Nano-Filtration Membrane For COD & TDS Reduction
Old Effluent Treatment Plant & RO Plant
Generated effluent treated in conservative ETP of capacity pf 900 KLD. ETP treated water feeds in RO plant, where feed parameter is COD 300 ppm & TDS < 5000 ppm. (In general TDS value is low around 2000-2200 ppm, In worst case TDS may increase up to 5000 ppm TDS ) RO plant design on 65% recovery. So, final reject generated around 300-320 KLD.
Challenges
Factory discharge limit is 120 KLD to CETP and RO reject qty is 300-320 KLD. SO, RO reject water needs to reduce with further treatment. General parameter of RO reject is COD 800 ppm and TDS < 6000 ppm. Along with this, it was difficult to allocate more space to expand the existing ETP for further treatment.
Due to high COD value in RO reject water , second stage RO plant was not possible, So, We provided Nano-filtration membrane technology for further treatment.
Solution With Nano-Filtration Membrane Technology
With the help of Nano-Filtration membrane technology RO reject water can treat further to reduce final reject volume. So, total reject water reduce to 110 KLD from 320 KLD after NF plant. Parameters limit of discharge water is < 3000 ppm COD and flexible in terms of TDS. So, issue resolved with the help of NF plant as it is use limited space and match their discharge qty limit.
Water quality of Nano-Filtration membrane permeate as below:
| PARAMETER | NF FEED | NF PERMEATE |
|---|---|---|
| COD (ppm) | 800 | < 50 |
| TDS (ppm) | 4500 | < 500 |
| TSS (ppm) | 10 | – |
| NF Plant Capacity | 416 KLD | |
| System Recovery | 65% | |
| CIP Frequency | DAILY | |
| Membrane | TORAY make CSM NF | |
Summary & Benefit
- Purpose fulfilled with after adding just Nano-Filtration technology in existing ETP scheme.
- In case of high TDS like 16500 ppm, NF treated water needs feed in RO plant for further treatment, In general case where NF feed TDS is 6000-8000 ppm, client can use NF treated water directly for cleaning and washing.
- Lower osmotic pressure required compare to RO & achieve high recovery.
- Best technology to remove diverse MW organic mixtures which is cause the COD in effluent.
- Nano-Filtration membranes are having hydrophobic surface, which is antifouling in nature. That’s why it can easily remove surface chocking.
- Due to current scenario of water pollution issue, they are planning to upgrade ETP to ZLD(Zero Liquid Discharge), for that might ad one more NF system to further concentrate the effluent and feed in MEE.