Sustainable ammonia resource recovery from landfill leachate by solar-driven modified direct contact membrane distillation

Abstract

The rapid world population growth and economic development have been increasing the pressure on natural resources, especially nutrients. Efforts are being made to recycle the key elements of resources that are normally wasted. In this context, ammonia recovery is of special economic interest, since it is one of the main nutrients in the fertilizer market. Landfill leachate (LFL) stands out as an ammonia-rich effluent widely produced worldwide. Thus, the aim of this study was to assess the performance of a solar-driven modified direct contact membrane distillation (M-DCMD) in the recovery of ammonia from LFL. Operational conditions (LFL pH and temperature (T), and concentration of the absorbing H2SO4 solution) were optimized and the maximum critical point (pH 10.8, T = 43 °C, and H2SO4 concentration 0.18 mol L−1) allowed for 98% removal and 59% recovery of ammonia. 1.5 kg of ammonia could be recovery from each 1 m3 of treated effluent, a monthly production of 21 tons of ammonia or 93.5 tons of ammonia sulphate. The obtained ammonium sulphate solution can be used as fertilizer. The membrane distillation system using solar heating demonstrated better economic performance since there is an economy with energy due to solar thermal energy being converted into electrical energy. This fact reduces the unit OPEX value and, consequently decrease the leachate total treatment cost, which was estimated at US$7.52/m3 of leachate treated.