1996 Volume 58 Issue 1 Pages 87-93
Using two kinds of methane fermentors controlled in the contact and conventional processes, the washed rice wastewater was experimentally treated. The contact process with a sludge return operation was able to maintain the microbe concentration from 7.6 to 14.8g-VSS/L which was approximately 5 to 10 times of the conventional process. The COD removal ratios were ranged from 95 to 98% for the both processes, and the digested gas yield was 0.37-0.39ml/mg-COD for the contact ml/mg-COD process and 0.36-0.45mlmg-COD for the conventional process. The values of νmax and Ks as apparent kinetic parameters for the processes were 0.27mg/mg·d and 177mg-COD/L for the contact process and 0.69mg/mg·d and -56mg-COD/L for the conventional process. These results showed that, by the contact process, the washed rice wastewater of 6000-15000mg-COD/L can be treated in 1.5-3.8 days, due to its higher concentration of microbes which had low activity to consume the substrate.
