Sewage treatment in the septic tank is an anaerobic (without oxygen) process in fact, it is anaerobic because sewage entering the tank is so high in BOD that any oxygen present in the sewage is rapidly consumed. However, BOD content of sewage is also important for septic systems. 30 mg of O 2 are consumed per liter of water over 5 days to break down the waste). Based on criteria for surface water discharge, the secondary treatment standard for BOD has been set at 30 mg BOD/L (i.e. This is because sewage high in BOD can deplete oxygen in receiving waters, causing fish kills and ecosystem changes. The Five-day BOD, or BOD 5, is measured by the quantity of oxygen consumed by microorganisms during a five-day period, and is the most common measure of the amount of biodegradable organic material in, or strength of, sewage.Д«OD has traditionally been used to measure of the strength of effluent released from conventional sewage treatment plants to surface waters or streams. The amount of oxygen required for this process is known as the biochemical oxygen demand or BOD. However, oxygen is required for this process of breaking large molecules into smaller molecules and eventually into carbon dioxide and water. These large organic molecules are easily decomposed by bacteria in the septic system. Organic substances refer to molecules that are based on carbon and include fecal matter as well as detergents, soaps, fats, greases and food particles (especially where garbage grinders are used). Wastewater is composed of a variety of inorganic and organic substances. One of the most commonly measured constituents of wastewater is the biochemical oxygen demand, or BOD. Go back to the I/A Compendium Index Basic Constituents of Wastewater If you understand the theory behind these basic treatment processes it is easy to see how and why the processes are applied in the various alternative technologies discussed later. Some very basic processes of wastewater treatment are also briefly discussed. It is important to understand what each of these terms mean and how each relates to the wastewater treatment process. You will see terms like BOD, total suspended solids, nitrification, and denitrification frequently when discussing wastewater treatment. Sector ResourcesДЇor resources available to Water and Wastewater Systems Sector partners, go to the Environmental Protection Agency website.Before you go on to read about the individual technologies discussed later in this document, it is helpful to understand some of the basics of wastewater treatment. Presidential Policy Directive 21 changed the name of the Water Sector to the Water and Wastewater Systems Sector in 2013. The Environmental Protection Agency is designated as the Sector Risk ManagementВ Agency for the Water and Wastewater Systems Sector. Each Sector Risk ManagementВ Agency develops a sector-specific plan through a coordinated effort involving its public and private sector partners. The Water and Wastewater Systems Sector-Specific Plan details how the National Infrastructure Protection Plan risk management framework is implemented within the context of the unique characteristics and risk landscape of the sector. Critical services, such as firefighting and healthcare (hospitals), and other dependent and interdependent sectors, such as Energy, Food and Agriculture, and Transportation Systems, would suffer negative impacts from a denial of service in the Water and Wastewater Systems Sector. The sector is also vulnerable to natural disasters. The result of any variety of attack could be large numbers of illnesses or casualties and/or a denial of service that would also impact public health and economic vitality. The Water and Wastewater Systems Sector is vulnerable to a variety of attacks, including contamination with deadly agents physical attacks, such as the release of toxic gaseous chemicals and cyberattacks. population has its sanitary sewerage treated by these wastewater systems. population receives their potable water from these drinking water systems, and about 75 percent of the U.S. There are approximately 153,000 public drinking water systems and more than 16,000 publicly owned wastewater treatment systems in the United States. Thus, ensuring the supply of drinking water and wastewater treatment and service is essential to modern life and the NationвЂ™s economy. Properly treated wastewater is vital for preventing disease and protecting the environment. Safe drinking water is a prerequisite for protecting public health and all human activity.

Sewage effluent definition