Biofilm Characteristics Of An Alternating Anaerobic/Aerobic Biofilter System For Phosphorous Removal

High phosphorus (P) concentration would cause eutrophication and led to the waste of P resource. Waste water P recovery has become a global strategy for phosphate resources. Recovery P from wastewater with low P concentration was high cost and followed by secondary pollution, it was necessary to enrich P to form P concentration increased streams by biological method combined with chemical recovery of P, to improve P recovery efficiency. This study adopted continuous anaerobic/aerobic alternate biological filter reactor (AABF) to remove and store P-and studied the feasibility of using carbon source amplification to induce P-release forming a high P concentration liquid to facilitate the subsequentP recovery. This paper used intracellular storage polymer dyeing, scanning electron microscopy (SEM) and restricted fragment length polymorphism (RFLP, an enzyme analysis technology) to investigate microbial community characteristics of composition and structure changes. The main results are as follows:(1) AABF system had high-P removal and storage capacity after biofilm domestication. The results showed that a higher P-removal efficiency (90.5%) and a good P-effluent quality (about0.5mg L-1) could be achieved and the biomass P levels as poly-Ps could be up to6.2%of cell dry weight. The lowest value was3.2%during carbon source regulation period indicating that there were PAOs in the biomass;(2) Metal cations played key roles in maintaining electron neutralization inside the bacterial cell. We found that potassium (K) and magnesium (Mg) co-transported with phosphate in and out of bacterial cells during P-removal, but calcium (Ca) does not;(3) In the AABF system operation, biomass P levels and P concentration of anaerobic release P liquid increased with the repetition of biomass’s P-release and P-uptake. P precipitation, maybe calcium phosphate would appear when metal cations concentration was high.(4) AABF system performed well when conducted carbon source regulation stimulating extensive biofilm P release to obtain high P liquid for P recovery. Appropriate carbon source regulation can improve the biofilm P release-absorption ability. P concentration of anaerobic release P liquid was71.59mg L"1while metal cations concentration was low, thus avoiding P precipitation.(5) Operating AABF with low carbon source P storage and amplification carbon source to induce P release for P harvestinghadinflunced the microbial community morphology in which the ball rod bacterial evoluted into filamentous bacterial. However this phenomenon did not affect the P removal function of the biofilter. Bacterium of β-proteobacteria proportion had increased from56.9%to72.5%of all the community composition of the biofilmin55days. Finally, γ-proteobacteria class became the only flora with abundance of98.03%after carbon source regulation applied to the biofilter.(6) One strain with high accumulating P ability named BFR-D2was seperated, whose P levels could be>11.0%of cell dry weight.16S rRNA sequencing results showed the strain belonging to pseudomonas genus.