Mathematical approach of the design and fabrication of a HDPE geomembrane biodigester for the recycling of biodegradable waste into biogas and organic liquid fertilizer

Abstract

The purpose of this work is to design a biodigester with high density polyethylene (HDPE) geomembrane material which will be effective in recycling biodegradable waste and produces both biogas and organic liquid fertilizer. A tubular trapezoidal biodigester is designed, following by the fabrication of a 300 litter’s prototype biodigester with a tarpaulin. After running air and water tightness of the system, quantified biodegradable waste are introduced with and observed for a period of 60 days. Several tests are then conducted on the biodigester to ensure that the system can support the load it will be subjected under normal functioning condition. These tests included shear test, peel test, and air tightness of the system. In order to predict the quantities of elements that can be produce by the biodigester, the nonlinear differential equations of the exchange inside the biodigester are written and solved by using the differential transformed method. Results obtained from the prototype and the HDPE geomembrane biodigester shows that, this design permits the recycle of biodegradable waste from any facility. The biogas obtained was proven to be rich in methane content and the organic liquid fertilizer was also rich in N-P-K fulfilling the basic requirement for plant healthy growth. The HDPE geomembrane biodigester could produce 1,250L of biogas daily at an approximate pressure 1.8 bars which can be approximated to 5 hours minimum bu4rning with a burner of 200L/h.