Value Addition by Recovery of Organic in Effluent Stream and Subsequent Reduction in Effluent Load
Chandrakant Mahalingam
Asst. G.M Special projects (Project Execution)
Deepak Fertilisers and Petrochemicals
Corporation Ltd

Kiran Gole
Asst. G.M Special projects (Process Engg )
Deepak Fertilisers and Petrochemicals
Corporation Ltd

Deepak Fertilisers and Petrochemicals Corporation limited (M/s DFPCL) is one of the leading producer of Industrial chemicals and Fertilisers, multi -product Indian conglomerate with a multi-product portfolio spanning industrial chemicals like Ammonia, Nitric acid, Iso-Propyl Alcohol, Methanol , Technical ammonium nitrate, bulk and specialty fertilisers, also providing farming diagnostics with solutions & mining services.

The major effluent generated in DFPCL complex at Taloja comprises both organic & salt effluents. M/s DFPCL has its own full flesh Effluent treatment plant complying all statutory norms. Continual efforts are imparted to minimise and recycle effluent streams and down the line DFPCL is aiming for Zero liquid discharge at site.

To address salt effluents, dedicated RO plant had been setup, where post treatment, able to recycle water at required purity ~800-1000 m3/day to process plants and this has reduced overall water consumption requirement of site.

The organic rich effluent which is generated from Iso-propyl alcohol plant was one of the major pain area in terms of high COD(Chemical oxygen demand) Load. The Isopropyl alcohol (IPA) formation reaction is highly exothermic & leads to formation of by- products like ethers. These by products are separated in series of distillation units to achieve final IPA purity > 99 .8% wt./wt. The bottom stream from separation column contains 85-88 % (wt ./wt.) water & 12-15 % (wt./wt.) organic which is diverted to Organic Waste Stream (OWS) pit. This bottom stream from Separation Column is having COD ~ 2,50,000 ppm and was a major contributor to organic load on ETP. The said stream was diluted with other effluent stream from IPA plant in Organic waste stream pit & the net COD (Chemical oxygen demand) load at plant battery limit was ~ 25,000 - 35,000 ppm which was sent to Effluent Treatment Plant (ETP) Bio reactor for further COD reduction.

To reduce the organic effluent load to ETP, DFPCL installed a” New Organic recovery column" with an intent of recovering organic at source and sale as value added product to merchant market and intangible gain to have substantial reduction in COD (Chemical oxygen demand) load. With installation of this column and successful commissioning in the month of September 2017, the organic load reduced from previous 12-15% to 0.004% attributing to COD (Chemical oxygen demand) reduction from 2,50,000 ppm to ~50 ppm. As per the intent the recovered Ethers were sold in market for various speciality applications as a value-added product in the kitty of DFPCL.

Image- New Organic Recovery Column

Journey for the Installation of "New Organic Recovery Column"

Step-1 Laboratory trials conducted for organic effluent to check feasibility of organic separation from water (some of the alcohols and ethers forms azeotrope with water at specific concentrations).
Step-2 For separation feasibility Simulation was done with M/s Sulzer, Pune .
Step-3 Market survey for product demand and costing, for enriched organic from effluent was conducted and concluded with demand prognosis and pricing .
Step-4 Organic Recovery Column Project conceptualisation was done. Intent of said project was to recover organic instead of treating organic effluent in conventional way i.e. by biodegradation thereby minimising effluent load on ETP plant and reduce COD (Chemical oxygen demand) by minimising losses at source.
Step-5 Detailed engineering was done by inhouse team.

The column internals were purchased from M/s Sulzer Pune and other hardware from parties of repute. The mechanical design for equipment such as reboiler , condenser, drums etc. was done by M/s Thyssenkrupp, Pune based on heat duties & operating conditions.All project activities had undergone through safety procedures like HAZOP (Hazard and operability study), HIRA (Hazard identification and Risk Analysis) and the compliance were strictly followed during the execution of project. This lead to project completion & commissioning in time with all EHS Safeguards.

The Organic Recovery Column is a commitment of Deepak Fertilisers and Petrochemicals Corporation Limited being a responsible corporate company and is one more feather in various eco-friendly initiatives taken year on year as a part of continual improvements in terms of Environment aspects and in the true sense a CSR initiative.