Testing and implementation of an advanced wastewater reclamation and recycling system in a major petrochemical plant

Abstract

This paper describes a major water reclamation project utilizing a membrane-based advanced treatment system to recover organic wastewater treatment system (OWWTS) effluent and cooling tower blowdown (CTB) for reuse in a large petrochemical plant in the Far East. The treatment process train includes chemical oxidation, dual media filtration (DMF), granular activated carbon (GAC) adsorption, ultrafiltration (UF), ultraviolet (UV) disinfection, reverse osmosis (RO), and degasification. The reclaimed pure water, which has a conductivity <240 μS/cm, is used as makeup water for the plant's ion exchange deionization (DI) system. Using this water for DI system makeup saves more than 80% of the expensive DI system regeneration cost and drastically reduces water purchase cost and wastewater discharge fees. The treatment system was tested on a pilot-scale (110 m3/d) basis for nearly 18 months. Various flux rates for UF/RO and accelerated biofouling tests for the hollow-fiber UF membranes were conducted. With excellent pretreatment, the thin film composite polyamide RO membranes were relatively clean and non-fouling after more than 2,000 hours of operation without chemical cleaning. A total overall water recovery of 73.6% was achieved consistently in the pilot plant. A full-scale plant treating an influent blended flow of 9,000 m3/d and recovering 6,600 m3/d of pure water has been constructed at the petrochemical plant. System startup and commissioning are expected to be completed in September 1999. The treatment system may be expandable by 50% with minimal facility addition in the future.