CSTR Digester Technology

The main features of the complete mix or CSTR design include the tanks, mixers, covers and heating systems. Some CSTR designs use a single mix tank where all phases of treatment (hydrolysis, methanisation etc) happen in a single tank. This tank would sometimes have a flexible membrane cover to store resulting biogas and would utilize mixers that mount on the side of the tank and penetrate into the tank generally with a propeller or mixing jets to mix the tank’s contents. Some CSTR systems will split treatment into two tanks running in series. This style accomplishes hydrolysis and acidification in the first tank and the methanisation in the second tank. This style is commonly noted by a first stage with a fixed roof with a roof mounted, high torque, slow speed propeller style mixer mounted from the top. The second stage methanisation tank will be noticeable by its domed shape flexible gas cover as shown in the picture below.

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