The Microbiology of Anaerobic Digesters

Preface

Completely mixed anaerobic digesters are the most commonly used treatment

system in North America for the degradation of municipal sludges. Although these

suspended-growth systems are not used as commonly at industrial wastewater treat-

ment plants, more and more industrial plants are using fixed-film anaerobic digesters

for the treatment of soluble organic compounds in their wastewaters.

Anaerobic digesters perform most of the degradation of organic compounds at

wastewater treatment plants. However, digesters often experience operational

problems that result in process upsets and increased operational costs. Examples

of process upsets and operational problems include foam and scum production,

decanting and dewatering difficulties, loss of treatment efficiency, toxic upsets, and

“souring” of the digester. Poorly operating anaerobic digesters often contribute to

operational problems in other treatment units such as the activated sludge process,

gravity thickener, clarifiers, and sludge dewatering facilities.

Because of the importance of anaerobic digesters in wastewater treatment

processes, a review of the microbiology of the bacteria and the operational condi-

tions that affect their activity is of value in addressing successful and cost-effective

operation. This book provides an in-depth review of the bacteria, their activity, and

the operational conditions that affect anaerobic digester performance. The identifi-

cation of operational problems and troubleshooting and corrective measures for

process control are presented.

This book is prepared for an audience of operators and technicians who are

responsible for the daily operation of anaerobic digesters. It presents troubleshoot-

ing and process control measures to reduce operational costs, maintain treatment

efficiency, and prevent system upsets.

The Microbiology of Anaerobic Digestersis the third book in the Wastewater

Microbiology Series by John Wiley & Sons. This series is designed for operators and

technicians, and it presents a microbiological review of the organisms involved in

wastewater treatment processes and provides biological techniques for monitoring

and regulating these processes.

Michael H. Gerardi

Linden, Pennsylvania

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