The management of wastewater is a key part of controlled urban and industrial developments especially with the current limitations of fresh water supply globally. Changing climate patterns have meant that people have to learn how to make their water last longer. In order to protect our limited water resources, it is important to make every drop of water count. Bearing this in mind, wastewater management strategies have been developed with the aim of increasing the amount of reusable water as well as the quality of water reintroduced to the environment. The effective extraction of solid contaminants from the water is a key step in restoring wastewater to reusable quality.
There are several methods in use today to separate solids from liquids in small and large-scale applications. The method you chose to use to separate the solid particles from a fluid is dependent on the size and type of solids as well as the final designation of the water. If you aim to reuse the water, you will need to employ highly efficient purification methods. Sedimentation and Filtration are the basic categories where most liquid waste management procedures begin.
In order to effectively treat Sewage water, the process is broken down into three main treatment phases.
Phase 1: Primary Treatment
Primary treatment involves the removal of solids from the wastewater. The most common process in this stage is Sedimentation. In some cases, the wastewater is passed through a filter in order to extract microscopic insoluble solids.
Sedimentation is the process by which particles suspended in a fluid settle at the bottom of the containment area or against a barrier as a result of forces acting on them. The three main forces employed in the sedimentation process include gravity, electromagnetism, or centrifugal acceleration. In wastewater treatment plants, the sedimentation processes are carried out in Settling Basins or Clarifiers. The Settling basins are large ponds in which the wastewater is left to stand while the heavy debris sinks to the bottom. Clarifiers are tanks with mechanisms set up to extract the solids as they are deposited at the bottom.
In wastewater treatment, due to the nature and volume of waste, filtration is employed to deal with the colloidal suspensions. A Colloidal Suspension is a fluid mixture where one substance is made up of microscopic particles which are suspended throughout the volume of the second substance. Filtration involves passing a fluid mixture through a fine filtration media that will only allow one component of the fluid through the media and retain the other one as a residue.
Phase 2: Secondary Treatment
This phase focuses on the extraction of biological matter and is carried out by residential water-borne micro-organisms. In this stage, organic compounds are oxidized and converted into carbon dioxide, water and bio-solids. Dissolved and colloidal organic compounds are taken through biochemical oxidation processes to break them down further and persistent organic pollutants are eliminated using chemical oxidation to kill the microorganisms by adding chlorine or hypochlorite to the water.
Phase3: Tertiary Treatment
The tertiary treatment stage mainly involves sludge treatment and disposal. It is the last stage before the wastewater can be released back into the environment. In this stage, the sludge can be taken through a final dewatering process before it can be incinerated or disposed of in landfills.
One of the most effective sludge dewatering methods involves the use of industrial centrifuges. A sludge dewatering centrifuge is one of the most effective methods to separate sludge from water because it removes more water than other methods. The centrifuge works by spinning the sludge in a high speed rotating cylindrical bowl which enacts centrifugal force on the sludge forcing the water out and leaving a solid material which is referred to as a cake. The cake can then be incinerated or mixed in with garden compost. Centrifugation considerably cuts down the transport and disposal costs of sludge.
Extraction of solid matter from wastewater in the preliminary stages of sewage treatment greatly cuts down the expenses and complications incurred along the way as you implement the more advanced treatment processes. The presence of heavy solids in later stages could result in lasting damage to sensitive equipment.