BIOLOGICAL DISPOSAL OF OXALATES

摘要

A method and system for the biological disposal of oxalate is described in which a biological reactor (10) having an alkalo- philic oxalate-degrading aerobic micro-organism in aqueous solution is employed. The biological reactor (10) comprises a vessel (12) containing the aqueous solution and having an input (14) for receiving dissolved oxalate from dissolver tank (24). Sodium oxalate (1), as a by-product of the Bayer process in an alumina refinery, ca n be introduced into the dissolver tank (24) in solid form together with trace elements and nutrients (3) for biological growth. T he system operates as a continuous feed process with dissolved oxalate being pumped from tank (24) into vessel (12) continuously in a controlled manner. The biological reactor (10) further comprises an aerator (18), including an oxygen probe (20) for monitoring the level of dissolved oxygen in solution. Bio- logical degradation of the sodium oxalate in a highly alkaline solution occu rs in the biological reactor with sodium carbonate and bicarbonate formed as end products in the effluent. The effluent is then pumped to causticiser reaction tank (28) and settler tank (34) for converting the sodium carbonate and bicarbonate in the effluent to useful sodium hydroxide which can be recycled in the Bayer process. A novel alkalophilic oxalate-degrading aerobic micro-organism of the Bacillus species is also described.