The traditional biological wastewater treatment process faces issues of inefficiency and high greenhouse gas emissions. This study firstly established a symbiotic system between Tribonema sp. and Pseudomonas sp. (an aerobic denitrifying phosphorus accumulation bacteria). Results showed that co-culture systems significantly increased the removal rates of nutrients from wastewater and the biomass and lipid content of both microorganisms. The optimal inoculation ratio was 25:1, resulting in the removal rates of PO₄^3--P, NH₄⁺-N, NO₃^--N, TN and TOC increased by up to 31.47%, 133.12%, 39.84%, 206.54%, 31.92%, and an increase of 6.72% and 80.11% in the biomass of Tribonema sp. and Pseudomonas sp., respectively, compared to single cultures. CO₂ release from respiration exceeded CO₂ fixation by microalgae. The CH₄ concentration in co-culture systems was lower than that in single cultures, with low levels of N₂O detected. This symbiotic system effectively transforms wastewater nutrients into biomass resources while minimizing greenhouse gas emission.