Lab Scale Analysis of Anaerobically Digested Municipal Wastewater Treatment

Finding alternative sources of energy for the growing world’s demand is a challenging task being considered by many scientists and engineers. Various types of renewable energy alternatives are being investigated by researchers around the world. In addition to their capacity for nutrient, metal and pharmaceutical and personal care product contaminant removal from wastewater, the abundance of duckweed (i.e., Lemna and Wolfia sp.) in wetlands and wastewater lagoons, and their rapid growth and need for biomass harvesting suggests their potential as an inexpensive source of biomass for Biofuel production. Two lab-scales, 10 L anaerobic digesters initially seeded with municipal wastewater digester sludge were constructed, maintained and monitored over the course of more than 24 months using duckweed as the sole carbon source to evaluate its effectiveness as biogas feedstock. The pH, gas production rate and gas composition were measured on a daily basis. The results from these measurements show that the stabilization of harvested duckweed via anaerobic digestion also represents an efficient means of Biofuel production in the form of methane gas. Methane production, solids and COD stabilization, and gas composition results from the duckweed fed anaerobic digesters are discussed in detail in this paper. These results were used to determine potential energy production from biomass harvesting for the control of total P from a municipal wastewater treatment lagoon in Northern Utah