Lanfax Labs in association with Choice tested 49 powder detergent concentrates in early 2007, resulting in "Wash Only" data for 35 powders in front loaders and 35 powders in top loaders. The report was published in "Choice" in the April edition. The data below extend to dual testing of products where one brand was suitable for both front and top loader. These data are presented independently of "Choice".
Phosphorus in detergents is supposedly based upon an industry standard of 7.8 g phosphorus per wash. The reason for this level is unclear as there is no obvious scientific evident to show this level is safe. Indeed, converting 7.8 g P/wash for a front loader using 75 L per wash, gives a concentration of 104 mg/L. Interesting that many of the sewage treatment works are required to remove phosphorus to less than 1 mg/L, the "acceptable" laundry detergents can produce up to 100 times that concentration in the whole water cycle from a front loader. In an average top loader, the phosphorus concentration would be about half that of the front loader, that is 50 times the discharge concentration from a sewage treatment works. Seems to me that somewhere there is a real problem with understanding the environmental effects of phosphorus, yet very little is being done to limit the phosphorus entering the sewers. Where wastewater is discharged to land, the acceptable phosphorus load is determined by the soil properties and the area of which the wastewater is spread. Because phosphorus is a plant nutrient, its value as a fertiliser can be measured.
From the data below, the wash is the concentration (mg/L) multiplied by the volume of water use in the wash (L) and divided by 1000 to bring milligrams to grams. In the case of these detergents sourced by Choice in early 2007 and analysed by Lanfax Labs, these calculation have been done before the data are graphed.
Phosphorus is a "builder" in the detergent and replacement of phosphorus with a substitute builder may not necessarily improve the environmental outcome of discharging the wastewater to land. Phosphorus is an essential plant and animal nutrient, a non-renewable resource that needs to be considered in light of its disposal. When discharging treated wastewater to rivers (as is typical of many municipal treatment works), the phosphorus has known environmental consequences that may lead to the deterioration of the water body. When the same wastewater is discharged to land application systems, the phosphorus can become a valuable nutrient, reducing the need for chemical fertilisers.
It is NOT fact that Australian natives do not tolerate wastewater because of the phosphorus in the water. The high pH, the sodicity, salinity, or over-irrigation are likely causes of failure in any horticultural scene. There is good evidence from tree plantations irrigated with municipal effluent that many Australian natives thrive with the nutrients in wastewater. Many golf courses are irrigated with municipal wastewater with few effects from the phosphorus, certainly more from the sodium and salinity issues. I certainly have knowledge of golf courses that irrigate municipal wastewater to Australian natives without detriment.
Additional examination of phosphorus and the relationship between product labelling with "NP" (no added phosphorus) and "P" (meets industry guidelines of less than 7.8 g per wash) are covered in PART B research as Lanfax Labs did not have the original packets to determine this labelling. The manufacturers label their products with the declaration that "the product contains no added phosphorus. Levels up to 0.5% may be present". Interesting, 0.5% is equivalent to 5000 parts per million (5000 mg/kg) - a far cry from nearly nothing!!
Interpretation: The shorter the bar, the lower the mass of phosphorus per wash. Note that the products specifically formulated for front loaders are mostly at the top of Figure 105A. That front loaders are being promoted as "environmentally preferable", that may be a false basis for such an assumption.
It can be seen from Figure 105C that there are a range of detergents with highly variable phosphorus levels. You need to choose the detergent to suit your situation.
Calculation:
| Laundry product's Phosphorus load (from graph 105A or 105B) | 1 grams per wash |
| Number of washes per week | 7 |
| Number of washes per year | 365 |
| Sodium load each year (wash load X number of washes per year) | 1 g x 365 = 365 g = 0.365 kg (1000 g = 1 kg) |
| Area to be irrigation with washing machine water over the whole year | 100 m2 |
| Actual load in kg/ha (phosphorus load divide by area and multiplied by 10000) | 36.5 kg/ha |
| Assessment (if P load greater than 30 kg/ha, need to increase area) | require slightly more than 100 m2 to adequately distribute the load |
If you are using a detergent specifically designed for a front loader with a load of say 5 g/wash, then you will require at least 500 m2 of lawn and garden to reduce the impact on the environment. With that in mind, there are many products on the market that are unsuitable for sustainable use on small urban lots.
Other phosphorus adsorbing action are present in many Australian soils that reduces the impact of phosphorus on the wider environment. This property is termed "phosphorus sorption capacity", but its description is beyond these pages to further explain.
NOTE: The spelling of the element is "phosphorus" and not "phosphorous", the latter term referring to the reduced form of the element. There are numerous examples, even in legal documents and government legislation where phosphorus is spelt incorrectly.