SOLID OXYGEN SOURCE FOR BIOREMEDIATION IN SUBSURFACE SOILS

Sodium percarbonate was encapsulated in poly(vinylidene chloride) to d etermine its potential as a slow-release oxygen source for biodegradat ion of contaminants in subsurface soils. In laboratory studies under a queous conditions, the encapsulated sodium percarbonate was estimated to release oxygen over about a two-month period. Microbial survival in the presence of encapsulated sodium percarbonate was markedly increas ed compared to the unencapsulated compound. In laboratory studies, the encapsulated sodium percarbonate was used to provide oxygen as an ele ctron acceptor for microorganisms during the biodegradation of propyle ne glycol. In 30 days at 12-degrees-C (similar to subsurface soil temp eratures), the concentration of propylene glycol was reduced tenfold a nd the number of propylene glycol degrading organisms increased tenfol d compared to live controls without the encapsulated sodium percarbona te. Killed controls did not show significantly reduced concentrations of propylene glycol compared to the live controls. Acidic soil conditi ons (pH 4.7) were neutralized to a pH of about 8.3 by the encapsulated sodium percarbonate.