Small arms range lead management issues: Activated carbon, molecular sieves (5A and 13X), and naturally occurring zeolites as lead adsorbents

Abstract

AbstractLead in storm water runoff from small arms ranges (SAR) at Barksdale AFB, LA, has exceeded Louisiana Pollution Discharge Elimination System (LPDES) limits. Range managers need cost‐effective ways to manage soluble, and clay colloid adsorbed, lead species. Two steps were suggested and undertaken to try to control soluble lead species. First, the soluble lead species were immobilized by adding phosphorous pentoxide (P2O5) to the top soil and mixing it in. Before treatment the combined range mean total lead was 865 μg l−1 from Jun 2001 to Mar 2002 at a pH = 7.1. After treatment the M‐16 SAR mean total lead from Oct 25 to Dec 5, 2002, in the soil being tested, was 59 μg l−1 at a pH = 7.4. Second, low‐cost adsorbents were investigated to “capture” lead ions in storm water before discharge to a receiving stream. Therefore, batch adsorption and kinetic studies were conducted to compare and evaluate different types of adsorbents for lead removal from aqueous media. Adsorbent materials such as activated carbon and naturally occurring zeolites (clinoptilolite and chabazite) are potential point‐of‐use materials for mitigating waste water runoff. Molecular sieves (13X and 5A) were selected because they provide a basis for comparison with previous studies and represent well‐characterized materials. The relative rate for lead adsorption was: 13X > chabazite > clinoptilolite > 5A > activated carbon. This article describes how environmental managers researched and identified a corrective action and developed a maintenance plan to bring the installation SAR into regulatory compliance. © 2003 Wiley Periodicals, Inc.