Biology subjects

Spiller, M.

Publications and source records attributed to Spiller, M..

3 recordsLinked to original sources

bioRxiv2025

Environmental impact of integrating decentralized urine treatment in the urban wastewater management system: A comparative life cycle assessment

As municipal wastewater treatment regulations become more stringent, integrating source-separated urine treatment into centralized urban wastewater management offers a hybrid solution. However, it is not clear how the environmental impacts of such hybrid systems compare to highly efficient centralized wastewater treatment plants (WWTPs) with low N2O emissions and electricity use. In this study, a consequential life cycle assessment was used to compare the environmental impact of three urine hybrid wastewater treatment systems - which combine decentralized urine treatment with a highly efficient central WWTP - to a centralized WWTP treating mixed wastewater (baseline). The studied urine treatment systems include partial nitrification & distillation, struvite precipitation & stripping/scrubbing, and partial nitritation/anammox. Additionally, the contribution of urine alkalinization to the overall impact was quantified. The results show that at least one hybrid scenario showed a lower environmental impact in 8 out of the 10 assessed impact categories. Global warming potential and marine eutrophication were found to be higher than the baseline. Additionally, it was identified that urine alkalinization increased the environmental impact of the treatment system in 7 out of the 10 impact categories. A Pareto frontier analysis was developed to guide decision makers on where hybrid solutions could be used as a strategy to reduce global warming impacts of conventional WWTPs. It was realized that using N2O emission factors of 75 WWTPs, 87% of centralized WWTPs had lower CO2 emissions compared to partial nitrification & distillation, and 91% compared to partial nitritation/anammox hybrid solutions. However, at energy demands of 1 kWh/PE and 2 kWh/PE, both hybrid solutions showed lower emissions than all the studied WWTPs. The study highlights the potential of hybrid wastewater treatment solutions to address specific environmental challenges in wastewater management and a strategy to reduce global warming impacts in WWTPs with high N2O emissions and electricity use. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=75 SRC="FIGDIR/small/636102v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@c97256org.highwire.dtl.DTLVardef@171989dorg.highwire.dtl.DTLVardef@da8e02org.highwire.dtl.DTLVardef@a151da_HPS_FORMAT_FIGEXP M_FIG Graphical abstract C_FIG

ecology↗

bioRxiv2024

Sodium azide mutagenesis induces a unique pattern of mutations

The nature and effect of mutations are of fundamental importance to the evolutionary process. The generation of mutations with mutagens has also played important roles in genetics. Applications of mutagens include dissecting the genetic basis of trait variation, inducing desirable traits in crops, and understanding the nature of genetic load. Previous studies of sodium azide-induced mutations have reported single nucleotide variants (SNVs) found in individual genes. To characterize the nature of mutations induced by sodium azide, we analyze whole-genome sequencing (WGS) of 11 barley lines derived from sodium azide mutagenesis, where all lines were selected for diminution of plant fitness owing to induced mutations. We contrast observed mutagen-induced variants with those found in standing variation in WGS of 13 barley landraces. Here, we report indels that are two orders of magnitude more abundant than expected based on nominal mutation rates. We found induced SNVs are very specific, with C[->]T changes occurring in a context followed by another C on the same strand (or the reverse complement). The codons most affected by the mutagen include the sodium azide-specific CC motif (or the reverse complement), resulting in a handful of amino acid changes and relatively few stop codons. The specific nature of induced mutations suggests that mutagens could be chosen based on experimental goals. Sodium azide would not be ideal for gene knockouts but will create many missense mutations with more subtle effects on protein function.

genomics↗

bioRxiv2023

Resource-efficient nitrogen removal from source separated urine with partial nitritation/anammox in a membrane aerated biofilm reactor

Source separation and decentralized urine treatment can cut costs in centralized wastewater treatment by diverting 80% of the nitrogen load in sewage. One promising approach for nitrogen removal in this context is partial nitritation/anammox (PN/A), reducing the aeration demand by 67% and organics dosage by 100% compared to nitrification/denitrification. Whilst previous studies with suspended biomass have encountered stability issues during PN/A treatment of urine, a PN/A biofilm was hypothesized to be more resilient. Its use for urine treatment was pioneered here for maximum rates and efficiencies in the energy efficient membrane-aerated biofilm reactor (MABR). Nitrogen removal rates of 1.0 g N L-1 d-1 and removal efficiencies of 80-95% were achieved during a 335-day stable operation at 28{degrees}C on stabilized (pH>11), diluted urine (10%). A balance between N2 and NO3 - formation was observed whilst optimizing the supply of O2 and was rate limiting for the conversion towards N2. Short-term operation on less- and undiluted urine yielded N removal rates of 0.6-0.8 g N L-1 d-1 and removal efficiencies of 93% on 66% urine and 85% on undiluted urine. Metataxonomic analysis and fluorescence in-situ hybridization confirmed the presence of biofilms consisting of nitrifiers (Nitrosomonas, Nitrospira) at the membrane side and anammox bacteria ("Candidatus Brocadia") at the anoxic bulk side. The findings suggest that a biofilm approach to PN/A treatment of urine overcomes stability issues, and a PN/A-MABR has significant potential for resource efficient decentralized treatment. In human long-duration deep-space missions, this gravity-independent technology could produce N2 to compensate artificial atmosphere losses whilst facilitating water recovery from urine. [GRAPHICAL ABSTRACT, COLOR] O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/572732v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1680b0corg.highwire.dtl.DTLVardef@1ad822dorg.highwire.dtl.DTLVardef@3d5c4borg.highwire.dtl.DTLVardef@764841_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗