Hyderabad: A team of scientists from the city-based CSIR-Indian Institute of Chemical Technology (CSIR-IICT), designed a unique effluent treatment plant for industrial aroma chemicals based on a high rejection hyperfiltration membrane technology.
Dr. S. Sridhar, Chief Scientist, and Sugali Chandra Sekhar, Principal Investigator & Senior Scientist, from the Membrane Separations Laboratory, designed the plant for the U.K. Aromatics Pvt. Ltd, Boisar, Maharashtra.
The effluent is a condensate coming from a multiple-effect evaporator (MEE).
It contains considerable content of total dissolved solids (TDS), turbidity, and color besides high chemical oxygen demand (COD) levels due to the presence of significant concentrations of aroma chemicals such as esters, flavors, and perfumes with smaller concentrations of toluene and cyclohexane solvents used in azeotropic distillation for isolation of the esters.
The membrane is specifically developed at CSIR-IICT from hydrophilized polyamide which is more hydrophilic, chemically inert, with a thicker selective skin layer as compared to commercial membranes.
Operation at a high pressure of > 25 atm provides greater impurity rejection, equivalent to that of seawater RO membranes. Dr. Sridhar stated that the pilot plant has an operational flexibility across a permeate capacity of 1000 – 2000 Lit/hr and removes TDS from an initial value of 1500 to 2500 ppm in the effluent feed to less than 100 ppm in the permeate water. A TDS rejection of more than 95% with an average COD removal of 75% is achieved at a permeate water recovery of 80%.
The pre-treatment assembly comprises coagulation, bag filtration, deep bed sand and activated carbon column, micron cartridge filter, anti-scalant dosing, and pH correction. The 20% reject stream is recycled to the MEE for the next operational cycle to ensure zero liquid discharge (ZLD) as per PCB regulations.
Dr. Sridhar stated that the capital expenditure for installing the plant is Rs 12 lakhs, and the operating expenses is approximately 10 to 12 paise per litre of effluent treated. He added that 200 MT of effluent has been treated till date at the company.