State of the Bay Report 2011-Final.pdf - Anchor Environmental

Chemical Oxygen Demand (mg/l) (Filtered)
Total Suspended Solids (mg/l)
May-09
May-09
Jul-09
Jul-09
Aug-09
Aug-09
Oct-09
Oct-09
Dec-09
Dec-09
Jan-10
Jan-10
Mar-10
Mar-10
May-10
May-10
Jun-10
Jun-10
Aug-10
Aug-10
Sep-10
Sep-10
Nov-10
Nov-10
Jan-11
Jan-11
Feb-11
Feb-11
Apr-11
Apr-11
Jun-11
Jun-11
Jul-11
Jul-11
Sep-11
Sep-11
Nov-11
Nov-11
Dec-11
Dec-11
State of Saldanha Bay & Langebaan Lagoon 2011
Activities & discharges
60
50
40
30
20
10
0
Figure 3.24. Monthly trends in Total Suspended Solids in effluent released from the Langebaan WWTW,
June 2009 - December 2011. Allowable limits as specified in terms of a General Authorisation
under the National Water Act 1998 are represented by the red line.
120.0
100.0
80.0
60.0
40.0
20.0
0.0
Figure 3.25. Monthly trends in Chemical Oxygen Demand in effluent released from the Langebaan WWTW,
June 2009-February 2011. Allowable limits as specified in terms of a General Authorisation
under the National Water Act 1998 are represented by the red line.
The levels of Ammonia Nitrogen discharged from the Langebaan WWTW have exceeded the
allowable limit of 3 mg/l since measurements began in June 2009, however, concentrations are now
more acceptable, with only the occasional reading above the limit (Figure 3.26). The levels of Nitrate
Nitrogen have not exceeded allowable limits since measurements began in 2009 (Figure 3.27)
Orthophosphate concentrations fluctuate in a seasonal pattern similar to that seen at the Saldanha
WWTW and have in the last two years remained mostly below the allowable (Figure 3.28). Levels of
free active chlorine have exceeded allowable limits 61% of the time since monitoring commenced
(Figure 3.29).
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