[Effects of Aerobic Carbon Sources on Biofilm with Simultaneous Phosphate Removal and Enrichment].

In a cyclic alternating O/A operation mode, phosphorus accumulating organisms (PAOs) can undertake phosphate removal and enrichment as the main process in wastewater treatment plants. The effects of the concentration of carbon sources during the aerobic stage on phosphate removal and enrichment performance of PAO biofilms, and the microbial population structure in the biofilms, were investigated. The results showed that the aerobic COD concentration decreased from 200 mg·L-1 to 0 mg·L-1, the phosphorus uptake rate improved by 1.29 times, the phosphorus concentration in effluent stabilized below 0.5 mg·L-1, the phosphorus release rate increased by 3.56 times, and the phosphate concentration in the circulating solution increased from 27.125 mg·L-1 to 55.91 mg·L-1. With respect to the change in microbial communities, the identification showed that the abundance of Proteobacteria increased by approximately two times, and the enrichment effects of Rhodocyclaceae and Anaerolineaceae increased by 2.28 and 5 times, respectively. Reducing the concentration of the carbon source in the aerobic section was beneficial to the screening and enrichment of PAOs, strengthening the removal of phosphate in the aerobic section and the release of phosphate in the anaerobic section. This resulted in an enriched phosphate solution. These observations provide a theoretical basis for future urban sewage treatment plants seeking to reduce their carbon demand.

[Microbial Population Dynamics During Domestication and Cultivation of Biofilm to Remove and Enrich Phosphate].

The purpose of this study was to develop a method to remove and recover high concentration phosphate solutions from wastewater. An experiment was carried out to cultivate and enrich phosphorus accumulating organisms (PAOs) in the biofilm with nylon as the biological carrier using artificial water distribution. Microflora morphology, species diversity, and the genetic relationship of biofilm during the process of biofilm domestication were studied by scanning electron microscopy (SEM) and MiSeq high-throughput sequencing. In addition, the feasibility of recycling a high concentration of phosphate in the conventional biofilm within a short time was validated. The membrane was hung in the biological carrier when the reactor was operated for 10 d. After the hanging of the film succeeded, the effluent COD was below 50 mg·L-1, the effluent phosphorus was close to zero, and the removal efficiency of phosphorus reached to above 95%. The operation was stable at this level for 40 d. The results from the SEM indicated that the microbial morphology in the biofilm was uniform with full oval-shaped spheres with a clear profile. MiSeq high-throughput sequencing indicated that the dominant phylum in the reactor included Proteobacteria, Chloroflexi, Bacteroidetes, Actinobacteria, Ignavibacteriae, and Nitrospirae. Proteobacteria, as the dominant genera, increased from 47% to 58%. Rhodocyclaceae, as the dominant phosphorus accumulating bacteria, increased from 17.9% to 28.9%. During the recovery period, the concentration of the phosphorus solution increased from 40mg·L-1 to 82 mg·L-1 by increasing the influent phosphate concentration and the COD concentration in the anaerobic phase, meeting the requirement of phosphorus recovery with the struvite method.