and gases. To design, develop, and model membrane processes, knowledge of th...

Membrane charge is fundamental to the separation of ions from a membrane and is a major factor in the separation efficiency of ultrafiltration, nanofiltration, and reverse osmosis membranes. Characterization of the charge properties of membranes can be performed using a variety of different methods. In this chapter, the electrokinetic phenomena of...

A novel technique employing an Uzigirs dip cell arrangement is used in conjunction with Laser Doppler Electrophoresis for the determination of the surface zeta potential for a UF, NF, and RO membrane. To the authors best knowledge this is the first study employing Laser Doppler Electrophoresis and Electro-osmotic Flow Mapping for membrane surface c...

Entomopathogenic fungi offer much potential for the control of arthropod pests. Very little is known about the impact of inoculum drift and runoff on aquatic non-target invertebrates. In general, there are no clear guidelines on risk assessment of these biological control agents and their secreted compounds. In the current study, Metarhizium brunne...

This aim of this work was to investigate the effects of mass transfer in three commercially available frontal nanofiltration systems (Amicon, Sterlitech and Membranology) using the rejection of uncharged poly ethylene glycol (molecular weight 3400) at different pressures and stirrer speeds using a 4000 MWCO membrane. The real rejection was calculat...

In this study a series of different molecular weight PEG solutions have been characterised for particle size and the results have been used, in conjunction with several other techniques, to determine the pore size of the Nadir UH004 membrane. The resulting information, in conjunction with experimentally determined rejection profiles for the PEG sol...

The fractionation of nitrogen (as ammonia/ammonium) and phosphorus (as phosphate ions) present in the dairy manure digestate was investigated using a nanofiltration membrane NF270. The filtration and separation efficiencies were correlated to pH across the range 3 < pH < 11. Filtration at pH 11 enabled higher permeate flux of 125–150 LMH at 20 bar,...

The world is currently facing the prospect of a severe global shortage of fresh water alongside finite energy resources and the development of energy-efficient desalination methods is of paramount importance to solve these complex problems. In this paper the basic principles of freeze concentration processes are presented. Even though the process h...

Adequate fresh water supply is an increasing global issue as water stress continues to grow in many areas of the planet Seawater desalination processes are essential to supply domestic needs as well as those of industry and agriculture. Membrane processes are now the dominant technology for desalination and will continue to grow in use for the fore...

The harvesting of the microalgae Scenedesmus species using a 200 L pilot-scale microfiltration system was investigated and critically assessed. The energy requirement was determined and correlated to the different operating parameters such as transmembrane pressure (ΔP), membrane area, temperature and initial biomass concentration. A filtration mod...

Membrane nanofiltration is extremely complex and is dependent on the micro-hydrodynamics and interfacial events occurring at the membrane surface and within the membrane nanopores. There is significant debate as to the exact nature of these complex phenomena and rejection is typically attributed to a combination of steric and electrical effects. Th...

The structuring of water at soft solid surfaces remains an area of great interest to colloid science as a whole and has many applications in relation to colloid stability, foams, and wetting films as well as being central to membrane separations. Quantitatively calculating the structural components of thin layers of water and the interaction forces...

The present study demonstrates the high potential for the application of a novel self assembled positively charged nanofiltration membrane, PA6DT-C, in processes such as the recovery of valuable cationic macromolecules in the bioprocess and pharmaceutical industries or removal of multi-valent cations such as dyes and heavy metals in the paper and p...

A review of the fabrication processes currently available to produce positively charged nanofiltration membranes has been conducted. The review highlights that there are few membranes and studies currently available. The preparation of a novel positively charged nanofiltration membrane is also described. This membrane was fabricated by surface modi...

For traditional separation processes there are widely available process design methodologies for scale-up and optimization. However, there is an increasing need for such a rational approach to membrane separation processes, identifying at an early stage operating limits and process options. Such predictive models will reduce development risk and ti...

Charged UF/NF membranes have been developed by phase inversion. The membranes were prepared with polyetherimide (PEI) and sulfonated poly(ether ether ketone) (SPEEK). SPEEK was used to improve the hydrophilic properties and permeability of the PEI membrane, as well as to provide surface charges. The membrane properties were reproducible when the pr...

For traditional separation processes there are widely available process design methodologies for scale-up and optimisation. However, there is an increasing need for such a rational approach to membrane separation processes, identifying at an early stage operating limits and process options. Such predictive models will reduce development risk and ti...

The world is currently facing the prospect of a severe global shortage of fresh water alongside finite energy resources and the development of energy-efficient desalination methods is of paramount importance to solve these complex problems. In this paper the basic principles of freeze concentration processes are presented. Even though the process h...