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Wastewater Treatment Technology Wastewater Minnesota Pollution Treatment Control Agency Technology 1997 Edition Minnesota Pollution Control Agency 520 Lafayette Road North St. Paul, Minnesota 55155-4194 (651) 296-6300 or (800) 657-3864 wq-wwtp8-23 WASTEWATER TREATMENT TECHNOLOGY by Emily Armistead Patricia Burford Russ Degerstedt Art Dunn Gene Erickson Del Haag Mike Hansel Cyndy Hanson Mike Herman Roger Kam Deb Lindlief Becky Lofgren Dwayne Nelson Bill Sexauer First Printing - June 1982 Second Edition - June1986 Third Edition - November 1997 Water Quality Division Minnesota Pollution Control Agency 520 Lafayette Road St. Paul, Minnesota 55155-4194 PREFACE Wastewater Treatment Technology is based largely on the series of handouts we developed for use at our training courses. We have also incorporated information from several other sources around the country and from the best source of all -- you the operator. In our experience doing training courses, you have taught us a lot. We hope this manual will be of as much help to you as you have been to us. ACKNOWLEDGMENT Special thanks to Ken Kerri at California State University, Sacramento, for the use of pictures and diagrams which appear in his self-study training course, Operation of Wastewater Treatment Plants. Also, thank you to the operators everywhere whose valuable contributions made this manual possible, and an extra special thank you to Emily Armistead and Mary Osborn for all of their time spent in organizing and typing this manual. DISCLAIMER Any reference to commercial products in this manual are forillustrative purposes only and do not constitute endorsement by the Minnesota Pollution Control Agency. TABLE OF CONTENTS CHAPTER PAGE 1 Collection Systems 1-22 2 Introduction to Wastewater 23-44 3 PreliminaryTreatment and Clarification 45-64 4 Trickling Filters 65-90 5 Rotating Biological Contactors 91-104 6 Activated Sludge 105-130 7 Stabilization Ponds 131-148 8 Soil Treatment Systems 149-166 9 Disinfection 167-178 10 Solids Handling 179-197 11 Sampling 198-209 12 Glossary 210-242 INTRODUCTION This manual was developed to provide beginning wastewater treatment operators with an overview of wastewater treatment and a basic understanding of the various treatment processes. The manual is also useful to veteran operators for learning more about those treatment processes which are different from their facilities. While the manual discusses the operation and maintenance of most types of wastewater treatment units, it is not meant to provide all the information needed to operate a facility. Entire manuals are devoted to the discussion of individual units or processes. Many of these manuals are listed at the end of each chapter for further reading. The manual is organized, as much as possible, to follow the normal path of wastewater through a treatment facility. It starts with the collection system, then goes through preliminary and primary treatment. Various secondary units are discussed, followed by disinfection and solids handling. Someone once said there are three reasons why a job doesn't get done. Either the person who is supposed to do the job: 1) doesn't know how; 2) doesn't have the right tools; or 3) doesn't want to do it. This manual is designed primarily to tackle the first reason -- lack of knowledge. While no one manual can totally accomplish this task, this manual starts that process. Manuals, of course, cannot supply tools, nor can they provide the desire to do a job, or to do it well. This comes only from operators who start to think of themselves as professionals. Many people think that operating a wastewater treatment facility means turning a fewnuts and bolts, changing oil and mowing the grass. This is simply not true. Operators must be chemists, plumbers, biologists, electricians and mathematicians, as well as public and labor relations experts. In short, an operator is really the manager of an expensive facility whose products are clean water and treated wastes. Operators cannot manage their facilities along. For the plant to run properly, there must be teamwork -- a partnership betweenthe owner and operator. The owners of a wastewater treatment facility are ultimately responsible for its operation. Their names are on the permit, and the operator reports to them. The owners might be the mayor, city manager, city council, the board of a sanitarydistrict or a private corporation. Operators are the people who actually operate and maintain the wastewater treatment facility, including buildings, grounds and equipment. Operators are the professionalswho make the day-to-day decisions on how the facilityshould be operated. In short, the owners are responsible for providing the necessary tools and materials needed to properly operate and maintain the facility. This includes laboratory and safety equipment. The owners are also responsible for providing or obtaining funds for plant expansion or major modifications. The owners should provide opportunity, time and incentives forthe operators to maintain and improve their level of expertise. This can include membership in professional organizations, attendance at training courses, or subscription to journals or correspondence courses which relate to wastewater treatment. Finally, the owners should treat the operators as professionals by consulting them before making any changes in operation or policy, and by establishing a salary level which encourages retention of skilled and experienced personnel. The operators are really the key to the performance of the facility. They protect the environment and the public health by providing continuous treatment and disposal of wastewater. They protect the owners by performing preventive maintenance, by keeping accurate records and by complying with state and federal regulations. Operators should use good health and safety practices at all times to protect themselves and others at the facility. Operators are also responsible for keeping people informed. Owners of the facility should be notified in advance of the need for tools, parts, supplies and possible future facility expansion, in order to make allotments in the budget for these costs. The public should be informed about the plant's operation and any emergencies which develop. Addressing complaints, answering inquiries from the news media and conducting plant tours are some additional responsibilities the operators have to the public. Operators must keep the state regulatory agency informed about plant operations and any emergencies by filling out monthly report forms and returning them on time. Finally, they should keep up-to-date on the latest methods and techniques in wastewater treatment through training courses, journals and professional organizations. Communication among the owners, operators, community and state regulatory agency is "' very important in order for the treatment facility to be operated properly and efficiently. A sample Annual Report and Annual Budget follow to help illustrate some ways in which this communication can be established. ANNUAL REPORT This year the $1.5 million Plantville Wastewater Treatment Facility treated the wastes of Plantville's 800 residents and local creamery; a total of 100,000 gpd or 36.5 million gallons this year. The plant complied with its permit requirements except for two occasions, during the month of January when the final clarifier froze, and on June 7 when 12 inches of rain fell in eight hours. Continuous service was provided to all but 20 homes on June 7 when the sewers backed up. In addition to the regular operations and maintenance of the plant, two major projects were completed this year: installation of 2,000 feet of sewer (Byer A venue extension) and construction of covers for the final clarifiers to prevent freezing. Electrical costs were reduced 25 percent by using the new dissolved oxygen meter purchased last year. This savings more than paid for the cost of the meter. The budget for the coming year includes funds for replacing the pump in the main lift station and repairing 1,000 feet of sewer on South Main Street. ANNUAL BUDGET The following is a list of some of the items which should be in the annual budget. Salary and Benefits Equipment Replacement Electricity Laboratory Equipment and Supplies Chlorine Insurance Natural Gas Training Gasoline Travel (for training) Equipment Repair (parts) Miscellaneous (includes material for sewer repair) In summary, the purpose of this manual is to provide, at least in part, the knowledge of how a wastewater treatment facility operates. The owner provides the tools; the operator must provide efficient plant operations. If the operator has, or can acquire, that professional attitude, tools and knowledge will be easier to obtain. COLLECTION SYSTEM TABLE OF CONTENTS PAGES INTRODUCTION 2 COLLECTION SYSTEMS AND COMPONENTS 2 Types of Collection Systems Basic Parts Material Used Manholes Lift Stations OPERATION AND MAINTENANCE 6 Pipeline Maintenance and Inspection Major Equipment Inspection Lift Station Operation & Maintenance Bar Screens and Baskets Dehumidifiers Ventilation Dry Well Dewatering Emergency Operation VELOCITY, FLOW MEASUREMENT 14 AND RECORDING Velocity Flow Measurement Flow Recording SAFETY 18 REFERENCES 22 1 INTRODUCTION The wastewater collection system is probably the oldest part of a wastewater facility. There is evidence that collection systems were used in India around 3750 B.C. The oldest sewer still in existence is an arched sewer built in Rome around the first century. It was used for carrying waste from the Roman Forum to the Tiber River. These old collection systems were all gravity flow sewers. Today, most collection systems are still designed as gravity flow, but in some cases, due to the topography of an area, lift or pumping stations must be provided to help convey wastewater to a treatment plant. COLLECTION SYSTEMS AND COMPONENTS A wastewater facility has many parts. These parts include pipes, conduits, structures, equipment and other 0 processes used to collect, transport, treat and dispose of 0 domestic and industrial wastes. The processes of a INTEP.CEl'TOR wastewater facility which we will discuss include both the LATERAL collection and transportation of wastes (a wastewater collection system).
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