A fermentation system for production of biogas from solid organic material, the system including at least one fermentation reactor. The fermentation reactor includes a vessel (37) for housing a feed mixture having liquid and solid particles and an outlet port (44), a strainer assembly (33) at the outlet port for filtering processed feed mixture from the vessel, and a biogasification reactor (37) in fluid communication with another fermentation reactor, the other fermentation reactor configured to produce a biomethane. The strainer assembly further includes a mixture driving member (53) positioned in the strainer body (47) adjacent the drain opening (51), the mixture driving member having a driving surface configured to receive the liquid passing through the filter member (60). The driving surface engages the filter member such that solid particles are driven from a surface of the filter member when the driving member is activated. A method of continuously producing a biogas and servicing a strainer assembly for a hydrolysis reactor are disclosed.