What is an appropriate method to use for reactive sulfide? The method that was described in Chapter 7 of SW-846 (220.127.116.11) no longer exists.
Reactive sulfide, formerly described in SW‐846 Section 18.104.22.168, referred to those sulfide species that could form hydrogen sulfide gas under mildly acidic conditions. In July 1985, EPA issued interim guidance describing certain threshold levels for cyanide‐ and sulfide‐bearing wastes and laboratory methods for evaluating such wastes. In April 1998, EPA withdrew the July 1985 guidance. Therefore, EPA does not recommend use of the interim threshold levels or methods to determine if a waste is hazardous based on the characteristic of reactivity. Sections 7.3.3 and 7.3.4 were amended by the Methods Innovation Rule (SW‐846 Final Update IIIB) published in the Federal Register, June 14, 2005 (Volume 70, Number 113), to withdraw specific reference to methodologies and threshold concentration levels.
However, the reactivity characteristic for waste must still be evaluated; 40 CFR §261.23 includes 8 different properties of a waste that would trigger the designation as “hazardous” based on the characteristic of reactivity. A waste is a reactive hazardous waste if it exhibits one or more of those properties. The regulations do not require specific test methods for any of these properties. Therefore, generators must use waste knowledge to determine if their waste exhibits the characteristic of reactivity. According to property (5) under §261.23, a waste is hazardous if it is a cyanide‐ or sulfide‐bearing waste which generates toxic gases or vapors at a quantity sufficient to present a health danger. It is the responsibility of the generator and their analytical laboratory to evaluate the waste for the reactivity characteristic, as EPA no longer specifies a procedure for this evaluation.