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Estimation of Waste Load
Malou San Diego-McGloneMarine Science Institute
University of the Philippines
Coastal Water Body
Precipitation Evaporation
Residual flux
Mixing flux
Runoff
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.
This spreadsheet calculates TN and TP load in waste 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).
ESTIMATION OF WASTE LOADEconomic Activity Discharge coef Source Activity level Total N Total P DIN DIP
(unit) (no) (unit) (kg/yr) (kg/yr) (mol/yr) (mol/yr)Householda. solid waste 1.86 kgN/prn/yr a person 0 0 0 0
0.37 kgP/prn/yr bb. domestic sewage 4 kgN/prn/yr c person 0 0 0 0
1 kgP/prn/yr cc. detergent 1 kgP/prn/yr c person 0 0
Urban runoff 1.9 mgN/liter d avg rain(m/yr) 0 0 0 0 (unsewered areas) 0.4 mgP/liter d x urban area(m2)
Livestocka. cattle 43.8 kgN/cow/yre cow 0 0 0 0
11.3 kgP/cow/yreb. horses 95.3 kgN/hor/yr e horse 0 0 0 0
16.4 kgP/hor/yr ec. sheep 4 kgN/shp/yre sheep 0 0 0 0
21.5 kgP/shp/yrea. piggery 7.3 kgN/pig/yr e pig 0 0 0 0
2.3 kgP/pig/yr eb. poultry 0.3 kgN/bird/yrf bird 0 0 0 0
0.7 kgP/bird/yrf
Aquaculturea. prawn 5.2 kgN/ton/yr g ton prawn 0 0 0 0
4.7 kgP/ton/yr gb. milkfish 2.9 kgN/ton/yr b ton fish 0 0 0 0
2.6 kgP/ton/yr b
Non-point agricultural runoffa. cropland erosion 1.68 kgN/ton b ton soil 0 0 0 0
0.04 kgP/ton b eroded/yr
SUM 0 0
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 InventoryMethods, 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. Sham. 1997. Nitrogen loading from coastal watersheds to receiving estuaries: 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 effluentson communal waterways. Institute of Aquaculture, College of Fisheries, Universityof 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.
Sources of Discharge Coefficients
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
*from San Diego-McGlone, M.L. ,S.V. Smith, and V. Nicolas. 1999.Stoichiometric interpretation of C:N:P ratios in organic wastematerials by (Accepted in Marine Pollution Bulletin).
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
The previous spreadsheet also approximates DIN and DIP. The following calculations illustrate how this is done.
4. Calculate DIN and DIP in the effluent dischargeAssumption: 25% of waste enter the bayUse stoichiometric ratio*
DIN/TN = 0.38DIP/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 wastematerials 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
114.00 118.00 122.00 126.004.00
8.00
12.00
16.00
20.00
Lingayen Gulf
Manila BaySo
uth
Chi
na S
ea
Lingayen Gulf divided into three boxes
119.90 120.00 120.10 120.20 120.30 120.40
16.00
16.10
16.20
16.30
16.40
16.50
16.60
Upper Gulf1764 km2, 81 km3
Bolinao126 km2, 0.3 km3
Nearshore
210 km2 , 3.2 km3
LINGAYEN GULFWater Budget (fluxes in 109m3/yr)
Upper Gulf1764 km2, 81 km3
Nearshore210 km2, 3.2 km3
Bolinao126 km2, 0.3 km3
Ocean
VR = 1
VR = 8
VR = 11
VQ = 0.2
VG = 0.7
VP = 0.3
VP =4
VQ = 2
VG = 0.4
VQ = 8
VG = 0.2
VP = 0.5
VE = 0.3
VE = 0.4
VE = 4
S2 = 34.0
S1N = 31
S1B = 33.5
LINGAYEN GULFSalt Budget (salt fluxes in 109 psu-m3/yr)
Upper Gulf1764 km2, 81 km3
Nearshore210 km2, 3.2 km3
Bolinao126 km2, 0.3 km3
Ocean
VX = 68
VRSR = 34
S3 = 34.4
VRSR = 376 VX = 940
VRSR = 260 VX = 87
= 2 days = 27 days
= 12 days
Table 1. Effluents produced by economic activities in Lingayen Gulf (in 106 mole yr-1).
ECONOMIC ACTIVITY NITROGEN PHOSPHORUS
Household activities 1,754 202 - domestic sewage 1,595 91 - solid waste 159 11 - detergents - 100Urban Runoff 126 5Agricultural Runoff 3,465 174 - crop fertilization 1,820 157 - cropland erosion 1,645 17Livestock 29 2 - commercial piggery 25 2 - poultry 4 -Aquaculture 22 2Total 5,396 385
ECONOMIC ACTIVITY NITROGEN PHOSPHORUS
Household activities 1,754 202 - domestic sewage 1,595 91 - solid waste 159 11 - detergents - 100Urban Runoff 126 5Agricultural Runoff 3,465 174 - crop fertilization 1,820 157 - cropland erosion 1,645 17Livestock 29 2 - commercial piggery 25 2 - poultry 4 -Aquaculture 22 2Total 5,396 385
VODIPO = 35
VODIPO = 35
VODIPO = 46
Nearshore
LINGAYEN GULFDIP Budget (fluxes in 106 moles/yr)
Upper Gulf Bolinao
Ocean
DIP1B = 0.4 DIP2 = 0.1µM
DIP1N = 0.4µM
VXDIPX = 20
VR DIPR= 2
VRDIPR = 0
VXDIPX = 26
DIP3 = 0.0µMVRDIPR = 1 VXDIPX = 94
VQDIPQ = 1
VQDIPQ = 88
VQDIPQ = 1
VGDIPG = 1
VGDIPG = 2
VGDIPG = 0DIP=-27
DIP = +10
DIP = -97
VODINO = 262
VODINO = 262
VODINO = 350
DIN1N = 1.7µM
VQDINQ = 4VQDINQ = 8
VQDINQ =128
Ocean
LINGAYEN GULFDIN Budget (fluxes in 106 moles/yr)
Upper Gulf
Nearshore
Bolinao
DIN1B = 3.9µM DIN2 = 0.8µMVXDINX = 211
VR DINR= 10
VRDINR = 2
VXDINX = 78
DIN3 = 0.5µMVRDINR = 7 VXDINX = 282
VGDING = 28
VGDING =11
VGDING = 39DIN = -180
DIN = -310
DIN = -313
Stoichiometric Links
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
(Area, Vol.)
% area
Nearshore Box
(210 km2,
3.2 km3)
10%
Bolinao Box
(126 km2,
0.3 km3)
6%
Upper Gulf Box
(1,764 km2,
81 km3)
84%
Whole System
(2,100 km2,
84.5 km3)
100%
mol m-2 yr-1 mol m-2 yr-1 mol m-2 yr-1 mol m-2 yr-1
DIP -0.46 -0.21 +0.006 -0.05DIN -1.5 -1.4 -0.2 -0.4
(p-r) +49 +23 -0.6 +6
(nfix-denit) +1,239 +2.0 -0.5 +0.3
Autotrophic
N fixation
Autotrophic
N fixation
Heterotrophic
Denitrification
Autotrophic
N fixation
Table 2. Summary of nonconservative fluxes in three boxes of Lingayen Gulf.
(Area, Vol.)
% area
Nearshore Box
(210 km2,
3.2 km3)
10%
Bolinao Box
(126 km2,
0.3 km3)
6%
Upper Gulf Box
(1,764 km2,
81 km3)
84%
Whole System
(2,100 km2,
84.5 km3)
100%
mol m-2 yr-1 mol m-2 yr-1 mol m-2 yr-1 mol m-2 yr-1
DIP -0.46 -0.21 +0.006 -0.05DIN -1.5 -1.4 -0.2 -0.4
(p-r) +49 +23 -0.6 +6
(nfix-denit) +2.0 -0.5 +0.3
Autotrophic
N fixation
Autotrophic
N fixation
Heterotrophic
Denitrification
Autotrophic
N fixation
+5.9
Table 3. Effects of changing waste load on (p-r) and (nfix-denit).
Change in waste load (p-r)
in mol m-2 yr-1
(nfix-denit)
in mol m-2 yr-1
0 load -0.5 -0.03
Current load +6 +0.3
0.5 x current load +2.5 +0.2
2 x current load +11 +0.9
IMPLICATIONS
The system is able to breakdown waste inputs and export most of these as N and P out of theGulf 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 willeventually affect the Gulf’s ability to process these materials.
Malou: [email protected]
LOICZ web pages: HTTP://WWW.NIOZ.NL/LOICZ/