[Perchlorate removal from underground water by anaerobic biological reduction with bark]

Batch experiments were conducted to check the feasibility of perchlorate removal from underground water with bark as a carbon source and reaction media, the effect of bark dosage, temperature and initial perchlorate concentrations on perchlorate reduction were also investigated. The results indicated that compared to corn cob, sweet potato and potato, bark in combination with perchlorate reducing microorganisms (PRMs) can efficiently achieve perchlorate removal from underground water, the concentrations of dissolved organic carbon (DOC) which was available to PRMs was the limiting factor that affected the perchlorate removal efficiency. Degradation of 10 mg perchlorate needed to consume 35-40 mg DOC when using bark as the solid carbon source. The removal rate of perchlorate was increased by about 3 fold when the bark dosage was increased from 1:500 to 3:500; however, further increase of solid-liquid ratio (over 5:500) provided no further benefit to the perchlorate reduction rate. The rate constant reached 1.365 mg x (L x d)(-1) at (38 +/- 1) degrees C which was the highest in the batch experiments. The activation energy was 31.08 kJ x mol(-1). Anaerobic biological reduction supported by bark had a good impact on the water quality; the high perchlorate concentration did not cause substrate inhibition.