Thursday, September 7, 2017

Water Treatment, CDC, Basic Guidelines

Community Water Treatment

Drinking water supplies in the United States are among the safest in the world. However, even in the U.S., drinking water sources can become contaminated, causing sickness and disease from waterborne germs, such as CryptosporidiumE. coli, Hepatitis A, Giardia intestinalis, and other pathogens.
Drinking water sources are subject to contamination and require appropriate treatment to remove disease-causing agents. Public drinking water systems use various methods of water treatment to provide safe drinking water for their communities. Today, the most common steps in water treatment used by community water systems (mainly surface water treatment) include:
 Figure illustrating the water treatment cycle, showing coagulation, sedimentation, filtration, and disinfection
Figure courtesy of EPA
  • Coagulation and Flocculation
    Coagulation and flocculation are often the first steps in water treatment. Chemicals with a positive charge are added to the water. The positive charge of these chemicals neutralizes the negative charge of dirt and other dissolved particles in the water. When this occurs, the particles bind with the chemicals and form larger particles, called floc.
  • Sedimentation
    During sedimentation, floc settles to the bottom of the water supply, due to its weight. This settling process is called sedimentation.
  • Filtration
    Once the floc has settled to the bottom of the water supply, the clear water on top will pass through filters of varying compositions (sand, gravel, and charcoal) and pore sizes, in order to remove dissolved particles, such as dust, parasites, bacteria, viruses, and chemicals.
  • Disinfection
    After the water has been filtered, a disinfectant (for example, chlorine, chloramine) may be added in order to kill any remaining parasites, bacteria, and viruses, and to protect the water from germs when it is piped to homes and businesses.

Monday, April 4, 2016

An Operator's Guide to Biological Nutrient Removal (BNR) in the Activated Sludge Process

ISBN-13/EAN: 9780820604169
Author: Michael Gerardi
Chemical Publishing
Book - Paperback 4"x6" Pocket Pal really fits in your pocket!
Pub Date: April, 2016
160 pages

Biological nutrient removal (BNR), the removal of nitrogen and phosphorus from wastewater, is a complex process. Although the activated sludge process is an efficient technology for the removal of biochemical oxygen demand (BOD) and total suspended solids (TSS), it provides less-than-optimal conditions for the removal of nitrogen and phosphorus, and presents numerous challenges to the operator trying to satisfy the many requirements for several different groups of bacteria. In addition to satisfying the requirements there are numerous, highly variable operational conditions that impact BNR. These conditions include: changes in strength and composition of the wastewater, alkalinity and pH, temperature, and presence of inhibitory and toxic wastes. Even fluctuations in flows, especially from inflow and infiltration, can adversely impact the aerobic, anoxic, and anaerobic conditions needed for successful BNR. 

Of the three treatment processes, nitrification, denitrification, and enhanced biological removal, nitrification is often the most difficult to achieve. Therefore, a large portion of this book reviews nitrification. Operators of the activated sludge process need to understand the basic biological, chemical, and physical requirements for BNR in order to improve the performance of these treatment processes. 

An Operator’s Guide to Biological Nutrient Removal (BNR) in the Activated Sludge Process is intended to help operators in the monitoring, troubleshooting, and process control of BNR. Numerous tables and figures are included in the book to help the operator understand the biological and chemical reactions that are involved in BNR processes and how the reactions can be monitored for process control.

Design of BNR processes is not addressed in this book. Design is addressed in numerous engineering publications. The book serves to help operators achieve permit compliance for nitrogen and phosphorus discharge limits and obtain cost-effective operation. - 

Contents -
List of Tables -
List of Figures -


Chapter 1 Introduction - 
Chapter 2 Nitrogenous and Phosphorous Compounds - 
Chapter 3 Nitrification: The Basics - 
Chapter 4 Nitrifying Bacteria - 
Chapter 5 Nitrification and Limiting Factors - 
Chapter 6 Promoting Nitrification - 


Chapter 7 Denitrification: The Basics - 
Chapter 8 Denitrifying Bacteria - 
Chapter 9 Denitrification and Limiting Factors - 


Chapter 10 Biological Phosphorus Removal: The Basics - 
Chapter 11 EBPR: Process Control - 
Abbreviations and Acronyms - 
Glossary - 

Bibliography -