Date of Award

May 2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Environmental Engineering and Earth Sciences

Committee Member

Annick Anctil

Committee Member

Cindy Lee

Committee Member

Marian Kennedy

Abstract

As the use of photovoltaic (PV) modules and batteries rapidly increases to meet the growing worldwide energy demand, so does the waste stream of these products at end-of-life (EOL). In locations without sufficient recycling laws or take-back programs, these products could be landfilled with municipal solid waste (MSW). To determine the potential effects from landfill disposal of these products, metal leaching from PV modules and two types of batteries (Li-ion and nickel metal hydride (NiMH)) was studied using the regulatory Toxicity Characteristic Leaching Procedure (TCLP) as well as batch leaching and outdoor column testing. The data from the leaching tests were used to build waste scenarios utilizing life cycle assessment (LCA) software.

The experimental data collected from the batch leaching tests and outdoor columns in Chapters 4, 5, and 7 demonstrate the complexity of characterizing PV and battery e-waste and developing EOL regulations and procedures that are applicable to each type of e-waste. In Chapter 4, the TCLP, the California Waste Extraction Test, and modified versions of both were performed on a multi-crystalline silicon module and cells and a copper indium gallium diselenide (CIGS) module. Metal leachate concentrations varied with changes in testing parameters, which raises doubt if regulatory methods can adequately characterize PV modules. In Chapter 5, the TCLP, microwave digestions, and batch leaching tests in two simulated leachates sampled over a period of 100 days were conducted for seven types of Li-ion batteries, one type of NiMH battery, and two types of PV modules. Additionally, one product of each type (Li-ion battery, NiMH battery, and PV module) was mixed with MSW components and a simulated landfill leachate to compare leaching in a more realistic waste matrix to the batch leaching tests. Results from the TCLP showed that one of the two PV modules and three of the eight batteries would be classified as hazardous waste in the US. For the batch tests with e-waste mixed with MSW, both lower (Pb and Hg) and higher (Co and Ni) metal leachate concentrations were observed than for the batch tests without MSW. Chapter 6 describes the design and build of the lysimeter test bed, which is utilized for column experiments in Chapter 7. Three columns were built to simulate the conditions within a bioreactor solid waste landfill and were subjected to outdoor temperature fluctuations. For the column with the c-Si module pieces, Pb was not detected in the leachate even though Pb was observed in the previous tests for this product described in Chapter 5. For the column with the NiMH power tool battery, Co, Cu, and Ni were measured in the leachate, but As, Hg, Pb, and Zn were not detected in the column leachate samples even though they were observed in the previous tests. For the column with the Li-ion laptop battery, Co, Cu, and Ni were measured in the leachate samples and were also found in the previous batch tests. Although As, Hg, and Pb were not found in the leachate samples, the other soluble and potentially mobile metals, including Co, Cu, and Ni, found in the leachate could be of concern in an improperly managed landfill and could cause contamination of soils and aquifers.

In Chapter 8, the data gathered from the leaching tests were used to build EOL scenarios for metal emissions to groundwater using LCA software and characterization methods to determine potential human and eco-toxicity effects. Additionally, composition data from disassembly and digestions were used to build assemblies of the PV module and Li-ion and NiMH batteries. The results showed that the worst-case EOL scenario effects exceeded those of the assemblies of each product, and with notable effects for the other scenarios, the inclusion of the potential for EOL metal leaching is merited in LCAs of these products. Appropriate characterization tools and techniques to ensure adequate protection of the environment are necessary to avoid a growing e-waste problem while simultaneously promoting renewable energy sources.

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