The Chemplast unit has multiple waste streams, primary source being the Caustic soda and PVC monomer plants. The combined waste water is heavy in contaminants like oil & grease, volatile organic compounds, and has a relatively high COD and TDS of about 10000 mg/l. The water is potentially bio-active and also has a high fouling and scaling tendency.
As an environmentally conscious corporate entity, Chemplast's primary intent was to treat the rejects from the Reverse Omosis system by Evaporation / Crystallization so as to achieve Zero Liquid Discharge (ZLD). They also wished to process the combined effluent to recycle the treated soft water for cooling tower make-up and other usages in the plant.
Wastewater rich in BOD, COD, oil & grease etc. leads to frequent fouling due to biological and organic compounds in a Reverse Osmosis membrane system, and is thus difficult to treat with any of the conventional effluent recycle & ZLD technologies.
For Chemplast, Aquatech designed a ZLD System based on the HERO™ (High Efficiency Reverse Osmosis) technology, an advanced RO process, wherein the RO section is operated in a high pH environment. The major parameters affecting the RO system operation are kept within limits enabling high (water) recoveries in the range of 88 – 90%.