Energy, economic and environmental feasibility of energy recovery from wastewater treatment plants in mountainous areas: a case study of Gharyan City – Libya

Abstract

Wastewater treatment facilities at high places can give chances for renewable and sustainable energy generation by putting hydroelectric turbines at the input and drain channels of wastewater treatment plants, and they can also use the sludge generated during the treatment process to make biogas, which can be used to generate power. The purified water is subsequently used to irrigate decorative plants along highways, in gardens, and in woods. The fermentation wastes are utilized as organic fertilizer to improve agricultural soil quality. At the Gharyan sewage station, a hybrid system consisting of a hydroelectric station and an electric generator powered by biogas is proposed in this research. This is because the city is distinguished by its high location, which is approximately 713 m above sea level. The results showed that the proposed system would provide an electric power of 490 kW, which is sufficient to cover 87.5% of the electrical energy consumption of the station. The amount of treated water is approximately 13,000 m3/day, and the amount of organic fertilizer is about 17 tons/day. The investment value is anticipated to be around $1,478,000, , while the cost of producing a unit of electric energy is expected to be 2.83 ¢/kWh. This system's yearly net profit is predicted to be $307,765. The capital's recovery period is anticipated to be 3.44 years. The planned hybrid system will limit the discharge of an estimated 1,886 tons of CO2 gas each year.