A dispersion lance is for use in combination with a fluid treatment system of the type which includes a flow duct in which a fluid stream is mixed with a treating agent. The dispersion lance includes a pipe mounted in the duct with its axis approximately transverse to the direction of the fluid stream flow, the pipe having a series of openings along its length for injecting a treating agent into the fluid stream. A baffle extends lengthwise along the pipe, the baffle having a cross-section the central portion of which is V-shaped, with the apex of the V facing upstream of the fluid stream flow, and with generally flattened wing portions extending from the legs of the V beyond the sides of the pipe in a direction where they transversely intersect the stream flow. The baffle acts to generate a low pressure zone on its downstream side which enhances turbulence in the fluid. The orifices of the pipe are located to inject the treating agent into the low pressure zone to better distribute and intermix the injected treating agent into the surrounding fluid.