Century Pulp & Paper, Lalkuan, Uttar Pradesh, India

Rayon Grade Pulp Unit Wastewater Treatment System

Century Pulp & Paper (CPP) is a very large unit belonging to the B.K.Birla Group and is located in the Terai belt of Nainital (Hill Station) of Uttar Pradesh. At this unit, CPP have a Rayon Grade Pulp manufacturing section which generates a low pH, high BOD, high COD wastewater effluent stream called Prehydralisate Liquor (PH Liquor).

Initially, CPP was treating this PH Liquor wastewater stream in open anaerobic lagoons in which 50 - 60% BOD reductions were achieved. In the process, the biogas generated by the anaerobic digestion was escaping into atmosphere - wasting a potential energy source as well as emitting potent greenhouse gases. Moreover, the high organic pollutant concentration remaining in the wastewater stream was overloading the subsequent Aerobic Activated Sludge Treatment System.

In order to rectify some of the problems posed by the existing treatment system, UEM proposed a Low Rate Anaerobic Digester System to treat the PH Liquor Stream. This system achieved a 90% reduction in BOD and a 70% reduction in COD while simultaneously generating and recovering biogas. The advantages of this Anaerobic System included high organic pollutant reductions (thus less loading and power consumption in subsequent Aerobic Stage) and the use of biogas as renewable non-conventional source of energy. The system was designed to treat a flow of 340 M3/day, BOD of 35,000 mg/l and COD of 70,000 mg/l, and produce an estimated 8,830 M3/day of biogas with an approximate heating value of 5,000 KCal/M3. This job has been completed successfully by UEM.