PHOSPHATE POLLUTION

 Phosphate, along with nitrogen and potsassium, is a vital nutrient for plant growth, and is a common ingredient in fertilisers applied to crops.

Phosphate used to be mined from huge mountains of guano - seabird droppings - but this has been used up, and so it is now obtained from phosphate-bearing rock. It is a finite resource, and will run out in 50-100 years, so it is totally unreasonable to poison our waters with a precious, diminishing resource. Phosphate fertilisers should be used carefully,  to supply plants (and animals) with exactly what they need, and not used on a routine basis.

Phpsphorus is also added to drinking water supplies in low doses, (0.5-2mg/litre) to prevent poisonous  lead dissolving into tap water. This is the source of about 5% of the phosphate in sewage. 

If rain washes phosphates into streams, rivers, lakes and the sea, it can cause overgrowths of algae, called eutrophication, in the water, which can kill other life forms by depriving them of sunlight.

Excellent work has been done by citizen scientists on the Somerset Levels on phosphate pollution that is threatening important Ramsay sites, mainly from sewage outfalls. More information here.

Phosphate can be removed from wastewater by reed beds and by chemical reactions. More here. Wessex Water does remove phosphates at some, but not all, of its sewage treatment plants.

The United Nations Environment Programme calls for a 50% reduction in phospate use, and a 50% increase in phosphate retrieval from wastewater.