Recycling　nutrients　(nitrogen,　phosphorus,　and　potassium)　from　human　urine　can　potentially　offset　more　than　13%　of　global　agricultural　fertilizer　demand.　Biological　nitrification　is　a　promising　method　for　converting　vol-atile　ammonia　in　high-strength　human　urine　into　stable　ammonium　nitrate　(a　typical　fertilizer),　but　it　is　usually　terminated　in　the　intermediate　production　of　nitrite　due　to　the　inhibition　of　nitrite-oxidizing　bacteria　by　free　nitrous　acid　(FNA).　This　study　aimed　to　develop　a　stable　nitrification　process　in　a　unique　two-stage　bioreactor　by　removing　critical　barriers　associated　with　FNA　inhibition.　Experimental　results　show　that　half　of　the　ammonium　in　high-strength　urine　was　successfully　converted　into　nitrate,　forming　valuable　ammonium　nitrate　(with　a　ni-trogen　concentration　greater　than　1500　mg　N/L).　The　ammonium　nitrate　solution　could　retain　most　phosphorus　(75%　+/-　3%)　and　potassium　(96%　+/-　1%)　in　human　urine,　resulting　in　nearly　full　nutrient　recovery.　Once　concentrated,　the　liquid　compound　fertilizer　of　ammonium　nitrate　was　generated.　Based　on　an　assessment　of　economic　and　environmental　impacts　at　the　urban　scale,　urine　diversion　for　nutrient　recovery　using　a　technical　combination　of　nitrification　and　reverse　osmosis　could　reduce　total　energy　input　by　43%,　greenhouse　gas　emission　by　40%,　and　cost　by　33%　compared　to　conventional　wastewater　management.　Further　research　is　needed　to　optimize　the　two-stage　nitrification　method　on　a　larger　scale.