Important Chemicals and Components Used in Treating Wastewater

Wastewater treatment plants in India consist an array of processes to expedite disinfection, and therefore requires various chemicals. Chemical unit processes are the chemical processes that include chemical reactions and are used along with physical and biological cleaning processes to attain different water standards. There are different chemical unit processes that include coagulation, chemical oxidation and advanced oxidation,chemical precipitation, and chemical neutralization and stabilization, and ion exchange. These processes can be applied to wastewater during cleaning. The major types of chemicals that are used to clarify wastewater in primary industrial treatment are categorized as pH adjustment chemicals, coagulant chemicals, and flocculent chemicals. Let’s take a look at these chemicals that are used in wastewater treatment plants.

pH Adjustment Chemicals

Wastewater treatment plants use different chemicals to adjust pH to modify the ionic charge of the wastewater. pH is an expression of the intensity of the acidic or basis state of wastewater. pH is, mathematically, the log (base 10) of the reciprocal of the hydrogen ion activity. Numerically, the pH ranges from 0 to 14. Out of these, 7.0 is neutral with below 7.0 condition being acidic and above 7.0 being basic. Choosing specific chemicals to control wastewater pH demands consideration of the chemical makeup of the wastewater.

Different chemicals used to raise wastewater pH are below:

Owing to its properties such as low cost, high capacity, and easy availability, the most commonly used chemicals are MgO (magnesium oxide), CaO (calcium oxide), Ca (OH) (calcium hydroxide), or Mg (OH) (magnesium hydroxide).

Sodium hydroxide (NaOH) is a controllable, commonly available, and convenient chemical, butis an expensive one. Sodium hydroxide is often used for occasional or small applications or where the limitation of sludge deposits is sought. Furthermore, caustic soda is available in its liquid form in two concentrations, i.e., 50 percent NaOH that begins to crystallize at 54 F (12 C). Therefore, it’s mandatory to properly storeor dilute it prior to use.

Coagulant chemicals

Chemicals that are used to adjust pH as well as to coagulate solids in the wastewater are coagulant chemicals. Considering the chemical makeup of the wastewater is imperative in selecting chemicals to coagulant solids.

Some of the chemicals used in coagulant solids in the wastewater treatment in India are Aluminum Chloride (AlCl3), Ferric Chloride, Aluminum Sulfate [Al2(SO4)3], and Ferric Chloride (FeCl3).

Flocculent Chemicals

Synthetic chemicals that have no effect on pH but are used to flocculate and separate solids from clarified wastewater are flocculent chemicals. In this method as well, it’s important to consider the makeup of the wastewater before you begin selecting the chemicals to flocculate and separate solids in the wastewater. Chemicals that are used to flocculate and separate solids in the wastewater treatment plants in India using rapid mix and gentle agitation are classified on the basis of different types of polymers.

o  AsAnionic polymers have a negative charge to the wastewater, these are applied with rapid mix and gentle agitation to attain solids separation.

o  As Nonionic polymers have a neutral charge to the wastewater, these are applied with rapid mix and gentle agitation to attain solids separation.

o  As Cationic polymers have a positive charge to the wastewater, these are applied with rapid mix and gentle agitation to attain solids separation.

These are commonly used in chemicals in wastewater treatment plants in India. Apart from these, different plants may use different chemicals and components, as the processes may differ. But the end, the goal of all plants remain same, to conserve water and our environment by taking small steps though wastewater treatments.