Transcript Phosphorus - Sustainable Sanitation

Ch. 5. Applications – sanitation in
practice
Pupils prepare
a meal with
produce from
school garden
Segregation of various
liquid flows from household
Campaign in India to request
bridegrooms to provide a toilet
Spreading chemical
fertilizers in a field
5.1 Phosphorus - Food security
& food for thought
Learning objectives: Phosphorus
as a resource, and its links to
sanitation and to food security
Our Globe sets the scene
We are in an era of unprecedented global environmental change
Jan-Olof Drangert, Linköping University, Sweden
Water and phosphorus
for food security
• Water molecules can be made
by using a lot of energy
• Water is renewable (sundriven cycle)
• Water is available in soil and
replenished annually by rain
• 70% of global water use is for
crop production
• Phosphorus (P) cannot be
manufactured or destroyed
• P is essentially immobile and is
mined in only a few countries
• P is naturally available in soil
and depleted by crops
• 90% of global P extraction is for
crop production
• A balanced diet results in the
loan of 1300 m3/yr to each
person on the planet based on
current practice. This is 70
times greater than the 50 l/d
per person for basic water
needs.
• A balanced diet results in the
depletion of 22.5 kg/yr of
phosphate rock (=3.2 kg/yr of P)
per person based on current
practice. 0.5 kg of this reaches
the average person’s food.
Source: Cordell, Drangert & White (2009a)
Both are critical to food production, but need to be managed differently
Historical sources of phosphorus (1800-2000)
Rapid population growth,
urbanization, intensive agriculture
and the Green Revolution =>
increased fertilizer production.
Recycling organic nutrients
dramatically decreases
Most manure was
recycled; Human waste
recycled in China;
No such thing as
synthetic or processed
fertilizer.
Repeated famines
and soil degradation
in Europe triggered
use of other sources
of fertilizers (guano,
ground bone).
Discovery of
phosphate rock.
Humanity became addicted to phosphate rock in the 20th century!
Phosphorus status in soils in Europe
Source: Efma, 2000b
World phosphate rock reserve estimates
(’000 tonnes)
P scarcity is worse than oil scarcity because P
CANNOT be substituted for in food production. So,
Source: USGS and ESRI
… the linear flow makes countries dependent economically and politically
Food security
phosphate rock dependence?
Courtesy IFA. Phosphate rock loading in Morocco.
Access to phosphate markets
World Bank, 2009
Future fertilizer price spikes are also possible
Peak phosphorus
The peak P timeline is disputed, but all agree the quality of
reserves is decreasing and production costs are increasing
Phosphorus through the global food system
Only 1/5 of the P in mined rock reaches the food on our plates!
Securing a sustainable phosphorus future
The future is not all dark!
Source: Cordell et al., 2009b
A waste management hierarchy for P recovery
The extended waste management hierarchy includes both liquid and solid waste
in urban sanitation systems and agriculture
1. Reduce (a) waste generation, and
(b) harmful contents in products;
2. Reuse the waste more or less
as it is;
3. Recycle the waste as input to
new products (including biogas);
4. Incinerate to extract the energy
content in the remaining waste;
5. Safely landfill residues from
the previous steps.
Jan-Olof Drangert, Linköping University, Sweden
Can we eat climate-smart and phosphorussmart?
• Think twice when shopping
Don’t buy more food than you have time to eat
• Eat up the food you cook
Serve reasonable portions and use the leftovers
• Use your senses
Look, smell, taste and feel the food. Most foodstuffs last longer than
their indicated ’use-by’ date if they are stored properly
• If you want to eat meat
Choose local produce and try to eat fish, chicken and no beef
• Eat more vegetarian food
Especially root crops and legumes
• Choose fruits and vegetables of the season
Preferably local products
Source: Sweden’s National Food Adminstration Report 2008:9
Nutrients in human excreta
Amount of nutrients from an average Swede per year
Important
nutrients
Urine
Faeces
500 Lt/year 50 Lt/year
Total
Nutrient need for
250 kg cereals
Nitrate (N)
5.6 kg
0.09 kg
5.7 kg*
5.6 kg
Phosphorus (P)
0.4 kg
0.19 kg
0.6 kg
0.7 kg
Potassium (K)
1.0 kg
0.17 kg
1.2 kg
1.2 kg
Total amount
7.0 kg
0.45 kg
7.5 kg
7.5 kg
i.e. N+P+K
(94%)
(6%)
(100%)
-
The Urine Equation:
An adult eats 250 kg of cereals per year, which has
been grown on less than 250 m2 and fertilised to
more than fifty per cent by the person’s urine.
Jan-Olof Drangert, Linköping University, Sweden
Nutrient fertiliser values and CO2 emissions
Million
SEK/yr
450
400
350
Economic value of NPKS in toilet water and sludge,
and reduced emissions of GHG compared to use of
chemical fertilisers
300
250
Toilet water
200
ww sludge
150
CO2 equiv
100
50
0
Nitrogen
Phosphorus
Potassium
Sulphur
H. Jönsson et al., 2012
Nutrient flows originating from households
To air:
1 % P,
40 % N
To compost
14 % P,
15 % N
Biowaste
Illegal
dumping
7 % P,
10 % N
To air:
1 % P,
15 % N
HH
Excreta
59 % P,
70 % N
Greywater
20 % P,
5%N
Septage
10 % P
10 % N
Effluent
48 % P,
20 % N
Compost
20 % P,
20 % N
To farm:
19 % P,
5%N
Illegal
dumping
4 % P,
5%N
Jan-Olof Drangert, Vatema
Nutrient flows originating from households
To air:
1 % P,
1%N
Compost
19 % P,
20 % N
Biowaste
Illegal
dumping
2 % P,
5%N
Faeces
19 % P,
7%N
HH
Greywater
20 % P,
5%N
Effluent
2 % P,
3%N
WWTP
20 % P
5%N
Dewater
15 % P
4%N
Urine
40 % P,
63 % N
Sludge
18 % P
2%N
Effluent
3 % P,
2%N
To air:
1 % P,
8%N
Compost
33 % P,
22 % N
To farm:
32 % P,
14 % N
Uncontrolled
dumping
1 % P,
2%N
To forest:
18 % P
2%N
To farm:
40 % P.
63 % N
Jan-Olof Drangert, Vatema
A pig and its potential impacts
Greenhouse
gases (18%)
I
m
p
o
r
t
Cereals
2.5 pigs/yr
5 m3
urine
Eutrophication
and dead
zones in seas
5/0.4/3
kg/yr
3.5 m3
faeces
4/1.6/1 kg/yr
Recycling
to farmland
Can fertilise
1500 m2 and
produce 800 kg
of rice
Jan-Olof Drangert, Linköping University, Sweden
Loss of food in each step of the food chain
Source: FAO, 2011
Plant requirement and nutrient removal
Crop
Cereals
Rice, paddy
Wheat straw
Maize
Sorghum
Tubers etc
Cassava root
Sweet potatoes
Potatoes
Others
Soy bean
Ground nuts
Banana fruit
/
Yield,
kg/ha
Dry
matter
N,
kg/ha
P,
kg/ha
K,
kg/ha
4000
4000
4000
4000
88%
85%
88%
88%
60/45
70/16
200/51
120/56
13/11
13/ 2
35/ 9
22/ 9
25
50
133
116
20000
10000
25000
36%
59%
23%
125/32
90/49
115/83
13/ 1
9/12
20/13
125
12
166
1000
1000
25000
91%
94%
31%
125/54
50/37
/67
13/ 5
7/ 4
/ 8
33
12
Why is it so difficult to apply P?
1000-2000
kg/ha.
10-100
kg/ha.
0.01-0.1
kg/ha.
Plant need 10-30 kg/ha,
but 0.5 kg/ha/day
Fast (t,d,w)
transport
Slow (m,y)
transport
Exercise: a closer look at phosphorus flows
Step 1
Step 2
Step 3
Step 4
Source: Cordell, Drangert & White (2009a)
Stay vegetable-based, and return farm waste, your
excreta, household and city organic waste to soil !!!
Recovery of P by using the waste hierarchy
Was the strong link between the water and
sanitation sectors in the 20th century a brief
detour in human history?
Most
common
agriculture
+
sanitation
All rural
What will
come next ?
water
+
sanitation
agriculture
+
sanitation
Essentially urban
Jan-Olof Drangert, Linköping University, Sweden
Epilogue
The green revolution in the 1950s saved the
world from hunger - by using irrigation water,
new crop varieties and chemical fertilisers
Next revolution must be to recycle the
nutrients used in food production !
“Two major opportunities for increasing the life of expectancy of
the world’s phosphorus resources lie in recycling by recovery
from municipal and other waste products and in the efficient use
in agriculture of both phosphatic mineral fertilizer and animal
manure” European Fertilizer Manufacturers Association (2006)
Jan-Olof Drangert, Linköping University, Sweden