̽��ֱ�� of Cambridge - sanitation

A sewage system that ‘digests’ and ‘cooks’ human waste

lw355 — Fri, 10 Feb 2017 08:40:35 +0000

We are surrounded by friendly and welcoming people, but the language barrier makes communication monumentally challenging. We feel far from the immaculate lawns and gleaming stone of King’s Parade on a summer’s day. Navigating through a cluster of buildings in sweltering heat, even the smell is new. It has a sort of rawness: uncooked meat, unrefined exhaust fumes, untreated sewage.

This isn’t a quick and isolated visit. Instead, it will be the first of many over the next two months to Vingunguti, a densely populated part of Dar Es Salaam, the largest city in Tanzania.

We are here as members of the student-led Cambridge Development Initiative (CDI), which runs several projects in the area. Ours focuses on engineering and, over the past three years, we have been designing and piloting an innovative sewage system to bring cheap and safe sanitation to households that are beyond the reach of the urban infrastructure.

Today we’re helping to lay pipes at shallow depths and gradients to expand our sewage network to 11 new houses, one of the aims on this trip. We’re helped along by the enthusiasm of members of the community, who are keen to have latrines that are connected to a sewage system.

Pit latrines are common here. Not only are they dangerous to empty, and frequently overflow in monsoon season, but these holes in the ground also contribute to the high incidence of water-borne diseases.

But it’s not just about cleaner toilets and streets. CDI’s innovation is the conversion of simplified sewage into useful products – fuel and fertiliser – using a system that has no net waste. ̽��ֱ��sewage flows into a ‘digester’ (designed by a SOWtech, a Cambridge-based company) that generates methane gas, which can then be used by households as a safer and cleaner alternative to charcoal for cooking. ̽��ֱ��effluent output of the digester is then ‘cooked’ using a solar-powered dryer (the EvapoDryer) to make fertiliser for agricultural purposes.

Once the new households are added, CDI will have managed to connect over 400 people to good-quality sanitation infrastructure, moving 1.9 tonnes of waste away from houses every day and generating products for the community that are either used in the households or sold by local entrepreneurs to establish an additional source of income.

On paper, this sounds great. But ensuring that it’s successful and sustainable in practice is tough. There are several case studies – even within Vingunguti – that highlight the dangers of not adequately including the community in projects that directly affect them. With its ethos of participatory development, the CDI model focuses on community organisation, financial ownership and targeted skills and knowledge training. Mobilising the community is a critical first step in the process.

After a community has identified the need for improved sanitation, a Sanitation Users Association (SUA) is established, bringing all the households together and giving them responsibility for managing construction and maintenance. In fact, the householders themselves finance and help to build the network. They are loaned the capital for their latrine construction and they pay this back through a microfinance scheme delivered by a Tanzanian NGO founded and run by a CDI alumnus.

Equally important is the involvement of students from universities in Dar Es Salaam, who are part of a complementary organisation (CDI Tanzania). We work alongside each other every day on all aspects of the project, from designing the network to facilitating community meetings. ̽��ֱ��Tanzanian students offer a unique and valuable perspective on the sanitation issues facing these areas – their insights are crucial to the success of the project.

To be sure that the project has a sustainable impact, we organise educational sessions for community members, delivered by our Tanzanian partners. One focus is health awareness sessions for women and children, covering topics like hand washing and malaria prevention. According to a recent survey, 97% of households agree that the project has improved the health of the community.

One local participant, Mr Mbetela, believes that the dangers of cholera and malaria have now been eliminated as a result of the CDI project. Fatima, another resident, says it has brought peace between neighbours because of the better conditions of the street. Ms Zacharia tells us that the new system has removed the embarrassment she used to feel when using exposed pit latrines.

As we prepare to return to Cambridge, we hear that the municipal water authority is looking to adopt our team’s sewage model, which could lead to 1,000 more people having access to safe, hygienic sanitation facilities in the coming years.

Meanwhile, CDI Cambridge and CDI Tanzania will carry on optimising the digester and cooker. Within 12 months, our goal is for there to be a fully functioning sanitation system, run and maintained by the community, removing human waste from households and turning it into essential products. ̽��ֱ��phrase ‘waste not, want not’ never seemed so apt.

Susannah is studying management at the Judge Business School, and Izhan has just graduated from the Department of Engineering.

Inset image: Susannah Duck and Izhan Khan; credit: Lloyd Mann.

To keep up to date with the latest stories about Cambridge’s engagement with Africa, follow #CamAfrica on Twitter.

Student volunteers Susannah Duck and Izhan Khan describe working with a Tanzanian community to install a system that turns sewage into essential products.

Equally important is the involvement of students from universities in Dar Es Salaam. We work alongside each other every day on all aspects of the project

Susannah Duck and Izhan Khan

Izhan Khan

Dar Es Salaam

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Better hygiene in wealthy nations may increase Alzheimer’s risk

fpjl2 — Wed, 04 Sep 2013 10:01:20 +0000

New research has found a “very significant” relationship between a nation’s wealth and hygiene and the Alzheimer’s “burden” on its population. High-income, highly industrialised countries with large urban areas and better hygiene exhibit much higher rates of Alzheimer’s.

Using ‘age-standardised’ data - which predict Alzheimer’s rates if all countries had the same population birth rate, life expectancy and age structure - the study found strong correlations between national sanitation levels and Alzheimer’s.

This latest study adds further weight to the “hygiene hypothesis” in relation to Alzheimer’s: that sanitised environments in developed nations result in far less exposure to a diverse range of bacteria, viruses and other microorganisms - which might actually cause the immune system to develop poorly, exposing the brain to the inflammation associated with Alzheimer’s disease, say the researchers.

“ ̽��ֱ��‘hygiene hypothesis’, which suggests a relationship between cleaner environments and a higher risk of certain allergies and autoimmune diseases, is well- established. We believe we can now add Alzheimer’s to this list of diseases,” said Dr Molly Fox, lead author of the study and Gates Cambridge Alumna, who conducted the research at Cambridge’s Biological Anthropology division.

“There are important implications for forecasting future global disease burden, especially in developing countries as they increase in sanitation.”

̽��ֱ��researchers tested whether “pathogen prevalence” can explain the levels of variation in Alzheimer’s rates across 192 countries.

After adjusting for differences in population age structures, the study found that countries with higher levels of sanitation had higher rates of Alzheimer’s. For example, countries where all people have access to clean drinking water, such as the UK and France, have 9% higher Alzheimer’s rates than countries where less than half have access, such as Kenya and Cambodia.

Countries that have much lower rates of infectious disease, such as Switzerland and Iceland, have 12% higher rates of Alzheimer’s compared with countries with high rates of infectious disease, such as China and Ghana.

More urbanised countries exhibited higher rates of Alzheimer’s, irrespective of life expectancy. Countries where more than three-quarters of the population are located in urban areas, such as the UK and Australia, exhibit 10% higher rates of Alzheimer’s compared to countries where less than one-tenth of people inhabit urban areas, such as Bangladesh and Nepal.

Differences in levels of sanitation, infectious disease and urbanisation accounted respectively for 33%, 36% and 28% of the discrepancy in Alzheimer’s rates between countries.

Researchers said that, although these trends had “overlapping effects”, they are a good indication of a country’s degree of hygiene which, when combined, account for 42.5% of the “variation” in countries’ Alzheimer’s disease rates - showing that countries with greater levels of hygiene have much higher Alzheimer’s rates regardless of general life expectancy.

Previous research has shown that in the developed world, dementia rates doubled every 5.8 years compared with 6.7 years in low income, developing countries; and that Alzheimer’s prevalence in Latin America, China and India are all lower than in Europe, and, within those regions, lower in rural compared with urban settings - supporting the new study’s findings.

̽��ֱ��results of the study are newly published by the journal Evolution, Medicine and Public Health, with these latest results coming hard on the heels of previous research led by Fox on the benefits of breastfeeding for Alzheimer’s prevention.

“Exposure to microorganisms is critical for the regulation of the immune system,” write the researchers, who say that say that - since increasing global urbanisation beginning at the turn of the 19th century - the populations of many of the world’s wealthier nations have increasingly very little exposure to the so-called ‘friendly’ microbes which “stimulate” the immune system - due to “diminishing contact with animals, faeces and soil.”

Aspects of modern life - antibiotics, sanitation, clean drinking water, paved roads and so on - lead to lower rates of exposure to these microorganisms that have been “omnipresent” for the “majority of human history”, they say.

This lack of microbe and bacterial contact can lead to insufficient development of the white blood cells that defend the body against infection, particularly those called T-cells - the foot soldiers of the immune system that attack foreign invaders in the bloodstream.

Deficiency of anti-inflammatory (“regulatory”) T-cells has links to the types of inflammation commonly found in the brain of those suffering with Alzheimer’s disease, and the researchers’ proposal that Alzheimer’s risk is linked to the general hygiene levels of a nation’s population is reinforced by their analysis of global Alzheimer’s rates.

“ ̽��ֱ��increase in adult life expectancy and Alzheimer’s prevalence in developing countries is perhaps one of the greatest challenges of our time. Today, more than 50% of people with Alzheimer’s live in the developing world, and by 2025 it is expected that this figure will rise to more than 70%,” said Fox.

“A better understanding of how environmental sanitation influences Alzheimer’s risk could open up avenues for both lifestyle and pharmaceutical strategies to limit Alzheimer’s prevalence. An awareness of this by-product of increasing wealth and development could encourage the innovation of new strategies to protect vulnerable populations from Alzheimer’s.”

While childhood - when the immune system is developing - is typically considered critical to the ‘hygiene hypothesis’, the researchers say that regulatory T-cell numbers peak at various points in a person’s life - adolescence and middle age for example - and that microorganism exposure across a lifetime may be related to Alzheimer’s risk, citing previous research showing fluctuations in Alzheimer’s risk in migrants.

̽��ֱ��team used the disability-adjusted life year (DALY) rates to calculate the incidence of Alzheimer’s across the countries studied. ̽��ֱ��DALY measurement is the sum of years lost due to premature mortality combined with years spent in disability – the World Health Organisation (WHO) says that one DALY can be thought of as “one lost year of ‘healthy’ life”.

̽��ֱ��researchers say this method is a much better measure than death rates as it “omits the effects of differential mortality rates” between developed and developing countries. ̽��ֱ��study was based on the WHO’s ‘Global Burden of Disease’ report, which presents world dementia data for 2004.

People living in industrialised countries may be more likely to develop Alzheimer’s due to greatly reduced contact with bacteria, viruses and other microorganisms - which can lead to problems with immune development and increased risk of dementia, suggests a new study.

There are important implications for forecasting future global disease burden, especially in developing countries as they increase in sanitation

Molly Fox

Better hygiene in wealthy nations may increase Alzheimer's risk

Prempcc via Flickr

Wash your hands

Age-standardised data

̽��ֱ��process of age-standardisation presents a “single summary rate that reflects the number of events that would have been expected if the populations being compared had had identical age distribution” (WHO 2001)

̽��ֱ��age-standardised data is calculated by adjusting the crude data for 5-year age groups by age-weights reflecting the age-distribution of the standard population. In the version of the WHO’s Global Burden of Disease report we utilised, the terminal age category has been extended from the previous 85+ to 100+, which allows for better adjustment for differences in the proportion of population in older strata.

̽��ֱ��age-adjusted and disability-adjusted life year (DALY) rates are calculated by “adjusting the crude estimates to an artificial population structure, the WHO Standard Population, that closely reflects the age and sex structure of most low and middle income countries” (WHO 2013).

̽��ֱ��effort to construct a standard population for comparing data across populations with varied age-structures began in the 1840s, and progressed to an international scale in 1960 and was then adopted by the WHO. Statisticians have been researching and improving this process for the past five decades.

̽��ֱ��new WHO World Standard was developed in 2000 to best reflect projections of world age-structures for the period 2000-2025. This new standard is based on the UN Population Division’s assessments every two years and future projections for every five years of each country’s population age-structure. This standardised procedure is widely accepted across the world, and is the basis for all relevant WHO-sponsored analyses.

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Safe water solutions

lw355 — Mon, 01 Nov 2010 15:38:27 +0000

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 sanitation¹ .

In Cambridge, research groups from several disciplines are working in regions worldwide where dirty, polluted and inadequate supplies of water make drinking, cooking and cleaning an everyday challenge for the communities who live there. We take a look here at some of their solutions.

Water cleaning with mussel power

Zoologist Dr David Aldridge is a keen advocate for the amazing abilities of mussels to clean up water. His work in China is using these remarkable organisms as cheap and sustainable water filters to improve water quality and, as a result, it is hoped that a local industry will develop to farm them.

China’s Lake Dianchi was once a rich haven of aquatic species but increasing levels of pollution from a cocktail of fertilizer run-off, sewage and the effluent from factories has caused a huge deterioration in water quality. ̽��ֱ��water is undrinkable and a hazard to those using it for washing, and the native aquatic wildlife has all but died off. Where once underwater visibility was over 10 metres, on a good day it’s now a mere 30 cm.

Using a set-up that could be replicated in many of the world’s polluted freshwaters, Dr Aldridge from Cambridge’s Department of Zoology and colleagues at the Chinese Academy of Sciences have deployed specially bred giant mussels – once native to the lake – in experimental enclosures along the lakeside.

̽��ֱ��mussels filter 50 litres of water a day, removing algae and suspended particles. ‘In just a few months,’ he explains, ‘not only did the water become clearer but native plants suddenly began to emerge from seeds buried for decades on the lake bed. These, in turn, provide habitat for insects, and then fish, and the system stabilises back to clearer water.’

One challenge has been the tendency of people living locally to eat the mussels. ̽��ֱ��team’s solution has been to turn to pearl farming to encourage the community to sustain the mussels in the lake. Chopsticks are used to insert a tiny bead of shell into the mussel, around which a pearl is formed. Recognising the potential impact of this idea on bolstering local industries, the World Bank awarded Dr Aldridge a Development Market Place Award to continue the work.

Dr Aldridge is also developing a means by which local authorities and managers of waterways can check the health of freshwater in their region, reducing the need for difficult and costly chemical testing. ‘We’re using the biology of the lake as an indicator of water quality. ̽��ֱ��number and type of organisms, or biotic index, provides a useful indication of the state of the water they live in. ̽��ֱ��guide book we are creating will enable users armed with only a hand net to monitor the condition of water in their province.’

Healthy water for households

Many people who lack access to safe water live in regions where conventional methods for supplying drinking water through water pipes are simply not possible or cost-effective. For these people, the alternative is to use household water treatment and safe storage systems (HWTS) based on chlorination, solar disinfection, ceramic filters or biosand filters.

As part of Dr Douglas Crawford-Brown’s wide research interests in water policy, he has been examining the effectiveness of reducing microbes in drinking water using low-cost HWTS in the developing world. As Executive Director of the Cambridge Centre for Climate Change Mitigation Research, in the Department of Land Economy, his research interests have an environmental perspective: ‘ ̽��ֱ��problem of ensuring safe water provision in the face of environmental change is a global one. But for developing countries, where large investments in infrastructure are not possible, it’s a massive concern.’

His work has been in collaboration with colleagues Dr Mark Sobsey and Dr Linda Venzcel at the ̽��ֱ�� of North Carolina, from which he moved two years ago, and Dr Christine Stauber at Georgia State ̽��ֱ��. Dr Crawford-Brown’s role in the long-term project has been to model the predicted human health impacts so that they can be compared against field epidemiological data in the Dominican Republic, Ghana, Honduras and Cambodia.

‘Our results show clearly that there is significant reduction in microbes, but also a residual concentration that can be quite difficult to remove,’ he explains. ‘In one project funded by the International Rotarians, we found that a simple sand filtration HWTS in the Dominican Republic halved the incidence of diarrhoeal disease, a major cause of death among infants in poor communities worldwide.’

Given that affordability of water systems is a critical regulatory issue, his research has also looked more widely at health–health trade-offs. ‘Trade-offs occur when the costs of water treatment in poor communities cause them to re-allocate limited finances, often away from buying medicine, unless public programmes are brought in to provide healthcare. Our goal is to provide policy makers with the evidence on which to base decisions on risk and in allocating budgets.’

Improving outcomes

Having worked for several years in rural Nepal trying to implement the use of water filtration units, Tommy Ngai from the Department of Engineering knows only too well that, despite their benefits, the adoption and continued use of HWTS is not always straightforward.

For the past four years he has been investigating how to scale up the dissemination of HWTS. Working with Dr Dick Fenner in the Centre for Sustainable Development in the Department of Engineering, 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. ̽��ֱ��outcomes are three programme-specific computer simulation models linking over 300 different variables. ̽��ֱ��models can help implementing organisations 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.

^{1 www.unep.org/pdf/SickWater_screen.pdf}

For more information about these projects, please contact Dr David Aldridge (da113@cam.ac.uk) at the Department of Zoology; Dr Douglas Crawford-Brown (djc77@cam.ac.uk) at the Department of Land Economy; Tommy Ngai (tommyngai@yahoo.ca) and Dr Dick Fenner (raf37@cam.ac.uk) at the Department of Engineering.

Research across the ̽��ֱ�� is helping to clean up water in regions around the world.

̽��ֱ��problem of ensuring safe water provision in the face of environmental change is a global one. But for developing countries, where large investments in infrastructure are not possible, it’s a massive concern.

Dr Douglas Crawford-Brown

Tommy Ngai

Water clarity improvement after filtration

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.

̽��ֱ��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. ̽��ֱ��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.

For more information about these and other projects, please contact Dr Heather Cruickshank (hjc34 AT cam DOT ac DOT uk).

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