Literally thousands of scenarios can be simulated in the model, whereas in the real world you can only try one strategy at a time.

Tommy Ngai

Research at the Department is helping to clean up water in regions around the world. Almost 900 million people worldwide lack access to safe water; polluted lakes and waterways diminish livelihoods and health; and 2.6 billion people (almost half the population of the developing world) lack access to adequate sanitation.

Researchers at the Department's Centre for Sustainable Development are working in regions where dirty, polluted and inadequate supplies of water make drinking, cooking and cleaning an everyday challenge for the communities who live there.

Improving outcomes

Having worked for several years in rural Nepal trying to implement the use of water filtration units, Tommy Ngai from the Centre for Sustainable Development knows only too well that, despite their benefits, the adoption and continued use of household water treatment and safe storage (HWTS) is not always straightforward.

For the past four years he has been investigating how to improve the dissemination and uptake of HWTS. Working with Dr Dick Fenner also from the Centre for Sustainable Development, his research has taken him to Nepal, southern India and Ghana, where he has carried out extensive interviews with project management staff, community workers, government officials, shopkeepers and household end users.

'It's not uncommon for communities either to not take up HWTS or for the equipment to be found lying abandoned a year or so later,' he explains. 'There may be a lack of awareness among potential users, or the devices may be too expensive to operate and maintain, or the supply chain unavailable, or there may be technical difficulties and ineffective post-implementation support.'

Ngai's research has, for the first time, captured the big picture of the many competing factors at play - from the technical and financial, to the social and institutional. The outcomes are three country-specific computer simulation models linking over 300 different variables, each relating to different types of HWTS solutions (such as ceramic filters, biosand filters and household chlorination) . The models are intended to help the program managers and consultants of smaller NGOs implementing HWTS programs to appreciate the complexity of project management, to understand the interactions and consequences of any policy strategy and, crucially, to make recommendations for increasing the success of an HWTS programme.

'Literally thousands of scenarios can be simulated in the model, whereas in the real world you can only try one strategy at a time,' he says. 'Comprehensive analysis showed that no single strategy will always work in all situations, and that some measures that have long-term benefits may at first appear counter-intuitive.'

One of the models has also been designed as an easy-to-use simulation game that can be run on a PC, allowing agencies and government officials to explore the effects of different potential intervention strategies concerning programme expansion, promotion, training, pricing and capacity building, and to predict adoption and sustained use of HWTS.

In his next post, as Director of Research Learnings at the Centre for Affordable Water and Sanitation Technology in Canada, www.cawst.org Ngai will be using his research to help NGOs and government policy makers to understand quickly how best to encourage sustained adoption of HWTS in their region.

Sanitation innovation

Ensuring access to safe water isn't the only challenge; it's also what you do with waste. An innovative study has come up with a prototype system that could improve sanitation in urban slums. The realities of high-density living in urban slums have made conventional approaches to improved sanitation practically impossible, with low-income families renting living space in tightly packed, unplanned settlements serviced by pit latrines.

Nate Sharpe's research in the Centre for Sustainable Development has come up with a solution for emptying pit latrines in the slums of Dar es Salaam, Tanzania, although his findings should be applicable to many other similar cities around the world. 'Pit latrines are filling up faster than ever and people are often forced to rely on unhygienic emptying methods,' he explains. 'If smaller amounts of the sludge could be removed more often, it becomes easy to transport - even on the back of a bicycle.'

Sharpe has designed a prototype bicycle-powered vacuum pump/tank system and a business model for small businesses to run a latrine-emptying service at a low enough price that even the poorest might be able to afford to make their latrine usable again. The next stage is to test the device in Tanzania and to put the device into production.

His research was completed as part of an MPhil in Engineering for Sustainable Development with Dr Heather Cruickshank, and is just one of around 35 similar projects annually that are finding innovative engineering solutions to a host of sustainability problems. Many focus on developing countries where, as Sharpe has highlighted, sometimes the solution lies not in the development of new technology but in the creation of a new business angle that works in the local community.

Options for sustainable sanitation

Amparo Flores, also working with Dr Dick Fenner, has recently successfully completed her PhD evaluating the sustainability of sanitation systems that are designed to recover all sludge from wastewater while minimizing the demand on other resources particularly water.

Amparo identified the advantages and disadvantages of this approach with conventional sanitation systems. The work involved a pilot study in Durban, South Africa in which Amparo developed a rigorous sustainability assessment methodology and compared the viability of conventional pit latrines with urine diversion dehydrating toilets. This work forms the basis of a new chapter on "Providing Sanitation Solutions" co-authored by Dick and Amparo, in the second edition of the book "Sustainable Development in Practice: case studies for engineers and scientists"

The bulk of Amparo's research focussed on Erdos Ecotown in Inner Mongolia in China and was a case study of the world's largest urban dry sanitation system designed for complete resource recovery. Amparo made two visits to China in 2007 and 2009 to study the operation of the system and evaluate the acceptability of the system to the local users. She compared the novel dry system against that of a nearby conventional water flush system based on technical, environmental, economic, and societal indicators.

She found that whilst the dry toilet system offered clear environmental advantages such as reduced water consumption, the recovery of valuable resources from domestic wastewater, reduced eutrophication, and reduced toxicity of agricultural soils these benefits come at the cost of higher energy consumption and greater infrastructure requirements. The dry system is more costly to operate. The less technologically mature dry toilet system required further improvements particularly with regards to odour control, toilet design, and faecal material handling. The conventional wet system was more popular with users. Amparo concluded that a toilet system that combines urine diversion with minimal flush water for faeces was a good alternative, and would still be significant progress towards sustainability.

Amparo has now returned home to Califiornia where she is working as a water quality manager in the California water industry.

For more information about these projects, please contact Tommy Ngai (tommyngai@yahoo.ca), Dr Dick Fenner (raf37@cam.ac.uk) and Dr Heather Cruickshank (hjc34@cam.ac.uk)