Screen in CSO Chamber

By

ACKNOWLEDGEMENT

I would like to thank my course supervisor for supporting me in everyaspect of my research for completing this thesis/dissertation project. I would further like to thank my familyand friends for their utmost support for my research,and understanding the reason of myabsence from homeand other events while conducting this research.

DECLARATION

I, [type your full name here], herebyaffirm thatall the work done in this dissertation/thesis represent my own work, and that the dissertation/thesis has not been submitted forany other academic examination. Furthermore, it represents my own opinions and has nothing to do with the opinion of the University

Signed __________________ Date _________________

ABSTRACT

Combined sewer overflows to receiving waters pose serious environmental, aesthetic and public health concerns. This paper reports on a device that utilizes the kinetic energy of sewage overflows flowing down an ogee-shaped weir to clean a perforated screen located in the lower section of the weir. The kinetic energy subsequently dissipates in a hydraulic jump that maintains the captured sewage solids in suspension prior to returning them to the sewer following the overflow event. The patented device, known as the Mischwasser-Siebsystem (MWSS), was selected by the Emschergenossenschaft for a pilot study at a CSO chamber discharging to the Vorthbach, a watercourse near Essen in Germany. The hydraulic design was supported by laboratory tests on a full-scale profile at Swinburne University in Melbourne,australia. The pilot MWSS was installed in late 2006 and subsequently monitored to identify any design, fabrication or installation problems. Some features required modifications while others such as the one-way valve worked extremely well.

TABLE OF CONTENTS

ACKNOWLEDGEMENTI

DECLARATIONII

ABSTRACTIII

CHAPTER 1: INTRODUCTION1

Background of the study1

Problem Statement1

Purpose of the study2

Rationale of the study2

Significance of the study3

CHAPTER 2: LITERATURE REVIEW5

Combined Sewer5

Combined Sewer Overflows7

The Ideal Intermittent Discharge Screening System15

Case Study - Effectiveness of CSO26

CHAPTER 3: METHODOLOGY35

Design Criteria35

Design Concept35

Hydraulic Theory36

CHAPTER 4: RESULTS & DISCUSSION40

Description Of Pilot MWSS40

Mode of Operation41

Practical Experience44

Discussion of Results45

CHAPTER 5: CONCLUSION47

REFERENCES49

CHAPTER 1: INTRODUCTION

Background of the study

Combined sewer overflows to receiving water bodies can cause serious environmental, aesthetic and public health concerns. CSO events occur when the combined sewage and storm water flow exceeds the capacity of the sewer system. Present measures to mitigate the impact of these events include temporary holding tanks at sewerage treatment plants, enlarged upstream sewers to provide transient storage, real time control of sewer systems, separation of sewage and storm water flows as well as various types of overflow screening devices. This paper reports on a new approach to the screening of sewer overflows that does not rely on mechanical cleaning and/or external power sources to clean a separating screen but rather on the kinetic energy of the overflowing sewage (UKWIR, 2006, pp. 45-61). It is being trialled in a pilot project conducted under the auspices of the Emschergenossenschaft at a CSO outlet discharging to the Vorthbach, a watercourse near Essen, Germany. Results from the instrumented CSO outlet had shown an unacceptable high frequency of overflow events that prompted the Emschergenossenschaft to retain a local consulting engineering company to investigate and report on measures that might be implemented ...