KIEFHABER, P. (2010): Sustainable Water and Waste-Water Management: Energy- and Material-Flow-Management - Quo vadis?. The Example 'Phosphorus-Recycling'. Kaiserslauten: Dr. Kiefhaber + zebe ingenieur consult gmbh. PDF
By taking the example of phosphorus, this essays shows that besides encompassing elaborate treatments to produce high quality water discharges to recipient bodies, the various substances brought into the water by human activities might also be extraordinarily valuable.