Formaldehyde → Tricalcium Phosphate

Participants

Reaction Conditions

Reaction Steps

1000 g of a bacterial activated sludge (solids content approximately 8.5%) emanating from a fully biological purification plant for industrial and communal effluents and consisting of a variety of microorganisms with traces of the following plant protection agents (herbicides) as impurities: N-methyl isopropyl carbamate (0.5 g); 4-amino-6-t-butyl-3-methyl thio-4,5-dihydro-1,2,4-triazin-5-one (0.5 g) and N-(3-benzthiazolyl)-N,N'-dimethyl urea (0.5 g) are initially heated with intensive stirring to 80° C. with 100 g of 30% formalin (1 mol) and 25 g of 85% phosphoric acid in a ground glass flask. The cell walls of the bacteria are thus ruptured and the plant protection agents present are deactivated and hydrolyzed by reaction of the NH2 - or NH-functional groups thereof with formaldehyde through N-methylolation (N--CH2 --O--CH2 --N) or methylene linkage (N--CH2 --N). After this primary reaction, samples are taken and centrifuged. By titrating the formaldehyde in the filtrates, it is analytically determined that 0.05 mol of formaldehyde has been consumed. A solution of 60 g of urea (1 mol) in 100 g of water and 10 g of 30% formalin (0.1 mol) are then added to the reaction mixture. After condensation for 15 minutes at 70° C., the mixture is cooled over a period of 30 minutes to a temperature of 45° C. and a readily filterable, powder-form biomass mixed condensate is obtained. This biomass mixed condensate is neutralized using calcium hydroxide as a result of which substantially insoluble calcium phosphate precipitates in very finely divided form in the biomass condensate dispersion. The powder-form product is filtered off and washed with a 2% aqueous ammonia solution. The product is then dried under reduced pressure at 70° C., giving a substantially odorless powder in a yield of 176 g. The nitrogen content amounts to 13.4%.

Provenance & Evidence