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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
How to obtain all the
information we need?
Jan-Olof Drangert, Linköping university, Sweden
world population increase
high population densities in urban areas
increased consumption and chemical compounds
modernity and prestige
Private activity Community concern
Factors pushing the sanitation sector to develop towards sustainability
scarcity of phosphorus and other nutrients
global warming
Jan-Olof D
rangert, Linköping university,
Sweden
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
- provide nutrients (N, P, K and S) from households and restaurants
- recycle nutrients and organics for food production and soil restoration
Jan-Olof Drangert, Linköping university, Sweden
- reduce emissions of CO2 and other greenhouse gases
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
• Water availability (intermittent supply?) and cost
• Energy availability (intermittent supply) and cost
• Collection and recirculation of solid waste, organic waste in particular, etc.
Jan-Olof 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
Jan-Olof Drangert, Linköping university, Sweden
There is no scarcity of natural resources for households
– only poor management of the natural resources we already command!
The crucial question to ask is therefore:
”What comes out at the end of the sanitation system?”
Where is sludge treated and where does it end up ?
Always start your investigation from the end of the process
Where does the treated effluent flow ?
Screen Sedimentation Aeration Clarifier Outflow
Jan-Olof Drangert, Linköping university, Sweden
Start from the end ! (centralised example)
Our thinking is now on global challenges as well as on local wishes for system performance and status
percolating
leachate
Dried sludge itself
We decide what quality we would like the final products to have.
J-O Drangert, Linköping university, Sweden
Sludge drying bed
CO
2 &
met
ha
ne
ga
ses
Treated greywater = clean water?
Jan-Olof Drangert, Linköping university, Sweden
Treatment results for small and large water
utilities
More than 2,000 persons
Less than 2,000 persons
Jan-Olof Drangert, Linkoping university, Sweden
A holistic sanitation selection algorithm
Is wastewater quality a major concern/problem?
yes
Is there enough space and infiltration/evaporation capacity on site?
Is there an aim/policy of reuse or sustainability?
no
no
Make alliances and find your way around
yes
yes
no
yesOn-site reuse of safe wastewaterIs wastewater pollution
caused by excreta? no
no
no
yes
Is treatment on site effective & affordable?
yes
no
yes
Is diversion of urine an affordable option ?
yes
ON/OFF
Is settled sewerage affordable ?
yes
Can urine be stored and used on site?
yes
Can faecal matter be composted on site?
Is household organic waste sorted ?
yes
Compost and use nutrients on site
yes
Is simplified sewerage affordable ?
yes
yes no no
Is infiltration or other reuse safe ?
no
Is swale/open ditch possible?
yes
yes
Reuse ofpolished water
no
yes
Is biological treatment affordable & safe?
no
Fertilise garden
yes
Swale/fish pond
Can the pollution be eliminated through source control ? gr
eyw
ater
Is biogas reactor feasible on site ?
Energy for household
yes
Collection & reuse off site
yes
Jan-Olof Drangert, Linköping University, Sweden
no
problem
Time to search for technical solutions!Jan-O
lof Drangert, L
inköping University, Sw
eden
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
Improvements made by resource-saving installations, rather than changes in individual behaviour – so far
- Green-house effect, acidification, and use of non-renewable energy reduced by 30%
Next step: residents become partners Jan-Olof Drangert, Linköping university, Sweden
Self-contained housing complex
WC
STP 130
130 L
55 L groundwater recharge
wetland
groundwater
well water
80 L
Jan-Olof Drangert, Linköping university, Sweden
50 L
80 L 10 L
70 L
25 L
15 L
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 eco-friendly products in ordinary hardware shops and outlets for contractors.
Small and large contractors, engineering firms, architects and plumbers are familiar with the requirements of eco-friendly installations.
Jan-Olof Drangert, Linköping university, Sweden