Classification of Phosphate Removal Bacteria and Improvement of Phosphate Removal in the Anaerobic-Aerobic Activated Sludge Process

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The enhanced biological phosphate removal in the anaerobic-aerobic activated sludge process is a very resources and energy saving method to remove phsphate from wastewater like sewage. From the previous researches, the anaerobic uptake of the organic substances like acetic acid, propionic acid, and other organics is thought to be one of the key mechanisms of the phosphate accumulating bacteria. In the present research, experimental investigations are carried out to classify the dominant bacterial flora in the anaerobic-aerobic activated sludge, and to identify the end products of the anaerobic uptake mechanisms of the organic substances. The important results are summarized as follows:(1)In the enhanced phosphate removal process, 18 to 50 per cent of total isolates were identified as Acinetobacter calcoaceticus var.lwoffi by the API 20E system.(2)In the anaerobic acetate uptake, the acetate was converted into the PHB stored in the biomass in accordance with the degradation of carbohydrate in the biomass.(3)In case of the propionic acid uptake, both PHB and PHV were formed to be accumulated in the biomass.(4)A conceptual metabolic pathway of the propionic acid conversion into PHV was postulated well quantitatively.(5)PHB and PHV are biodegradable plastics.