Valorizing municipal solid waste: Waste to energy and activated carbons for water treatment via pyrolysis

Globally, as societies urbanize and demand for energy increases, the need to manage mounting quantities of municipal solid waste (MSW), produce renewable energy, and insure clean water supplies becomes more pressing each year. These issues could be addressed by integrating pyrolysis of MSW to recover liquid and gaseous biofuels and a solid biochar, with CO2 activation of the latter to produce activated biochars for water treatment. This potential conversion pathway is experimentally demonstrated by pyrolyzing a model MSW stream at 408 °C, the peak mass loss rate pyrolysis temperature and compared to pyrolysis at 900 °C. As pyrolysis temperature increases, we see conversion of plastic intermediaries into paraffins and polycyclic aromatic compounds, though the desirable gas components (methane, hydrogen, carbon monoxide) of the pyrolysis gas increase substantially. The CO2 activated biochars (activated at 600 °C and 900 °C) show surface areas over 300 m2/g, with the lower pyrolysis temperature and higher activation temperature yielding the highest areas. Adsorption experiments were performed with methylene blue to determine the ability of the activated MSW-biochar to remove organic pollutants from water. Adsorption is well described by the Langmuir isotherm, with equilibrium adsorption capacities upwards of 250 mgdye/g for all activated biochars.