Wastewater or water should be treated if water is contaminated with pollutants. There are different methods and technology to treat wastewater. And also, there are defined parameters, characteriscs and standards in wastewater treatment and they should be considered in any water treatment process. In this tutorial, we will learn basics of wastewater treatment.
Water is one of the most abended materials in the world. But about 97% of water from the total is saline water. From freshwater, around 69% in ice caps and glaciers, 30% contains as groundwater and less than 0.27% contain in rivers and lakes. Most rivers and lakes are polluted due to many natural and anthropogenic (people done things) reasons. Therefore, there is a very small amount of water is on the earth that we can use as it is.
If we used polluted water, it may cause many health impacts. Diseases related to water can be categorized as below.
More than 5 million people die every year due to these diseases. Therefore, the quality of water is very important. If we have not enough pure water in nature, we have to treat water before use.
Wastewater generation is increasing day by day. Discharging wastewater to the environment without causing any adverse effects is the biggest challenge in every industry. Most of the time wastewater is treated and discharged into this irrigation system.
Various environmental legislations and standards are available according to the type of industry and discharge method place of wastewater discharge.
These tolerance limits are introduced to protect the environment. If you dispose of wastewater to the environment without following these standards you will be guilty and offense according to the law. Not only that it will cause to interrupt equilibrium in ecosystems. Therefore, we have to treat wastewater before disposed to the environment.
To understand wastewater/water treatment, understanding impurities is very important because we used their properties to remove them from water.
Impurities in water can be divided into three categories as below.
Treatment of wastewater means
For that, different methods and techniques are used. Selections of proper unit operation is one of the most important factors in design. Influent water quality, required effluent water quality, cost of treatment method and space availability for the treatment plant are the most important factors to select unit operations. The treatment unit operations can be divided into three categories as below.
Unit operations use for the treatment are depend on impurities present in water. See table 1 to get a basic understanding of treatment methods that we can use according to impurities.
Table 1: Suitable treatment methods according to the impurities in wastewater
There is a series to use these unit operations. According to that treatment steps are categorized as preliminary, primary, secondary, tertiary and advance. The wastewater treatment processes main steps are described in table 2.
Table 2: Steps of wastewater treatment process
The typical process flow diagram shows in figure 1.
Figure 1: Typical flow diagram of wastewater treatment
You should do continuous testing such as COD, BOD, TSS etc. for water after treatment processes. If one or few parameters are deviated from given ranges, immediate attention should be given to identify where the problem is.