Abstract
Photographic processing wastewater was continuously treated with an aerobic fixed-bed reactor filled with the granular activated carbon on which microorganisms were fixed, with 24 hours of hydraulic retention time. The pH values of all the effuluents began to decrease abruptly after the experiment was started, and 7 of the initial pH value went down to about 3 in 7days finally. The conversion of thiosulfate to sulfate by sulfer bacterium was attributed to the decrease of pH. The COD removal ratio decreased with increase of the COD load, i.e., when the loads were 1.7, 3.5, 4.9 and 13g·kg-1 GAC·d-1, the removal ratios were 75, 59, 55 and 45% respectively.
Two-stage system with the aerobic fixed-bed reactor above-mentioned was applied to the waste water treatment. On the basis of the material balance of COD and sulfate in the reactor, it was estimated that 63% of the removed COD was attributed to the oxidation of thiosulfate to sulfate in the first stage. On the other hand, the formation of sulfate was little detected in the effuluent of the second stage. The application of the system to the wastewater treatment led to such high removal efficiency that the removal ratios of COD and BOD were 83 and 99%, respectively.
The short period acclimation and high removal efficiency were found in the reactor filled with the granular activated carbon in comparison with that of the porous ceramics.
