52 36 Smit, A.L., Bindraban, P.S., Schroder, J.J., Conijn, J.G., van der Meer, H.G., 2009. Phosphorus in agriculture: global resources, trends and developments. Report 282. Plant Research International, Wageningen. STOWA, 2009. Nieuwe Sanitatie. URL: http://themas. stowa.nl/Themas/Nieuwe_sanitatie.aspx?mID=7213&rID=846. STOWA, 2008. Projectplan Betuwse Kunstmest versie 210808a, pp. 20. URL: http:// themas.stowa.nl/Uploads/ nieuwe%20sanitatie/projecten/ Betuwse%20kunstmest/projectplan%20Betuwse%20 Kunstmest%2021%20 augustus%202008.pdf. Human urine Phosphate recovery from urine requires a modiï¬ed sanitation system to collect urine and faeces separately. Phosphate from urine can then be precipitated by evaporation or after precipitation into struvite. Various initiatives for separate urine collection have been introduced on a local scale (Smit et al., 200936, STOWA, 200937); an overview of the full scale on which this recovery technique is applied in the Netherlands is not available. A new initiative for the large-scale recovery of phosphate from urine was recently presented by the Rivierenland Water Board and GMB Watertechnologie (STOWA, 200838). They have built a pilot plant to recover phosphate using urine from the Organon âWomen for Womenâ initiative, as well as from other sources. The pilot plant will have an annual capacity of over 1 million litres of urine, but the amount of phosphate that can be recovered from it as struvite precipitate is unclear. 37 38 Waste water Phosphate is usually recovered from waste water after precipitation into struvite (MgNH4PO4.6H2O) or calcium phosphate (Ca3(PO4)2) and adding various other chemicals. The struvite process is robust, and only needs limited amounts of MgO. There is currently only one plant in the Netherlands that produces calcium phosphate pellets from sewage inï¬uent (Geestmerambacht sewage works). The phosphate in the pellets is recovered and added to the phosphate rock feed at the Thermphos furnace operation in Vlissingen (Duley, 200139). Phosphate recovery from waste water by struvite precipitation is further only used in some industrial applications, such as a potato processing plant (Lamb/Weston/ Meyer in Kruiningen), a calf manure treatment plant in Putten, and a few bio-mass fermentation installations. No data is available on the amount of phosphate recovered in this way. Klapwijk et al. (2002)40 estimate that 18 ktons P2O5 can be recovered annually by waste water plants. 39 Duley, B., 2001. Recycling Phosphorus by Recovery From Sewage. Rhodia Consumer Specialties UK Ltd for Centre Europeen dâEtudes des Polyphosphates, pp. 17. URL: http://www.nhm.ac.uk/research-curation/research/projects/phosphaterecovery/index.htm. Schipper, W., A. Klapwijk, B. Potjer, W.H. Rulkens, B.G. Temmink, F.D.G. Kiestra & A.C.M. Lijmbach, 2004. Phosphate Recycling in the Phosphorus Industry. Phosphorus Research Bulletin Vol. 15 (2004) p. 47-51. 40 6.4 Opportunities for a more sustainable use of phosphate A more sustainable use of phosphate requires the eï¬cient use of the nutrient and re-use of available phosphate sources. Intensive animal production systems are generally not eï¬cient at phosphate use (Smit et al., 2009). One opportunity to improve the sustainable use of phosphate is to improve nutrient use eï¬ciency in agricultural systems. Re-using phosphate requires adapting the phosphate industry to available secondary sources. A number of recommendations to achieve this transition are presented in the following sections. Pagina 61
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