Manusanun Deddoung. Microbial Population Dynamic in Anaerobic Hybrid Reactor at Different Conditions of Start-Up Period. Master's Degree(Biotechnology). King Mongkut's University of Technology Thonburi. KMUTT Library.. : King Mongkut's University of Technology Thonburi, 2553-01-15.
Microbial Population Dynamic in Anaerobic Hybrid Reactor at Different Conditions of Start-Up Period
Abstract:
The research focused on the effect of upflow feeding velocity and substrate
concentration on the biofilm acceleration at the initial stage of start-up period of
anaerobic hybrid reactor (AHR). The optimization of upflow feeding velocity and
substrate concentration will enhance the microbial attachment on nylon fiber and the
substrate transfer for microbial growth and metabolism. So, the biofilm could be grown
and developed rapidly which shorten start-up period of AHR and retained
. microorganism inside the reactor. Four AHRs was operated by classification into two
stages of the start-up period namely "initial stage of start-up period" and "operating
stage of start-up period".
The initial start-up stage of four AHRs were run at four different conditions of upflow
feeding velocity and substrate (glucose) concentration for 20 days. Glucose
concentration and upflow feeding velocity were assigned for four reactors namely RI
(0.25 rn/h and 500 mg/l), R2 (0.05 mlh and 2,500 mg/l), R3 (0.25 m/h and 1,000 mg/l)
and R4 (0.10 m/h and 2,500 mg/l), respectively. By comparing the obtained data into
three aspects in term of substrate concentration effect, upflow feeding velocity effect
and organic loading rate (OLR) effect, it was concluded that R2 shows the higher
biofilm quality in term of microbial activities and ratio of methanogens to nonmethanogens
than the other reactors, even though microbial quantity was in the second
level by less than R3 during 20 first day of start-up period. In R2, the microbial
quantity, ratio of methanogens to non-methanogens, and microbial activities of
methanogens and methanogens were 3.52 mg VSS/m2 , 50:42, and 0.26 and 12.25 g
COD/g VSS-d, respectively.
The second stage of increasing step of OLR was run four AHRs continually from the
initial stage by increasing OLR consequently from 1 kg COD/m3-d until the system
failed. This part was aimed to further investigate the capacity of AHR for wastewater
loading and reactor performance and stability after the initial stage of start-up at four
different conditions of upflow feeding velocity and substrate concentration applied to
R1, R2, R3, and R4. The results indicated that R2 shows the better performance in term
of COD reduction efficiency and methane content than the others. The stability of R2
kept in pH ~ 7 and ratio of total volatile acid to alkalinity (TVAIAlk) ~ 0.76 at OLR 3
kg COD/m3-d.
These results suggested that upflow feeding velocity and substrate concentration
affected on microbial quantity and quality during the initial stage of start-up period. The
lower upflow feeding velocity with high concentration of feeding substrate will obtain
the good specification of biofilm in term of high ratio in quantity of methanogens to
non-methanogens and high microbial activities of methanogens and non-methanogens
which shorten period of start-up and maintained long term operation with high
performance and stability.