Microbial degradation of methanesulfonic acid (MSA) is a missing link in the biogeochemical sulfur cycle. Atmospheric dimethyl sulfide, arising from marine algae, cyanobacteria and salt marsh plants is the principal sulfur compound entering the atmosphere from aquatic and terrestrial environments. MSA has been identified as a major product of the photochemical oxidation of dimethyl sulfide in the atmosphere. Dimethyl sulfide and MSA are predominantly biogenic in origin and are the main gaseous links in the biogeochemical sulfur cycle. MSA is a stable compound and does not undergo photochemical decomposition. Removal of MSA from the atmosphere is by wet and dry deposition. MSA partitions into aerosol, in nucleating droplet formation and is deposited in rain and snow. Analysis of Antarctic ice cores gives evidence of its global deposition over many thousands of years.
The search for methylotrophs and sulfur bacteria, able to derive energy from the degradation of MSA, has recently been revealed. Organisms that are involved in the microbial degradation of MSA are identified as facultatively heterotrophic methylotrophs and include Escherichia coli K-12 and Chlorella fusca.
However, information on the fate of MSA in wastewater is almost nonexistent. It has been determined, using Daphnia magna toxicity assay, that pure MSA has an LC.sub.5O of only 2 mg/L. Therefore, MSA in wastewater poses significant environmental problems in the form of aquatic toxicity. A waste treatment system for MSA degradation to non toxic levels is highly desirable. Unfortunately, there has been no adequate secondary liquid waste treatment system for MSA degradation. Although, as noted above, reports describe microbial degradation of MSA, they are confined to low concentration inherent biodegradability of the compound in a laboratory scale, not high concentration secondary liquid waste treatment. Further, biodegradation of MSA in a typical activated sludge treatment system has not been taught or suggested. The present invention establishes use of a continuous, acclimated activated sludge culture that removes up to 99% of MSA in a secondary liquid waste treatment system at concentrations as high as 1000 mg/L MSA. The acclimated system of the present invention has also been found to utilize MSA as the sole source of carbon for growth and energy, at concentrations as high as 1000 mg/L.