Systems for microorganism sustenance in an activated sludge unit

A system for maintaining a living culture of activated sludge in a refinery activated sludge unit during an extended refinery maintenance shut down, comprising

• a refinery activated sludge unit that comprises:
• i) an aeration chamber configured to receive refinery wastewater via at least one inlet and further configured to facilitate mixing of the refinery wastewater with a living culture of activated sludge to produce treated wastewater comprising lower levels of at least one of ammonia, amines, and organic carbon, wherein the living culture of activated sludge comprises aerobic prokaryotes, aerobic eukaryotes, or mixtures thereof configured to nitrify ammonia to form nitrites and nitrates;
• ii) a clarifier to receive treated wastewater from the aeration chamber and facilitate settling of the living culture to produce clarified wastewater, and an outlet for further to allow the clarified wastewater to leave the clarifier;
• iii) a conduit operably connected to the clarifier outlet to receive at least a portion of the clarified wastewater, wherein the conduit comprises at least one valve operable to redirect the clarified wastewater into the aeration chamber, wherein the conduit is configured to receive an organic food source at a point that is upstream from the aeration chamber, wherein the organic food source comprises acetic acid at a concentration from about 5 mM to about 20 mM, phosphate ion at a concentration from about 500 uM to about 1 mM, ammonium ion at a concentration from about 1 mM to about 2 mM and sodium hydroxide at a concentration sufficient to maintain the pH of the clarified wastewater between 7 and 8.5.