Field suspension of ZVI powder in TASK™ Sweep Efficiency Agent The chemistry used allows shear-thinning properties that improve its capability to be adequately distributed in the subsurface. Tersus also provides an “activation” step after injection. When injecting ZVI in a biodegradeable polymer suspension, the ZVI reactions will not occur until the polymer degrades. We can supply an enzyme breaker designed for fluids having a pH of 6.0 or higher. The enzyme breaker is added to the chase water following the injection of the ZVI suspension.