Continuously-stirred tank reactor (CSTR) complete-mix anaerobic digester tanks utilize unique paddle mixers to ensure homogeneous mixing. Ideally operating in the 6-15% total solids (TS) range at mesophilic or thermophilic temperatures (project-dependent), a variety of feedstocks can be processed. Possible feedstocks include manure, biosolids, food waste, brewery waste, energy crops, and other low-solids organics. CSTR digester tanks are available in different sizes and can be combined, depending on tank size and expansions. CSTR applications include dairies, wastewater treatment plants, food processors, and more. CSTR can also be paired with the horizontal plug-flow digester, for processing higher solids feedstocks like wastewater sewage sludge, waste from food processors, breweries, and more.