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: mcglonem@msi01.cs.upd.edu.ph

LOICZ web pages: HTTP://WWW.NIOZ.NL/LOICZ/