Sewage Management Methods

A Detailed Study of Sewage Management Methods

As you know that waste generation is one of the most inescapable and natural activities of human lifestyle. For the existence of human, water is compulsory to perform various activities. These life processes include domestic works, industrial manufacturing, services like railways, restaurants, etc. All these usages generate a large amount of wastewater. Even though the natural water reservoir replenishes periodically, but the resource is not unlimited.

Thus, sewage management methods by recycling the used wastewater are necessary for present and next generations. If this misuse of water resource continues, adverse situations such as scarcity or draught are inevitable in upcoming days.

To prevent this type of pollution, you need to learn about the systematic methods of sewage treatment.

Definition of Sewage Treatment

Sewage treatment suggests a process that can eliminate impurities from household sewage and industrial wastewater. Majorly, four methods of sewage water treatment are followed – physical, biological, chemical, and sludge water treatment. By following these methods, the wastewater is disinfected from all the sewage materials and converted into treated water that is safe for both human usages and environment.

This entire containment removal process occurs before this impure used water reach the natural water bodies such as lakes, rivers, oceans, and estuaries. As the availability of pure water is scarce, the difference between clean and polluted water is completely based on impurity concentration and intend of usage. 

In other words, water is considered polluted when that is not fit for any specific intention like drinking, fishing, swimming, etc. Water contaminations primarily happen due to the drainage of impure wastewater into groundwater or surface water. And different sewage management methods can prevent water pollution significantly.

However, before a discussion about these methods, you should know about the principal pollutants and sewage types at first.

Types of Wastewater

Typically, three types of sewage are there-

  • Domestic Sewage

Domestic wastewater includes the used water from apartments or households. This type of wastewater is also known as sanitary sewage. It can be the water that runs down from the shower or body waste as well.

  • Industrial Wastewater

Industrial wastewater carries contaminated water from chemical or manufacturing processes. Various pollutant chemicals can be present in this sewage.

  • Storm Sewage

Strom water implies the runoff sewage that comes from the atmosphere in the form of water particles collected in open channels. This can include rain, drizzle, snow, etc. 

Above 99.9% of the entire wastewater comes from domestic sewage. Even though the principal containments are described as plant nutrients and organic materials, domestic wastewater also contains harmful microbes. 

Major Pollutants

  • Organic Substances

The quantity of perishable or biodegradable organic materials in wastewater is calculated by BOD or biochemical oxygen demand. BOD is the oxygen amount required by microbes to decompose these organic substances in wastewater. It is one of the most vital criteria for the operation and design of sewage management methods. 

  • Suspended Solids

Suspended solids are another crucial element of sewage. The amount of sludge generated in a water treatment plant depends on the entire suspended solids included in the wastewater. Storm and industrial sewage carry a large volume of suspended solids than domestic wastewater. 

  • Plant Nutrients

Primarily, domestic wastewater carries chemical elements like phosphorous and nitrogen, which are the fundamental nutrients for plants’ growth. If these elements are excessively present in surrounded water bodies like lakes, it can boost the growth of algae. This may accelerate the natural ageing of these water bodies.

  • Microbes

Moreover, domestic wastewater also carries various microbes that come from the intestinal tract of humans. Coliform bacteria are found in high concentration. In present days, an excessive coliform count has been observed in sewage pollution.

Sewage Treatment Methods

By employing various wastewater treatment methods, containments like chemicals and sewage can be eliminated from wastewater and recycled for further usages. Mostly, there are four methods of sewage treatment that are listed below in tabular format with important points-

Methods of Sewage Treatment

Process and Characteristics

Physical Treatment

  • Several physical processes, like sedimentation, skimming, and screening, are employed to eliminate solid wastes.

  • By sedimentation, heavy or insoluble particles can be separated.

  • Another effective method is aeration to circulate air (oxygen) through wastewater.

  • Filtration is applied to filter out all containments and make the water usable.

  • Most importantly, no chemical is applied to the physical treatment of wastewater.

Biological Treatment

  • Different biological processes are involved in decomposing the organic substances present in sewage like human waste, food, oil, etc. 

  • An aerobic process involves bacteria that can break down these organic materials and transfer into CO2. In this process, O2 is produced.

  • An anaerobic process involves fermentation of the waste material at high temperature. In this process, O2 is not generated.

  • Composting is a specific kind of aerobic process which uses various carbon sources to treat the sewage.

Chemical Treatment

  • In this process, several chemicals are used to treat water.

  • Chlorine is a common oxidising agent that eliminates germs and bacteria in water.

  • Ozone is also regarded as an oxidising agent to purify wastewater.

  • By adding base or acid, wastewater is also treated to keep the pH neutral. This is known as neutralisation.

Sludge Treatment

  • It is one of the most effective solid-liquid separation methods.

  • This requires the least possible remaining moisture in solid phase.

  • Also, it needs the lowest possible remaining solid molecules in isolated liquid phase.

Disposal Methods of Sewage

Sewage disposal methods are the basic components of a sewage management system. It disposes the used water from households, factories, etc. and helps to keep the environment clean. Following are some well-known sewage disposal methods practised around the globe.

  1. Municipality Systems

In municipality wastewater system, there is a treatment plant connected to the source of wastewater. By treating the used water, this plant efficiently removes near about 95% of impurities. Then, by an anaerobic process, the sludge is again treated to ensure the safety of using this water.

  1. Off-Site Sewage System

Due to the increasing urbanisation, the off-site sewage system has resulted. In urban areas, the houses are built on plots, and each plot is connected to a wastewater line. These wastewater lines collect waste from various households and flow towards a community sewage treatment plant. Here, excess water is directed towards a nearby river or irrigation area once the treatment is done.

  1. On-Site Sewage System

Another name of the on-site sewage system is a septic system. This disposal system is composed of a septic tank where the sewage can be settled, treated and similarly slurred on the same place of waste generation. In this process, the wastewater is disposed and treated by natural ways. Usually, an on-site system comprises of a septic tank and disposal field that is the soil absorption place. The wastewater slurry is carried out to this leach field where microorganisms can decompose it over a period. These sewage disposal methods are reliable, hygienic, economical, and efficient. 

  1. Full Wastewater System

In full wastewater disposal system, the sewage water is collected from households and then directed to various sewer pipes. During this process, all solid wastes go through multiple sharp blades or macerators. It helps to decrease the dimension of solid waste before further processing.

  1. Lagoons

Lagoons signify large open ponds that can collect wastewater from households. These water bodies contain a large number of microorganisms that decomposes the waste. Sunlight and wind act as catalysts in this process by accelerating the decomposition process. Moreover, algae also assist in the breeding process of bacteria in waste. Due t the presence of algae, these lagoons appear as greenish.

  1. Pit Latrines

Pit latrines are the century-old sewage disposal method found in human civilisation. In present days, these are found in rare places with restricted water supply. This disposal system includes borehole, trench latrines, ventilated improved pit. Shallow trench latrines are used by large gatherings for a shorter time and once they are nearly full, closed with soil.

Methods of Sewage Collection

A sewage system is typically designed by various underground channels to carry wastewater away discharged by localities. The collection system configures with pipes, manholes, drains, holding basins, catch basins, inlets, pimp stations that can move sewage from the collection point to discharge. The pipe systems and other appurtenances are primary methods of sewage collection in urban places.

  • Combined System

A combined collection system carries both storm and domestic wastewater. This collection system is typically constructed with pipelines or tunnels of wide diameter. However, in rainy seasons, this system sometimes fails as water treatment plants cannot treat a heavy volume of storm sewage.

  • Separate System

In relatively newer cities, separate wastewater systems that carry domestic and storm wastewater separately are found. The surface runoff sewage or stormwater disposes of in open water streams like a river. Smallholding basin or catch basins can be installed for heavy water flow during wet seasons. However, domestic wastewater is directed to a treatment plant.

From the in-detailed discussion about methods of sewage treatment, you have understood the treatment process, collection process, and disposal methods. You can also check our online classes on Vedantu website for other chemistry chapters.

For a further note on sewage management methods, you can now download our Vedantu app too.

FAQ (Frequently Asked Questions)

1. What Do You Mean By Wastewater?

Wastewater refers to the impure water produced from human activities and surface runoff. This sewage can be classified into three major types – domestic, industrial, and storm wastewater.

2. What Are The Common Methods Of Sewage Treatment?

In water treatment plants, sewage can be treated by four common methods – physical process, biological method, chemical process and sludge method.

3. Why Do You Think Wastewater Management Is Important?

Sewage is a combination of various nutrients, chemicals, and metals. By sewage treatment, these valuable materials can be recovered, and this way, the increasing demand for natural resources can be reduced. Moreover, water recycling can also help to maintain the natural water level.

4. What Are The Wastewater Treatment Methods?

The common stages of wastewater treatment methods are the primary method, secondary process, and tertiary treatment.