Further　reducing　the　organic　requirements　is　essential　for　the　sustainable　development　of　partial　denitrification/anammox　technology.　Here,　an　innovative　mixotrophic　partial　denitrification/anammox　(MPD/A)　installation　fed　with　pyrite　and　few　organics　was　realized,　and　the　average　nitrogen　and　phosphorus　removal　rates　were　as　high　as　96.24　+/-　0.11%　and　79.23　+/-　2.06%,　respectively,　with　a　C/N　ratio　of　0.5.　To　understand　the　nature　by　which　MPD/A　achieves　efficient　nitrogen　removal　and　organic　conservation,　the　electron　transfer-dependent　nitrogen　escape　and　energy　metabolism　were　first　elucidated　using　multiomics　analysis.　Apart　from　heterotrophic　denitrification　and　anammox,　the　results　revealed　some　unexpected　metabolic　couplings　of　MPD/A　systems,　in　particular,　putative　nitrate-dependent　organic　and　pyrite　oxidation　among　nominally　heterotrophic　Denitratisoma　(PRO3)　strains,　which　accelerated　nitrate　gasification　with　a　low-carbon　supply.　Additionally,　Candidatus　Brocadia　(AMX)　employed　extracellular　solid-state　electron　acceptors　as　terminal　electron　sinks　for　high-rate　ammonium　removal.　AMX　transported　ammonium　electrons　to　extracellular　gamma　FeO(OH)　(generated　from　pyrite　oxidation)　through　the　transient　storage　of　menaquinoline　pools,　cytoplasmic　migration　via　multiheme　cytochrome(s),　and　OmpA　protein/nanowires-mediated　electron　hopping　on　cell　surfaces.　Further　investigation　observed　that　extracellular　electron　flux　resulted　in　the　transfer　of　more　energy　from　the　increased　oxidation　of　the　electron　donor　to　the　ATP,　supporting　nitrite-independent　ammonium　removal.