Struvite formation

Occasionally, phosphates can form undesirable crystals in foods. The most common example is struvite, a magnesium-ammonium phosphate of the composition Mg(NH4)P04-6H20. Struvite crystals are easily mistaken by consumers for broken pieces of glass. Most reports of struvite formation have been related to canned seafood, but occasionally the presence of struvite in other foods has been reported. It is assumed that in canned seafood, the struvite is formed from the magnesium of sea water and ammo-... 

PHOSPHORUS REMOVAL FROM WASTEWATER AND STRUVITE FORMATION... 

When using magnesium as a sacrificial electrode, phosphate can be precipitated as struvite [31]. Stmvite is a preferred product over iron or aluminum phosphates, because it is a better phosphate fertilizer [32]. Without base addition, the process can only be applied to stored urine, because a high pH value is required for struvite formation. 

Formation of mortars and ceramics using ammonium drhydrogen phosphate has been studied by several investigators (Kato et al. [28], Takeda et al [29], Abdelrazig and Sharp [17], Popovics et al [21], Abdelrazig et al. [19], and El-Jazairi [20]). As shown in Table 9.1, the main products of reaction of calcined MgO with ammonium drhydrogen phosphate are struvite and schertelite. In the presence of sufficient water, the latter converts to struvite by the reaction... 

Often formed in addition to these two phases are dittmarite (MgNH4P04-H20) and stercorite (MgNH4P04-4H20), which differ in composition from stmvite in the amount of hydration. Formation of struvite from these phases will depend on the amount of water that is available for the complete reaction [17-19]. 

Struvite stones (also called triple phosphate or infection stones) are composed of magnesium ammonium phosphate hexahydrate. The formation of such stones requires urinary tract infection with urea splitting organisms and such stones are therefore more common in females and in certain patient populations (e.g, paraplegics), The risk of progression to CKD appears higher in patients who develop infection stones than in other forms of stone disease. 

If there is sufficient water present, then the reaction can go to completion with the subsequent formation of struvite ... 

Only phosphate mineral formation will be considered here. Sulfide equilibria are discussed in detail in Part II and calcium-carbonate saturation states will be considered in another paper (or see Aller, 1977). NH4" is unlikely to be involved in the formation of specific insoluble phases such as struvite (MgNH4P04 6H2O), given the measured concentrations of the ions involved (Martens et al., 1978). The major interactions of with sedimentary particles include reversible and irreversible adsorption reactions (Nommik, 1%5 Mortland and Wolcott, 1%5 Muller, 1977 Rosenfeld, 1979). 

The formation of nucleotides from nucleosides was more successful. Heating uridine in the presence of NH4H2PO4 with an excess of urea yields uridine nucleotides that have phosphate groups at the 2 , 3 or 5 -positions of nucleosides together with lower yields of products that have two or more attached phosphate group 19). When the mineral struvite (MgNH4P04H20) is used in place of NH4H2PO4 in the synthesis a 25% yield of the 5 -pyrophosphate of uridine is obtained. 20)... 

Rat Studies. The computer calculations were tested by inducing the experimental formation of brushite/struvite bladder stones in rats. The inhibition of stone formation by the feeding of 5000... 

Approximately 10% of the human population (with regional differences indicating both genetic and environmental factors [33]) is affected by the formation of stones or calculi in the urinary tract. Urolithiasis is not only a painful condition, but also causes annual costs to the health system in the order of billions of dollars in the USA alone [34, 35]. Based on their composition, structure and location in the urinary tract, renal stones have been classified into 11 groups and their formation mechanisms have been discussed together with alterations in urinary parameters and metabolic risk factors for renal lithiasis [35]. Approximately 70% of these stones contain calcium oxalate monohydrate (COM) and dihydrate as major components, while other calculi are composed of ammonium magnesium phosphate (struvite), calcium phosphates (hydroxyapatite and brushite), uric acid and urates, cystine and xanthine. An accurate knowledge of the solubilities of these substances is necessary to understand the cause of renal or bladder calculi formation and find ways towards its prevention and treatment [36]. 

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