The present invention discloses a crystalline aluminum phosphite, preparation and an application thereof. The compound has the following structural formula (I):

##STR00001##

where, x is an integer of 1-6; n, y and p are an integer of 1-4; M is Ca, Mg, Al, Zn, Fe, Sn or Ti. The preparation method includes: after dissolving phosphorous acid and hydrogen phosphite into water, adding concentrated phosphoric acid for reaction at 80-90° C., then performing drying at low temperature, dehydration reaction at high temperature, washing and drying. The compound has very high thermal decomposition temperature, high phosphorus content, and good flame retardant property, low water absorption and low acidity; moreover, the compound can serve as a halogen-free flame retardant component of high polymer materials.

Provided are wastewater treatment processes that involves struvite precipitation and a microbial fuel cell for the recovery of nutrients and energy from a digester effluent.

An equilibrium solution, such as a beverage product, containing a calcium salt of a sequestrant (such as calcium hexametaphosphate), coordinated compound of a calcium sequestrant and a sequestrant allows the delivery of bio-available calcium while maintaining the preservative qualities of the sequestrant (such as sodium hexametaphosphate). In one embodiment, the reaction of a salt such as calcium hydroxide and a sequestrant such as sodium potassium hexametaphosphate (sodium potassium polyphosphate) yields such an equilibrium solution in a beverage matrix. Calcium hexametaphosphate having a relatively short phosphate chain is disclosed, as well as the method of making that material, and beverage compositions containing the material together with a sequestrant preservative, such as SHMP.