FINAL REPORT - Grand River Conservation Authority

Grand River Watershed-Wide Wastewater Optimization Pilot Project
(kg/person/d)
45
40
35
30
25
20
15
10
5
0
Figure 11: Per capita TKN Loading
typical median
A B C D E F G H I J K L M N
The following observations can be made concerning Figures 7 to 11:
The median per capita flows for the 14 WWTPs surveyed (Figure 7) was 369
L/person•d close to the typical value of 450 L/person•d. Two of the WWTPs
(A and D) displayed evidence of inflow/infiltration as their per capita flows
were above 500 L/person•d. One WWTP (Plant J) has very high per capita
flows that are attributed to industrial discharges.
For the ratio of peak day flow to annual average flow, Figure 8, the median
value was 1.9. Four WWTPs (B,C, D and H) had ratios above 2.5. Plants A
and D which had high per capita flows, did not have high ratios for peak day
to annual average flow. This suggests that infiltration rather than inflow is the
potential source of the higher per capita flows.
For the per capita BOD 5 loadings, Figure 9, the median value for the WWTPs
in the survey was 80 g/person•d, which is equal to the expected value of 80
g/person•d. Plant E had a per capita BOD 5 loading twice that expected for a
WWTP treating municipal discharges. During Workshop #3, operations staff
identified that the WWTP is subject to significant industrial loads. Similarly,
Plant J is known to have substantial BOD 5 loading from an industrial
discharge. Plants C and I are small facilities using infrequent grab samples to
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