Experimental Study of the Biogas Production from Typical Food Waste in Iraq

Abstract

This work aimed to assess the production of biogas from locally widely available food waste likes; potatoes, tomatoes and carrots that are extensively used in Iraqi cuisine. Three digesters were used in the fermentation process, as well as two small digesters, where the effect of the buffer solution was tested. The effect of cellulose and starch content were studied since they are dominant in these food types. The highest amount of the biogas production was obtained from potatoes which contain a high amount of starch and an ideal ratio of carbon to nitrogen ratio. The lowest amount of biogas was from tomatoes which contain a high percentage of cellulose as well as the lowest carbon to nitrogen ratio. Tomato fermentation continued for 90 days, while potato and carrot continued for 105 days. Digestion in the smaller reactors gave better production by controlling the PH value. The production was 280 ml in 23 days while the uncontrolled digestion was 240 ml in 34 days. The production in the seventh week began to rise gradually until the end of the experiment. The proportion of methane in the digestion of tomato was almost 59. The digestion of potatoes associated with higher PH than that in tomato digestion. It began to produce methane in the fifth week of the experiment giving higher methane production of 69 proportion. Carrots produced methane in the fourth week of the experiment in a less period than potatoes. The proportion of methane was about 64. Potatoes production was better than carrot and tomatoes. The use of bio-active bacteria in the second test gave better results compared to the first test in reducing fermentation period as well as increase production.