Nitrifying bacterial growth inhibition in the presence of algae and cyanobacteria

Abstract

Nitrifying bacteria, cyanobacteria, and algae are important microorganisms in open pond wastewater treatment systems. Nitrification involving the sequential oxidation of ammonia to nitrite and nitrate, mainly due to autotrophic nitrifying bacteria, is essential to biological nitrogen removal in wastewater and global nitrogen cycling. A continuous flow autotrophic bioreactor was initially designed for nitrifying bacterial growth only. In the presence of cyanobacteria and algae, we monitored both the microbial activity by measuring specific oxygen production rate (SOPR) for microalgae and cyanobacteria and specific oxygen uptake rate (SOUR) for nitrifying bacteria. The growth of cyanobacteria and algae inhibited the maximum nitrification rate by a factor of 4 although the ammonium nitrogen fed to the reactor was almost completely removed. Terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that the community structures of nitrifying bacteria remained unchanged, containing the dominant Nitrosospira, Nitrospira, and Nitrobacter species. PCR amplification coupled with cloning and sequencing analysis resulted in identifying Chlorella emersonii and an uncultured cyanobacterium as the dominant species in the autotrophic bioreactor. Notwithstanding their fast growth rate and their toxicity to nitrifiers, microalgae and cyanobacteria were more easily lost in effluent than nitrifying bacteria because of their poor settling characteristics. The microorganisms were able to grow together in the bioreactor with constant individual biomass fractions because of the uncoupled solids retention times for algae/cyanobacteria and nitrifiers. The results indicate that compared to conventional wastewater treatment systems, longer solids retention times (e.g., by a factor of 4) should be considered in phototrophic bioreactors for complete nitrification and nitrogen removal.

A Meta-Analysis of the Bacterial and Archaeal Diversity Observed in Wetland Soils

“…As the third most abundant minor phyla, Cyanobacteria occupy a broad range of habitats across all latitudes. They are widespread in freshwater, marine, and even in the most extreme niches such as hot springs and hypersaline bays [12, 59, 60]. Evidence suggests that Verrucomicrobia are abundant within the environment and important.…”

Effect of lake water on algal biomass and microbial community structure in municipal wastewater-based lab-scale photobioreactors

“…It has been also shown that bacterial community structure in lakes is partly shaped by the phytoplankton structure and dynamics through alga-derived organic matter (Paver et al 2013). Research conducted by Choi et al (2010) found that algae and cyanobacteria can inhibit nitrifying bacteria growth in a bioreactor by a factor of 4 while the community structure of the nitrifying bacteria was unchanged in the process. Since there was an increase in pH, it may also be possible that it had a Fig.…”

Cultivation ofScenedesmus dimorphuswith domestic secondary effluent and energy evaluation for biodiesel production

“…Sometimes, the growth of cyanobacteria and algae also could inhibit the nitrification rate conducted by nitrifying bacteria. [30] To avoid the negative effect of bacterial contamination, in the fourth stage, a UV-sterilizer was integrated into the photobioreactor system to inactivate the bacteria in the DSE. After sterilization, the microalgal cells attachment was alleviated.…”