Title: Mesophilic temperature range effect on anaerobic digestion of residential grass cuttings using simple batch digester

Authors: Ishmael M. Ramatsa; Esther T. Akinlabi; Robert Huberts

Addresses: Department of Chemical Engineering, University of Johannesburg, Cnr Joe Slovo and Beit St, 2001 Doornfontein, Johannesburg, Gauteng, South Africa ' Department of Chemical Engineering, University of Johannesburg, Cnr Joe Slovo and Beit St, 2001 Doornfontein, Johannesburg, Gauteng, South Africa ' Department of Chemical Engineering, University of Johannesburg, Cnr Joe Slovo and Beit St, 2001 Doornfontein, Johannesburg, Gauteng, South Africa

Abstract: In the current study the main objective was to look into how the temperature and other resulting parameters impact on the stability of a biogas reactor during digestion of the residential grass cuttings in an oxygen deficient environment over a period of ten days. During this period of digestion ammonia nitrogen was found to be below inhibitory limits. N/C ratio of the grass was found to be 20.54 and total solids about 87.88%. pH levels for temperatures close to optimum fluctuated between 6.99 and 7.2. Concentration of ammonia nitrogen recorded for all temperatures were all below inhibiting range. A high constant acetic acid concentration was recorded for 40°C, indicating that metanogenesis was stopped, causing a cessation of biogas production. This was accompanied by a low pH level. The highest daily methane compositions produced during the digestion at the temperature of 32, 34, 36 38 and 40°C were 49, 52, 56.2, 53 and 26% respectively.

Keywords: ammonia inhibition; temperature; HOAC; methane; pH.

DOI: 10.1504/IJRET.2017.088989

International Journal of Renewable Energy Technology, 2017 Vol.8 No.3/4, pp.421 - 433

Available online: 21 Dec 2017 *

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