SUPPLEMENTARY EFFLUENTS NOTES
A hypothetical wastewater treatment works final effluent summary report is
attached. 6 out of 31 parameters are included in the table, and the reason for
choosing these six parameters is due to the fact that they are controllable by the
operators at the facility. The ones not included are beyond the control of the
operator, and may result due to upstream pollution and discharge contraventions.
The figures in brackets are the discharge limits per parameter.
Plant Date Flow TSS COD NH3 Nitrate Ortho P E.Coli
Ml/d mg/l mg/l mgN/l mgN/l mgP/l Per
(25) (75) (10) (1) 100ml
Athlone 27/2/07 84.5 24 94 1.4 5.3 5.1 210 000
Bellville 28/2/07 56.9 11 48 12.0 1.7 1.0 50 000
Cape Flats 27/2/07 33.0 67 148 6.5 0.5 8.5 1 750
Klipheuwel 26/2/07 - 5 76 18.7 15.5 15.8 100
Mitchells 26/2/07 30.0 32 90 1.4 7.3 8.4 48 000
Parow 27/2/07 1.1 2 45 20 0.0 1.0 5
Llandudno 26/2/07 0.4 4 66 6.0 15.5 12.0 7 500
Potsdam 27/2/07 38.2 14 90 14.0 0.6 7.0 390 000
The high E.coli at Athlone, which does not have an applied disinfection
facility, could be as a result of high flow rates and too little retention times.
The maturation ponds are supposed to utilise the ultra violet rays from the
sun to reduce the amount of E.coli. This situation can be rectified by
applying formalised disinfection.
The high E.coli at Llandudno, which has a chlorination facility, could be
due to excess demand, or the fact that the plant may be depleted of its
The Mitchells Plain non-compliance in terms of the E.coli is similar to that
of Athlone, except that the maturation ponds are working as it should, but
that there could be sludge or raw wastewater overflow in the ponds.
Ortho-Phosphate does not have a general standard, but a special standard
for highly sensitive areas, eg Potsdam and Rietvlei.
TSS, COD and NH3 are harmful to the environment, mainly aquatic life if
the general standards are exceeded.
E.coli non-compliances have negative effects if in direct human contact.
Nitrates and Ortho-P excesses result in nutrient pollution and can result in
the proliferation of weeds in aquatic systems.
Very high ammonia discharges could be due to aeration capacity or
process problems, eg mechanical breakdown at the plant, lack of capacity,