Anaerobic digestion (AD) of sludge at wastewater treatment plants can benefit from addition of essential trace metals such as iron, nickel and cobalt to increase biogas production for utilization in combined heat and power systems, fed into natural gas pipelines or as a vehicle fuel. This study evaluated the impact and benefits of Ni/Co and olivine addition to the digester at mesophilic temperatures. These additions supplement previously reported research in which iron-rich olivine (MgSiO4) was added to sequester CO2 in-situ during batch AD of sludge. Trace element addition has been shown to stimulate and stabilize biogas production and have a synergistic effect on the mineral carbonation process. AD with 5% w/v olivine and 1.5 mg/L Ni/Co addition had a 17.3% increase in methane volume, a 6% increase in initial exponential methane production rate and a 56% increase in methane yield (mL CH4/g CODdegraded) compared to the control due to synergistic trace element and olivine addition while maintaining 17.7% CO2 sequestration from olivine addition. Both first-order kinetic modeling and response surface methodology modeling confirmed the combined benefit of the trace elements and olivine addition. These results were significantly higher than previously reported results with olivine addition alone [1] (Linville et al., 2016).

Areas of Focus: Energy Markets
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Energy Markets
Well-functioning markets are essential for providing access to reliable, affordable energy. EPIC research is uncovering the policies, prices and information needed to help energy markets work efficiently.
Energy Efficiency
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Energy Efficiency
Improving energy efficiency is lauded as a promising way reduce emissions and lower energy costs. Yet, a robust body of research demonstrates that not all efficiency investments deliver. EPIC faculty...
Environment
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Environment
Producing and using energy damages people’s health and the environment. EPIC research is quantifying the social costs of energy choices and uncovering policies that help protect health while facilitating growth.