Phosphate Recovery

The best laundry detergent for a better environment

The availability of affordable and efficient products on the laundry market has greatly contributed to improving human comfort and hygiene. It is important, however, that these benefits are not gained at the expense of the environment.
As is the case with most human activities, even the "perceived greener" ways of washing clothes may have an impact on the receiving environment.
If water protection measures are to be efficient, all the sources of water pollution must be considered instead of detergents of phosphate alone. Countries, such as Sweden, which have truly succeeded in raising the quality of their aquatic environment, are also the countries which have made the necessary investments in waste-water treatment.

Efficient water treatment requires phosphate

In the early seventies, the Nordic countries launched a vast construction programme of sewage-water treatment facilities. These plants included phosphate and nitrogen removal.
These plants have a removal rate of phosphate from sewage on average higher than 90% and several water boards, such as Helsingborg and Stockholm, recommend the use of phosphate-based detergents.
From the technical point of view, three reasons justify this choice:

Phosphate treatment is simple and effective;
Phosphate substitutes increase the amount of useless sludge which has to be disposed of either by incineration of in landfill sites;
The phosphate concentrated in sludge can be recovered for recycling.

Two Life Cycle Analysis studies^1-2 addressed the question of the impact of detergent builders on the environment, throughout their entire life cycle (production, consumption and disposal). Their conclusions are unanimous. When assessed on a cradle-to-grave basis, under all modelled conditions, phosphate builders appear as the best environmental choice.

Wastewater treatment throughout Europe. The EU urban wastewater directive requires that phosphorus from wastewater be reduced by 80% in areas sensitive to eutrophication (Urban Wastewater Directive 21^st May 1991).

The option of phosphorus removal makes economic sense. Expenditure necessary to remove the phosphate present in wastewater in all the sensitive areas of the European Union amount to the equivalent cost of three litres of petrol a year per ihabitant³.

¹The Swedish Phosphate Report, Landbank Environmental & Consulting, 1995.

²The Environmental and Economic Impact of Key Detergent Builder Systems in the European Union, Imperial College of Science, Technology and Medicin, 1994.

³ J.K. Morse, J.N. Lester and R. Perry, The Economic and Environmental Impact of Phosphorus Removal from Wastewater in the European Community, 1993.

Wastewater treatment: phosphate or phosphate-free?

The water authority of Stockholm recently commissioned a study to evaluate the impact of several types of detergents on water treatment and the environment. The results are striking:

With concentration of suspended solids in their effluent on average 10 times higher, phosphate-free powders lead to a substantial increase of sludge.
The use of phosphate based products means lower discharge of organic material, which directly influences the amount of oxygen necessary for its degradation.
Finally, as for ecotoxicity towards micro-organisms, phosphate based products again are presented as the least damaging.

Phosphate resources require efficient water treatment

The need for phosphorus is expected to increase both in agriculture and industry and more than ever, phosphorus removal from wastewater (human sources and cleaning products) will become necessary, not only to prevent nutrient enrichment of rivers, but also to lengthen the availability of a finite resource.
Farmers in several countries spread sewage sludge on their fields as a nutrient source. Techniques are now available which allow the utilisation of phosphates recovered from wastewaters.
The production of detergents containing recycled phosphate is within reach. It will then be not only the most efficient, the least expensive and the most environmentally friendly detergent, it will also be the most sustainable way to wash laundry.

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