| 摘要 |
<p>A method is provided for reducing the oxygen demand of waste water having a partial organic composition, especially a solution commonly known as mostos which is the waste effluent of a molasses fermentation and distillation process. The waste water is fed into an anaerobic digester near the top thereof so as to flow downwardly through the interior of the digester. The digester is at least partially filled with a high surface area media. The digester contains a microorganism which preferentially produces methane when in contact with the organic material in the waste water and also reduces the oxygen demand of materials therein. Also preferentially, the microorganisms tend to grow on the media surface. Nitrogen and phosphorous containing materials are added as necessary to promote growth of the microorganisms. As the waste water flows downwardly through the digester, methane is released therefrom which bubbles to the surface whereupon the methane is collected for combusting to produce energy. A buffering component may be added to the digester so as to produce an optimum pH for the process. Preferred temperatures of the digesting process are 95 DEG F. and the range of 125 DEG to 130 DEG F. During the process a portion of the biomass of the microorganisms growing on the media surface is sloughed therefrom and settles to the floor of the digester. The sloughed biomass along with a portion of the waste water is recirculated from the bottom of the digester to the top thereof, preferably at a rate of five times the flow of the influent to the digester. An effluent flow is removed from the digester in such a manner as to overflow the top thereof without allowing atmospheric air therein. When necessary to aid in removing biomass from the filter media, the collected methane may be selectively recirculated into the bottom of the digester and bubbled up through the waste water therein. A pressure of approximately one pound per square inch is preferably maintained on the digester to urge carbon dioxide produced during the process to remain in solution with the effluent.</p> |
