Photocatalytic reduction of oxo-anions

A method of removing oxo-anion from oxo-anion-contaminated water, the method comprising:

• providing a water treatment system comprising:
• a flow regulation control system configured to combine oxo-anion-contaminated water with at least one of a reduction-promoting agent and a hole scavenger;
• a reactor fluidically coupled to the flow regulation control system, the reactor comprising a photocatalyst;
• a first set of system control probes positioned upstream of the flow regulation control system and configured to monitor the concentration of oxygen and oxo-anion reduction products in the oxo-anion-contaminated water;
• a second set of system control probes positioned downstream of the reactor and configured to monitor concentration of the oxo-anion and oxo-anion reduction products in treated effluent from the reactor;
• and
• a controller configured to control the flow regulation control system, thereby controlling the flow rate of the oxo-anion-contaminated water and the at least one reduction-promoting agent and the hole scavenger to the reactor based at least in part on the concentration of oxo-anion and reduction products of the oxo-anion in the treated effluent from the reactor;
• flowing the oxo-anion contaminated water and at least one of the reduction-promoting agent and the hole scavenger in the water treatment system to yield a mixture;
• providing the mixture to the reactor;
• and
• photocatalytically reducing the oxo-anion in the mixture within the reactor to yield the treated effluent, wherein the flow rate of the oxo-anion-contaminated water and at least one of the reduction promoting agent and the hole scavenger is automatically controlled by the controller based at least in part on the concentration of oxo-anion and reduction products of the oxo-anion in the treated effluent.