As the most important components of detergents, the content of sodium tripolyphosphate in detergents varies from 10% to 50%. Phosphorus is most likely to cause rapid algal growth, and its excessive content is one of the main causes of eutrophication. There are high concerns that the discharge of large amounts of phosphorous washing water could lead to over-fertilisation of surface water.
Actually, the factors that cause over-fertilization are complex. It is not only related to the concentration of nutrients, algae reproduction is also closely related to other factors such as temperature, light, water flow, algae predators and other factors. Although the amount of phosphate brought into the environment by detergents is large, it is not the only factor that has an impact on the environment, so it is not practical to attribute the source of eutrophication to sodium tripolyphosphate in washing powder.
There are two ways to reduce the amount of phosphorus in the environment, sewage treatment and controlling the source of phosphorus pollution. The data shows that the water quality of some countries where phosphorus is restricted and prohibited is not significantly improved. For example, the washing powder with no phosphorus in Japan accounted for 84% in 1984, and now it is basically phosphorus-free, but the measurement results of phosphorus in the largest water show that it is similar to that before phosphorus ban in the late 1970s. On the contrary, some countries like Netherlands and Sweden that don’t have phosphorus bans, have strengthened environmental protection by adopting tertiary wastewater treatment and maintaining good water quality. Therefore, reducing the amount of phosphorus discharged into the environment can be achieved by reforming the components of detergents, changing agricultural production models, using advanced wastewater treatment technologies such as precipitation to remove phosphorus, and using biological control technologies.
