Case Study: Square

Project ID:

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
Capacity: 60 m3/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.

Items   Existing Values Required Value
Fe (mg/L) 10 <0.3
As (ug/L) 8-10 < 5
Turbidity (NTU) Up to 10 < 3
(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 Dryden Aqua Air Diffusers. Aeration capacity: 60 m3/hr
  • Pre-coagulation of the water with Poly Aluminum Chloride (PAC), followed by mixing the chemical in a Dryden Aqua’s Zeta Potential Mixer (ZPM)
  • Filtration with a pressure filter using Dryden Aqua Actived Filter Media (AFM®) Grade 1, at 5 meters/hour filtration velocity
  • There is also a Dryden Aqua DryOx treatment once a week to deal with bacteria in the aeration tanks, and on filter shell / laterals.


Items Existing Values Required Values After Treatment  
Fe (mg/L) 10 < 0.3 0.03
As (ug/L) 8-10 < 5 3 check2
Turbidity (NTU) Up to 10 <3 <0.6 check2
Pseudomonas bacteria
(units/100 ml)
> 1000 < 1 < 1 check2


“...implementation of the Dryden Aqua AFM® systems has
provided us with significant performance benefits…”

“…we will continue to work with Dryden Aqua and implement
AFM® systems for all our manufacturing facilities…”

“…we are now committed to a multi-million dollar effluent
treatment program with Dryden Aqua as one of our key

Dryden Aqua’s Deliverables: