Anaerobic digestion of food wastes for biogas production

Abstract

Abstract: Five types of food wastes were investigated as feedstock for a potential centralized anaerobic digester system in the area of Sacramento, California to produce biogas energy.  The wastes were from a soup processing plant, a cafeteria, a commercial kitchen, a fish farm, and grease trap collection service.  Digestibilities of the food wastes, individually and in mixtures, were conducted at mesophilic (35℃) and thermophilic (50℃) temperatures and at two food to microorganism ratios (F/M) of 0.5 and 1.0, for 28 days.  A continuously fed mesophilic single-stage anaerobic digester was evaluated using a mixture of the five food wastes at organic loading rates of 0.5 to 1.0 g VS/L/d.  In the batch digestion tests, fish and grease trap wastes required longer time to complete the digestion and had higher biogas yields than the other wastes.  The continuously-fed digester required the addition of sodium hydroxide to maintain pH at proper levels in the digester.  Alkalinity of about 2,500 mg CaCO₃/L and pH above 7 was maintained by adding 0.2 g NaOH/g VS.  The results of this study indicated that it was necessary to use the chemicals, such as NaOH, to control the pH of the single-stage anaerobic digester treating the food waste.  For commercial applications, the cost of chemicals and proper management of additional salts in the digester effluent need to be carefully considered.

 

Keywords: anaerobic digestion, bioconversion, biogas, continuous digestion, food waste

 

DOI: 10.3965/j.issn.1934-6344.2010.04.051-062

  Citation: Xiguang Chen, Rowena T. Romano, Ruihong Zhang.  Anaerobic digestion of food wastes for biogas production.  Int J Agric & Biol Eng, 2010; 3(4): 51－62.