Resistance of faecal coliforms and enterococci populations in sludge and biosolids to different hygienisation treatments.
The composition of the most abundant facultative anaerobic bacteria populations [faecal coliforms (FC) and enterococci (ENT)] in sludge can be modified after different treatments. These involve the disposal or reuse of sludge and include: anaerobic digesters, incineration, composting, pasteurization and lime treatments. In this study, three treatment types (mesophilic anaerobic digestion, composting and pasteurization) were compared in terms of their ability to reduce both bacterial populations. The diversity and any changes in composition of main phenotypic groups for both populations were also analyzed. Mesophilic anaerobic digestion (MAD) was carried out at 35 degrees C for 20 days. Digested sludge was then dehydrated by centrifugation at 2,500 rpm. Composting (COM) was performed at 55 degrees C with windrow phases. Pasteurization was assayed at 60 degrees C for 90 min (P60), at 80 degrees C for 60 min (P80). A 1-1.5 log unit reduction was observed for FC, and 1 log unit reduction was noted for ENT by MAD treatment. In composting, this reduction proved higher for FC than for ENT (6 log and 3-4 log units, respectively). Optimal pasteurization was obtained at 80 degrees C for 60 min, resulting in a 5 log unit reduction for FC and a 2 log unit reduction for ENT. High diversity indices (Di) for both bacterial populations were detected both before and after implementation of the different treatments. Analyses of the population's similarity provided that FC were diverse both before and after COM, P60 and P80 treatments. However, no differences were observed on the composition of ENT populations after the different treatments assayed.
Bonjoch
X
X
Department of Microbiology, University of Barcelona, Barcelona, Spain. xbonjoch@ub.edu
Blanch
A R
AR
D000693:Anaerobiosis; D019149:Bioreactors; D016000:Cluster Analysis; D015169:Colony Count, Microbial; D004755:Enterobacteriaceae / Q000254:growth & development / Q000502:physiology*; D016983:Enterococcus / Q000254:growth & development / Q000502:physiology*; D005243:Feces / Q000382:microbiology; D006358:Hot Temperature; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000379:methods*
D012722:Sewage
Appl Environ Microbiol. 1999 Oct;65(10):4425-30
10508070
J Microbiol Methods. 2007 Jul;70(1):119-26
17481755
Bioresour Technol. 2003 Jan;86(2):177-81
12653284
Microb Ecol. 1982 Jun;8(1):61-9
24225699
Appl Environ Microbiol. 1991 Nov;57(11):3171-7
1781680
Can J Microbiol. 2006 Apr;52(4):279-86
16699577
Appl Environ Microbiol. 1990 Jun;56(6):1851-7
16348225
J Gen Appl Microbiol. 2005 Dec;51(6):361-8
16474196
Appl Environ Microbiol. 1976 Oct;32(4):537-46
10839
J Appl Microbiol. 1999 Apr;86(4):723-9
10212418
Can J Microbiol. 1998 Oct;44(10):998-1002
9933917
Appl Environ Microbiol. 1992 Feb;58(2):636-41
16348651
Appl Environ Microbiol. 2003 Mar;69(3):1452-6
12620828
J Appl Microbiol. 2003;94(6):994-1002
12752807
J Appl Microbiol. 2002;92(2):210-4
11849347
J Appl Microbiol. 2004;96(2):279-88
14723689
Schriftenr Ver Wasser Boden Lufthyg. 2000;105:337-40
10842835
Appl Environ Microbiol. 1997 Jul;63(7):2708-15
11799982
Water Res. 2004 Mar;38(5):1113-20
14975643
Water Res. 2003 Nov;37(19):4561-72
14568041
J Appl Bacteriol. 1991 Jun;70(6):525-30
1938678
J Appl Bacteriol. 1982 Dec;53(3):331-4
7169386
Appl Environ Microbiol. 1980 Feb;39(2):361-8
16345510
Int J Antimicrob Agents. 2000 May;14(4):337-42
10794956
Water Sci Technol. 2001;44(11-12):223-30
11804099