Scores:
12
MNiSW
120.9
ICV
 
 

ADAPTATION OF THE ACTIVATED SLUDGE TO THE DIGESTATE LIQUORS DURING THE NITRIFICATION AND DENITRIFICATION PROCESSES

Przemysław Kowal 1  ,  
Xi Lu 2,  
 
1
Faculty of Civil and Environmental Engineering, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233, Gdansk, Poland
2
Institute of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China
J. Ecol. Eng. 2017; 18(5):104–109
Publish date: 2017-09-01
KEYWORDS:
TOPICS:
ABSTRACT:
The activated sludge process of the digestate liquors after chemical separation was conducted using a 10 L lab-scale sequencing batch reactor (SBR) and a 0.50 m3 pilot-scale SBR independently (with pH control). Due to the relatively high concentration of free ammonia (FA), clear inhibitory effects of the digestate liquors on the nitrifying bacteria were observed. The adaptation of the activated sludge to the toxicity was evaluated by the trend of ammonia uptake rate (AUR) and nitrate utilization rate (NUR). The lab-scale AUR values decreased from 5.3 to 2.6 g N/(kg VSS·h) over time after the addition of digestate liquors (5 – 10% of the reactor working volume), indicating an apparent FA inhibition on the nitrification process in the FA concentration range of 0.3 - 0.5 mg N/L. The pilot-scale AUR values increased from 1.8 to 3.6 g N/(kg VSS·h) in the first two weeks and then decreased to 2.4 g N/(kg VSS·h), showing a lag of the inhibition on the nitrifying bacteria at the FA concentration ≈ 0.15 mg N/L. The lab-scale NURs increased from 2.6 to 10.4 g N/(kg VSS·h) over time, and the pilot-scale NURs increased from 1.0 to 4.0 g N/(kg VSS·h) in a similar pattern. The clear dependence of both the lab- and pilot-scale NURs on time indicated the adaptation of the heterotrophic biomass to the digestate liquors. Ethanol instead of fusel oil was found to be a more efficient external carbon source for better adaptation of the activated sludge under unfavorable conditions.
CORRESPONDING AUTHOR:
Joanna Barbara Majtacz   
Faculty of Civil and Environmental Engineering, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233, Gdansk, Poland