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REP-PCR在活性污泥膨胀检测中的应用

Polish Journal of Microbiology 2010, Vol. 59, No1, 11 20

ORIGINAL PAPER

Introduction

Activated sludge process is one of the most popu-lar methods of wastewater treatment. It is commonly used world-wide to neutralize industrial, municipal and domestic wastewater. In this method, wastewater treatment plants (WWTP s), beside mechanical steps of treatment, also utilize microorganisms for the puri-fication of wastewaters. Microorganisms observed in activated sludge belong to different taxonomy group, the major group being the Eubacteria. Bacteria are responsible for removing organic substances which are present in wastewater. Complex organic com-pounds are decomposed into simple one as a result of complicated metabolic processes. However, beside Eubacteria, other microorganisms also occur in acti-vated sludge: filamentous organisms fungi, actino-mycetes; protozoa: ciliate, flagellate, heliozoan and metazoan: rotifer, nematodes. All of these micro-organisms create a specific community in which each group plays an important role in the entire activated sludge process. The quantitative participation of indi-vidual microorganism groups changes seasonally and depends on temperature, pH or waste composition (Mehandjiyska, 1995;Lacko et al., 1999).

Filamentous structure and capability of production of an extracellular polymeric substance (EPS) by most microorganisms is responsible for the creation of activated sludge flocks. The structure of these flocks determines the efficiency of wastewater treatment in the activated sludge process. Loose structures of flocks decreases settleability which is their most restrictive attribute. Poor settlement has a negative effect on the critical stage of the process sedimentation and separation of microbial biomass from effluent stream. This observed unwanted effect is called bulking of activated sludge.

The most widely cited possible reasons of bulking process are: excessive growth of filamentous bacte-ria, (continuous competition between filaments and

Repetitive Extragenic Palindromic PCR (REP-PCR) as an Alternative Method

for Detection of Bulking in Activated Sludge

DAGNA A. SO£TYSIK, ILONA A. BEDNAREK*, TOMASZ M. LOCH, SABINA E. GA£KA,

DANIEL J. SYPNIEWSKI, GRZEGORZ M. MACHNIK, DARIA K. B£ASZCZYK Department of Biotechnology and Genetic Engineering, Medical University of Silesia, Sosnowiec, Poland Received 30 June 2009, revised 20 January 2010, accepted 25 January 2010

A b s t r a c t

Bulking of activated sludge is a world-wide problem which negatively affects wastewater treatment efficiency. The most common reasons of bulking are bacterial community changes, especially excessive growth of filamentous bacteria (filamentous bulking) or excess of biopolymers on the surface of non-filamentous microbes (non-filamentous or Zoogleal bulking). Because of the complex nature of the bulking phenomenon finding a successful bulking control strategy remains a very important issue that awaits new options and advices. The REP-PCR fingerprinting method has been applied to distinguish a bacterial community in non-bulking and bulking activated sludge. The characteristic REP-PCR fingerprinting patterns were compared with each other in terms of the presence or absence of bands and in terms of measured integrated optical density (IOD) of the bands. The obtained fingerprinting patterns, using Ward s clustering method, have been analyzed to determine homology/similarity relations between specific non-bulking and bulking sludge sampling. The received clustering results were in high concordance with activated sludge typing which generally is done based on physicochemical sludge analysis. The proposed REP-PCR method and statistical analysis of fingerprinting patterns seems to be a simple, rapid and effective method revealing differences between populations in non-bulking and bulking activated sludge. It may be useful for routine activated sludge monitoring and may be helpful in the early detection of the bulking process.

K e y w o r d s:activated sludge bulking, REP-PCR fingerprinting, Ward s clustering

* Corresponding author: I. Bednarek, Department of Biotechnology and Genetic Engineering, Medical University of Silesia, Narcyzów 1 Street, 41-200 Sosnowiec, Poland; phone: (+48) 32 3641040; e-mail: dribednarek@http://www.wendangku.net/doc/f19b33c5aa00b52acfc7ca52.html.pl