water treatment Chemicals

Water treatment Chemicals

Dhaka Water Supply and Sewerage Authority (DWASA) provides water supply in its service areas of about 400 km in Dhaka city and its surroundings.
It has been relying heavily on groundwater as a source of water supply and at present 78% supply is from groundwater. However, the current groundwater abstraction is beyond sustainable yields, as groundwater table in Dhaka is declining at some 2 to 3 meter per year. DWASA has now planned that majority of its new water source will be from rivers.
Saidabad Water Treatment Plant (SWTP) is presently the major surface water treatment
plant in Dhaka.

Ingredients for Water Treat?

  • Aluminum Sulphate 50 Kg Bag Bangladesh
  • Dap 25 Kg Bag China
  • De Coloring 30 Kg Jar China
  • De Foaming 200L Drum Taiwan
  • Ferrous Sulphate 25 Kg Bag China
  • Lime powder 50 Kg Bag Bangladesh
  • PAC 25 Kg Bag China
  • Phosphoric Acid 30 Kg Jar China
  • Polymer 25 Kg Bag China
  • Sodium Bi Sulfite 25 Kg Bag China
  • Sodium Chloride 50 Kg Bag Bangladesh
  • Sodium Hyrosulfite 50 Kg Drum India
  • Sodium Sulphate 50 Kg Bag China

Process includes:
Water Intake—————-Aeration—————–Biological Pretreatment———–Clarifier——————Rapid Sand Filter——————-Chlorination———–Storage——–Distribution Network————Aeration and Biological pretreatment (intrification)

Sludge generated from the clarifier and backwash water is either pumped to the lagoon
to the sludge thickener. The thickened sludge is then discharged to the sludge drying bed
from the lagoon and sludge thickener.


The major priority of these standards and guidelines for sludge management in
Bangladesh are to ensure that human health and the environment are strictly protected from any negative impacts of sludge management.

Bangladesh Water Act 2013 (BWA) is a framework Law to integrate and coordinate the water resources management in the country. The Water Act will establish a new, integrated approach to the protection, improvement and sustainable use of countries rivers, lakes, estuaries, coastal waters and groundwater. The BWA has been passed in the parliament on August. 2013 and received President’s assent on 2 Day of May 2013.

Chemical feeding & mixing

In the flash mixing chamber, mixing of chemical is done through hydraulic mixing.
Chemicals are injected in the weir. Aluminum sulfate, lime, and chlorine are three main chemicals used at SWTP, filtration for post-chlorination (as disinfectant) while the lime is used during the flocculation or in the clear water tank for pH adjustment.
Whereas during the rainy season a low dosage of chlorine is used.

Key measures of the Water Act

  • Right to water
  • Adoption of National Water Policy and National Water Resources Plan
  • Clearance Certificates
  • Water Stressed Areas and Safe Yield
  • Restricting abstraction, Protection Orders and Compliance Order
  • Right to information and false information
  • Water resource protection / pollution control and water quality standards.

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