| Currently, kitchen waste AD research on technology of single-phase focuses more on low concentrations at lower load conditions, particularly on reactor start-up, operation characteristics, change of parameters and treatment results. However, studies about single-phase anaerobic digestion system of kitchen waste at the high load conditions are relatively scarce.Firstly, batch anaerobic digestion of kitchen waste and different groups was carried out and the biogas production potential of the batch AD; Secondly, kitchen waste dry fermentation experiments were conducted where changes of various monitoring indicators in the entire kitchen waste dry fermentation process of start, operation, imbalances and stabilization, with focus on dry fermentation mechanism and the construction of dry fermentation hydrolytic kinetic model; Finally, the micro-aerobic biogas desulfurization mechanism was studied, desulfurization mechanism was analyzed, and the oxygen-sulphur balance and purification efficiency in the desulfurization process were calculated.The research results show that: under the mid-temperature conditions, the gas production rate of the batch anaerobic digestion of kitchen waste and other food is: starch> kitchen waste> protein> edible oil> fat> paper(cellulose, etc.), with the bio-energy in the range of 17.58-19.34 MJ/m3; the marsh gas production potentials(CH4 /VS) of kitchen waste, starch, protein, edible oil, fat and paper(cellulose, etc), and edible oil were 395.49,395.22,354.46,229.26,465.77, 468.3 Nm L/g, respectively. The methane concentration in marsh gas produced by batch anaerobic digestion of kitchen waste and other food ranged between 51.09 and 57.32%.The kitchen waste dry fermentation experiment process can be straightforwardly divided into four stages, namely: adaptation phase(0 ~ 13 d), start-up phase(14~34 d), inhibition phase(35~72 d) and recovery and stabilization phase(72~120 d). Different stages showed significant differences in the slanting degree of the gas production curve depending on gas production rate and the quantity of input material. When Na OH was used to adjust the p H value of reflux leachate of the day, the p H value on the 72 nd days rose to 7.4, and gas production was significantly increased, reaching 19.88 L / d. At this time, material input was once a day, each input was 1kg, the p H rose to over 23% on the 98 th day. The daily production of the system maintained between 15.35 ~ 21.03 L / d, and the rate of biodegradation at this phase kept stable at 55.1%.The micro-oxygen biological desulfurization technology with pure oxygen or air as the micro-oxygen source allows hydrogen sulfide concentrations in the marsh gas produced by anaerobic digestion to stay below 500 mg / Nm3, while making no significant impact on methane production and the anaerobic digestion process. When pure oxygen and air are compared as micro oxygen sources, the use of air as the oxygen source for a newly-built micro anaerobic digestion plant looks more economical.The analysis of the batch anaerobic digestion model of single group kitchen waste indicates that starch was closer to the cylindrical granules model fitting, where R2 = 0.9742, k = 0.4374d-1; cellulose closer to the spherical particle model fitting, where R2 = 0.9412, k = 0.0621d-1; fat and protein closer to the first-class kinetic model fitting, and for fat R2 = 0.7125, k = 0.0325d-1, and for protein R2 = 0.7981, k = 0.1341d-1.During the dry kitchen waste fermentation, depending on the hydraulic retention time(HRT), organic loading rate(OLR) and the maximum gas production rate of kitchen waste at different fermentation stages, the reaction rate constant k was obtained as 0.133d-1. The p H suppression coefficients at the four phases were I1 = 0.7143, I2 = 0.0547, I3 = 0 0151, and I4 = 0.6655, respectively, and the fitting formula for the relationship between the cumulative gas production(L) versus time(d) was: y = 0.1139x2- 5.0447 x + 77.737. |
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