Microalgal-bacterial　system　(MBS)　is　potential　biotechnology　in　wastewater　treatment　because　it　can　remedy　defects　of　conventional　processes　(e.g.,　insufficient　carbon　source　and　imbalanced　elements　ratio).　However,　the　mechanisms　of　nitrogen　(N)　transport　and　removal　in　MBS　are　still　unclear.　In　this　study,　it　was　discovered　that　MBS　was　conducive　to　adsorb　NH4+-N　and　NO3–-N　through　electrical　neutralization,　while　extracellular　polymeric　substances　(EPS)　could　provide　binding　sites　(e.g.,　–OH　and　–CH3)　for　enhancing　N　transport　and　removal.　The　microalgae-bacteria　interaction　could　accelerate　N　transport　and　removal　from　aqueous　solution　to　cell.　More　importantly,　the　microalgal　starch　biosynthetic　metabolism　exhibited　demonstrating　the　energy　production　potential　could　be　boosted　via　MBS.　Overall,　the　NO3–-N　and　NH4+-N　removal　efficiencies,　and　energy　yield　were　82.28%,　94.15%,　and　86.81　kJ/L,　respectively,　which　are　better　than　other　relevant　studies.　Altogether,　it　is　meaningful　for　revealing　the　applicability　of　MBS　for　treating　wastewater　and　producing　energy.　©　2022