Case Study-Square

Objective: Protect the UV-unit and the membranes from ferric and bio fouling

Company Square Pharmaceuticals
Location Gazipur, Bangladesh
Year 2014
Description Pre-treatment for Reverse Osmosis and UV
Goal Protect the UV-unit and the membranes from ferric and bio fouling
Capacity 60m3/hour
Water Source Ground Water

The Problems:

Square Pharmaceuticals, the largest pharmaceutical company in Bangladesh, had an existing pretreatment to a Reverse Osmosis and UV system, which included:

  • Multimedia filter
  • Activated Carbon Column
  • 5 micron Cartridge Filter

The main problem was Pseudomonas bacteria growth in sand and carbon filters.

Parameter Existing Value Required Value
Fe (mg/L) 10 <0.3
As (ug/L) 8-10 <5
Turbidity (NTU) upto 10 <3
BOD (PPM) 2000 <10
Pseudomonas bacteria (units/100 ml) >1000 <1

Technical Solution:

The existing pre-treatment was replaced with the following system:

  • Aeration of the ground water with a detention time of two (2) hours using Air Diffusers. Aeration capacity: 60 m3/hr
  • Pre-coagulation of the water with Poly Aluminum Chloride (PAC), followed by mixing the chemical in a Zeta Potential Mixer (ZPM)
  • Filtration with a pressure filter using Actived Filter Media (AFM®) Grade 1, at 5 meters/hour filtration velocity
  • There is also a DryOx treatment once a week to deal with bacteria in the aeration tanks, and on filter shell / laterals.


Parameter Existing Value Required Value After Treatment
Fe (mg/L) 10 <0.3 <0.03
As (ug/L) 8-10 <5 3
Turbidity (NTU) upto 10 3 <0.6
Pseudomonas bacteria (units/100 ml) >1000 <1 <1

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