Design and optimization of a novel intestinal reactor to efficiently improve organic waste uniformity and solid content in high solid organic waste anaerobic digestion

Abstract

High solid anaerobic digestion (HSAD) technology, a major treatment method for solid organic waste. Existing HSAD reactors comprise primarily vertical and horizontal reactors. Vertical reactors use high-pressure pneumatic stirring, which has high energy consumption and poor stirring performance. Horizontal reactors use long-uniaxial mechanical stirring, which occupies large land areas and has high strength requirements for stirring shaft material. In addition, during the operation of the two reactor types, the continuous liquefaction of the solid waste produces solid-liquid stratification, thus affecting mixing effects and decreasing the reactor volume rate. To solve the above problems, we designed a new simulated intestinal anaerobic digestion reactor with a natural solid-liquid separation system, short-axis mechanical stirring, and a stirring blade optimized through CFD. Use of the solid-liquid separation system increased the solid content in the reactor by 44%–55%. The operation results indicated that the homogenization of the solid waste with the optimal stirring blade was more than 50% greater than that of a conventional vertical reactor. The intestinal reactor solves the problems of poor uniformity and solid content decrease during anaerobic digestion in traditional HSAD, decreases the strength requirements for stirring shaft material, and has potential to increase urban waste treatment capacity.