Managing the other side of the water cycle: Making wastewater an asset

1.000,00

Description

1. INTRODUCTION

From a natural resources perspective, human settlements can be
seen as transformers of valuable resources such as water and
food into nutrients and organic material mixed in water, or better known as wastewater/sewage and excreta. Almost all the cities in developing countries discharge wastewater without any treatment. It is estimated that
90% of the urban areas worldwide do not have proper sanitation. In modern
cities, discharges of wastewater create small rivers before they reach the sea or
other recipients. These untreated wastewaters are causing major health and
pollution threats to downstream and underground waters and to the aquatic
life. Uncontrolled and direct reuse of wastewater is commonplace. Often the
urban or rural poor rely on this resource for their livelihood to grow foods
and vegetables. This practice will put at risk their own health, the health of
the consumers and the environment as a whole. In few cases, these wastewater “rivers” are treated with the aim to protect the environment from gross pollution. Only in a few cases, however, the concept of resources management
has been implemented for planning and design when dealing with municipal
and industrial wastewaters.
Today ongoing degradation of freshwater and marine ecosystems is amplified
by climate change effects such as droughts and floods. These threatening
impacts have given incentives to redesign water and waste management systems of human settlements to meet sustainability criteria, i.e. planning the discharges of wastewater should be safely integrated into water resources management and ecosystem preservation. The World Panel on Financing Water
Infrastructure concluded that a high proportion of the extra US $100 billion
required annually is needed for wastewater services (Camdessus Report, Winpenny, 2003).
Traditionally, water supply, sanitation and water management investments are
planned, designed and managed separately and for different time-scales. The
provision of environmentally sound systems that take into account the whole
water cycle in the communities – water supply, wastewater, solid waste collection, treatment and reuse – requires an integrated approach involving a variety
of stakeholders and overcoming sector-boundaries and the rural-urban divide.

However, several interlinked key questions need to be first addressed such as:
which barriers should be overcome to improve the prospects of reaching the
water supply and sanitation targets in the rural, urban and peri-urban areas?
How can known technologies be best applied to solve development questions?
How can we make the management of wastewater effective, sanitation affordable and reuse safe? Can cities in developing countries cope with the infrastructure and capacity requirements needed to simultaneously face the (i) water
supply and (ii) sanitation needs of growing urban populations, (iii) to reuse
the municipal wastewaters in a safe, productive and efficient way, and (iv) to
protect the public health and the urban and peri-urban environment? Does
linking management of human excreta and wastewater to water reuse help
meet the MDG water and sanitation target together with food security targets?
Which institutional settings are suitable for sanitation and reuse in these
areas? How can we make a strong economic and environmental case for sanitation by turning waste and wastewater into a resource? How can financing
(waste)water reclamation and reuse be made a key part of dependable future
water supply strategies? Can sustainable solutions be found through dialogue
involving practitioners, researchers, policymakers, and local communities?
This paper looks at options for closing the loop between human settlement
discharges and their surrounding watersheds in an Integrated Water Resources
Management (IWRM)1
context. It gives an overview of the sanitation challenges, of the related development and management issues, and of attempts to
answer some of the above mentioned questions. Several examples are used to
illustrate different approaches in Managing the Other Side of the Water Cycle.

The foci of the IYS and the larger ambitions of the Millennium Development
Goals (MDGs) are targeted at the poorest, under-served, and neglected populations. This paper intends to complement and provide feasible solutions to
the IYS/MDG agendas.
Wastewater/sewage is both a problem and a resource with a big impact on the
lives of poor communities. Achievement of the water and sanitation MDGs
will magnify the urgency and desirability of the next great challenge – that of
safe management and beneficial exploitation of wastewater. Poor communities
bear the brunt of the current situation, and will be major beneficiaries of this
initiative.
With the IYS and beyond the 2015 MDG milestone, it is becoming urgent to
apply international energy and imagination to mobilizing the resources needed – technological, creative and societal as well as financial – for the “downstream” parts of the water and waste cycle – the collection and treatment of
wastewater, and the recycling and reuse of treated effluent and its by-products. If the wastewater challenge is not tackled, there is a danger that the
potential health and other benefits from the investments being made to meet
the MDGs will be negated by the pollution that ensues. It takes many years to
introduce a new paradigm and it is timely for preliminary steps to be taken
now in order to put this on the political agenda for the post-2015 period
when new global policy priorities will have to be agreed.
The management of wastewater rests on several compelling arguments:
• It is necessary for the welfare of several billion people, whose health,
dignity and amenity is compromised by the squalor and hazards of current
arrangements.
• It is necessary to rescue human and natural environments that are being
ruined by pollution.
• It is necessary to start recycling the essential resources from wastewater,
e.g. nutrients and water itself in order to sustain human livelihoods and
ecosystems.
• It is equally imperative for economic reasons, since ill-managed wastewater
has a high economic cost, and can act as a brake on investment and
further development.
• Finally, the growing shortage of water that is expected from population
growth, urbanization and climatic changes increases the importance of
re-using water to the maximum extent that is feasible.

The early history of sanitation
The history of sanitation goes back to the early historic times
(Cooper, 2001). In the Mesopotamian Empire (3500-2500 BC),
some homes were already connected to a stormwater drain system. In Babylon, latrines were connected to 450 mm diameter vertical shafts in the
ground. In the Indus city of Mohenjo-Daro, in Pakistan, from about 2500 to
1500 BC, many houses had drains that led to closed sewers. Some earthenware pipes, latrines and cesspools were connected to drainage systems in the
streets.
At King Minos Royal Palace at Knossos, Crete, by 1700 BC, four separate
drainage systems emptied waste through terra cota pipes. The oldest known
flushing device, a latrine with a rooftop reservoir, served King Minos and was
reborn 3000 years later. In Greece, from 300 AC to 500 AD, public latrines
drained into sewers which carried sewage and stormwater to a collection basin
outside the city. Brick-lined conduits transported the wastewater to agricultural lands to irrigate and fertilize crops and fruit orchards.
Around 600 BC, the Romans built the Cloaxa Maxima, the central sewer system. This brick-lined covered sewer had seven branches – one for each hill –
and rich customers had to pay to be connected to the sewer. These sewers
were also used to drain the streets during rainstorms. Urine was collected in
public urinals and sold to dyers, tanners and other merchants. Those who
could not afford to get connected to the sewer system used jars in their rooms,
which were emptied into public cesspits. These cesspits were daily emptied by
city-paid workers and the contents were used as fertilizer . Cloacina was the
Roman goddess of the sewer and was responsible for the preservation and
hygiene of the public drainage systems.
In the Dark Ages, sanitation practices regressed to a primitive level. Paris’ first
covered sewer was built in Montmartre in 1370 and dumped sewage into the River Seine by the Louvre. Once plagues began ravaging the cities of Europe in the 16th century, François I in 1539 ordered property owners to build cesspools for sewage collection. The first water closet was designed in 1596 and the first chemical treatments of wastewater (use of lime in Paris) were recorded in the 18th century.

 

0Shares