Phosphorus removal performance and population structure of phosphorus-accumulating organisms in HA-A/A-MCO sludge reduction process

Bioengineered. 2016 Sep 2;7(5):327-333. doi: 10.1080/21655979.2016.1197026. Epub 2016 Aug 3.


We developed a new sludge reduction HA-A/A-MCO (Hydrolysis-Acidogenosis-Anaerobic/Anoxic -Multistep Continuous Oxic tank) process, which has improved phosphate (P) and nitrogen (N) removal. Its biological treatment unit uses an A2/O P & N removal process with hydrolysis acidification, multistep continuous aeration, and continuous flow, coupled with sidestream P removal by draining out anaerobic P-bearing wastewater. The process has advanced synchronization of P and N removal and sludge reduction. The improved performance is closely associated with the population structure of P-accumulating organisms (PAOs). This study investigated the relationship between P removal performance and the population structure of PAOs. The results show that the average effluent P content of HA-A/A-MCO process was only 0.44 mg/L, when the influent P concentration was 8∼12 mg/L. The effluent met the A standard set by GB18918-2002. PAOs were able to effectively release 1 mg of P and absorb 2.8 mg of P. The system removed P by draining out anaerobic P-rich wastewater, as P had been reduced in the aerobic absorption process. This reduced the need for excess P uptake ability of the PAOs. The bacterial pure culture method was applied to isolate 5 PAOs with typical P absorption and removel features. 16SrDNA amplification and sequence analysis revealed that Acinetobacter sp. and Lampropedia sp played dominant roles in anaerobic P-releasing process. Moreover, Devosia sp. and Bdellovibrio sp were the primary strains in the aerobic tank, and, they were the major stains for P absorption. Uncultured Bacterium and other uncultured strains were detected in the anoxic tank.

Keywords: anaerobic phosphorus release; nitrogen and phosphorus removal; phosphorus-accumulating organisms; population structure; sludge reduction.

MeSH terms

  • Acinetobacter / metabolism
  • Aerobiosis
  • Anaerobiosis
  • Bacteria / isolation & purification
  • Bacteria / metabolism*
  • Bdellovibrio / metabolism
  • Bioreactors / microbiology*
  • DNA, Bacterial / genetics
  • Equipment Design
  • Nitrogen / metabolism
  • Phosphates / metabolism
  • Phosphorus / isolation & purification*
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Sewage / chemistry*


  • DNA, Bacterial
  • Phosphates
  • RNA, Ribosomal, 16S
  • Sewage
  • Phosphorus
  • Nitrogen