Design, Fabrication and Performance Evaluation of The Dewatering Machine for Bio-Digestate

Abstract

The report entitled “DESIGN, FABRICATION AND TESTING OF DEWATERING MACHINE FOR BIODIGESTATE” is intended to modify the design of dewatering machine fabricated by Sherpa et al., 2017. and modify the design and fabricate and conduct performance evaluation. In Nepal there is a huge need for the fertilizer and dewatering of the bio digested from the biogas could be an alternative for replacement of the imported chemical fertilizers with the organic fertilizer. The dewatering machine is modified based on the literature review, recommendation from the previous studies and consultation with the experts. The design has been made in the “SOLIDWORKS” software. The modifications were fabricated at GRIT engineering works pvt ltd. The slurry for the testing was obtained from Organic farm house, Kapan. The major modifications were 5 Hp motor with 1440 rpm and gear with reduction of 1:40, spring assembly system at the end of the outlet and sieve. The testing and performance analysis were carried out at different operating speeds i.e. 36, 25, 16, 12, 10 and 8 rpm with the help of Variable Frequency Drive (VFD). The result shows that the capacity of the dewatering machine is 79.90 kg/hr. and the optimum operating speed for the dewatering process was to be 10 rpm. The liquid yield, extraction efficiency and extraction losses were found to be 90.77%, 71.64% and 26.30%. The installation cost of the dewatering machine is NRs 384000 and the payback period, internal rate of return and net present value is calculated as 2 years 6 month 4 days, 28.53% and Nrs 179006.35 respectively.