Treatment of Sewage Waste for the Production of Methanol, Purified Water, and Fertilizer via Hydrolysis-Gasification-Methanol Synthesis Pathway

Our project evaluates the technical and economic feasibility of producing methanol from municipal wastewater, demonstrating how an abundant source of wastewater can be transformed into valuable fuels and co-products. Methanol is a clean-burning alternative fuel that generates lower greenhouse gas emissions than gasoline or diesel and can be produced from renewable feedstocks. Municipal sewage offers a consistent, local biomass source; for this design, we will source a portion of New Brunswick's overall 15 million kg of sewage produced per day. The proposed system integrates dehydration, ultrafiltration, sedimentation, gasification [C6H10O5 + H2O → 6CO + 6H2,], electrolysis [H2O → ½O2 + H2], and methanol synthesis [CO + 2H2 → CH3OH] into a continuous process which produces methanol, purified water, and fertilizer. While methanol is our primary desired product, intended to power off-grid communities, our process is financially sustained through the production of purified water. Fertilizer is a tertiary product. Carbon efficiency was found to be around 80% on the basis of cellulose converted to methanol, demonstrating an excellent recovery of useful carbon from waste. Using a feed basis of 500,000 kg of sewage a day, our process extracts approximately 181 kg of methanol. This allows for the daily generation of roughly 1,150 kWh of energy, enough to power over 75 off-grid homes. Using the same feed basis, daily operating costs for our plant would reach slightly over $48,000/day while our revenue would be over $73,000/day meaning our plant would be able to generate $25,000/day or around $9,000,000/year. This represents about $18 generated in revenue for each kg of wastewater processed. Overall, our process allows for the effective conversion of otherwise harmful pollutants into useful products such as methanol, purified water, and fertilizer. This reduces the environmental impact of sewage waste while simultaneously providing a pathway for sustainable resource recovery and generating a considerable profit.