A passive, gravity-driven treatment system for treatment of a waste stream exiting a diagnostic system, wherein the system comprises: (a) a homogenizing reservoir fluidly connected to the diagnostic system for receiving the waste stream and a radical initiator, wherein the waste stream comprises an oil-phase fluid component and an aqueous fluid component containing at least one target compound, wherein as a result of buoyancy, the oil-phase fluid component rises and floats above the aqueous fluid component when in the homogenizing reservoir so as to form an upper layer of oil effluent and a lower layer of target effluent, wherein the radical initiator is disposed in the target effluent; (b) a radical generating reservoir fluidly connected to the homogenizing reservoir via a channel, wherein the channel is connected to a first outlet of the homogenizing reservoir and to an inlet of the radical generating reservoir, wherein the first outlet is positioned near a base of the homogenizing reservoir, wherein the inlet is positioned at or near a base of the radical generating reservoir, wherein gravity facilitates flow of the target effluent from the homogenizing reservoir to the radical generating reservoir via the channel; (c) a radical generator coupled to the radical generating reservoir, wherein the radical generator is configured to irradiate the target effluent while the target effluent is disposed in the radical generating reservoir, and promote advanced oxidation processes (AOPs) that breakdown said target compound, wherein the radical initiator is effective for accelerating said AOPs when the radical initiator is exposed to the radical generator, thus reducing a detectable concentration of the target compound such that the target effluent becomes a treated effluent; (d) a first disposal unit for receiving the treated effluent exiting from a waste outlet of the radical generating reservoir; and (e) a second disposal unit for receiving the oil effluent exiting from an oil waste outlet of the homogenizing reservoir, wherein the oil waste outlet is positioned above the lower layer of target effluent so as to provide a route for gravity-facilitated drainage of the oil effluent from the homogenizing reservoir. (a) a homogenizing reservoir fluidly connected to the diagnostic system for receiving the waste stream and a radical initiator, wherein the waste stream comprises an oil-phase fluid component and an aqueous fluid component containing at least one target compound, wherein as a result of buoyancy, the oil-phase fluid component rises and floats above the aqueous fluid component when in the homogenizing reservoir so as to form an upper layer of oil effluent and a lower layer of target effluent, wherein the radical initiator is disposed in the target effluent; (b) a radical generating reservoir fluidly connected to the homogenizing reservoir via a channel, wherein the channel is connected to a first outlet of the homogenizing reservoir and to an inlet of the radical generating reservoir, wherein the first outlet is positioned near a base of the homogenizing reservoir, wherein the inlet is positioned at or near a base of the radical generating reservoir, wherein gravity facilitates flow of the target effluent from the homogenizing reservoir to the radical generating reservoir via the channel; (c) a radical generator coupled to the radical generating reservoir, wherein the radical generator is configured to irradiate the target effluent while the target effluent is disposed in the radical generating reservoir, and promote advanced oxidation processes (AOPs) that breakdown said target compound, wherein the radical initiator is effective for accelerating said AOPs when the radical initiator is exposed to the radical generator, thus reducing a detectable concentration of the target compound such that the target effluent becomes a treated effluent; (d) a first disposal unit for receiving the treated effluent exiting from a waste outlet of the radical generating reservoir; and (e) a second disposal unit for receiving the oil effluent exiting from an oil waste outlet of the homogenizing reservoir, wherein the oil waste outlet is positioned above the lower layer of target effluent so as to provide a route for gravity-facilitated drainage of the oil effluent from the homogenizing reservoir.