Pilot-scale evaluation of sulfite-activated ferrate for water reuse applications

Ferrate is a promising, “green” (i.e., iron-based) pre-oxidation technology in water treatment, but there has been limited research on its potential benefits in a water reuse (wastewater recycling) paradigm. Recent studies have shown ferrate treatment processes can be improved by activation, the addition of reductants (i.e., sulfite) to the reaction. Prior bench scale experimentation suggests sulfite-activated ferrate may be a feasible option for water reuse applications; however, extent questions need to be addressed. This study evaluated the viability of sulfite-activated ferrate in water reuse treatment through continuous-flow experiments using synthetic and field-collected secondary wastewater effluents. The effluents were processed through the piloting system which included various physicochemical processes such as ferrate pre-oxidation, coagulation, clarification, and dual-media filtration. In each trial, the system was run continuously for eight hours with data collected via grab samples and online instrumentation with real-time resolution. Results demonstrate that reuse systems using activated ferrate pre-oxidation can produce effluents with water quality meeting most regulatory requirements without major impacts on downstream physicochemical processes. When compared to traditional ferrate pre-oxidation, activation showed several improvements such as lower byproduct yields. Operationally, activated ferrate does increase the development of headloss across the dual-media filter. In general, sulfite-activated ferrate is viable in a water reuse setting, resulting in several improved water quality outcomes. Results from this work create a pathway for adaptation at scale

Sulfite activation changes character of ferrate resultant particles

The activation of ferrate with sulfite increases oxidative transformation of recalcitrant organic compounds; however, it also changes the characteristics of the iron particulates that result from the ferrate reduction. In this study, particles resulting from ferrate reduction both with and without sulfite were compared in a laboratory matrix simulating water treatment conditions at the bench-scale. Characteristics examined included magnetization, morphology, size, and surface charge. The activation of ferrate with sulfite changed the characteristics of resultant particles in several important ways. Activated ferrate resultant particles were less magnetic, more polydisperse including a higher fraction of nanoparticles, and exhibited a less-crystalline morphology compared to particles resulting from ferrate self-decay. Surface charges between the two particle types were similar, and negative. The relatively rapid formation of Fe(III) from Fe(VI) activation leads to particles of different character, likely though a greater supply of precursory low molecular weight iron hydroxo-species. Particles resulting from activated ferrate used as a preoxidant will impact downstream processes in important ways, such as gravimetric or magnetic separations and contaminant adsorption. Ferrate activation presents a possible trade-off between improved oxidation and impeded downstream physicochemical processes, and formation and fate of formed particles warrants consideration

Abatement of circumneutral mine drainage by Co-treatment with secondary municipal wastewater

Acid mine drainage is a persistent and problematic source of water pollution. Co-treatment with municipal wastewater at existing wastewater treatment plants has several advantages; however, potential impacts on plant physicochemical and biological processes have not been well explored. The primary purpose of this bench-scale study was to examine the impact of co-treatment by combining a mild acid mine drainage at various ratios with municipal wastewater, followed by sludge settling and supernatant comparative analysis using a variety of effluent water quality parameters. These measurements were combined with carbonate system and adsorption isotherm modeling to elucidate the mechanisms underlying the experimental results. Acid mine drainage addition decreased municipal wastewater effluent PO43− concentrations below 0.2 mg/L with greater than 97% removal, demonstrating co-treatment as an alternative solution for municipal wastewater nutrient removal. Biochemical oxygen demand remained similar to controls with \u3c10% variation after co-treatment. Coagulation from metals in acid mine drainage was incomplete due to PO43− adsorption, confirmed by comparing experimental results with Langmuir isotherm behavior. Sweep flocculation was the dominating particle aggregation mechanism, and co-treatment led to improved particle clarification outcomes. Improved clarification led to up to 50% Fe removal. Final pH had little variation with all conditions having pH \u3e 6.0. Carbonate system modeling adequately explains pH effects, and can also be applied to varying acid mine drainage matrices. The impact of acid mine drainage addition on the municipal wastewater microbial community was also investigated which provided evidence of microbial adaptation. This study demonstrates post-aeration co-treatment enables mitigation of mild acid mine drainage without adversely affecting wastewater treatment plant processes. Reported results also frame required future studies to address extant questions prior to full-scale adaptation

Potential Implications of Acid Mine Drainage and Wastewater Cotreatment on Solids Handling: A Review

Acid mine drainage (AMD) is a persistent and extensive source of water pollution and ecological degradation. Cotreating munici- pal wastewater (MWW) with AMD using existing infrastructure at conventional wastewater treatment plants (WWTPs) may serve as a potential option for AMD abatement. However, commonly elevated iron and aluminum concentrations and low pH of AMD could negatively impact various processes at a WWTP. The focus of this mini review was on determining how cotreating MWW with AMD could impact the solids handling processes at a WWTP. While no studies have explored the solids that could be generated during cotreatment in a WWTP, numerous articles separately discuss the solids generated during AMD or MWW treatment. Reviewing this literature revealed that iron and aluminum, common metals in AMD, are already present in MWW sludge and typically benefit most solids handling processes. The addition of AMD would elevate iron and aluminum concentration but would likely result in improved sludge dewatering, removal of odor-causing compounds during processing, and a decreased bioavailability of trace metals and water-soluble P in land applications. This review concludes that cotreating MWW with moderate to low volumes (\u3c50%) of AMD at WWTPs will have minimal impact on, and likely improve, solids handling processes

Physicochemical implications of cyanobacteria oxidation with Fe(VI)

Increases in harmful algal blooms has negatively impacted many surface-sourced drinking water utilities. To control these blooms, many water utilities implement pre-oxidation with ozone, chlorine, or permanganate; however, pre-oxidation of algae has both positive and negative water quality outcomes. This study investigated ferrate (Fe(VI)) as an alternative oxidant by measuring its effect on cell lysing, surface characteristics, and coagulation in waters containing the cyanobacteria Microcystis aeruginosa. Bench scale studies were conducted to examine the complex combination of processes in a Fe(VI)-algae system. These processes were characterized by fluorescence index, surface charge, collision frequency modeling, particle counts and sphericity, total nitrogen, and ferrate decomposition measurements. Results showed that Fe(VI) lysed algal cells, but further oxidation of released organic matter is possible. The presence of algae did not significantly impact the rate of Fe(VI) decomposition. Fe(VI) pre-oxidation may also be capable of decreasing the formation of nitrogenated disinfection byproducts through subsequent oxidation of released nitrogen rich organic matter. Streaming current and zeta potential results indicate destabilization of the resulting algae and iron suspension was incomplete under most conditions. Particle collision frequency modeling indicates fluid shear to be an important aggregation mechanism of the resulting suspension. Overall, Fe(VI) is a viable alternative to other strong oxidants for water utilities struggling with harmful algal blooms, but the final fate of the resulting organic matter must be further studied

Predicting Cellular Growth from Gene Expression Signatures

Maintaining balanced growth in a changing environment is a fundamental systems-level challenge for cellular physiology, particularly in microorganisms. While the complete set of regulatory and functional pathways supporting growth and cellular proliferation are not yet known, portions of them are well understood. In particular, cellular proliferation is governed by mechanisms that are highly conserved from unicellular to multicellular organisms, and the disruption of these processes in metazoans is a major factor in the development of cancer. In this paper, we develop statistical methodology to identify quantitative aspects of the regulatory mechanisms underlying cellular proliferation in Saccharomyces cerevisiae. We find that the expression levels of a small set of genes can be exploited to predict the instantaneous growth rate of any cellular culture with high accuracy. The predictions obtained in this fashion are robust to changing biological conditions, experimental methods, and technological platforms. The proposed model is also effective in predicting growth rates for the related yeast Saccharomyces bayanus and the highly diverged yeast Schizosaccharomyces pombe, suggesting that the underlying regulatory signature is conserved across a wide range of unicellular evolution. We investigate the biological significance of the gene expression signature that the predictions are based upon from multiple perspectives: by perturbing the regulatory network through the Ras/PKA pathway, observing strong upregulation of growth rate even in the absence of appropriate nutrients, and discovering putative transcription factor binding sites, observing enrichment in growth-correlated genes. More broadly, the proposed methodology enables biological insights about growth at an instantaneous time scale, inaccessible by direct experimental methods. Data and tools enabling others to apply our methods are available at http://function.princeton.edu/growthrate

Molecular characterization and clinical relevance of metabolic expression subtypes in human cancers.

Metabolic reprogramming provides critical information for clinical oncology. Using molecular data of 9,125 patient samples from The Cancer Genome Atlas, we identified tumor subtypes in 33 cancer types based on mRNA expression patterns of seven major metabolic processes and assessed their clinical relevance. Our metabolic expression subtypes correlated extensively with clinical outcome: subtypes with upregulated carbohydrate, nucleotide, and vitamin/cofactor metabolism most consistently correlated with worse prognosis, whereas subtypes with upregulated lipid metabolism showed the opposite. Metabolic subtypes correlated with diverse somatic drivers but exhibited effects convergent on cancer hallmark pathways and were modulated by highly recurrent master regulators across cancer types. As a proof-of-concept example, we demonstrated that knockdown of SNAI1 or RUNX1—master regulators of carbohydrate metabolic subtypes-modulates metabolic activity and drug sensitivity. Our study provides a system-level view of metabolic heterogeneity within and across cancer types and identifies pathway cross-talk, suggesting related prognostic, therapeutic, and predictive utility

Sulfite-activated ferrate for water reuse applications

Ferrate is a promising, emerging water treatment technology. However, there has been limited research on the application of ferrate in a water reuse paradigm. Recent literature has shown that ferrate oxidation of target contaminants could be improved by “activation” with the addition of reductants or acid. This study examined the impact of sulfite-activated ferrate in laboratory water matrix and spiked municipal wastewater effluents with the goal of transforming organic contaminants of concern (e.g., 1,4-dioxane) and inactivating pathogenic organisms. Additionally, the formation of brominated disinfection byproducts by activated ferrate were examined and a proposed reaction pathway for byproduct formation is presented. In particular, the relative importance of reaction intermediates is discussed. This represents the first activated ferrate study to examine 1,4-dioxane transformation, disinfection, and brominated byproduct formation. Results presented show that the sub-stoichiometric ([Sulfite]:[Ferrate] = 0.5) activated ferrate treatment approach can oxidize recalcitrant contaminants by \u3e50%, achieve \u3e4-log inactivation of pathogens, and have relatively limited generation of brominated byproducts. However, stoichiometrically excessive ([Sulfite]:[Ferrate] = 4.0) activation showed decreased performance with decreased disinfection and increased risk of by-product formation. In general, our results indicate that sub-stoichiometric sulfite-activated ferrate seems a viable alternative technology for various modes of water reuse treatment

Broadening the model of science - Recognizing different types of contributions

Resources for Society for the Improvement of Psychological Science (2016) Meeting - Diversity & Alternative Contribution