Website University of Edinburgh
Job title: Design and Testing of Thermal and Membrane-Based Desalination Devices
Responsible To: Dr Mignard / Dr Semiao
Department: Chemical Engineering and Civil Engineering / Institute for Energy Systems
Duration: 3 months
Placement Ref: EQU/2019/042
Basic purpose of the placement and its primary objectives:
Support of a joint research programme with Strathmore University’s Energy Research Centre, Nairobi, Kenya; involving desalination of brackish and/or fluoride-containing groundwater in Turkana County.
In Kenya and in other areas in Eastern Africa and around the world, people are dependent on groundwater for their potable supply. This water is often brackish and in Kenya is often contaminated by fluoride that presents a health hazard. The conventional way of removing salts in general and fluoride in particular relies on Reverse Osmosis (RO) using membranes that retain salt and let through the water. However, this technology is costly to purchase, maintain and power. RO requires significant energy consumption for pressurising the water against the generated osmotic pressure at the membrane surface, even after recovering the pressure energy from residual untreated brine (ca. 3 kWh / m3). It also requires extensive pre-treatment and is prone to failure, and due to the costs involved tends to fall into disrepair and disuse.
Previous work has focused on two possible other approaches:
- The design of thermal devices that are powered by solar energy. This would be particularly suited for small scale applications. Laboratory and field tests have been conducted for these devices.
- Membrane desalination using Nanofiltration rather than Reverse Osmosis, which should result in lower energy consumption and simpler design to lower specifications due to lower pressure. Laboratory data have been obtained showing retention rates of fluoride and permeation rates at different pressures.
The basic purpose of this work would be to ascertain the design of small scale plants that would be based on these principles and on previous results, and conduct further testing with a view to optimise the operating conditions with respect to achieving the lowest cost in £/L of freshwater produced.
Primary objectives would be to answer the following questions:
- What are the basic requirements for pre-treatment of the water before desalination, and can these be kept as minimal as possible?
- Are there designs and sequences of operations that are more effective?
- What are the optimised conditions of operation?
- How would the resulting costs compare with conventional Reverse Osmosis?
- Engineering study of pre-treatment requirements
- Preliminary testing of pre-treatment method
- Design of testing methods for desalination devices or critical components of these devices
- Testing of desalination devices or their critical components
- Preliminary costings over the life time of a device
- Writing up of an evaluation report
Knowledge and skills required:
The successful candidate will have completed as part of their prior training on a laboratory project. They should be able to demonstrate conscientious execution of the project and analysis of the data, as well as critical appraisal of the results and discussion of further work.
Students with a track record of working on technical assignments in the context of a developing country would be at an advantage. However, the following is also desirable:
- Prior Chemistry (Analytical or Environmental Chemistry) Laboratory training and experience, e.g. to 2nd yr Chemical Engineering level or more.
- Some basic Chemical Engineering conceptual design ability and knowledge of costing methods would be helpful.
- Good sense of observation and rigorous approach to investigative research (Asking questions, and devising and executing methods to get answers)
- Still able to think independently and critically while being a good team worker.
- Mindful of Health and Safety
- Able to communicate and negotiate with Kenyan partners if required.
Laboratory based during normal working hours (9-5pm).
The Closing date is 7th March 2019.