Removal of Nitrogen and Phosphate from Fertilizer Industry Wastewater by Magnesium Ammonium Phosphate Formation and Electrochemical Treatment

摘要

A pilot-scale MAP (magnesium ammonium phosphate) precipitation system was applied for the removalof high-strength nitrogen compounds from fertilizer industry wastewater. The system was composed ofa biological pre-treatment process for nitrate removal and a physico-chemical MAP precipitation processfor ammonia removal. Although influent nitrogen loading was severely fluctuated, the stable nitrogenremoval could be achieved. For the recovery of magnesium and phosphate from crystallized MAP,ammonia stripping was also conducted. The MAP precipitants could be transformed to MHP(magnesium hydrogen phosphate), and the magnesium and phosphate used for MAP formation wasrecovered to above 90%. Also, most phosphate increasing by the supplement of phosphate andmagnesium for the formation of MAP precipitants could be eliminated rapidly within 3 minutes byelectrocoagulation during the electrolysis procedure.