Sewage Purification

Sewage is the wastewater that is produced by domestic water use, industrial uses and every other use or water source that eventually ends up in sewage pipes or transfer systems. Sewage purification is a process that is most widely performed in wastewater treatment plants that operate globally, using various technologies and methods and that can be in very large municipal plants or smaller solutions for a specific house, farm, plant or area.

The process of sewage purification entails removing various contaminants that are domestic and human waste and also effluents or runoff. Sewage purification is done using physical, biological and chemical methods. The purpose of sewage purification processes is mainly to produce water or fluid waste that can be reused for various uses or disposed of ecologically. In some methods also a solid waste (sludge) solution that can be reused as fertilizer or that can be disposed of with minimal ecological and health hazards.

The main use of treated water from sewage purification is for irrigation in agriculture, but with certain methods and complex processes the water purification level is so high that they can be used as drinking water.

Technical details about sewage purification

Sewage wastewater contains both water or liquids and solids of different sorts and origins, sewage purification needs to remove as much as possible or needed of the solids, other obstructions and of course biological and chemical contaminants.

Sewage purification involves a few stages and has a lot of methods by which it is done globally, main stages are:

  • Pre-treatment: screening and removal of solids (mainly inorganic solids) from the wastewater, sometimes also by sedimentation. After this grit removal is next.
  • Primary treatment: mainly done by sedimentation in large basins or tanks, this separates sludge and other materials such as fat from the wastewater. The primary treatment stage of sewage purification is complex, has a lot of methods and is the longest.

Sewage purification methods

Wastewater treatment and sewage purification can achieve various levels of purification, some plants produce water that reach the secondary (biological) treatment level while others produce very pure water at the tertiary level – this can be used to a variety of uses, including agricultural produce irrigation.

In general, all common methods of sewage purification use sedimentation processes by which solids (sludge) sink to the bottom – in some cases this primary sludge is removed for further treatment. After this comes the secondary or biological treatment of sewage purification, this involves biological processes and the use of bacteria that “eats” away a lot of the hazardous contaminants. Use of oxygen by various implementation techniques is very important. After the secondary stage of sewage purification comes final settlement of biological solids and then a tertiary treatment that removes even better the rest of the biological and organic materials in the water. Tertiary treatment uses filters of various types.

Other methods or technologies that take part in the above general sewage purification processes are:

  • Anaerobic or aerobic digestion of contaminants – mainly for sludge.
  • Constructed wetlands that have plants that oxygenates the water and absorbs toxins.
  • Sedimentation and oxygenation lagoons
  • Incineration of treated sludge.
  • Producing fertilizers from treated sludge.
  • Filter and/or oxidizing beds.
  • Nutrient, Nitrogen, Phosphorus removal.

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