3 research outputs found
Prospects for Biological Nitrogen Removal from Anaerobic Effluents during Mainstream Wastewater Treatment
Growing interest in the anaerobic
treatment of domestic wastewater
requires a parallel focus on developing downstream technologies that
address nitrogen pollution, especially for treatment systems located
in eutrophication-impacted watersheds. Anaerobic effluents contain
sulfide and hydrogen sulfide (a corrosive gas), dissolved methane
(a potent greenhouse gas), ammonium, and residual organic carbon predominantly
in the form of volatile fatty acids. Conventional approaches to nitrogen
removal are energy- and chemical-intensive and are not appropriate
for application to anaerobic effluents. Innovative, energy efficient
nitrogen removal processes are being developed and involve several
novel chemotrophic processes. This review provides information about
these processes, identifies how to control and retain the most desirable
microorganisms, and considers the impact of reactor configuration
on performance. Given the complexity of the technologies under development
that remove nitrogen from anaerobically treated domestic wastewater,
we conclude that computational models can support their development
and that sensor-mediated controls are essential to achieving energy
efficiency
Urine Bacterial Community Convergence through Fertilizer Production: Storage, Pasteurization, and Struvite Precipitation
Source-separated
human urine was collected from six public events
to study the impact of urine processing and storage on bacterial community
composition and viability. Illumina 16S rRNA gene sequencing revealed
a complex community of bacteria in fresh urine that differed across
collection events. Despite the harsh chemical conditions of stored
urine (pH > 9 and total ammonia nitrogen > 4000 mg N/L), bacteria
consistently grew to 5 ± 2 × 10<sup>8</sup> cells/mL. Storing
hydrolyzed urine for any amount of time significantly reduced the
number of operational taxonomic units (OTUs) to 130 ± 70, increased
Pielou evenness to 0.60 ± 0.06, and produced communities dominated
by <i>Clostridiales</i> and <i>Lactobacillales</i>. After 80 days of storage, all six urine samples from different
starting materials converged to these characteristics. Urine pasteurization
or struvite precipitation did not change the microbial community,
even when pasteurized urine was stored for an additional 70 days.
Pasteurization decreased metabolic activity by 50 ± 10% and additional
storage after pasteurization did not lead to recovery of metabolic
activity. Urine-derived fertilizers consistently contained 16S rRNA
genes belonging to Tissierella, Erysipelothrix, Atopostipes, Bacteroides, and many <i>Clostridiales</i> OTUs; additional experiments must determine whether pathogenic species
are present, responsible for observed metabolic activity, or regrow
when applied