Microbial Communities and Their Performances in Anaerobic Hybrid Sludge Bed-Fixed Film Reactor for Treatment of Palm Oil Mill Effluent under Various Organic Pollutant Concentrations

Table 4

Microbial populations and activities in startup seed, sludge, and packed zones of AHR under various operating conditions.

	EUB		ARC
Condition/zone	Population	Activity	Population	Activity
	(Copies rDNA/g VSS)	(g COD/g VSS day)	(Copies rDNA/g VSS)	(g COD-CH4/g VSS day)
Startup seed	1.2 × 10^7	1.00	8.2 × 10^4	0.12
Sludge zone
C1	3.5 × 10^8a	1.08^a	1.1 × 10^5a	0.10^a
C2	4.4 × 10^8b	1.58^b	4.8 × 10^5b	0.11^b
C3	6.4 × 10^9c	1.65^c	7.5 × 10^5c	0.14^c
Packed zone
C1	9.0 × 10^7a	0.43^a	3.3 × 10^5a	0.18^a
C2	4.3 × 10^8b	0.74^b	8.4 × 10^5b	0.25^b
C3	8.6 × 10^8c	0.91^c	9.1 × 10^7c	0.34^c

Values are the averages of three determinations taken at the end of operating conditions.
Averages followed by the different letter in the same column among operating condition C1–C3 are statically different at 95% level by the paired 𝑡-test.