Convergent community structure of algal-bacterial consortia and its effects on advanced wastewater treatment and biomass production

Abstract

Microalgal-bacterial consortium is an effective way to meet increasingly stringent standards in wastewater treatment. However, the mechanism of wastewater removal effect has not been properly explained in community structure by phycosphere. And little is known about that the concept of macroecology was introduced into phycosphere to explain the phenomenon. In the study, the algal-bacterial consortia with different ratios of algae and sludge were cultured in same aerobic wastewater within 48 h in photobioreactors (PSBRs). Community structure at start and end was texted by metagenomic analysis. Bray-Curtis similarities analysis based on microbial community showed that there was obvious convergent succession in all consortia, which is well known as "convergence" in macroecology. The result showed that Bray-Curtis similarities at End (overall above 0.88) were higher than these at Start (almost less than 0.66). In terms of community structure, the consortium with 5:1 ratio at Start are the more similar with the consortia at End by which the maximum removal of total dissolved nitrogen (TDN, 73.69%), total dissolved phosphorus (TDP, 94.40%) and NH₃-N (93.26%) in wastewater treatment process and biomass production (98.2%) higher than other consortia, according with climax community in macroecology with the highest resource utilization than other communities. Therefore, the macroecology can be introduced into phycosphere to explain the consortium for advanced wastewater treatment and optimization community structure. And the study revealed a novel insight into treatment effect and community structure of algal-bacterial consortia for advanced wastewater treatment, a new idea for to shortening the culture time of consortium and optimize predicting their ecological community structure and predicting ecological community.

Figure 1

PSBR with Consortia with algae/sludge 10:1, 5:1, 1:1, 1:5 and 1:10 (donated as R1 to R5).

Figure 2

Concentration of water quality compositions in consortia. Consortia with algae/sludge 10:1, 5:1, 1:1, 1:5 and 1:10 (donated as R1 to R5). Nutrient and COD in different ratio of algal–bacterial consortia. And the pH in water. Ammonia nitrogen, total nitrogen, total phosphorus, COD, pH were shown in (A), (B), (C), (E) and (F) respectively.

Figure 3

The promotion of the biomass concentration. Consortia with algae/sludge 10:1, 5:1, 1:1, 1:5 and 1:10 (donated as R1 to R5).

Figure 4

Algal–bacterial Consortia multistage species composition at the Start and End. Consortia with algae/sludge 10:1, 5:1, 1:1, 1:5 and 1:10 (donated as R1 to R5). Start (the operation start-up, the 0 h) and End (the operation end, the 48th h). Autotroph, heterotroph, other of algae, other of bacteria (donated as I To IV). Chlorophyta, Chlorophyta, Cyanophyta, Chloroflexi, Proteobacteria, Bacteroidetes, Bacteroidetes and Nitrospirae in Phylum (donated as A to F). Chlorophyceae, Chlorophyceae, Cyanophyceae, Unclassified_p_Chloroflexi, proteobacteria, Betaproteobacteria, proteobacteria, Gammaproteobacteria, Alphaproteobacteria, Deltaproteobacteria, Unclassified_p_Bacteroidetes, Unclassified_p_Bacteroidetes, Nitrospirales in Class (donated as a to o). Chlorococcales, Nostocales, Unclassified_p_Chloroflexi, Pseudomonadales, Burkholderiales, Unclassified_c_Betaproteobacteria, Pseudomonadales, Burkholderiales, Unclassified_c_Gammaproteobacteria, Rhodobacterales, Myxococcales, Unclassified_c_Alphaproteobacteria, Thauera, Unclassified_p_Bacteroidetes, Nitrospirales in Order (donated as 1 to 15). Chlorella, Scenedesmus, Anabaena, Spirulina, Unclassified_p_Chloroflexi, Acinetobacter, Unclassified_o_Pseudomonadales, Burkholderiales, Unclassified_c_Betaproteobacteria, Pseudomonas, Comamonas, Unclassified_c_Gammaproteobacteria, Unclassified_o_Rhodobacterales, Unclassified_o_Myxococcales, Unclassified_c_Alphaproteobacteria, Thauera, Unclassified_p_Proteobacteria, Unclassified_p_Bacteroidetes, Nitrospira donated as (1) to (19).