Papers and Reports

The 36-year-old Secondary Treatment regulation (40 CFR 133.102) has little relevance to wastewater treatment facilities that must meet stringent nitrogen and phosphorus limits. Advanced wastewater treatment facilities consistently reduce effluent 5-day biochemical oxygen demand (BoD) and total suspended solids (TSS) concentrations to less than 30 mg/L. However, permit writers lack the flexibility to exclude requirements for these parameters from national Pollutant Discharge Elimination System (nPDES) permits. A new regulatory framework is needed for the following practical, legal, and financial reasons: o When a treatment facility meets stringent nutrient limits, it also meets BoD, carbonaceous BoD (cBoD), and TSS limits because of design and operating requirements. Including technology-based limits in nPDES permits for nutrient-removal facilities does not benefit the environment, scientists, regulators, or permittees. 0 Redundant permit limits subject permittees to double or even triple legal jeopardy. If a plant fails to meet a 30-mg/L cBoD effluent limit, it also will fail to meet a 5.0-mg/L ammonia–nitrogen limit. If the plant fails to meet a 30-mg/L TSS limit, it also will fail to meet a 0.5-mg/L total phosphorus limit. In both cases, one event would prompt two (or more) violations. o Sampling and analyzing BoD, cBoD, and TSS every day or even 3 days a week is not an effective use of valuable laboratory resources. Such resources could be better used for process control. Eliminating BoD and TSS limits for these facilities would not affect receiving-water quality, but it would reduce costly, unnecessary monitoring.