Waste treatment with limestone

Our research shows that in terms of effectiveness and economics the most promising environmental control technology (ECT) for dealing with high-sulfur coal wastes from the United States consists of sequential slurry coating of the waste with lime and limestone. In the eonfiguration tested (0.35% lime and 1.1% limestone), this technique controlled the waste effluent quality for 4 months. The effluent pH remained between 7.3 and 7.6, and the trace element concentrations (aluminium, calcium, manganese, iron, cobalt, nickel, and copper) were within acceptable limits. This treatment offers a potentially viable approach disposal of these wastes. 

Some groundwater plumes contaminated by dissolved wastes can be treated by a permeable bed of material placed in a trench through which the groundwater must flow. Limestone in a permeable bed neutralizes acid and precipitates some heavy metal hydroxides or carbonates. Synthetic ion exchange resins can be used in a permeable bed to retain heavy metals and even some anionic species, although competition with ionic species present naturally in the groundwater can reduce the effectiveness of this treatment method. 

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