Sulphur
The concentration of sulphur in the liquid detergents will have the same effect under anaerobic treatment (in a septic tank or first chamber of an aerated wastewater treatment system) as will the sulphur that comes in the powders. Sulphur is reduced in an anaerobic environment (in the absence of air) to produce hydrogen sulphide (rotten egg gas). The source of the sulphur in the liquid has not been investigated.
Figure LF6-S Concentration of sulphur per wash when recommended dose for front loading washing machine's full wash (75 L)
Figure LT6-S concentration of sulphur per wash when recommended dose for top loading washing machine's full wash (150 L)
Assessment
When the concentration of sulphur in liquid detergents is compared with the sulphur in the powder detergent, the liquid have significantly lower levels. The average sulphur concentration of liquids for front loading machines was 6.2 mg/L (median 4.2 mg/L) compared to the powders of 27.3 mg/L (median 9.2 mg/L). For the top loaders, the average for the liquids was 4.8 mg/L (median 3.1 mg/L) and the powders average was 25.7 mg/L (median 10.4 mg/L). In the liquids, the sulphur concentration was about one-fifth that of the powders, therefore a significant saving in sulphur can be derived by choosing liquid detergents.