Evaluation of heavy metal leaching under simulated disposal conditions and formulation of strategies for handling solar panel waste.

ABSTRACT

With the steady growth in the worldwide solar installed capacity, there is an immediate concern about the fate of the solar panels at the end of their life. Solar panel waste is often disposed of indiscriminately, exposing the environment to chemical hazards. The major objective of the current study was to evaluate the leaching potential of the polycrystalline solar panel waste under different simulated disposal conditions through toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP) and pH static leaching procedure tests. Moreover, the study evaluates the effects of ageing and the breakage of the Glass Laminate Encapsulation (GLE) of solar panels on their leaching potential. Among the metals studied (silver (Ag), aluminium (Al), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb), and zinc (Zn)), the concentrations of Pb were as high as 9.3 mg/L, 1.4 mg/L, 6.7 mg/L in the TCLP, SPLP, and pH static test respectively. This indicated the hazardous nature of the waste with leaching potential of Pb above the permissible limits stipulated by various regulatory bodies. The presence of GLE reduced the mobility of Pb by a factor of 4.1-8.8 in the TCLP test, thereby rendering the waste as non-hazardous for its disposal in a landfill. However, the indiscriminate disposal of solar panel waste in the natural environment as simulated by the SPLP test indicated its harmful nature irrespective of the physical condition. Ageing of the solar panels before disposal and acidic pH conditions also positively influenced the leaching potential of the selected metals subjected to their reactivity and the accessibility of internal layers of waste to the leaching solution. Strategies such as extended producer responsibilty, advance-recycling fee, and incentivizing the recycling industry will lead to both economic benefit creation and effective waste management of this waste stream.