The Value of Wastewater: An Econometric Evaluation of Recoverable Resources in
Wastewater for Reuse
Christopher Stacklin, P.E.1
1
Orange County Sanitation District, Fountain Valley, CA, USA
*Email: [email protected].
ABSTRACT
In the past, wastewater had been looked at as a nuisance stream, requiring treatment before being
discharged to receiving bodies of water. As the scarcity and price of clean drinking water
continues to rise across the world, the value of wastewater, for its recoverable water content is
also increasing. Presently, the paradigm of wastewater is changing with the development of
practical reuse and recovery technologies. Now wastewater is viewed as a resource based on
recoverable components such as nutrients, carbon, and inorganics in addition to water and
energy.
Synergies for this paradigm change exist in several aspects. New wastewater discharge
regulations limiting nutrients such as phosphate for example, is in sync with world market
demand of phosphate. Renewable energy regulation is fostering inventive energy recovery uses
for biosolids from POTWs. Water reuse and recovery as well as energy recovery for POTWs are
providing concentrated waste streams which make recovery of wastewater components much
easier than before. Technologies which focus on resource recovery are in operation and are
under development for some of the many components in wastewater.
But what is the value of wastewater? In consideration of recoverable components in wastewater
including water, nutrients, metals, plastics, and energy, an econometric model can be developed
to show the value of wastewater per unit of flow from a typical POTW and extended to state,
region, country and worldwide.
Further, by specifying the statistical relationship that is believed to hold between the various
economic quantities pertaining to a particular economic phenomenon under study, the
econometric model can be extended to reflect the current and future value of wastewater.
This paper presents an econometric model and results which characterize the potential value of
wastewater as a resource which can useful for development of pro formas and evaluation of
capital investment in recovery of resources in wastewater. The econometric model is built at a
plant level with macro-economic scaling which incorporates population growth, commodity
supply and demand, capacity utilization lending to price forecast. The model is built using
known POTW capacity in the United States, converting to a per capita basis, and then reconverting to a capacity based on regional population growth estimates.
Figures 1 and 2 show some results of the econometric model. The world potable water recovery
opportunity is US$ 505 billion in 2010 and rising to US$681 billion in 2050, increasing at 0.87%
per year (2010 dollars, no inflation) based on a 693,318 MGD factored world sewage discharge
capacity. The world nutrient recovery opportunity totals US$ 10.4 billion in 2010, growing to
US$ 26.4 billion in 2050. Phosphorus increases from US$ 8.1 billion in 2010 to US$ 15.4
billion in 2050 based on the World Bank price of US$ 109/ton and increasing at 1.0% per year.
Water Extractable Phosphorus rises from US$ 655 million in 2010 to US$ 1.2 billion in 2050.
Nitrate/Nitrite increases from US$ 1.7 billion in 2010 to US$ 9.8 billion in 2050.
Figure 1. World Potable Water and Nutrient Recovery Opportunity.
The world energy recovery opportunity is from US$ 20.0 billion in 2010 to US$ 45.3 billion in
2050, growing at 3.2% per year. The biosolids component ranges from US$ 5.9 billion to US$
16.2 billion, a 4.3% per year increase. Digester Gas is from US$ 14.1 billion in 2010 to US$
29.1 billion in 2050, or 2.7% per year growth.
While metal recovery technology from POTW effluent has not yet become economically viable,
the world metals recovery opportunity in 2010 totals to US$ 585 billion and is dominated by
silver at US$ 310 billion, or 53% of the total. Note that because silver is the largest portion and
silver is moderately speculative, the metals recovery potential will be subject to large swings.
Aluminum is US$ 69 billion for 12% of the total, magnesium is US$ 62 billion for 11% of the
total, titanium is US$ 47 billion for 8% of the total, and iron is US$ 24 billion for 4% of the total.
Figure 2. World Energy and Metals Recovery Opportunity.
Model development and more detailed and scalable results will be discussed.
KEYWORDS: Wastewater, Econometrics, Water Reuse, Nutrient Recovery, Paradigm Shift
CHANGING THE PARADIGM OF WASTEWATER AND POTWs
POTWs traditionally dealt with the disposal of wastewater and sludge. Treatment technologies
focused on making the wastewater compatible for discharge to the receiving body of water.
Sludge was converted to biosolids and landfilled or land applied.
A combination of environmental regulation and scarcity of resources give us pause to look at
POTWs in a relatively new light. Over the past few decades, potable water can be recovered
from the wastewater. Digester gas can be raised for electric power production. Biosolids can be
combusted for power.
Recent technological innovations allow nutrients such as phosphate to be recovered for
agricultural use. Future technologies for metals recovery and contingent plans for metals
reclamation are being planned.
With this paradigm shift, what used to be called a Publically Owned Treatment Works in now a
Water Resource Recovery Facility (WRRF). Considering WRRF’s and all of the components in
wastewater that it receives, a value can be assigned to these components to get a true, but
approximate idea of the total value recoverable resources in wastewater.
Henceforth, the goal of this paper is to develop a resource recovery model of a WRRF, then
apply an econometric evaluation to estimate the total value recoverable resources in wastewater.
BUILDING A RESOURCE RECOVERY MODEL
The Basic Approach
How would you determine the value of wastewater? Key metrics needed to determine the value
are the capacity of the components in wastewater and the marketable value placed on those
components.
Ideally, metrics would be available where the capacity of every wastewater treatment facility in
the world is identified and the relative amounts of components in the wastewater are clearly
described. The reality is that this information either is not available at all or is not affordably
available.
The fundamental approach taken in this evaluation is that the capacity of the components is a
function of human population. At a fundamental level, population drives discharges of sanitary
of domestic wastes. As populations increase and countries develop, so do industrial and
commercial discharges to sustain the populations. Although not all developing regions capture
and treat these wastes and have the same level of industrial and commercial development as
other countries, the potential exists. As regional economies continue to grow through
globalization, what is being discharged from developing regions will approach that of developed
regions.
The approach is to therefore define the wastewater treatment capacity in the United States, then
use the population to ratio the capacity to other countries and geographic regions. Constituents
that can be typified within wastewater can also be proportioned relative to capacity and therefore
quantified after which the price per unit can be applied and the value determined.
Geographic regions considered in this economic evaluation include Africa, Asia, Europe, Latin
American and the Caribbean, Northern America, Oceania.
Determining Capacity in the United States
The wastewater treatment capacity in the United States can be approximated using the datum
collected from the EPA’s Clean Watersheds Needs Survey. (U.S. EPA, 2008) The EPA's Office
of Wastewater Management conducts a Clean Watersheds Needs Survey every four years, the
most recent of which having been published in 2008. The survey is conducted in response to
Sections 205(a) and 516 of the Clean Water Act.
While the survey does not include every facility in the United States, the survey is relatively
close, representing metrics from 14,275 facilities. The facilities have a combined existing total
flow rate of 31,206 million gallons per day.
Given the wastewater treatment capacity in the United States and the population growth, the
future treatment capacity and wastewater components discharged can also be forecasted.
Defining Capacity in Other Geographic Regions
The Population Division of the Department of Economic and Social Affairs of the United
Nations Secretariat publishes the World Population Prospects every two years. This evaluation
uses estimates and projections from the 2010 revision. (United Nations, 2010) The population is
estimated from each country starting July 1, 2010 using the most recent population data available
from a population census or a population register. Projections are made from assumptions on
fertility, mortality and international migration trends. Population metrics from countries are
summed to their perspective geographic region. Because projections are made from these
assumptions, a number of variant cases were developed. The medium variant was selected for
this evaluation as shown in Table 1.
Table 1. Medium variant 2010 population projection of select geographic regions (in thousands).
Geographic Region
2010
2015
2020
2025
2030
2035
2040
2045
2050
South America
392,555
412,909
431,471
447,830
461,496
472,331
480,325
485,537
488,073
Central America
155,881
166,487
176,389
185,492
193,747
200,966
207,037
211,906
215,569
Latin America and the Caribbean
590,082
622,437
652,182
678,778
701,606
720,307
734,748
744,929
750,956
Northern America
344,529
359,638
374,394
388,472
401,657
413,945
425,467
436,348
446,862
36,593
39,355
42,056
44,651
47,096
49,367
51,475
53,435
55,233
310,384
323,885
337,102
349,758
361,680
372,889
383,460
393,454
403,101
Oceania
United States
Europe
738,199
742,067
744,177
743,890
741,233
736,922
731,826
726,029
719,257
Asia
4,164,252
4,375,482
4,565,520
4,730,130
4,867,741
4,978,236
5,060,964
5,115,457
5,142,220
Africa
1,022,234
1,145,316
1,278,199
1,417,057
1,562,047
1,713,090
1,869,561
2,029,824
2,191,599
World
6,895,889
7,284,296
7,656,528
8,002,978
8,321,380
8,611,867
8,874,041
9,106,022
9,306,128
Given the wastewater treatment capacity of the United States, the population forecast of the
United States and the population of a specific geographic region, the wastewater treatment
capacity can be proportioned to another geographic area.
Calculating the Quantity of Components in Wastewater
The components considered in this evaluation can be grouped under nutrients, energy, (potable)
water, and metals. The nutrients, metals, and energy were characterized from the sludge portion
of wastewater only (versus the water portion). Metrics typifying sludge were derived from a
national sewage sludge report released by the U.S. EPA in 2009. (U.S. EPA, 2009)
The EPA collected samples from 74 POTWs in 35 states from 2006 to 2007. The EPA analyzed
145 constituents including nutrients, metals, polycyclic aromatic hydrocarbons, semi-volatiles,
flame retardants, pharmaceuticals, and steroids and hormones. While all constituents could have
potential recoverable value, this resource recovery model considered only the recoverable value
of nutrients and metals characterized in the report.
Table 2. Summary of nutrient and metals results from (U.S. EPA, 2009).
Class
Solids
Analyte
Percent Solids
Units
%
Minimum
Maximum
0.43
93.5
84
7.6
234
84
1.6
6,120
84
11
9,550
84
2,620
118,000
84
0.00065
0.3392
Aluminum
84
1400
57,300
Antimony
72
0.45
26.6
Arsenic
84
1.18
49.2
Barium
84
75.1
3,460
83
0.04
2.3
Boron
80
5.7
204
Cadmium
84
0.21
11.8
Calcium
84
9,480
311,000
Chromium
84
6.74
1160
Nitrate/Nitrite
Water-extractable Phosphorus
mg/kg
Phosphorus
WEP Ratio
Metals
# Detects
84
Fluoride
Anions
Observed Dry-weight Concentration
Beryllium
unitless
mg/kg
Class
Analyte
Units
Observed Dry-weight Concentration
# Detects
Minimum
Maximum
Cobalt
84
0.87
290
Copper
84
115
2,580
Iron
84
1,575
299,000
Lead
84
5.81
450
Magnesium
84
696
18,400
Manganese
84
34.8
14,900
Mercury
84
0.17
8.3
Molybdenum
84
2.51
132
Nickel
84
7.44
526
Selenium
84
1.1
24.7
Silver
84
1.94
856
Sodium
84
154
26,600
Thallium
80
0.02
1.7
Tin
78
7.5
522
Titanium
83
18.5
7,020
Vanadium
84
2.04
617
Yttrium
84
0.7
26.3
Zinc
84
216
8,550
Energy was evaluated as thermal heat in digester gas and biosolids. Other forms of energy such
as direct electric power production from fuels cells were not considered.
The heat value of biosolids was estimated using in-house facility data tempered with data from
other sources. (U.S. DOE, 2001) (U.S. DOE/EIA, 2012) (U.S. EPA , 2007) (U.S. DOE/EIA,
2010) The heat value was set at 6556 BTU/lb, dry basis although it is recognized that there will
be variations at other facilities.
Since wastewater capacity is known, the value of the components in biosolids can be estimated
by determining the ratio of solids to influent. Although it is recognized that this number varies
from facility to facility, literature values were not readily available, so the ratio was estimated
from in-house facility data as per Table 3. The solids to influent ratio on a dry basis was
calculated to be 0.013%.
Table 3. Solids to influent ratio.
Parameter
Average
Combined Influent, MGD
Combined Influent, lb/d
229
1,913,063,328
P1, Wet Tons/Year
103,834
P2, Wet Tons/Year
125,513
Total Biosolids, Wet Tons/Year
229,348
Total Biosolids, lb/Day Wet
1,256,700
Solids to Influent Ratio Wet
0.07%
Total Solids, percent
20%
Total Biosolids, Dry Tons/Year
45,870
Total Biosolids, lb/Day Dry
251,340
Solids to Influent Ratio Dry
0.013%
The heat value of digester gas was set at 650 BTU/scf, dry basis based on Metcalf and Eddy.
(Tchobanoglous, 2003) The digester gas energy to influent ratio was calculated to be 144% from
in-house facility data shown in Table 4.
Table 4. Digester gas energy to influent ratio.
Parameter
Combined Influent, MGD
Combined Influent, lb/d
Average
229
1,913,063,328
P1, Mcf/month
50
P2, Mcf/month
79
Parameter
Average
Total Digester Gas, Mcf/month
129
BTU/scf dry
650
BTU/d
Energy to Influent Ratio
2,756,293,094
144%
Determining the Price of Components of Wastewater
The price components of wastewater were primarily based on or adjusted to 2010 U.S. dollars.
Table 5 shows the price forecast of nutrients and metals in sludge. Note that components
denoted by a “1” indicate that the prices are developed from the World Bank, Development
Prospects Group in 2005 U.S. dollars. (World Bank, Development Prospects Group, 2012)
The other component prices are developed from the U.S. Geological Survey Mineral
Commodities Summary. (U.S. Geological Survey, 2011) (U.S. Geological Survey, 2012)
Energy prices for digester gas and biosolids are shown in Table 6. The prices are developed
from the U.S. Energy Information Administration Annual Energy Outlooks for anthracitic coal
and natural gas. (U.S. EIA, 2012) (U.S. EIA, 2012) The prices are adjusted to the corresponding
heat value of biosolids and digester gas.
Table 5. Price forecast of nutrients and metals in sludge.
Commodity
Nitrate/Nitrite
W/E Phosphorus 1
Phosphorus 1
Aluminum 1
Antimony
Arsenic
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper 1
Iron ore 1
Lead 1
Magnesium
Manganese
Mercury
Molybdenum
Nickel 1
Selenium
Silver 1
Sodium
Thallium
Tin 1
Titanium
Vanadium
Yttrium
Zinc 1
World Bank (Actual + Forecast)
Extrapolated
Avg. Rate
2010
2015
2020
2025
2030
2035
2040
2045
2050
$0.20
$0.30
$0.38
$0.46
$0.54
$0.62
$0.70
$0.78
$0.86
8.3%
$0.05
$0.05
$0.04
$0.03
$0.06
$0.06
$0.06
$0.07
$0.07
1.0%
$0.05
$0.05
$0.04
$0.03
$0.06
$0.06
$0.06
$0.07
$0.07
1.0%
$0.87
$0.91
$0.89
$0.85
$0.86
$0.86
$0.86
$0.85
$0.85
-0.1%
$4.01
$6.88
$9.40
$11.92
$14.45
$16.97
$19.50
$22.02
$24.54
12.8%
$0.72
$0.84
$0.77
$0.69
$0.62
$0.55
$0.47
$0.40
$0.33
-1.4%
$228.00 $244.85 $301.95 $359.04 $416.13 $473.22 $530.31 $587.40 $644.49
4.6%
$0.18
$0.18
$0.20
$0.21
$0.23
$0.24
$0.26
$0.28
$0.29
1.5%
$1.77
$2.83
$3.62
$4.42
$5.22
$6.01
$6.81
$7.61
$8.40
9.4%
$5.14
$7.52
$9.59
$11.66
$13.73
$15.81
$17.88
$19.95
$22.02
8.2%
$20.85
$31.61
$38.39
$45.17
$51.95
$58.73
$65.50
$72.28
$79.06
7.0%
$3.03
$2.45
$2.03
$2.00
$2.80
$2.95
$3.09
$3.24
$3.39
0.3%
$0.06
$0.04
$0.03
$0.03
$0.05
$0.05
$0.05
$0.06
$0.06
0.0%
$0.86
$0.86
$0.74
$0.75
$0.92
$0.98
$1.03
$1.08
$1.13
0.8%
$2.43
$3.44
$4.35
$5.26
$6.16
$7.07
$7.98
$8.89
$9.79
7.6%
$0.00
$0.01
$0.01
$0.01
$0.01
$0.01
$0.02
$0.02
$0.02
10.3%
$14.16
$24.59
$33.69
$42.80
$51.90
$61.00
$70.11
$79.21
$88.32
13.1%
$15.80
$26.33
$30.94
$35.56
$40.18
$44.79
$49.41
$54.03
$58.65
6.8%
$8.76
$6.48
$6.76
$6.92
$7.96
$8.37
$8.77
$9.18
$9.59
0.2%
$37.83
$66.98
$88.61 $110.23 $131.86 $153.49 $175.12 $196.75 $218.37
11.9%
$260.75 $270.08 $193.96 $189.44 $240.95 $238.70 $236.45 $234.20 $231.96
-0.3%
$0.07
$0.08
$0.08
$0.09
$0.10
$0.11
$0.11
$0.12
$0.13
2.2%
$2,689.80 $3,381.73 $4,137.28 $4,892.84 $5,648.39 $6,403.95 $7,159.50 $7,915.06 $8,670.61
5.6%
$8.20
$9.10
$8.37
$8.03
$9.28
$9.61
$9.95
$10.28
$10.61
0.7%
$4.87
$7.55
$8.58
$9.61
$10.64
$11.67
$12.69
$13.72
$14.75
5.1%
$6.50
$10.66
$12.66
$14.65
$16.65
$18.64
$20.64
$22.63
$24.63
7.0%
$44.91
$84.56
$98.78 $113.01 $127.24 $141.46 $155.69 $169.92 $184.14
7.8%
$0.87
$0.84
$0.73
$0.73
$0.86
$0.89
$0.92
$0.95
$0.98
0.3%
Table 6. Energy price forecast for digester gas and biosolids.
Commodity Pricing per unit
Anthracite Coal, nominal US$ per short tons
Anthracite Coal, nominal US$ per mmBTU
Biosolids Equivalent, nominal US$ per short tons
Biosolids Equivalent, nominal US$ per mmBTU
Natural Gas Average Price, nominal US$ per mmBTU
Digester Gas Equivalent, nominal US$ per mmBTU
2010
$153.59
$6.14
$42.25
$3.22
$7.33
$4.63
2015
$189.11
$7.56
$99.18
$3.97
$6.60
$4.17
2020
$198.45
$7.94
$104.08
$4.16
$6.93
$4.38
Forecast, $ per Unit
2025
2030
2035
$212.18 $225.36 $238.32
$8.49
$9.01
$9.53
$111.28 $118.19 $124.99
$4.45
$4.73
$5.00
$7.93
$8.50
$9.52
$5.01
$5.37
$6.01
2040
$260.55
$10.42
$136.65
$5.47
$10.06
$6.35
2045
$284.86
$11.39
$149.40
$5.98
$10.62
$6.71
2050
$311.44
$12.46
$163.34
$6.53
$11.22
$7.09
Growth
Rate
1.80%
2.57%
7.17%
2.57%
1.10%
1.33%
The price of drinking water was fixed at U.S.$650 per acre-feet and the number is based on the
premise of treating secondary effluent using RO/AOP. The number was tested using other
referenced sources. Water usage rates in 30 U.S. cities averaged US$608/acre-foot. (Circle of
Blue, 2011) The average water rate based on 15 countries was US$1,140/acre-foot and for the
U.S. was US$629/acre-foot. (Pacific Institute, 2009) (Janice A. Beecher and Jason A. Kalmbach,
2010). The price was not adjusted upward as a forecast using economic indicators such as
inflation or GDP. As such, water prices reflected in this evaluation are conservative.
RESULTS OF THE ECONOMETRIC MODEL
World
The potential value of resources in wastewater for the World is on the order of US$1.120 trillion
in 2010 to US$2.026 trillion in 2050, or a 2.0% per year growth rate as shown in Figures 3
through 5.

The World population is 6.90 billion in 2010 to 9.31 billion in 2050, or a 0.9% per year
growth rate

The potential value of nutrients in wastewater for the World is on the order of US$10
billion in 2010 to US$26 billion in 2050, or a 3.8% per year growth rate

The potential value of energy in wastewater for the World is on the order of US$.020
trillion in 2010 to US$.045 trillion in 2050, or a 3.2% per year growth rate
o Digester gas is on the order of US$14 billion in 2010 to US$29 billion in 2050, or
a 2.7% per year growth rate
o Biosolids is on the order of US$6 billion in 2010 to US$16 billion in 2050, or a
4.3% per year growth rate

The potential value of water in wastewater for the World is on the order of US$505
billion in 2010 to US$681 billion in 2050, or a 0.9% per year growth rate

The potential value of metals in wastewater for the World is on the order of US$.585
trillion in 2010 to US$1.273 trillion in 2050, or a 2.9% per year growth rate
Figure 3. World resource recovery opportunity forecast and sector.
Figure 4. World nutrient and energy recovery opportunity forecast.
Figure 5. World water and metals recovery opportunity forecast.
United States
The potential value of resources in wastewater for the United States is on the order of US$50
billion in 2010 to US$88 billion in 2050, or a 1.9% per year growth rate shown in Figures 6
through 8.

The United States population is 310 million in 2010 to 403 million in 2050, or a 0.7% per
year growth rate

The potential value of nutrients in wastewater for the United States is on the order of
US$0.47 billion in 2010 to US$1.14 billion in 2050, or a 3.6% per year growth rate

The potential value of energy in wastewater for the United States is on the order of
US$0.90 billion in 2010 to US$1.96 billion in 2050, or a 2.9% per year growth rate
o Digester gas is on the order of US$0.64 billion in 2010 to US$1.26 billion in
2050, or a 2.5% per year growth rate
o Biosolids is on the order of US$0.27 billion in 2010 to US$.70 billion in 2050, or
a 4.1% per year growth rate

The potential value of metals in wastewater for the United States is on the order of
US$26 billion in 2010 to US$55 billion in 2050, or a 2.7% per year growth rate

The potential value of water in wastewater for the United States is on the order of US$23
billion in 2010 to US$30 billion in 2050, or a 0.7% per year growth rate
Figure 6. United States resource recovery opportunity forecast and sector.
Figure 7. United States nutrient and energy recovery opportunity forecast.
Figure 8. United States water and metals recovery opportunity forecast.
Europe
The potential value of resources in wastewater for Europe is on the order of US$120 billion in
2010 to US$157 billion in 2050, or a 0.8% per year growth rate shown in Figures 9 through 11.

The European population is 738 million in 2010 to 719 million in 2050, or a -0.1% per
year growth rate

The potential value of nutrients in wastewater for Europe is on the order of US$1.12
billion in 2010 to US$2.04 billion in 2050, or a 2.1% per year growth rate

The potential value of energy in wastewater for Europe is on the order of US$2.14 billion
in 2010 to US$3.50 billion in 2050, or a 1.6% per year growth rate
o Digester Gas is on the order of US$1.51 billion in 2010 to US$2.25 billion in
2050, or a 1.2% per year growth rate
o Biosolids is on the order of US$0.63 billion in 2010 to US$1.25 billion in 2050,
or a 2.4% per year growth rate

The potential value of water in wastewater for the Europe is on the order of US$54
billion in 2010 to US$53 billion in 2050, or a -0.1% per year growth rate

The potential value of metals in wastewater for the Europe is on the order of US$63
billion in 2010 to US$98 billion in 2050, or a 1.4% per year growth rate
Figure 9. Europe resource recovery opportunity forecast and sector.
Figure 10. Europe nutrient and energy recovery opportunity forecast.
Figure 11. Europe water and metals recovery opportunity forecast.
Asia
The potential value of resources in wastewater for the Asia is on the order of US$676 billion in
2010 to US$1119 billion in 2050, or a 1.6% per year growth rate shown in Figures 12 through
14.

The Asian population is 4.16 billion in 2010 to 5.14 billion in 2050, or a 0.6% per year
growth rate

The potential value of nutrients in wastewater for Asia is on the order of US$6.3 billion
in 2010 to US$14.58 billion in 2050, or a 3.3% per year growth rate

The potential value of energy in wastewater for Asia is on the order of US$12.1 billion in
2010 to US$25.0 billion in 2050, or a 2.7% per year growth rate
o Digester gas is on the order of US$8.52 billion in 2010 to US$16.10 billion in
2050, or a 2.2% per year growth rate
o Biosolids is on the order of US$3.57 billion in 2010 to US$8.93 billion in 2050,
or a 3.8% per year growth rate

The potential value of water in wastewater for Asia is on the order of US$305 billion in
2010 to US$376 billion in 2050, or a 0.6% per year growth rate

The potential value of metals in wastewater for Asia is on the order of US$353 billion in
2010 to US$703 billion in 2050, or a 2.5% per year growth rate
Figure 12. Asia resource recovery opportunity forecast and sector.
Figure 13. Asia nutrient and energy recovery opportunity forecast.
Figure 14. Asia water and metals recovery opportunity forecast.
Africa
The potential value of resources in wastewater for Africa is on the order of US$166 billion in
2010 to US$477 billion in 2050, or a 4.7% per year growth rate shown in Figures 15 through 17.

The Africa population is 1.02 billion in 2010 to 2.19 billion in 2050, or a 2.9% per year
growth rate

The potential value of nutrients in wastewater for Africa is on the order of US$1.55
billion in 2010 to US$6.22 billion in 2050, or a 7.5% per year growth rate

The potential value of energy in wastewater for Africa is on the order of US$2.97 billion
in 2010 to US$10.67 billion in 2050, or a 6.5% per year growth rate
o Digester gas is on the order of US$2.09 billion in 2010 to US$6.86 billion in
2050, or a 5.7% per year growth rate
o Biosolids is on the order of US$0.88 billion in 2010 to US$3.81 billion in 2050,
or a 8.4% per year growth rate

The potential value of water in wastewater for Africa is on the order of US$75 billion in
2010 to US$160 billion in 2050, or a 2.9% per year growth rate

The potential value of metals in wastewater for Africa is on the order of US$87 billion in
2010 to US$300 billion in 2050, or a 6.1% per year growth rate
Figure 15. Africa resource recovery opportunity forecast and sector.
Figure 16. Africa nutrient and energy recovery opportunity forecast.
Figure 17. Africa water and metals recovery opportunity forecast.
Latin America and the Caribbean
The potential value of resources in wastewater for Latin America and the Caribbean is on the
order of US$96 billion in 2010 to US$163 billion in 2050, or a 1.8% per year growth rate shown
in Figures 18 through 20.

The Latin America and the Caribbean population is 590 million in 2010 to 751 million in
2050, or a 0.7% per year growth rate

The potential value of nutrients in wastewater for Latin America and the Caribbean is on
the order of US$0.89 billion in 2010 to US$2.1 billion in 2050, or a 3.5% per year growth
rate

The potential value of energy in wastewater for Latin America and the Caribbean is on
the order of US$1.7 billion in 2010 to US$3.7 billion in 2050, or a 2.8% per year growth
rate
o Digester gas is on the order of US$1.2 billion in 2010 to US$2.4 billion in 2050,
or a 2.4% per year growth rate
o Biosolids is on the order of US$0.51 billion in 2010 to US$1.3 billion in 2050, or
a 4.0% per year growth rate

The potential value of water in wastewater for Latin America and the Caribbean is on the
order of US$43 billion in 2010 to US$55 billion in 2050, or a 0.7% per year growth rate

The potential value of metals in wastewater for Latin America and the Caribbean is on
the order of US$50 billion in 2010 to US$103 billion in 2050, or a 2.6% per year growth
rate
Figure 18. Latin America and the Caribbean resource recovery opportunity forecast and sector.
Figure 19. Latin America and the Caribbean nutrient and energy recovery opportunity forecast.
Figure 20. Latin America and the Caribbean water and metals recovery opportunity forecast.
Oceania
The potential value of resources in wastewater for Oceania is on the order of US$5.9 billion in
2010 to US$12.0 billion in 2050, or a 2.6% per year growth rate shown in Figures 21 through 23.

The Oceania population is 37 million in 2010 to 55 million in 2050, or a 1.3% per year
growth rate

The potential value of nutrients in wastewater for Oceania is on the order of US$55
million in 2010 to US$157 million in 2050, or a 4.6% per year growth rate

The potential value of energy in wastewater for Oceania is on the order of US$106
million in 2010 to US$269 million in 2050, or a 3.8% per year growth rate
o Digester gas is on the order of US$75 million in 2010 to US$173 million in 2050,
or a 3.3% per year growth rate
o Biosolids is on the order of US$31 million in 2010 to US$96 million in 2050, or a
5.2% per year growth rate

The potential value of water in wastewater for the Oceania is on the order of US$2.7
billion in 2010 to US$4.0 billion in 2050, or a 1.3% per year growth rate

The potential value of metals in wastewater for Oceania is on the order of US$3.1 billion
in 2010 to US$7.6 billion in 2050, or a 3.6% per year growth rate
Figure 21. Oceania resource recovery opportunity forecast and sector.
Figure 22. Oceania nutrient and energy recovery opportunity forecast.
Figure 23. Oceania water and metals recovery opportunity forecast.
DISCUSSION
Resource Recovery Opportunities
Based on 2010 results, metals comprises the highest value of recoverable constituents at US$585
billion followed by potable water at US$505 billion in 2010 followed by energy at US$20 billion
and nutrients at US$10 billion shown in Figure 24. However, economically viable technologies
for recovery of metals in wastewater sludge are not available for WRRFs.
Water,
$504,800
Energy, $20,017
Metals,
$584,882
Nutrients,
$10,430
Figure 24. Recoverable constituents in 2010.
Nutrient Recovery Potential and Phosphate Rock Prices Stability
Figure 25 shows the nutrient recovery potential by geographic region lead by Asia at US$6.3
billion. The value is influenced by the relative large population in China. Africa is next at
US$1.5 billion.
$7,000
$6,299
$6,000
$5,000
$4,000
$3,000
$2,000
$1,546
$1,117
$1,000
$893
$469
$55
$0
United States
Europe
Asia
Oceania
Africa
Latin America
Figure 25. 2010 Nutrient recovery by geographic region in US$ millions.
The U.S. Geological Survey estimates world phosphate rock reserves at 71 billion metric tons.
(U.S. Geological Survey, 2012) Annual mine production is estimated to be 191 million metric
tons for 2011. If world demand for phosphorus rises as a function of population growth rate
which averages 0.87% per year, the reserves amount to a 200 year supply. The reserve estimate
was adjusted upward by including reserves from Iraq, Saudi Arabia, India, Mexico, and Peru.
Prior estimates lead to the belief that phosphate rock is in finite supply which would cause future
prices to speculate. This would add to the importance of recovery of nutrients for WRRFs. As
such, phosphorus prices used in this model are based on projections by the World Bank and do
not reflect this instability. Prices are shown in Figure 26 and increase an average of 1% per year.
$0.08
$0.07
$0.06
$0.05
$0.04
$0.03
$0.02
$0.01
$0.00
2010
2015
2020
2025
2030
2035
2040
2045
2050
Figure 26. Phosphate rock prices, real 2005 US$ per metric ton.
Metal Recovery Potential
The world metals recovery opportunity in 2010 totals to US$ 585 billion and is dominated by
silver at US$ 310 billion, or 53% of the total. Note that because silver is the largest portion and
silver is speculative, the metals recovery potential will be subject to large swings. Aluminum is
US$ 69 billion for 12% of the total, magnesium is US$ 62 billion for 11% of the total, titanium is
US$ 47 billion for 8% of the total, and iron is US$ 24 billion for 4% of the total.
Price Volatility and Global Climate Change
The calculated values of resources do not reflect impacts of global climate change. Climate
change will influence population mobility in the geographic regions defined in this evaluation
and will also impact price by creating instabilities, notably with the value of water.
Titanium
Vanadium
Thallium
Tin
Sodium
Yttrium
Zinc*
Antimony Beryllium
Arsenic* Boron
Aluminum
Chromium*
Cobalt
Iron Lead*
Magnesium
Silver
Cadmium*
Copper*
Manganese
Mercury*
Molybdenum*
Nickel
Selenium*
Figure 26. Metals recovery potential in 2010.
Climate change influences rainfall patterns and therefore, as water becomes unavailable in some
regions while other regions may experience abnormally high rainfall amounts, the existing water
delivery infrastructures will become inadequate. Potentially, new infrastructures will have to be
built at high cost, driving up the price of water.
An advantage of water recycling by WRRFs is that existing water is reused within an existing
region an infrastructure, mitigating some of the capacity requirements for new water delivery
systems.
BIBLIOGRAPHY
Circle of Blue. (2011). The Price of Water: A Comparison of Water Rates Usage in 30 US Cities.
Janice A. Beecher and Jason A. Kalmbach. (2010). 2010 Great Lakes Water Rates Survey Report
Final. Institute of Public Utilities at Michigan State University: Great Lakes Commission.
Pacific Institute. (2009). World Water Development Report. Watertech Online.
Tchobanoglous, G. B. (2003). Wastewater Engineering (Treatment Disposal Reuse). ISBN 0-07041878-0. Metcalf & Eddy, Inc. McGraw-Hill Book Company 4th ed.
U.S. DOE. (2001, September 21). New Solid Fuels From Coal and Biomass Waste. Final Report
- RDD:01:43755-001-000-05. Washington, DC, USA.
U.S. DOE/EIA. (2010). Biosolids Equivalents Derived from Natural Gas. Washington, DC,
USA.
U.S. DOE/EIA. (2012, May 30). Heating Fuel Comparison Calculator. Washington, DC, USA.
U.S. EIA. (2012). Annual Energy Outlook with Projections to 2035, Coal Supply, Disposition,
and Prices, Reference case. DOE-EIA-0383. Washington, DC, USA.
U.S. EIA. (2012). Annual Energy Outlook with Projections to 2035, Natural Gas Supply,
Disposition, and Prices, Reference case. DOE-EIA-0383. Washington, DC, USA.
U.S. EPA . (2007, September). Biomass CHP Catalog, Part 3. Combined Heat and Power
Partnership. Washington, DC, USA.
U.S. EPA. (2008). Clean Watersheds Needs Survey 2008 Report to Congress. EPA-832-R-10002. Washington, DC, USA.
U.S. EPA. (2009, January). Targeted National Sewage Sludge Survey Report. EPA-822-R-08016. Washington, DC, USA.
U.S. EPA. (2009, April). Targeted National Sewage Sludge Survey Statistical Analysis Report.
EPA-822-R-08-018. Washington, DC, USA.
U.S. Geological Survey. (2011). Mineral Commodity Summaries 2011: U.S. Geological Survey.
Washington, DC, USA.
U.S. Geological Survey. (2012). Mineral Commodity Summaries 2012: U.S. Geological Survey.
Washington, DC, USA.
U.S. Geological Survey. (2012). Phosphate Rock. Mineral Commodity Summaries. Washington,
DC, USA.
United Nations. (2010). Population Division of the Department of Economic and Social Affairs
of the United Nations Secretariat. World Population Prospects: The 2010 Revision.
World Bank, Development Prospects Group. (2012, June 12). Commodity Prices and Price
Forecast in Real 2005 US Dollars. Commodity Price Forecast Update.