Wastewater Treatment

Troubleshooting and Problem Solving

Glenn M. Tillman

• Publisher: Routledge
• Year: 2017
• eBook ISBN: 9781351405195
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Environmental Management
• Index: Technology & Engineering

Wastewater Treatment is another indispensable work from the author of Water Treatment. Both books are helpful tools for crisis identification and, most importantly, resolution. Tillman writes in a concise, well organized format - perfect for fast reference. This operator's guide presents basic troubleshooting and problem solving information for typical problems that can occur during the operation of processes used at municipal and industrial wastewater treatment plants. Common problems and the recommended operator responses are listed in tabular form for individual unit processes. Entry level operators will benefit greatly from the problems Tillman addresses, while experienced operators will appreciate it as a handy reference. The information compiled in this volume has been collected from various equipment manfacturers' operation and maintenance manuals, U.S. Environmental Protection Agency (EPA) technology transfer documents, the authors personal experience as a plant Operations and Maintenance manual writer, and his experience as a plant manager and operator. He includes only the most common wastewater treatment unit processes. He gives an overview of the treatment objective of the unit process, and then provides each with a troubleshooting table divided into Indicators/Observations: Possible Cause; Check or Monitor; Possible Solutions columns. Wastewater Treatment reads like the best of training manuals. Tillman's know-how, combined with his clarity, make this book required occupational reading. The brief, straightforward format and easy-to-read tables make the guide an accessible problem solving reference.

1	USER’S GUIDE

This operator’s guide has been developed as a first source for troubleshooting and solving treatment problems commonly encountered in the daily operation of municipal and industrial wastewater treatment plants. The material is presented in a brief, straightforward format and in easy-to-follow tables to improve the guide’s accessibility as a problem solving reference. There is less explanation of how a particular unit process is supposed to work and more on what to do if it is not working properly. Information has been compressed and concentrated with this in mind.

The following chapter covers general troubleshooting procedures appropriate for any unit process at any plant. The chapter provides information on how to troubleshoot, what to look for, and how to correctly lock out equipment to be inspected or worked on. All of the remaining chapters in the guide are devoted to troubleshooting information appropriate for solving problems with individual unit processes commonly encountered at typical wastewater treatment plants.

2	GENERAL TROUBLESHOOTING PROCEDURES

2.1.    INTRODUCTION

There are a wide variety of common operational and mechanical problems that can occur periodically to prevent the proper processing of wastes by a treatment plant. Each section of this handbook covers a unit process, the different problems that could occur, and how to correct them. Before this specific guidance can be followed, however, an operator should be familiar with how to “smoke out” or correctly identify the problem.

2.2.    HOW TO TROUBLESHOOT

The first step in troubleshooting is to correctly identify the problem. This involves a physical inspection of the equipment or the unit process performance. The problem may be obvious or may require careful investigation. Once identified, monitoring, analyses, and/or observation should be performed before an informed decision can be made as to which corrective measures should be used. In some cases, this data collecting step can be a simple visual observation. In other cases this step may require sampling and laboratory procedures to determine performance efficiency. All information collected should be carefully reviewed in deciding the correct solution to the problem.

The problems covered in this guidebook are those which occur frequently at municipal and industrial wastewater treatment facilities. The solutions suggested are common practice in the industry and are usually successful. There are problems, however, that can resist correction or do not fit into the categories listed here. These may require expert advice from equipment manufacturers or consultation with engineers.

If any of the troubleshooting guidance is found to be ineffective, modify the guidance to fix the problem using your own observations, insight, and experience. Remember that it is the operator’s ability to blend experience with technical advice that determines the successful performance of any treatment plant.

2.3.    BASIC TROUBLESHOOTING SKILLS

Before investigating the cause of any equipment or process problem, check all the basic operating conditions. Verify that:

■  The circuit breaker is closed (on).

■  Operating switches are in their proper position.

■  For pumps, all needed suction and discharge valves are open, and seal water is available.

■  There are no obvious signs of failure, such as jammed, loose, broken, or burned equipment.

■  Mounting bolts are tight; couplings, drive bolts, and chains are aligned and correctly tensioned.

Remember to always look for the simplest, most obvious correction to the problem first. If there are no obvious problems, attempt to restart. If the equipment circuit breaker immediately opens after starting, suspect an electrical short (an “overcurrent” condition).

If the equipment runs for a short time but then stops or displays an equipment “fail” alarm, suspect an overload condition (the motor is overloaded and draws more current than is safe).

Remember that accurate troubleshooting is as much an art as a science. A good operator develops his senses to constantly be on the lookout for problems. Operators learn how to “smoke out” the cause of process and equipment problems. Problems may be seen, heard, smelled, or even felt. Troubleshooting often involves an operator’s developed intuition regarding what went wrong and how to fix it.

2.4.    EQUIPMENT LOCKOUT

Before you work on any mechanical equipment you are troubleshooting, be sure that it is locked out to protect yourself and the safety of other workers. Equipment lockout involves the physical opening (disconnection) of that equipment’s electrical circuit breaker and the steps taken to prevent the accidental closing (reconnection) of the circuit breaker while the equipment is being worked on.

To ensure that this equipment lockout has occurred, a lockout procedure should be performed by the personnel who will be performing the work. The following general procedures are offered as a safe, logical lockout sequence to follow:

Step 1

■  Notify your co-workers that a specific piece of equipment is being locked out.

■  If the equipment is in service, shut the equipment down.

Step 2 - At the Equipment Motor Control Center

■  Locate the equipment’s circuit breaker.

■  Open (disconnect) the correct circuit breaker.

■  Attach an “OUT-OF-SERVICE” tag to the open circuit breaker. Fill in information on why and by whom the equipment was taken out of service.

■  Physically lock the circuit breaker open, if possible, to further ensure the safety of plant personnel.

■  Dissipate any residual energy that may be “stored” in the equipment.

■  Check the previous steps and try to start the equipment to verify that it will not operate.

2.5.    REMOVING LOCKOUT

After mechanical equipment has been inspected or worked on, the following general guidelines can be used as a correct sequence for removing equipment from lockout.

Step 1 - At the Equipment

■  Notify your co-workers that the equipment is being taken out of lockout status.

■  Remove any tools or parts from the immediate area of the equipment.

■  Ensure that all guards and safety devices have been reinstalled.

■  Be sure that all employees are completely clear of the equipment.

Step 2 - At the Motor Control Center

■  Remove any locks from the circuit breaker.

■  Close the correct equipment circuit breaker.

■  Start the equipment.

■  If the equipment does not operate properly, lockout the equipment again and arrange for further repairs. Verify that an OUT-OFSERVICE tag is still in place.

Step 3

■  If the equipment operates properly, remove the OUT-OF-SERVICE tag.

■  Verify that the equipment status has been entered into the daily log.

The lockout procedures described are adapted from Occupational Safety and Health Administration (OSHA) lockout/tagout rules. The specific rule, Standard 29 CFR Part 1910.147, must be adhered to in detail whenever a guard or other safety device is removed, or whenever you reach into locked out equipment to perform a repair. Minor changes and adjustments on equipment that occur during normal operation are not strictly obligated to follow the OSHA guidelines, but measures should still be taken to provide effective protection.

You are encouraged to obtain a copy of the OSHA standard if you have any questions about correct lockout procedures. It is available from the U.S. Department of Labor, Occupational Safety and Health Administration, Room N3101, Washington, D.C. 20210; telephone [phone].

3

SCREENING

3.1. PROCESS OVERVIEW

■ Wastewater flows through a screen bar rack to remove large floating objects that could clog pumps or pipes.

■ Coarse screens or bar racks are usually made of parallel iron or steel bars spaced 2 to 4 inches apart. Fine screens are spaced 1/2 to 2 inches apart.

■ Screens are usually placed in a chamber or channel at a slanted angle pos...

Table of contents

• Cover
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• 1.0. USER’S GUIDE
• 2.0. GENERAL TROUBLESHOOTING PROCEDURES
• 3.0. SCREENING
• 4.0. SHREDDING AND GRINDING
• 5.0. GRIT REMOVAL
• 6.0. PRIMARY CLARIFICATION
• 7.0. LAGOONS/PONDS
• 8.0. TRICKLING FILTERS
• 9.0. ROTATING BIOLOGICAL CONTRACTORS (RBCs)
• 10.0. ACTIVATED SLUDGE
• 11.0. SECONDARY CLARIFIERS
• 12.0. NITRIFICATION
• 13.0. DENITRIFICATION
• 14.0. EFFLUENT FILTRATION
• 15.0. CARBON ADSORPTION
• 16.0. CHLORINATION
• 17.0. GRAVITY THICKENING
• 18.0. DISSOLVED AIR FLOTATION (DAF) THICKENING . .
• 19.0. ANAEROBIC DIGESTION
• 20.0. AEROBIC DIGESTION
• 21.0. CENTRIFUGATION
• 22.0. VACUUM FILTRATION
• 23.0. PRESSURE FILTRATION
• 24.0. BELT FILTRATION
• 25.0. BASIC MECHANICAL PROBLEMS
• BIBLIOGRAPHY