How can a peri-urban sanitation system, such as baffled reactors and small-bore sewers, be adapted for flood-prone zones?

In large cities of the developing world in Africa and Asia, sewerage can often only be found in the centre, leaving large urban and peri-urban areas unserved, including slums / informal settlements. When sewerage exists, it is often non-functioning or leading to poor treatment facilities. As a result, sanitation coverage in developing cities is often low, with widespread health and dignity issues.

In the absence of service provision, residents usually come up with their own solutions, such as pit latrines. In peri-urban areas, there can be the possibility to install decentralised wastewater treatment facilities, especially for new housing developments, or as part of slum upgrading projects. Such facilities allow the use of improved toilets and can be managed at community level.

An example decentralised wastewater treatment facility for 5,000 residents would include:

* Flush or pour-flush toilets (needing 1-2 litres of water per flush) in or near houses.

* Septic tanks or related systems (anaerobic baffled reactors – ABRs) for primary treatment (separating sludge and liquid effluent). These can be shared between houses but then need transport through simplified sewers.

* Solids-free small sewers to transport the effluent.

* Secondary treatment e.g. in the form of constructed wetlands.

 

However, many developing cities are susceptible to the effects of climate change, and especially flooding due to increased rain in low-lying, coastal and/or flood-prone areas. Many cities have seen an increase in rain and flash floods. During such floods, one of the most significant disruptions residents have to face is access to water and sanitation, when toilets are inaccessible, or when treatment facilities cannot work anymore.

This is the case for example in many cities in Bangladesh.

The Challenge

The challenge is therefore to adapt existing technologies, such as the system described above which includes several sub-surface elements, to flood-prone conditions. Notably:

1) How can the system still function during flooding?

2) How can it remain accessible to residents, especially the most vulnerable ones?

3) How can pollution be prevented?

The solution proposed must be appropriate for the context described above, especially in terms of capital and recurring costs, and currently available technologies.

Entry

Teams of up to 3 people, aged 18-35 on 30 September 2014.

The entry submitted by competitors or teams of competitors must be made of:

* A concept design for your proposal on a one A1 poster with a maximum of 1500 words and should include at least two diagrams / sketches.

* The submission should include the name(s) of the participants their date of birth and contact details.

* Three copies should be provided.

* Additionally the competitors should also supply a CD or memory stick with a pdf version of their submission.

Submissions must be received by 1st September 2014.

Please send your entries to: Edward Clarke/ SoPHE YEA, C/O Arup, 13 Fitzroy Street, London, W1T 4BQ

The Award

An in-country technical visit to verify the applicability of the design.

Additional information can be found on the SoPHE website http://www.cibse.org/society-of-public-health-engineers-sophe/sophe-young-engineers-award-2014