[Treatment of pectin wastewater by anaerobic biological process]

Anaerobic biological process was used to treat pectin wastewater with acclimated sludge. The effects of the influent pectin concentration and the degradation temperature were investigated, and the intermediate products in pectin degradation were measured. Compared with the unacclimated sludge, the results showed that using acclimated sludge, the pectin removal efficiency was increased by 59.2%. The degradation rate of pectin at influent concentrations of 100, 2500 and 4500 mg x L(-1) were 4.5, 49.8 and 74.0 mg x (L x h)(-1), respectively, indicating that the degradation rate increased with the increase of the influent pectin concentration. The COD removal efficiency was relatively low (41.6% -82.0%) when the influent pectin concentration was lower than 500 mg x L(-1), but it could maintain above 91% when the influent pectin concentration was beyond 1000 mg x L(-1). The higher the temperature was, the shorter the time was needed for pectin degradation. The COD removal efficiency of anaerobic sludge for pectin wastewater was increased from 38.6% to 91.5% when the temperature ranged from 5 degrees C to 35 degrees C, but it was gradually weakened when the temperature exceeded 35 degrees C. The main intermediate products in pectin degradation were supposed to be acetic acid, propionic acid, lower ester, and alkyl alcohols (C12-C40).