The SVSR group, in association with researchers at UNSW Sydney, reports progress on a proof-of-concept for a reusable Graphene Oxide (GO) membrane to capture waste water vapours from ageing sewerage systems.
Sewer gas, primarily hydrogen sulphide, which smells like rotten eggs, causes both complaints from the public and often leads to corrosion damage, which is an expensive problem faced globally today. Corrosion in sewer systems and drinking water systems is estimated to cost close to AU$1bn in Australia  annually and US$36bn  in the US.
The GO membrane developed by materials scientist Dr Rakesh Joshi at UNSW has already been shown to be effective in capturing water and water vapour and superior to existing moisture absorbers, such as silica.
The ability to fine tune the spaces between the layers of graphene oxide in the membrane leads to its capacity to be used in other applications.
In what is believed to be the first test of the membrane for industrial application in Australia, Dr Joshi designed an experiment to evaluate the GO membrane under simulated conditions found in sewerage networks.
“We knew of the enormous potential GO has for the reduction of humidity in confined areas such as sewerage networks. We wanted to know if the membrane could capture hydrogen sulphide, H2S, a noxious odour and corrosive gas, commonly found in sewerage networks,” said Duncan Reynolds, Research and development Manager, SVSR.
The experiment confirmed that hydrogen sulphide molecules adhered to the surface of the graphene oxide membrane at high relative humidity.
In addition to humidity, the material was tested for low to very low gas flow rates and hydrogen sulphide concentrations at approximately 10ppm.
Future research will determine the conditions for de-adsorption of hydrogen sulphide, chemical changes that occur in the hydrogen sulphide, the performance of regenerated GO membranes and comparative studies against activated carbon.
UNSW Water Research Centre/School of environmental Engineering provided critical feedback on the results, which relate to the complex environment in a sewerage system. These points will be explored in future research.
“There is more evaluation work to be done but we are confident to move forward because of the great potential for this product to provide a long-term solution for sewerage networks. The membrane could potentially support adequate ventilation and odour control,” said Reynolds.
There are currently over 10,000 vent shafts throughout Australia, most of which are in Greater Sydney, which were designed and built from the 1940s to the 1970s.
The vent shafts are often located in sensitive residential back yards or footpaths adjacent to roads and essential services
“The real challenge is finding a sustainable solution. We are aiming for this product, which could potentially be reused, to be retro-fitted to existing infrastructure,” said Reynolds.
Most of the filter products currently in use, which use carbon, cannot be reused.
The SVSR group is the leading sewer vent shafts design, fabrication and installation. Founded more than twenty five years ago, the company has a long-held traditional of innovation and collaboration, with SVSR also a member of the nandin innovation centre located an ANSTO.
-  ACA (2010) The Australian Corrosion Association Inc. Corrosion Challenge Project, Australian Corrosion Association, in DNV GL – Report No. OAPUS310GKOCH (PP110272)-1, Rev. 3, Accessed 08/11/2019: http://impact.nace.org/documents/appendix-a.pdf
-  FHWA (2002) Corrosion Costs and Preventive Strategies in the United States, Summary of Federal Highways Administration Publication FHWA-RD-01-156 Accessed 08/11/2019: http://impact.nace.org/documents/ccsupp.pdf