We are pleased to publish the Nexus Network thinkpiece ‘Imagining a sewerless society’ by Ben Martin, Peter Cruddas, Paul Hutchings from Cranfield University. Here is an overview of the topics, taken from the thinkpiece:
What’s wrong with Conventional sewers?
Conventional sewer systems have a heavy impact across the nexus of water, energy, food and the environment. Large water demands can increase water scarcity and require significant energy for the conveyance of huge volumes of diluted sewage.
Urban systems are frequently overloaded leading to discharge of raw sewerage directly to the environment whilst the vast potential for nutrient recovery is underdeveloped at a time when such outputs could have a role to play in global fertiliser markets.
Moreover, the challenge of expanding centralised sewers or, even more demanding, developing new sewer systems is hampered by a number of significant barriers, including the significant economic costs and planning challenges.
In developing countries, this is felt most keenly. The World Health Organization estimated that diarrhoeal disease alone killed 226 million people n the 20th Century; the majority of whom lived in low income countries, with poor sanitation and hygiene. Meeting this sanitation challenge has so far been beyond the conventional wastewater paradigm with no imminent solution from the prevailing model addressing the problem of sanitation access in poor, crowded cities.
A sewerless society
In light of the current and emerging technologies in ecological sanitation and resource recovery from human waste, this paper imagines two scenarios in which a sewerless society could function:
Scenario one: Household toilets become standalone, decentralised processing plants. The households are wholly responsible for reuse and recycling technologies, which would include the useful by-products generated from the self-contained toilet. Unusable waste is reduced to such an extent that it can be introduced to existing waste systems without significant impact.
Scenario two: A centralised processing approach is taken, whereby waste processing facilities become resource manufacturing sites, producing energy and fertilisers from the waste collected at household level. The efficiency of these plants will depend greatly on the design of the household toilet, as low efficiency methods are already available but requiring significant transport and post-processing capabilities. Advancing toilet designs in the same direction as the self-contained concept would reduce the amount of waste required to be collected, whilst also increasing the efficiency of the centralised plants.
Read the full thinkpiece
You can read the full thinkpiece here MartinCruddasandHutchings_SewerlessSocietyNexusThinkpiece2015
About the authors
Dr Ben Martin is a Research Fellow at Cranfield University, and has been involved in developing a waterless toilet design with Gates Foundation funding. For his PhD he developed a novel nutrient recovery system from wastewaters, and holds an Environmental Science degree from Lancaster University. Ben is the corresponding author for the paper.
Dr Peter Cruddas is a Research Fellow at Cranfield University looking at energy recovery from waste systems, including his PhD thesis on biogas generation from wastewater treatment and the use of thermal processing for faecal sludge management. He holds a BEng (hons) in Civil Engineering from the University of Bradford and an MSc in Water Management from Cranfield University.
Paul Hutchings is a Research Assistant at Cranfield University conducting PhD research into community management models for water supply in rural India. He holds BA (Hons.) and MA (Dist.) degrees in Geography from the University of Liverpool and has worked as a mix-methods researcher at the Chartered Management Institute.
Image credit: Clean Team‘ social enterprise short residence time toilet, demonstrated by a customer in Kumasi, Ghana.