Anaerobic treatment plant for effluent - with circulation from digester to settling tank induced by methane gas rising in central column

摘要

Water-borne effluent is treated anaerobically in a vessel comprising a digestion chamber equipped with a feed for the effluent, above the digester, a pptn. chamber with a central opening and an inclined floor, a column rising through the central hole in the floor of the pptn. chamber which overflows into an annular space between the column and a sleeve, a gas collector and an overflow for clean water. The bottom of the central column is dished outwards so that the methane gas generated flows into the column and induces a circulation of liq. upwards through the column and over the overflow. To ensure that effective sepn. of the gas from the liquid takes place in the annular zone, a flocculant is pref. added. The water and sludge flow beneath the lower lip of the sleeve into the settling chamber. The floor of the chamber is pref. inclined down toward the central opening to ensure that the sludge flows out between the central column and the lower edge of the floor. For larger treatment plants where this may be impractical, the floor is equipped with a mechanical sludge scraper. Due to the construction of the central rising column and the arrangement of the settling chamber and digestion chamber, short circuiting of the digestion and settling streams is avoided. By adjusting the vertical position of the column, the throughput can also be regulated.