Figure 5. (a) Nitrate degradation kinetics with Fe0 filings, or a mixture of Fe0 filings with Wards peat and/or an Azoarcus tolulyticus Tol-4 denitrifying bacterium. Initial NO3- concentration was 6,000 mg/L in these laboratory studies, and controls were added with Wards peat or Tol-4 bacterium only (without addition of Fe0 filings). (b) Identification of NO3- degradation byproducts with Fe0 filings and Wards peat.