Effects of Dilution on Removal of Organic Carbon and Nitrogen From Miso-production Wastewater by Aurantiochytrium sp. L3W and Resultant Fatty Acid Production

In this study, we investigated effects of dilution on (i) removal of dissolved organic carbon (DOC) and nitrogen (DN) from the miso-processing (MP) and bean-boiling (BB) wastewaters by cultivation of Aurantiochytrium sp. strain L3W, (ii) its biomass yield in terms of the DOC and DN consumptions, and (iii) production of lipid and fatty acids including docosahexaenoic acid (DHA). Dilution resulted in the less biomass and lipid productions; however, the remarkable increase of biomass yield was attained. By diluting more than 5 times, the DN concentration in the BB and MP wastewater samples was maintained within the range in the sewage discharge standard for nitrogen set by the municipal government of Higashi-hiroshima City. However, the remaining DOC after cultivation was estimated to exceed the sewage discharge standard for biochemical oxygen demand in spite of 20 times dilution. The DHA content in the biomass of strain L3W was 10.7 mg/g in the 10 times diluted BB wastewater sample and 16.8 mg/g in the 20 times diluted MP water sample.