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```Estimation of Waste Load
Malou San Diego-McGlone
Marine Science Institute
University of the Philippines
Precipitation
Evaporation
Residual flux
Runoff
Coastal Water Body
Mixing flux
Groundwater
Sewage/Waste
Sources of Waste (human activity)
household activities
livestock
agriculture
urban runoff
aquaculture
manufacturing
Steps in the Calculation of Waste Load
1. Identify relevant human activities
households - solid waste, domestic
sewage, detergent
livestock -
piggery, poultry, cattle
agriculture - soil erosion, fertilizer
runoff
urban runoff - unsewered areas
aquaculture - prawns, fish
manufacturing - food, textiles, chemicals
2. Determine the level of each human activity
from government statistics, preferably at
local level
household - size of the population
livestock - no of pig, chicken, cow
aquaculture - tons of prawn, fish
urban runoff - urban area
agriculture - tons of soil eroded
3. Approximate TN and TP (in effluent discharge)
TN = activity level x discharge coefficient
TP = activity level x discharge coefficient
T
The discharge coefficients for various human activities
are given in the following spreadsheet.
generated by various human activities.
Knowledge of the activities relevant to the coastal
area is necessary and the only input needed in the
spreadsheet would be the level of the waste
generating activity (fill in white cells).
Economic Activity Discharge coef
Source
(unit)
Household
a. solid waste
1.86 kgN/prn/yr a
0.37 kgP/prn/yr b
b. domestic sewage
4 kgN/prn/yr c
1 kgP/prn/yr c
c. detergent
1 kgP/prn/yr c
Urban runoff
(unsewered areas)
Livestock
a. cattle
b. horses
c. sheep
a. piggery
b. poultry
Aquaculture
a. prawn
b. milkfish
Non-point agricultural
runoff
a. cropland erosion
SUM
1.9 mgN/liter d
0.4 mgP/liter d
Activity level
(no)
(unit)
Total N
(kg/yr)
Total P
(kg/yr)
DIN
(mol/yr)
DIP
(mol/yr)
person
0
0
0
0
person
0
0
0
0
person
avg rain(m/yr)
0
0
0
0
0
0
x urban area(m2)
43.8
11.3
95.3
16.4
4
21.5
7.3
2.3
0.3
0.7
kgN/cow/yre
kgP/cow/yre
kgN/hor/yr e
kgP/hor/yr e
kgN/shp/yre
kgP/shp/yre
kgN/pig/yr e
kgP/pig/yr e
kgN/bird/yrf
kgP/bird/yrf
cow
0
0
0
0
horse
0
0
0
0
sheep
0
0
0
0
pig
0
0
0
0
bird
0
0
0
0
5.2
4.7
2.9
2.6
kgN/ton/yr g
kgP/ton/yr g
kgN/ton/yr b
kgP/ton/yr b
ton prawn
0
0
0
0
ton fish
0
0
0
0
ton soil
0
0
0
0
0
0
1.68 kgN/ton
0.04 kgP/ton
b
b
eroded/yr
Sources of Discharge Coefficients
References:
a Sogreah. 1974. Laguna de Bay Water Resources Development Study.
Laguna Lake Development Authority, Pasig City, Philippines.
b Padilla, J., L. Castro, A. Morales, C. Naz. 1997. Evaluation of economy-environment
interactions in the Lingayen Gulf Basin: A partial area-based environmental
accounting approach. DENR and USAID, Philippines.
c World Bank. 1993. Environmental Sector Study. Towards Improved Management of
Environmental Impacts. Washington, D.C., USA.
d Gianessi, L. and H. Peskin. 1984. An overview of the RFF Environmental Data Inventory
Methods, Sources and Preliminary Results. Vol 1. N.W., Washington, D.C.:
Renewable Resources Division, Resources for the Future.
e World Health Organization (WHO). 1993. Rapid Assessment of Sources of Air, Water,
and Land Pollution. Geneva, Switzerland
f Valiela, I., G. Collins, J. Kremer, K. Lajitna, M.Geist, B. Seely, J.Brawley, and C.H.
New methods and application. Ecological Applications. 7(2):358-380.
g Gonzales, J.A., H,J. Gonzales, R.C. Sanares, and E.T. Tabernal. 1996. River pollution:
an investigation of the influence of aquaculture and other agro-industrial effluents
on communal waterways. Institute of Aquaculture, College of Fisheries, University
of the Philippines in the Visayas. 89pp.
h Howarth, R.W., G. Billen, D. Swaney, A. Townsend, N. Jaworski, K/ Lajitha, J.A. Downing,
R. Elmgren, N. Caraco, T. Jordan, F. Berendse, J. Freney, V. Kudeyarov, P. Murdoch,
and Z. Zhao-Liang. 1996. Regional nitrogen budgets and riverine N and P fluxes for
drainages to the North Atlantic Ocean; Natural human influences. Biogeochemistry.
35:75-139.
TN and TP (in the spreadsheet) are
approximated using the following calculations.
TN = activity level x discharge coefficient
Ex. for Domestic Sewage
activity level = 2000 persons
discharge coefficient = 4 kgN/person/yr
TN = 4 kgN/person/yr x 2000 persons
TN = 8000 kgN/yr
TP = activity level x discharge coefficient
discharge coefficient = 1 kgP/person/yr
TP = 1 kgP/person/yr x 2000 persons
TP = 2000 kgP/yr
If only BOD and COD data are available, TN and TP
can be approximated using the following ratios*
TN/BOD = 0.5
TP/BOD = 0.042
COD/BOD = 2.6
Ex if available data is BOD at 5 mg/L
TN = 5 mg/L x 0.5 = 2.5 mg/L
Ex if available data is COD at 5 mg/L
TN = 5 mg/L x 1/26 (BOD/COD) x 0.5
= 1 mg/L
*from San Diego-McGlone, M.L. ,S.V. Smith, and V. Nicolas. 1999.
Stoichiometric interpretation of C:N:P ratios in organic waste
materials by (Accepted in Marine Pollution Bulletin).
The previous spreadsheet also approximates DIN
and DIP. The following calculations illustrate how
this is done.
4. Calculate DIN and DIP in the effluent discharge
Assumption: 25% of waste enter the bay
Use stoichiometric ratio*
DIN/TN = 0.38
DIP/TP =0.5
DIN = TN÷atomic wt N x DIN/TN x 25%
DIN = 8000 kgN/yr ÷14 g/mole x 0.38 x 0.25
DIN = 54,000 moles/yr
DIP = TP÷atomic wt P x DIP/TP x 25%
DIP = 2000 kgP/yr÷31 g/mole x 0.5 x 0.25
DIP = 8,000moles/yr
*from San Diego-McGlone, M.L. ,S.V. Smith, and V. Nicolas. 1999.
Stoichiometric interpretation of C:N:P ratios in organic waste
materials by (Accepted in Marine Pollution Bulletin).
The following N and P budgets of a Philippine bay
(LINGAYEN GULF) are given to illustrate how
waste is quantified and show that this is an
important input to the system.
NITROGEN AND PHOSPHORUS BUDGETS
FOR LINGAYEN GULF
20.00
Lingayen Gulf
16.00
Manila Bay
12.00
8.00
4.00
114.00
118.00
122.00
126.00
16.60
16.50
16.40
Upper Gulf
16.30
Bolinao
1764 km2, 81 km3
126 km2, 0.3 km3
16.20
16.10
16.00
119.90
120.00
120.10
120.20
120.30
120.40
Lingayen Gulf divided into three boxes
LINGAYEN GULF
Water Budget (fluxes in 109m3/yr)
VR = 11
VP = 0.3
VE = 0.3
VP =4
Ocean
VE = 4
VQ = 2
VQ = 0.2
VG = 0.7
Upper Gulf
Bolinao
126 km2, 0.3 km3
VR = 1
VG = 0.4
1764 km2, 81 km3
VR = 8
VQ = 8
Nearshore
210 km2, 3.2 km3
VP = 0.5
VE = 0.4
VG = 0.2
LINGAYEN GULF
Salt Budget (salt fluxes in 109 psu-m3/yr)
VRSR = 376 VX = 940
Ocean
Bolinao
126
km2,
0.3
VRSR = 34
Upper Gulf
1764 km2, 81 km3
km3
S1B = 33.5
 = 2 days
S3 = 34.4
S2 = 34.0
VX = 68
 = 27 days
VRSR = 260
VX = 87
Nearshore
210 km2, 3.2 km3
S1N = 31
 = 12 days
Table 1. Effluents produced by economic activities in
Lingayen Gulf (in 106 mole yr-1).
ECONOMIC ACTIVITY
Household activities
- domestic sewage
- solid waste
- detergents
Urban Runoff
Agricultural Runoff
- crop fertilization
- cropland erosion
Livestock
- commercial piggery
- poultry
Aquaculture
Total
NITROGEN
PHOSPHORUS
1,754
1,595
159
126
3,465
1,820
1,645
29
25
4
22
5,396
202
91
11
100
5
174
157
17
2
2
2
385
LINGAYEN GULF
DIP Budget (fluxes in 106 moles/yr)
Ocean
VXDIPX = 94
VQDIPQ = 1
VQDIPQ = 1
VODIPO = 46
DIP3 = 0.0µM
VRDIPR = 1
VRDIPR = 0
Bolinao
DIP=-27
Upper Gulf
DIP = +10
VODIPO = 35
VGDIPG = 1
VGDIPG = 0
DIP1B = 0.4
VXDIPX = 20
DIP2 = 0.1µM
VR DIPR= 2
VXDIPX = 26
Nearshore
DIP = -97
DIP1N = 0.4µM
VQDIPQ = 88
VODIPO = 35
VGDIPG = 2
LINGAYEN GULF
DIN Budget (fluxes in 106 moles/yr)
Ocean
VGDING = 39
VXDINX = 282
VQDINQ = 8
VQDINQ = 4
VODINO = 350
DIN3 = 0.5µM
VRDINR = 7
VRDINR = 2
Bolinao
DIN = -180
DIN1B = 3.9µM
Upper Gulf
DIN = -310
VODINO = 262
VGDING = 28
VXDINX = 211
DIN2 = 0.8µM
VR DINR= 10
VXDINX = 78
Nearshore
DIN = -313
DIN1N = 1.7µM
VQDINQ =128
VODINO = 262
VGDING =11
Net ecosystem metabolism (p-r) or photosynthesis minus
respiration, can be calculated using the formulation
(p-r ) = -DIP  (C:P)part
Estimates of (nfix-denit) or N-fixation minus denitrification,
can be approximated using the formulation
(nfix-denit) = DIN - DIP  (N:P)part
where (C:P)part and (N:P)part are the ratios of organic
matter reacting in the system
Table 2. Summary of nonconservative fluxes in three
boxes of Lingayen Gulf.
Nearshore Box
Bolinao Box
Upper Gulf Box
Whole System
(Area, Vol.)
(210 km2,
3.2 km3)
(126 km2,
0.3 km3)
(1,764 km2,
81 km3)
(2,100 km2,
84.5 km3)
% area
10%
mol m-2 yr-1
6%
mol m-2 yr-1
84%
mol m-2 yr-1
100%
mol m-2 yr-1
DIP
-0.46
-0.21
+0.006
-0.05
DIN
(p-r)
(nfix-denit)
-1.5
-1.4
-0.2
-0.4
+49
+5.9
+1,239
+23
+2.0
-0.6
-0.5
+6
+0.3
Autotrophic
N fixation
Autotrophic
N fixation
Heterotrophic
Denitrification
Autotrophic
N fixation
Table 3. Effects of changing waste load on
(p-r) and (nfix-denit).
(p-r)
in mol m-2 yr-1
(nfix-denit)
in mol m-2 yr-1
-0.5
+6
+2.5
+11
-0.03
+0.3
+0.2
+0.9
IMPLICATIONS
 The system is able to breakdown waste inputs
and export most of these as N and P out of the
Gulf with some amount retained, perhaps in the
sediments.
 Since the average nutrient concentrations of N
and P in the upper Gulf have not varied much over
the years, this is an indication of the system’s
current assimilative capacity.
 However, buildup of organic matter is critical
for the nearshore and Bolinao boxes and will
eventually affect the Gulf’s ability to process these
materials.

Malou:
[email protected]

LOICZ web pages:
HTTP://WWW.NIOZ.NL/LOICZ/
```