Water Treatment Procedures and Stages
According to Government Regulation of the Republic of Indonesia Number 82 of 2001 concerning Water Quality Management and Water Pollution Control, water quality management is an effort to maintain water so that the desired water quality is achieved according to its designation so that water quality remains in its natural condition. Meanwhile, the clean water treatment Indonesia is carried out if the raw water does not meet the physical requirements for drinking water such as surface water, for example river water, lake water, reservoir water. The complete processing process generally goes through several process stages as follows:
Screening serves to separate or take floating objects such as tree branches, leaves, papers and garbage found in raw water. Generally, a coarse filter is used instead of a fine screen. This process is important for treating surface water because usually surface water is used for waste disposal and other types of waste water treatment plant, there are many aquatic plants such as water hyacinth. With the screening process, it can prevent the occurrence of damage and blockages in processing installation equipment such as pumps, valves (flow regulating valves) and other equipment. Sanitai Drinking Water
2. Pre-sedimentation (Preliminary Deposition)
The deposition process functions to separate suspended matter consisting of coarse sand, fine sand and very fine mud from raw water. Generally, it takes 2-3 hours for this type of particle to settle (Razif, 1985).
3. Coagulation and flocculation
The coagulation process is the process of administering coagulant with the intention of reducing the repulsion between colloidal particles. The flocculation process is the process of administering flocculants with the intention of combining small flocs so that they become larger and larger so that they are large enough to be deposited.
The main purpose of the coagulation and flocculation processes is to separate the colloids in the raw water. Colloids are fine particles, therefore they are very difficult to precipitate or take a very long time. Colloids are generally electrically charged, either positive or negative depending on the origin. If it comes from inorganic then the electric charge is positive, whereas if it comes from organic then the electric charge is negative. In order for the colloids to be easily deposited, their size must be increased by combining them through the coagulation and flocculation processes by adding coagulants and flocculates. Colloids are classified into hydrophobic colloids which are difficult to react with water and hydrophilic colloids which easily react with water, because of these properties, hydrophilic colloids require more coagulant substances than hydrophobic colloids.