Feasibility of EPA's Advanced Technology Tiers, 1997 Environmental Conference Proceedings

An integral part of EPA’s long-term goals, as declared in the proposed Cluster Rule, is an industry committed to continuous environmental improvement - an industry which aggressively pursues research to identify technologies that reduce and ultimately eliminate pollutant discharges. Implementation of pollution prevention technologies by moving towards closed-loop process operation, would increase reuse of recoverable materials and energy while reducing use of raw materials and generation of air emissions and hazardous and non-hazardous wastes. The proposed Cluster Rule establishes an incentive program consisting of three “Tiers” of BAT limitations beyond the baseline BAT. The most Advanced Technology Tier (III) limits AOX to 0,05 kg/kkg and the total flow of pulping and evaporator condensates and bleach plant wastewater to 5m 3 /kkg. This presentation first documents the current status of the “Advanced Technologies” in the industry and the discharges from “Advanced Technology” mills in the Nordic Countries and in North America. Several new mills have established effluent flow goals comparable to the Tier II and III levels, but in practice these levels have proven difficult to achieve. Plugging and scaling of equipment, as well as corrosion, have been major concerns. Recovery of bleach plant effluents disturbs the chemical balance and causes an increase in solid waste discharge, which is being experienced in many mills attempting closed cycle operation. Internal regeneration and reuse of bleach chemicals to reduce the waste is technically known, but not used in practice yet. Processes for chloride, potassium, calcium and other non-process element removal all result in increased solid waste. The feasibility of using the advanced technologies in a base mill employing baseline BAT, Option A, is evaluated for the three technology Tiers defined by EPA. The basis for the evaluation is the studies undertaken by the Authors’ organization in 1993 - 1996 on low effluent and closed loop bleached kraft mill concepts /1,2,3/. The study shows that conversion of an existing mill to meet Tier I level requirements is technically feasible and may be an attractive option when taking into account the cost benefits and the incentives offered. Some of the Tier II and III technologies, such as the pulping and bleaching technologies are proven in the industry. Some others, such as reduction of the process effluent flow to 10 (Tier II) or 5 (Tier III) m 3 /ADt have not yet been proven in practice. The costs and risks related to these technologies are not...