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Details of Grant 

EPSRC Reference: EP/N022130/1
Title: Osmotic Membrane Technologies for Energy Neutral Wastewater Treatment: Process Performance and Optimization
Principal Investigator: Sloan, Professor WT
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: School of Engineering
Organisation: University of Glasgow
Scheme: First Grant - Revised 2009
Starts: 01 July 2016 Ends: 31 May 2018 Value (£): 98,575
EPSRC Research Topic Classifications:
Water Engineering
EPSRC Industrial Sector Classifications:
Environment Energy
Related Grants:
Panel History:
Panel DatePanel NameOutcome
25 Nov 2015 Engineering Prioritisation Panel Meeting 25th and 26th November 2015 Announced
Summary on Grant Application Form
The United Nations estimates that the world produces around 1,500 cubic kilometers of wastewater annually, of which more than 80% is untreated. On average, treating 1 cubic meter of sewage consumes ~0.5-0.6 kWh of energy, ranking the fourth most energy intensive sector in the UK. With the increasing concern over declining quality of natural water bodies, greenhouse gas emission and the escalating price of fossil fuels, the conventional paradigm of sewage treatment needs a step-change. There is a rapidly expanding global water market in creating and delivering low energy and environmentally sustainable sewage treatment technologies which are required not only for enhanced treatment efficiency but also resource exploitation.

Compared to energy-intensive aerobic counterparts, anaerobic sewage treatment processes are more attractive due to their low energy consumption and sludge production and their production of bioenergy. However, it is crucial to pre-concentrate dilute sewage before anaerobic digestion in order to achieve improved treatment efficiency and energy recovery.

Forward osmosis (FO) is a natural process by which clean water passes from dirty feed water towards a salt 'draw' solution with higher osmotic pressure when the two solutions are separated by a semipermeable membrane. It is an emerging water treatment technology and has been identified as an ideal candidate for concentrating liquid due to its superior retention of organic matter as well as its low energy requirement. However, as yet, the full potential of FO has not been realised in full-scale treatment technologies. The greatest gains in deploying FO may be achieved by eschewing the more traditional reactor designs and exploring radically new technologies that integrate biotechnology and membrane science to deliver a step change in the efficiency and sustainability of water supply, treatment and reuse.

In this study, we propose to develop a novel osmotic membrane bioreactor for energy-neutral anaerobic wastewater treatment. Our conceptual design comprises two stages: (1) osmotic pre-concentration and (2) high retention anaerobic membrane bioreactor (HRAnMBR). In Stage-1, clean water passes from sewage to ocean water that is separated by a semi-permeable membrane at nearly zero energy input. It is even possible to gain energy when a small amount of pressure is added on the ocean water side, a process called pressure retarded osmosis (PRO). Nearly all organics are retained in the concentrated sewage due to the high retention nature of membranes. This pre-concentration stage facilitates the efficient anaerobic digestion in Stage-2. The water that has permeated through membrane has high quality and can be discharged back to the ocean with no environmental impact. In Stage-2, the organics in pre-concentrated sewage are degraded and converted into renewable energy by anaerobic digestion. In the HRAnMBR, high retention membrane plays two roles: (1) further clean the anaerobically treated sewage and (2) significantly enhance biogas recovery and thus the overall energy balance during sewage treatment. This 18-month project will focus on simplified systems where we can build models of water flux, pollutant removal and biogas production in response to key variables (e.g., membrane materials, wastewater/draw solutions composition, temperature, reactor configuration). Design and operation guidelines of the system will also be established.

The whole system is highly attractive in terms of treating wastewater to meet the further stringent water quality standards, reduced footprint and reduced energy costs. More importantly, it has the potential to make sewage treatment a net energy producer. We already have a relationship with Scottish Water who is interested in the proposed technology to provide water and wastewater services to small rural communities. The technology can be sold in the huge global market for decentralised water supply and treatment.

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