Abstract
This research demonstrates the feasibility and advantages of a 2-step process for the biological treatment of sulfidic spent caustics under halo-alkaline conditions (i.e. pH 9.5; Na+ = 0.8 M). Experiments with synthetically prepared solutions were performed in a continuously fed system consisting of two gas-lift reactors in series operated at aerobic conditions at 35 °C. The detoxification of sulfide to thiosulfate in the first step allowed the successful biological treatment of total-S loading rates up to 33 mmol L-1 day-1. In the second, biological step, the remaining sulfide and thiosulfate was completely converted to sulfate by haloalkaliphilic sulfide oxidizing bacteria. Mathematical modeling of the 2-step process shows that under the prevailing conditions an optimal reactor configuration consists of 40% ‘abiotic’ and 60% ‘biological’ volume, whilst the total reactor volume is 22% smaller than for the 1-step process.
Original language | English |
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Pages (from-to) | 723-730 |
Journal | Water Research |
Volume | 46 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2012 |
Keywords
- sulfur-oxidizing bacteria
- oxidation processes
- alkaline conditions
- hydrogen-sulfide
- soda lakes
- kinetics