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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 (1000 per 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 Plain 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 chlorine stocks. 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, etc.
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