In the present study, it is described that the removal of aqueous ammonium in wastewater released from the steel industry and thermal power plant is possible in using powder MgHPO 4 while the removal nature depends on the solution pH and various contaminant in the wastewater. The removal rate of aqueous ammonium increased with increase of an initial solution pH. Although apparent removal rate increased upon adding phenol that was contained in wastewater from steel industry, it was found that an addition of an excess amount of NaOH into the solution but not phenol directly contributed to the increase of the removal rate. The removal amount decreased upon adding SO 4 2and Ca 2+ that were in wastewater from the thermal power plant.

The recovery of aqueous phosphate from a model solution consisting of NH 4 + , NO 2 and NO 3-, which are contained in a surplus that phosphate in rivers in Tokushima Prefecture, Japan, using boehmite together with the elution behaviors of phosphate from dephosphorization slag using various eluates were examined. The recovery of aqueous phosphate using boehmite was not influenced by the coexistence of those nitrogen-containing contaminants under various pH conditions. For the elution behaviors of phosphate from dephosphorization slag, it was found that aqueous HNO 3 among various acidic and basic solutions was a suitable solution as an eluate. Present study suggests that the employment of the unused resources such as aqueous phosphate in rivers and phosphate in the dephosphorization slag can be used as a possible candidate as a new raw material for rare phosphate.

Aqueous ammonium is a threat to the vitality of various fish and the present study examined the feasibility of its removal from both seawater and freshwater using magnesium hydrogen phosphate (MgHPO 4 ). Regardless of the type of water, aqueous ammonium was favorably removed particularly under basic conditions such as a pH = 10. Even under neutral conditions (pH = 7), some aqueous ammonium can be removed. The results of the present study showed that MgHPO 4 can be used to remove a serious threat to the vitality of fish posed by the dilute concentration of aqueous ammonium in both seawater and freshwater. The resultant formation of magnesium ammonium phosphate (MAP) was detected by X-ray diffraction (XRD), which confirmed the removal of aqueous ammonium. It is common knowledge that MAP is a fertilizer for waterweeds, which are essential for the growth of the fish while simultaneously promoting their nourishment.