Table A: General Chemical Characteristics Characteristic Maximum Remarks in this column are for Concentration guidance only. g/m 3 MBAS (Methylene blue active 500 MBAS is a measure of anionic substances) surfactants. High MBAS can: - adversely affect the efficiency of activated sludge plants - impair the aesthetics of receiving waters Ammonia - (as N) High ammonia: -Free ammonia 50 - may adversely effect the safety of -Ammonium salts 200 operations & maintenance personnel - may significantly contribute to the nutrient load to the receiving environment. Kjeldahl nitrogen 150 High Kjeldahl nitrogen may significantly contribute to the nutrient load of the receiving environment. A value of 150 g/m should be used as a guideline for 3 sensitive receiving waters. Total phosphorus 50 High phosphorus may significantly (as P) contribute (as P) to the nutrient loading of the receiving environment. A value of 50 g/m should be used as a guideline 3 for sensitive receiving waters. Sulphate Sulphate: (measured as SO4) 500 - may adversely affect wastewater 1500 (with good mixing) system structures. - may increase the potential for the generation of sulphides in the wastewater if the sewer is prone to become anaerobic. Sulphite - (as SO2) 15 Sulphite has potential to release S02 gas and thus adversely affect the safety of operations & maintenance personnel. It is a strong reducing agent and removes dissolved oxygen thereby increasing the potential for anaerobic conditions to form in the wastewater. Sulphide - Sulphides in wastewater may: as HS on acidification 5 - cause corrosion of wastewater system structures, particularly the top non-wetted part of a sewer. - generate odours in sewers which could cause public nuisance. - release the toxic H2S gas which could adversely affect safety. Chlorine - (as Cl2) Chlorine: - Free chlorine 3 - can adversely affect the safety of - hypochlorite 30 operations & maintenance personnel. - can cause corrosion of wastewater system structures. Dissolved Aluminium 100 Aluminium compounds, particularly in the presence of calcium salts, have the potential to precipitate as a scale which may cause a sewer blockage. Page 19