Phosphorus
The concentration of phosphorus in the liquid laundry detergent was measured after the recommended dose of detergent was mixed with water and shaken for 30 minutes. The value measured (mg/L) was multiplied by the volume of the wash water (litres) to determine the load of phosphorus (milligrams).
Table LF4-P is a ranking of the phosphorus load for the liquids when mixed at the rate for front loading washing machines (75 L per full wash).
Table LT4-P is a ranking of the phosphorus load for the liquids when mixed at the rate for top loading washing machines (150 L per full wash).
Assessment
The load of phosphorus in many of the liquids, whether used for front loader or top loader rates, are below detectable levels (0.001 g/wash), while many were also below 1 g/wash which has been used to make some calculations of land application area in a previous page (phosphorus in powders).
The differences between the powders and the liquids in the load of phosphorus is most noticeable in the front loader where the average liquid was 0.58 g/wash (median 0.003 g/wash) and the average powder was 1.37 g/wash (median 0.54 g/wash). For the top loaders, the average phosphorus load in the liquids was 1.09 g/wash (median 0.012 g/wash) and for the powders, the average was 2.25 g/wash (median 1.74 g/wash).
It is possible within each of the powders and the liquids to choose products that have no phosphorus or very low levels to suit the conditions of on-site disposal.
Analysis of phosphorus labelling
There are two common labels used by manufacturers to identify the amount of phosphorus in their products. The "NP" symbol denotes that there has been no added phosphorus to the product, although minor amounts may be present in the various ingredients they use. The "P" symbol denotes that the product contains less than an industry imposed upper limit for phosphorus (not sure how this value was derived). An analysis of the product labels of the products tested in this range of laundry products is given below.
This section is yet to be completed - please be patient!