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