The influence of spent household batteries to the organic fraction of municipal solid wastes during composting

The objective of this work was to investigate the potential transfer of 9 heavy metals from spent household batteries (zinc–carbon and alkaline–manganese batteries) to the organic fraction of municipal solid wastes during active composting. Six runs were performed including one control and 2 replications. Eleven types of alkaline and non-alkaline batteries were added at 3 different levels to the organic fraction of municipal solid wastes, namely at percentages equal to 0.98% w/w (low), 5.2% w/w (medium) and 10.6% w/w (high). Experiments were performed in 230 l insulated plastic aerobic bioreactors under a dynamic air flow regime for up to 60 days. Iron, copper and nickel masses contained in the organic fraction of the wastes were found significantly higher in the high level runs compared to the corresponding masses in the control. No metal transfer was obtained in the low and medium level runs. Metal mass balance closures ranged from 51% to 176%. Metals' concentrations in the leachates were below 10 mg l−1 for most metals, except iron, while an increasing concentration trend versus time was measured in the leachates of the high level runs. In all cases, the contents of 5 regulated heavy metals in all end products were below the Hellenic limits.

Research highlights
► Simulated MSW were composted with spent household batteries at variable contents.
► Fe, Cu and Ni transferred from batteries to the MSW at the high spike level.
► Alkaline batteries had a greater mass reduction compared to non-alkaline batteries.
► Leachate metal contents were below the limits for non-hazardous wastes.
► Metals’ mass balance closures were within acceptable ranges.