A combined anaerobic digester system and gas-to-liquid system is disclosed. The anaerobic digester requires heat, and produces methane. The gas-to-liquid system produces heat, and converts methane to higher-value products, including methanol and formaldehyde. As such, the combination of the two systems results in significant savings in terms of capital and operating expenses. A process for producing bio-formaldehyde and bio-formalin from biogas is also disclosed.