Beneficial effects of intermittent feedstock management on biogas and methane production.

Intermittent supply of easily degradable carbohydrates can be used for on-demand biogas production. The study tested the effects of splitting feeding portions of sugar beet silage (S) on biogas production rates and total yield, respectively and if methane production rates follow those ones of biogas. Four experimental AD reactors were operated for 117 days at organic loading rates of 2.0 kg m d and VS ratios of maize silage (M) to S of 3:1. While M was supplied hourly (h-h), reactors differed only regarding the intermittent S supply, provided at once (h), twice (h, h) and three times (h, h, h) per twelve-hour observation period. Biogas and methane production rates rose simultaneously after S supply and lasted depending on S intakes. Biogas and methane yields were significantly increased at S given once and twice per period. Appropriate feedstock management can thus influence production rates and increase biogas and methane yields.