Transcript 2.5 Selection of arrangement

2.5
A way forward …
a tool for selecting sustainable sanitation
arrangements
Learning objective: awareness that
selecting a sustainable arrangement
is more than just a matter of
choosing between technical solutions
Jan-Olof Drangert, Linköping university, Sweden
Factors pushing the sanitation sector
to develop towards sustainability
world population increase
high population densities in urban areas
increased consumption and chemical compounds
global warming
modernity and prestige
Private activity
Community concern
Jan-Olof Drangert, Linköping university, Sweden
scarcity of phosphorus and other nutrients
The role of sanitation in solving the looming
water and nutrient crises and global warming
- save H2O (demand management) and prevent pollution of H2O
- use treated greywater to save on ground- and surface water
- sanitise nutrients (P, K and S) from households and restaurants
- recycle nutrients and organics for food production and soil
restoration
-
reduce emissions of CO2 and other greenhouse gases
Jan-Olof Drangert, Linköping university, Sweden
Many framework issues to consider
• Challenges for the present sanitation arrangements
• Policies, building codes and other regulations
• New housing area, densification or retrofit
• Landscape, soil and groundwater characteristics
• Wind, temperature variation and rainfall pattern
• Open areas (gardens etc.) and urban agriculture
• Availability (intermittent supply?) and cost of water
• Availability (intermittent supply) and cost of energy
• Collection and recirculation of solid waste, organic
waste in particular, etc.
Jan-Oloof Drangert, Linköping university, Sweden
Up to now the WC has set the standard, but
from now on the resilience of nature will do so
El Grand Canal, Mexico City with
”treated” effluent
Courtesy of Ian Adler, IRRI-Mexico
Wastewater and stormwater
drainage in Bangalore, India
J-O Drangert, Linköping university, Sweden
A new approach for sustainability
The discharged waste is an unlimited resource!
- if it is clean enough
The crucial question to ask is therefore:
”What comes out at the end of the sanitation system?”
There is no scarcity of natural resources for households
– only poor management of the natural resources we
already command!
Jan-Olof Drangert, Linköping university, Sweden
Always start your investigation from the
end of the process
Screen
Sedimentation
aeration
clarifier
outflow
Where is sludge treated and where
does it end up ?
Where does the treated effluent flow ?
Jan-Olof Drangert, Linköping university, Sweden
Start from the end !
(centralised example)
We decide what quality we
would like the final products
to have.
Sludge
drying bed
CO2 & methane
gases
Our thinking is now on global challenges as well as
on local wishes for system performance and status
percolating
leachate
J-O Drangert, Linköping university, Sweden
Treated greywater = clean water?
Jan-Olof Drangert, Linköping university, Sweden
More than 2,000 persons
Treatment
results for small
and large water
utilities
Less than 2,000 persons
Jan-Olof Drangert, Linkoping university, Sweden
A holistic sanitation selection algorithm
ON/
OFF
no
Is there an aim/policy of
reuse or sustainability?
Make alliances and
find your way around
yes
Is wastewater quality a
major concern/problem?
Is there enough space and
infiltration/evaporation
capacity on site?
no
Is simplified sewerage
affordable ?
no
yes
no
yes
Is wastewater pollution
caused by excreta?
no
yes
Can the pollution be
eliminated through
source control ?
yes
yes
Is household organic
waste sorted ?
Is diversion of urine an
affordable option ?
yes
yes
Compost and use
nutrients on site
yes
Can faecal
matter be
composted
on site?
no
Energy for
household
Jan-Olof Drangert,
Linköping University, Sweden
no
no
feasible on site ? yes
Collection & reuse off site
yes
no
Is settled sewerage
yes
affordable ?
no
yes
no
yes Is biogas reactor
Is swale/open
ditch possible?
Is treatment on site
effective & affordable?
yes
Can urine
be stored
and used
on site?
yes
On-site reuse of
safe wastewater
greywater
yes
Fertilise
garden
Is infiltration or other
reuse safe ?
no
Is biological treatment
affordable & safe?
yes
yes no
problem
Swale/fish
pond
yes
Reuse of
polished water
Time to search for technical solutions!
A new housing area in central Stockholm
Courtesy of Stockholm Water, Sweden
Some achievements in the new district
- Household water consumption down 40%
- Hot water use (35% of total water use) not measured yet,
but expected to decrease 15-25% (= energy saving)
- Eutrophication of the receiving lake reduced by 50%
- 60% of phosphorus and nitrogen returned to agriculture
- Green-house effect, acidification, and use of non-renewable
energy reduced by 30%
Improvements made by resource-saving installations,
rather than changes in individual behaviour – so far
Next step: residents become partners
Jan-Olof Drangert, Linköping university, Sweden
Self-contained housing complex
25 L
WC
50 L
15 L
10 L
wetland
STP 130
70 L
well
water
80 L
55 L
groundwater
recharge
groundwater
Jan-Olof Drangert, Linköping university, Sweden
A vision for sanitation arrangements
National and local governments provide guidelines for
installation and operation of eco-friendly arrangements.
A single household or a housing company can find ecofriendly products in ordinary hardware shops and outlets
for contractors.
Small and large contractors, plumbers and engineering
firms, architects are familiar with the requirements of
eco-friendly installations.
Jan-Olof Drangert, Linköping university, Sweden