NOVELTY - A marsh gas is prepared by entering emission stem liquid, extract, water, and evaporator waste from reconstituted tobacco production process as high concentration wastewater into wastewater collection tank, filtering through grill, entering into production collecting tank, sieving, entering into reactor, adding caustic soda, polymeric ferric sulfate, and polyacrylamide (PAM), mixing into flotation tank, placing sludge gas into sludge tank for further processing, and homogenizing into conditioning tank for water quality and regulation.    USE - Preparation of marsh gas (claimed).    ADVANTAGE - Preparation process is energy-saving and environment-friendly.    DETAILED DESCRIPTION - A marsh gas is prepared by entering emission stem liquid, extract, water, and evaporator waste from reconstituted tobacco production process as high concentration wastewater into wastewater collection tank, filtering through grill, entering into production collecting tank, sieving, entering into reactor, adding caustic soda, polymeric ferric sulfate, and polyacrylamide (PAM), mixing into flotation tank, placing sludge gas into sludge tank for further processing, homogenizing into conditioning tank for water quality and regulation, performing anaerobic reaction into upflow anaerobic sludge blanket (UASB) anaerobic reactor, removing sulfur to obtain marsh gas, dehydrating, entering anaerobic sludge into sludge tank in which pH of UASB anaerobic reactor is 6.8-7.8, entering remaining waste into anoxic/oxic (A/O) anaerobic-aerobic reactor pool, performing chemical oxygen demand (COD), biochemical oxygen demand (BOD), and nitrogen removal treatment, entering into secondary settling tank for solid-liquid separation, entering aerobic sludge into sludge tank, entering liquid waste into ozone oxidation pool, performing ozone catalytic oxidation reaction, entering into biological aerated filter, performing suspended solids (SS), COD, sediment oxygen demand (SOD), nitrification, denitrification, and phosphorus removal, and entering into clean water tank in which disqualified liquid is entered into flotation tank.    DESCRIPTION OF DRAWING(S) - The drawing shows a flow diagram of a preparation of marsh gas. (Drawing includes non-English language text).