A photoelectrochemical cell for wastewater treatment comprising: at least one cathode and at least one anode, wherein the anode comprises a material configured for an anodic oxidation reaction in the presence of the wastewater, wherein at least one of the anode and cathode comprises an optically pervious material; a chamber having a base portion and a wall portion extending from the base portion, and an inlet and an outlet at the wall portion of the chamber, wherein the inlet and the outlet are in fluid communication with the chamber and are disposed at opposing ends of the chamber, where the base portion of the chamber comprises openings, the openings arranged in order of increasing cross-sectional area with increasing distance from the inlet to the outlet, and where the chamber is open at the top with an opening defined by the wall portion, which opening is arranged opposing to the base portion; and an aerator configured to provide oxygen gas to the photoelectrochemical cell, wherein . the anode and the cathode are disposed in the chamber; the cathode is configured for cooperating with the anode to drive one or more cathodic reduction reactions in the presence of the wastewater; the anode and the cathode are disposed to allow irradiation of at least a portion of a space between the anode and the cathode by a light source through the optically pervious material to activate at least one photon based reaction in the wastewater; and the aerator is in fluid communication with the openings at the base portion of the chamber at least one cathode and at least one anode, wherein the anode comprises a material configured for an anodic oxidation reaction in the presence of the wastewater, wherein at least one of the anode and cathode comprises an optically pervious material; a chamber having a base portion and a wall portion extending from the base portion, and an inlet and an outlet at the wall portion of the chamber, wherein the inlet and the outlet are in fluid communication with the chamber and are disposed at opposing ends of the chamber, where the base portion of the chamber comprises openings, the openings arranged in order of increasing cross-sectional area with increasing distance from the inlet to the outlet, and where the chamber is open at the top with an opening defined by the wall portion, which opening is arranged opposing to the base portion; and an aerator configured to provide oxygen gas to the photoelectrochemical cell, wherein . the anode and the cathode are disposed in the chamber; the cathode is configured for cooperating with the anode to drive one or more cathodic reduction reactions in the presence of the wastewater; the anode and the cathode are disposed to allow irradiation of at least a portion of a space between the anode and the cathode by a light source through the optically pervious material to activate at least one photon based reaction in the wastewater; and the aerator is in fluid communication with the openings at the base portion of the chamber the anode and the cathode are disposed in the chamber; the cathode is configured for cooperating with the anode to drive one or more cathodic reduction reactions in the presence of the wastewater; the anode and the cathode are disposed to allow irradiation of at least a portion of a space between the anode and the cathode by a light source through the optically pervious material to activate at least one photon based reaction in the wastewater; and the aerator is in fluid communication with the openings at the base portion of the chamber <EOS>