Technical Support Document for Best Management Practices for Spent Pulping Liquor Management, Spill Prevention, and Control.

摘要

This document presents information for Best Management Practices (BMPs) for bleached papergrade kraft and soda, and papergrade sulfite mills. EPA promulgated these BMPs pursuant to section 304(e), section 307(b) and (c), section 402(a), and section 501(a) of the Clean Water Act (CWA) for mills subject to 40 CFR Part 430, Subpart B - Bleached Papergrade Kraft and Soda, and Subpart E - Papergrade Sulfite. The BMPs establish controls that will reduce the release of toxic, conventional, and nonconventional pollutants to navigable waters. The principal objective of the BMPs is to prevent losses and spills of spent pulping liquor (also referred to as 'black liquor' at kraft mills) from equipment items in pulping liquor service; the secondary objective is to contain, collect, and recover, or otherwise control, spills, losses and intentional liquor diversions that do occur. The BMPs also apply to pulping by-products, such as turpentine and soap, for mills that process these items. Economic operation of kraft and sulfite pulping processes is predicated on the recovery of inorganic pulping liquor chemicals and energy from the organic material dissolved from the wood supply during the pulping processes. However, the nature of pulp screening, washing and pulping liquor recovery systems is such that losses of spent pulping liquors (e.g., kraft black liquor and sulfite red liquor) are routine. Liquor is lost from seals on brownstock washers, pumps and valves in liquor service, knotters and screens, sewered evaporator boil-out solutions, and other intentional liquor diversions during maintenance, startups and shutdowns. Spent pulping liquor is also lost in spills resulting from process upsets, tank overflows, mechanical breakdowns, operator errors, and construction activities.