ALTERNATIVE TREATMENT STRATEGY FOR A HIGH STRENGTH PHARMACEUTICAL WASTEWATER

In August 1999, a pharmaceutical manufacturer initiated a wastewater management project for its batch chemical synthesis plant in the southeastern region of the United States (Facility). The goal was to construct a wastewater pretreatment system that would ensure compliance with the Effluent Guidelines, while providing the flexibility to handle variable flows, loads, and regulated solvent compositions. In addition, the new pretreatment system would have to minimize additional hazardous air pollutant (HAP) emissions to allow the Facility to maintain its MACT synthetic minor status.Two treatment schemes were chosen for pilot testing: (1) removal of volatile organic compounds (VOCs) in an air stripper followed by biological treatment in a sequencing batch reactor (SBR) with diffused aeration and, (2) biological treatment in a sequencing batch reactor (SBR) with high purity oxygen (HPO) aeration.Pilot testing was conducted for a period of 10 months using a trailer-mounted SBR pilot unit. Testing of the air stripper plus diffused air SBR was conducted during the first four months. The SBR pilot unit was operated during the following six months as a single-stage HPO SBR system. Influent and effluent samples were collected and analyzed for selected VOCs and conventional wastewater parameters. Comparative testing of the HPO and diffused air systems was conducted using measured spike addition of VOCs to examine the pilot unit's response to changes in influent concentrations. Pilot unit influent, effluent, and off-gas samples were collected during each test for VOC analysis. The test results were used to perform system mass balances.The pilot testing results demonstrated that the both treatment alternatives would comply with the EG criteria. Influent toluene concentrations of 50 to 100 ppm were routinely reduced to below the method detection level of 0.005 ppm. The testing further showed that the HPO biotreatment pilot system provided high VOC removals via biodegradation and very low HAP emissions. Approximately 0.3 percent of the influent toluene load was emitted to the atmosphere with the high purity oxygen system versus 12.6 percent with diffused aeration.