28 Chemicals from manure Fermentation of manure can produce a number of substances. One promising example is the production of cyanophycin, a polymer that can be used as a basic material for producing paint and nylon (alternative A). Cyanophicin is an interesting material for the chemical industry, since it is high in nitrogen, which is useful for the production of a number of chemicals. A second potential candidate is fumaric acid which can be converted into amber acid, a basic material for producing plastic (Alternative B). In the process, a considerable amount of chitine is produced, which is used in water purification, as a coating for plant seeds or as an absorption material. The production of amber acid is done by different steps, wich are wellknown, but were never combined in a large scale plant. Phosphate as fertilizer substitute Some companies and water treatment operators have a reactor for removing phosphate from waste water flows and converting it into struvite, which is used as manure. Struvite is formed using magnesium oxide (MgO). A useful alternative is magnesium chloride MgCl2, which can be produced with much less energy. MgCl2 can be extracted directly from salt layers in the Veendam region. The watery residual flow contains chloride ions which not every crop can tolerate. This residual flow must therefore be used as a fertilizer only with crops that are tolerant to chloride ions, such as grass. At least half of Dutch agricultural land consists of grass, so the market seems big enough. Struvite production can also be combined in a smart way with co-fermentation of manure and agricultural residual flows. A triple advantage can be achieved by separating acidified manure and heating it to a temperature of 95 °C or even 110 °C. The first benefit is that the phosphate dissolves faster. The second is that (hemi)cellulose is opened up and can thus contribute to the formation of extra biogas. The third advantage is that the manure is hygienized at the high temperature and can possibly be sold as fertilizer. The costs and benefits of each of the options mentioned above are assessed in this report. Especially the benefits are hard to calculate, because the future value of the products from manure, such as the biogas, electricity or chemical substances is still very much uncertain. 103301_Binnen.indd 28 18-05-2010 13:16:16 Pagina 35
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