WWTP Design and Operation Modifications to Improve Management of Biosolids Regrowth, Odors, and Sudden Increase in Indicator Organisms
Published on 15. March 2016
150 pages
978-1-78040-457-8 (ISBN)
Description
Available as eBook only
The overall goal of this project was develop approaches to manage the issues of regrowth, odors, and sudden increase (ROSI) of indicator and pathogenic bacteria in biosolids.
The project entailed two phases. The first phase was focused on filling critical research gaps that provided the fundamental insights for developing solutions to these issues which includes method development. The second phase focused on developing and implementing solutions in the field.
The hypothesis that sudden increase is a result of incomplete inactivation of indicators was supported by the results from this work. The results suggest that Method 1680 underestimates the viable density of indicators in samples after thermal treatment. In addition, that results showed that to achieve complete inactivation of indicators, a slightly higher time-temperature regime will be needed and this new "best practices" time-temperature curve has been developed as part of the work. It should be emphasized that the current EPA time-temperature requirements appear to be sufficient for Salmonella, the bacterial pathogen used in the regulations. Several processes that utilize temperature about 75 degreesC were able to eliminate SI. Gas chromatography-olfactometry was used to identify the persistent/long term odorants in centrifuged biosolids. The main persistent odorants contributing to cake odors were indole, skatole, p-cresol, and butyric acid. Interestingly, all of these compounds are breakdown products of organics such as proteins, carbohydrates and fats, suggesting that processes which eliminate these precursors will help reduce odors in biosolids. Odor panel results showed that the level of odors measured after longer term storage, was correlated to the shorter term TVOSC concentrations. Mechanistically this was expected since the short term TVOSCs and longer term odorants are produced by similar pathways.
Several amendments added to centrifuge cake were able to significantly reduce odors and/or regrowth. The incubation of anaerobically digested biosolids with protein degrading enzymes resulted in additional gas production as well as a reduction in odors after dewatering. Also, better digestion was associated with lower odors, and primary sludges produced greater odors compared to secondary sludges.
The overall goal of this project was develop approaches to manage the issues of regrowth, odors, and sudden increase (ROSI) of indicator and pathogenic bacteria in biosolids.
The project entailed two phases. The first phase was focused on filling critical research gaps that provided the fundamental insights for developing solutions to these issues which includes method development. The second phase focused on developing and implementing solutions in the field.
The hypothesis that sudden increase is a result of incomplete inactivation of indicators was supported by the results from this work. The results suggest that Method 1680 underestimates the viable density of indicators in samples after thermal treatment. In addition, that results showed that to achieve complete inactivation of indicators, a slightly higher time-temperature regime will be needed and this new "best practices" time-temperature curve has been developed as part of the work. It should be emphasized that the current EPA time-temperature requirements appear to be sufficient for Salmonella, the bacterial pathogen used in the regulations. Several processes that utilize temperature about 75 degreesC were able to eliminate SI. Gas chromatography-olfactometry was used to identify the persistent/long term odorants in centrifuged biosolids. The main persistent odorants contributing to cake odors were indole, skatole, p-cresol, and butyric acid. Interestingly, all of these compounds are breakdown products of organics such as proteins, carbohydrates and fats, suggesting that processes which eliminate these precursors will help reduce odors in biosolids. Odor panel results showed that the level of odors measured after longer term storage, was correlated to the shorter term TVOSC concentrations. Mechanistically this was expected since the short term TVOSCs and longer term odorants are produced by similar pathways.
Several amendments added to centrifuge cake were able to significantly reduce odors and/or regrowth. The incubation of anaerobically digested biosolids with protein degrading enzymes resulted in additional gas production as well as a reduction in odors after dewatering. Also, better digestion was associated with lower odors, and primary sludges produced greater odors compared to secondary sludges.
More details
Series
Language
English
Place of publication
London
United Kingdom
Target group
College/higher education
Professional and scholarly
File size
5,12 MB
ISBN-13
978-1-78040-457-8 (9781780404578)
Copyright in bibliographic data and cover images is held by Nielsen Book Services Limited or by the publishers or by their respective licensors: all rights reserved.
Schweitzer Classification
Content
- Cover
- Copyright
- Acknowledgements
- Abstract and Benefits
- Table of Contents
- List of Tables
- List of Figures
- List of Acronyms and Definitions
- Executive Summary
- Chapter 1.0: Introduction
- 1.1 Project Overview
- 1.2 Sudden Increase
- 1.2.1 History of Sudden Increase Research
- 1.2.2 Why Are FC Bacteria Not Culturable After Thermal Treatment?
- 1.3 Odors
- 1.4 Regrowth of Fecal Coliform and E. coli.
- 1.5 Research Objectives
- 1.5.1 Track I: Supporting Research (Monitoring, Methods, and Mechanisms) for Odors, SI, and Regrowth
- 1.5.2 Track II: Effect of Processes on Odors, SI, and Regrowth
- 1.6 Research Management
- Chapter 2.0: Research Approach and Methods
- 2.1 Research Overview
- 2.1.1 Supporting Research - SI and Odors
- 2.1.1.1 Comparison of Methods for Enumerating Fecal Coliform and E. coli
- 2.1.1.2 Evaluation of Odors and Odorants Other Than TVOSC
- 2.1.2 Effect of Processes on SI, Regrowth, and Odors
- 2.1.2.1 Evaluation of Time-Temperature Curves for Inactivation of FC/E. coli
- 2.1.2.2 Evaluation of Impact of Different Processes on SI, Regrowth, and Odors
- 2.2 Research Approach
- 2.3 Experimental Methods
- 2.3.1 Alternative Culturing Methods for Enumeration of E. coli and Fecal Coliforms
- 2.3.2 Time-Temperature Experiments
- 2.3.3 Odor Evaluations
- 2.3.4 Odor Compound Monitoring - Virginia Tech
- 2.3.5 Odor Compound Monitoring - Bucknell
- 2.4 Quality Assurance/Quality Control
- 2.4.1 Overview
- 2.4.2 Data Validation and Evaluation
- Chapter 3.0: Results and Discussion: Insights Into Sudden Increase
- 3.1 Overview of Experiments
- 3.2 Evaluation for Contamination to Explain SI
- 3.3 Alternative Culturing Methods
- 3.3.1 GAD Method, Media Additives, Low Temperature Storage
- 3.3.1.1 Microplate and Tube Comparison Using MUG and GAD Confirmation of E. coli
- 3.3.1.2 Membrane Filtration Methods With Resuscitation Steps
- 3.3.1.3 Methionine Addition
- 3.3.1.4 Pyruvate Addition
- 3.3.1.5 Low-Temperature Storage
- 3.4 Evaluation of Other Standard Methods for FC/E. coli Enumeration
- 3.5 Evaluation of Method 1680 Formulation Using Pure Cultures of E. coli
- 3.6 Additional Time-Temperature Experiments
- 3.6.1 Inter-Laboratory Comparison of Time-Temperature Experiments
- 3.7 Evaluation of Time-Temperature Requirements
- 3.8 Summary and Conclusions
- Chapter 4.0: Results and Discussion: Long-Term/Persistent Odors
- 4.1 Evaluations of Odors
- 4.1.1 Long-Term - Persistent Odors
- 4.1.1.1 What Is Their Pattern of Production With Regard to Time of Appearance and Decline?
- 4.1.1.2 Indole and Skatole
- 4.1.2 Correlation Between Short-Term and Persistent Odor Compounds
- 4.1.3 How Do Various Pre- or Post- Anaerobic Digestion Methods Impact Persistent Odorants?
- 4.2 Odor Compound Generation Potential of Primary and Secondary Sludge
- 4.2.1 VOSC from Primary Sludge, WAS and Mixed Primary and WAS
- 4.2.2 Butyric Acid and P-Cresol in Primary Sludge, WAS and Mix
- 4.2.3 Indole and Skatole in Primary Sludge, WAS and Mixed Primary, and WAS
- 4.2.4 Effect of SRT on Odorants
- 4.3 Summary and Conclusions
- Chapter 5.0: Results and Discussion: Effect of Different Processes on ROSI
- 5.1 Effect of Processes on Sudden Increase
- 5.1.1 Effect of Processes on SI Overview
- 5.1.2 Defining the SI Threshold Using qPCR
- 5.1.3 Processes Without Full-Scale Centrifuge Dewatering
- 5.1.4 Full-Scale Processes With Centrifuge Dewatering
- 5.1.5 Proposed Best Practices Curve to Supplement EPA Time-Temperature Curves
- 5.1.6 Field Trial Using Proposed Best Practices Curve
- 5.2 Effect of Digestion and Dewatering Processes on Odorant Production
- 5.3 Field Trial: Effect of Long-Term Storage on Regrowth and Odors
- 5.3.1 Project Overview
- 5.3.2 Odor Panel Results
- 5.3.3 Fecal Coliform Results
- 5.4 Addition of Amendments to Control Regrowth and Odors
- 5.4.1 Addition of Products to the Cake
- 5.4.2 Ferrate Addition During Dewatering
- 5.5 Effect of Microwave Treatment on Regrowth and Odors - Field Trial
- 5.6 Effect of Electro-Dewatering on Regrowth and Odors - Field Trial
- 5.7 Summary and Conclusions
- 5.7.1 Sudden Increase
- 5.7.2 Odors and Regrowth
- Chapter 6.0: Communication
- 6.1 Communication Plan
- Chapter 7.0: Summary, Conclusions, and Recommendations
- 7.1 Summary of Work
- 7.1.1 Sudden Increase
- 7.1.2 Odors and Regrowth
- 7.2 Significance and Implications to Practitioners
- 7.3 Recommendations
- References
