Bacteriophage PRD1 and silica colloid transport and recovery in an iron oxide-coated sand aquifer

Bacteriophage PRD1 and silica colloids were co-injected into sewage-contami nated and uncontaminated zones of an iron oxide-coated sand aquifer on Cape God, MA, and their transport was monitored over distances up to 6 m in thr ee arrays. After deposition, the attached PRD1 and silica colloids were mob ilized by three different chemical perturbations (elevated pH, anionic surf actant, and reductant). PRD1 and silica colloids experienced less attenuati on in the contaminated zone where adsorbed organic: matter and phosphate ma y be hindering attachment of PRD1 and silica colloids to the iron oxide coa tings. The PRD1 collision efficiencies agree well with collision efficienci es predicted by assuming favorable PRD1 deposition on iron oxide coatings f or which the surface area coverage was measured by microprobe analysis of s ediment thin sections. zeta potentials of the PRD1, silica colloids, and aq uifer grains corroborated the transport results, indicating that electrosta tic forces dominated the attachment of PRD1 and silica colloids. Elevated p H was the chemical perturbation most effective at mobilizing the attached P RD1 and silica colloids. Elevated surfactant concentration mobilized the at tached PRD1 and silica colloids more effectively in the contaminated zone t han in the uncontaminated zone.