From SciDev.Net
Faeces to fertiliser: innovations to solve the world’s
toilets crisis
By: Inga Vesper
Nearly 1.4 billion people worldwide lack access to even
basic toilet facilities.
With nearly 1.4 billion people still lacking access to even the
most basic toilet, researchers around the world are looking for innovative
solutions, writes Inga Vesper.
First, some good news. Since the year 2000, the number of people
forced to defecate in the open has fallen by more than half to an estimated 673
million. However, 2 billion people still lack basic sanitation services, with
more than 700 million relying on rudimentary holes or pits, a World Health
Organization (WHO) report showed.
The problem is concentrated on around 60 high-burden countries,
mostly in Africa and Asia, where water is scarce and infrastructure — such as
sewer systems and water treatment plants — can be difficult to maintain. Open
defecation is widely practised in some countries, but it is not a suitable
alternative. It contaminates food and water through flies and can be dangerous
to girls and women, as it forces them to seek out isolated spots away from
their homes.
“People don’t want governments or agencies to impose what kind of toilet they have in their home. What they want is someone to deal with the aftermath,” Rémi Kaupp, sanitation engineer, WaterAid
But changing toilet practices is surprisingly difficult. “It’s
something quite intimate,” says Rémi Kaupp, a sanitation engineer for the
UK-based charity WaterAid. “People don’t want governments or agencies to impose
what kind of toilet they have in their home. What they want is someone to deal
with the aftermath.”
The answer for Kaupp is on-site sanitation. The traditional pit
latrine, where waste is collected in a pit under a seat, is the go-to solution
for most households without access to a sewage system. But latrines have their
own problems. Pits need to be emptied, a job that is dangerous without proper
equipment. The waste stinks. If latrines are shared, they may get so dirty
people resort to open defecation instead.
In Tanzania, a project led by WaterAid established a professional
and safe pit emptying service for locals in Dar-es-Salam’s Kibondemaji
district. The service processes faecal sludge to make cooking gas, manure
fertiliser and water fit for gardening. The service is paid-for, but market
research in the community meant the team managed to set a price that was
affordable, says Abel Dugange, WaterAid’s director of technical services in
Tanzania.
Dugange describes how his team needed to set up infrastructure
from scratch. “To have a complete sanitation business chain, we needed to have,
for example, transfer stations for solid waste collections, before they are
ferried to major dumping sites.” He says the biggest challenge they faced was
funding and buying land for this purpose. “Sanitation businesses seemed not to
be well known to most banks, so it took time to educate them.”
Dugange’s team also needed to provide workers with safety tools,
such as proper boots, masks and gloves. Dealing with faecal sludge is a health
hazard, which makes collection and storage difficult in low-income,
low-resource settings. Due to the hassle of digging new pits, many communities
share latrines, which reduces the work load for individuals, but can also make
latrines less safe and private.
A smelly business
The answer could be collection of faeces in the home. A team at
the University of Delaware in the United States is working on a membrane liner
with ventilation holes that can be put into standard 40-litre drums. The
laminate liner allows the water to evaporate from the faecal matter while
retaining pathogens. As a result, the contents dry out and are safer to remove
and handle.
The technology was field-tested in Kanpur, India, but problems
remain with the time the sludge needs to dry, and with smells. “The laminate
works best in warm and dry climates, since these conditions enhance evaporative
drying,” says Paul Imhoff, an environmental engineer at the University of
Delaware, who worked on the study. He added that the costs were too high but
remained positive that the technology had promise. “There is a need for less
expensive laminate membranes and better design to allow more efficient air flow
and drying,” he says.
Other innovations cover settings where sewage systems are
available, but water is scarce. A water toilet uses around 14 litres a flush,
which, for a family with two children, translates into around 250 litres of
water a day. At Britain’s Cranfield University, a team has developed a
“waterless” flush, where faeces are deposited in a rotating bowl, which is then
scraped clean using a swipe activated by a handle.
Diagram showing parts of a dry
flush toilet
The system requires neither water nor electricity and can be
installed in a traditional white ceramic toilet, making it attractive for
individual households. A field test in eThekwini in South Africa showed that
the swiper worked reasonably well, but since no water ran down the sides of the
bowl, fouling of the porcelain remained a problem. The system also struggled to
deal with menstrual blood.
“The design and the white colour of the pedestal were praised, but
the functionality of the flush was noted to still need improvement,” says Jan
Hennings, a PhD student at Cranfield who worked on the trial. “Ultimately, we
believe that the flush could function well enough that it could be implemented
with other waterless sanitation technologies.”
From faeces to fertilizer
If faecal sludge is safely collected, it can turn into an
important resource. Human faeces contain beneficial biomaterials and, through
composting, make excellent soil conditioners. However, even with sanitation
systems present, many poorer cities fail to dispose of faeces properly. In
Maputo, Mozambique, for example, nearly 90 per cent of faeces are collected
through latrines, but more than half is left untreated due to unsafe disposal,
leakage and lack of proper treatment facilities.
An example of a waste-flow diagram: Maputo, Mozambique. Credit: Peter Hawkins
A project in the Bangladeshi municipality of Sakhipur co-composts
human faeces and other solid biowaste before selling it on to farmers as
fertilisers. Abdullah Al-Muyeed, WaterAid’s head of policy and advocacy in
Bangladesh, says that nearly half of the faeces created in the area are now
turned into compost at a special plant.
“The first barrier was integrating people and the municipality in
decision-making to treat both faecal sludge and solid waste together,” he says.
Al-Muyeed and his team worked over several years with local
leaders and the farmers’ school to bring about a change of mind. Another
barrier was the price of the resulting compost, which, even now, is subsidised
by the government to make it affordable.
However, the system now brings much-needed income to the region
and has raised awareness of faeces as a resource. “The technology is very much
applicable to other countries as well,” Al-Muyeed says.
In many countries, toilets are still a matter of money. In
Namibia, the WHO report showed, only four per cent of the country’s poorest
have access to one, compared to nearly 90 per cent of the richest. So toilet
innovation must tackle not only the technical challenges of providing safe
sanitation, it must consider local preferences, finances and customs.
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