Characterizing the Opportunity Space for Sustainable Hydrothermal Valorization of Wet Organic Wastes.

Resource recovery from wet organic wastes can support circular economies by creating financial incentives to produce renewable energy and return nutrients to agriculture. In this study, we characterize the potential for hydrothermal liquefaction (HTL)-based resource recovery systems to advance the economic and environmental sustainability of wastewater sludge, FOG (fats, oils, and grease), food waste, green waste, and animal manure management through the production of liquid biofuels (naphtha, diesel), fertilizers (struvite, ammonium sulfate), and power (heat, electricity). From the waste management perspective, median costs range from -193 $·tonne-1 (FOG) to 251 $·tonne-1 (green waste), and median carbon intensities range from 367 kg CO2 eq·tonne-1 (wastewater sludge) to 769 kg CO2 eq·tonne-1 (green waste). From the fuel production perspective, the minimum selling price of renewable diesel blendstocks are within the commercial diesel price range (2.37 to 5.81 $·gal-1) and have a lower carbon intensity than petroleum diesel (101 kg CO2 eq·MMBTU-1). Finally, through uncertainty analysis and Monte Carlo filtering, we set specific targets (i.e., achieve wastewater sludge-to-biocrude yield >0.440) for the future development of hydrothermal waste management system components. Overall, our work demonstrates the potential of HTL-based resource recovery systems to reduce the costs and carbon intensity of resource-rich organic wastes.

Spatially Varying Costs of GHG Abatement with Alternative Cellulosic Feedstocks for Sustainable Aviation Fuels.

Cellulosic biomass-based sustainable aviation fuels (SAFs) can be produced from various feedstocks. The breakeven price and carbon intensity of these feedstock-to-SAF pathways are likely to differ across feedstocks and across spatial locations due to differences in feedstock attributes, productivity, opportunity costs of land for feedstock production, soil carbon effects, and feedstock composition. We integrate feedstock to fuel supply chain economics and life-cycle carbon accounting using the same system boundary to quantify and compare the spatially varying greenhouse gas (GHG) intensities and costs of GHG abatement with SAFs derived from four feedstocks (switchgrass, miscanthus, energy sorghum, and corn stover) at 4 km resolution across the U.S. rainfed region. We show that the optimal feedstock for each location differs depending on whether the incentive is to lower breakeven price, carbon intensity, or cost of carbon abatement with biomass or to have high biomass production per unit land. The cost of abating GHG emissions with SAF ranges from $181 Mg-1 CO2e to more than $444 Mg-1 CO2e and is lowest with miscanthus in the Midwest, switchgrass in the south, and energy sorghum in a relatively small region in the Great Plains. While corn stover-based SAF has the lowest breakeven price per gallon, it has the highest cost of abatement due to its relatively high GHG intensity. Our findings imply that different types of policies, such as volumetric targets, tax credits, and low carbon fuel standards, will differ in the mix of feedstocks they incentivize and locations where they are produced in the U.S. rainfed region.

Intensive Microalgal Cultivation and Tertiary Phosphorus Recovery from Wastewaters via the EcoRecover Process.

Mixed community microalgal wastewater treatment technologies have the potential to advance the limits of technology for biological nutrient recovery while producing a renewable carbon feedstock, but a deeper understanding of their performance is required for system optimization and control. In this study, we characterized the performance of a 568 m3·day-1 Clearas EcoRecover system for tertiary phosphorus removal (and recovery as biomass) at an operating water resource recovery facility (WRRF). The process consists of a (dark) mix tank, photobioreactors (PBRs), and a membrane tank with ultrafiltration membranes for the separation of hydraulic and solids residence times. Through continuous online monitoring, long-term on-site monitoring, and on-site batch experiments, we demonstrate (i) the importance of carbohydrate storage in PBRs to support phosphorus uptake under dark conditions in the mix tank and (ii) the potential for polyphosphate accumulation in the mixed algal communities. Over a 3-month winter period with limited outside influences (e.g., no major upstream process changes), the effluent total phosphorus (TP) concentration was 0.03 ± 0.03 mg-P·L-1 (0.01 ± 0.02 mg-P·L-1 orthophosphate). Core microbial community taxa included Chlorella spp., Scenedesmus spp., and Monoraphidium spp., and key indicators of stable performance included near-neutral pH, sufficient alkalinity, and a diel rhythm in dissolved oxygen.

Evaluation of 1,2-diacyl-3-acetyl triacylglycerol production in Yarrowia lipolytica.

Plants produce many high-value oleochemical molecules. While oil-crop agriculture is performed at industrial scales, suitable land is not available to meet global oleochemical demand. Worse, establishing new oil-crop farms often comes with the environmental cost of tropical deforestation. The field of metabolic engineering offers tools to transplant oleochemical metabolism into tractable hosts while simultaneously providing access to molecules produced by non-agricultural plants. Here, we evaluate strategies for rewiring metabolism in the oleaginous yeast Yarrowia lipolytica to synthesize a foreign lipid, 3-acetyl-1,2-diacyl-sn-glycerol (acTAG). Oils made up of acTAG have a reduced viscosity and melting point relative to traditional triacylglycerol oils making them attractive as low-grade diesels, lubricants, and emulsifiers. This manuscript describes a metabolic engineering study that established acTAG production at g/L scale, exploration of the impact of lipid bodies on acTAG titer, and a techno-economic analysis that establishes the performance benchmarks required for microbial acTAG production to be economically feasible.

Implications of Biorefinery Policy Incentives and Location-Specific Economic Parameters for the Financial Viability of Biofuels.

Cellulosic biofuels are part of a portfolio of solutions to address climate change; however, their production remains expensive and federal policy interventions (e.g., Renewable Fuel Standard) have not spurred broad construction of cellulosic biorefineries. A range of state-level interventions have also been enacted, but their implications for the financial viability of biorefineries are not well understood. To address this gap, this study evaluated the efficacy of 20 state-level tax incentives from 14 states and their interactions with other location-specific economic parameters (e.g., state income tax rates, electricity prices). To characterize implications of location-specific policies and parameters on biorefinery cash flows, we developed a new BioSTEAM Location-Specific Evaluation (BLocS) module for the open-source software BioSTEAM. Leveraging BLocS and BioSTEAM, we characterized the minimum ethanol selling price (MESP) for a cellulosic biorefinery (using corn stover as feedstock) and two conventional biorefineries (using corn or sugarcane as feedstock) for comparison. Among state-specific scenarios, nonincentivized MESPs for the corn stover biorefinery ranged from 0.74 $·L-1 (4.20 $·gallon gasoline equivalent [gge]-1) [0.69-0.79 $·L-1; 3.91-4.48 $·gge-1; Oklahoma] to 1.02 $·L-1 (5.78 $·gge-1) [0.95-1.09 $·L-1; 5.39-6.18 $·gge-1; New York], while the tax incentive-induced MESP reduction ranged from negligible (Virginia) to 5.78% [5.43-6.20%; Iowa]. Ultimately, this work can inform the design of policy incentives for biorefineries under specific deployment contexts.

Roadmap from Microbial Communities to Individuality Modeling for Anaerobic Digestion of Sewage Sludge.

Biological models describing anaerobic digestion (AD) of sewage sludge have been widely applied to test various control and operation strategies. Anaerobic digestion model 1 (ADM1) provides a generic platform that includes the main processes of AD, excluding homoacetogenesis and the microbial structure. Homoacetogenic bacteria have been identified as important competitors for hydrogen consumption and acetate production. Although recent advances in meta-omics techniques have improved our characterization of AD microbial communities, conventional models treat functional groups as homogeneous and overlook the physiology and behavior of microbial individuality, limiting insights into mechanisms governing process performance. A novel microbial individuality model (MIM) that integrates kinetics, energetics, and agent-based modeling to describe a microbiome's behavior as heterogenic populations, including homoacetogenesis, was developed. The MIM was validated with two datasets from previous studies through daily biogas production, methane content, compound concentrations, and microbial relative abundance changes. The MIM identified the emergence of Methanosaeta at low concentrations of acetate. Moreover, this simulation supports experimental studies confirming that the overlooked homoacetogenesis is an important hydrogen sink in AD. Validated MIMs are expected to provide insights into syntrophic and competitive interactions among microbiomes in AD systems while testing different operational parameters in a virtual environment. The MIM offers a methodological framework to other biological treatment systems and their microbial community dynamics.

Solids Residence Time Impacts Carbon Dynamics and Bioenergy Feedstock Potential in Phototrophic Wastewater Treatment Systems.

The use of wastewater-grown microalgae has the potential to reduce the cost of algae-derived biofuels while simultaneously advancing nutrient recovery at water resource recovery facilities (WRRFs). However, a significant barrier has been the low yield and high protein content of phototrophic biomass. Here, we examine the use of solids residence time (SRT) as a selective pressure in driving biochemical composition, yield, biofuel production, and WRRF nutrient management cost. We cultivated mixed phototrophic communities in controlled, laboratory-scale photobioreactors on the local WRRF secondary effluent to link SRT with biochemical composition and techno-economic analysis to yield insights into biomass composition and downstream processing effects on minimum fuel selling price. SRT significantly impacted biochemical composition, with total and dynamic carbohydrates the highest at low SRT (total carbohydrates being 0.60 and 0.32 mg-carbohydrate·mg-protein-1 at SRT 5 and 15 days, respectively). However, there were distinct differences between extant, steady-state performance and intrinsic potential, and longer SRT communities were able to accumulate significant fractions (51% on an ash-free dry weight basis, AFDW %) of carbohydrate reserves under nutrient starvation. Overall, hydrothermal liquefaction (HTL) was found to be more suitable than lipid extraction for hydrotreating (LEH) and combined algal processing (CAP) for conversion of biomass to fuels, but LEH and CAP became more competitive when intrinsic carbon storage potential was realized. The results suggest that the use of algae for nutrient recovery could reduce the nutrient management cost at WRRFs through revenue from algal biofuels, with HTL resulting in a net revenue.

Defining Nutrient Colocation Typologies for Human-Derived Supply and Crop Demand To Advance Resource Recovery.

Resource recovery from human excreta can advance circular economies while improving access to sanitation and renewable agricultural inputs. While national projections of nutrient recovery potential provide motivation for resource recovery sanitation, elucidating generalizable strategies for sustainable implementation requires a deeper understanding of country-specific overlap between supply and demand. For 107 countries, we analyze the colocation of human-derived nutrients (in urine) and crop demands for nitrogen, phosphorus, and potassium. To characterize colocation patterns, we fit data for each country to a generalized logistic function. Using fitted logistic curve parameters, three typologies were identified: (i) dislocated nutrient supply and demand resulting from high density agriculture (with low population density) and nutrient islands (e.g., dense cities) motivating nutrient concentration and transport; (ii) colocated nutrient supply and demand enabling local reuse; and (iii) diverse nutrient supply-demand proximities, with countries spanning the continuum between (i) and (ii). Finally, we explored connections between these typologies and country-specific contextual characteristics via principal component analysis and found that the Human Development Index was clustered by typology. By providing a generalizable, quantitative framework for characterizing the colocation of human-derived nutrient supply and agricultural nutrient demand, these typologies can advance resource recovery by informing resource management strategies, policy, and investment.

Navigating Data Uncertainty and Modeling Assumptions in Quantitative Microbial Risk Assessment in an Informal Settlement in Kampala, Uganda.

Decision-makers in developing communities often lack credible data to inform decisions related to water, sanitation, and hygiene. Quantitative microbial risk assessment (QMRA), which quantifies pathogen-related health risks across exposure routes, can be informative; however, the utility of QMRA for decision-making is often undermined by data gaps. This work integrates QMRA, uncertainty and sensitivity analyses, and household surveys in Bwaise, Kampala (Uganda) to characterize the implications of censored data management, identify sources of uncertainty, and incorporate risk perceptions to improve the suitability of QMRA for informal settlements or similar settings. In Bwaise, drinking water, hand rinse, and soil samples were collected from 45 households and supplemented with data from 844 surveys. Quantified pathogen (adenovirus, Campylobacter jejuni, and Shigella spp./EIEC) concentrations were used with QMRA to model infection risks from exposure through drinking water, hand-to-mouth contact, and soil ingestion. Health risks were most sensitive to pathogen data, hand-to-mouth contact frequency, and dose-response models (particularly C. jejuni). When managing censored data, results from upper limits of detection, half of limits of detection, and uniform distributions returned similar results, which deviated from lower limits of detection and maximum likelihood estimation imputation approaches. Finally, risk perceptions (e.g., it is unsafe to drink directly from a water source) were identified to inform risk management.

Global Sensitivity Analysis of Environmental, Water Quality, Photoreactivity, and Engineering Design Parameters in Sunlight Inactivation of Viruses.

Sunlight-mediated inactivation of microorganisms is a low-cost approach to disinfect drinking water and wastewater. The reactions involved are affected by a wide range of factors, and a lack of knowledge about their relative importance makes it challenging to optimize treatment systems. To characterize the relative importance of environmental conditions, photoreactivity, water quality, and engineering design in the sunlight inactivation of viruses, we modeled the inactivation of three-human adenovirus and two bacteriophages-MS2 and phiX174-in surface waters and waste stabilization ponds by integrating solar irradiance and aquatic photochemistry models under uncertainty. Through global sensitivity analyses, we quantitatively apportioned the variability of predicted sunlight inactivation rate constants to different factors. Most variance was associated with the variability in and interactions among time, location, nonpurgeable organic carbon (NPOC) concentration, and pond depth. The photolysis quantum yield of the virus outweighed the seasonal solar motion in the impact on inactivation rates. Further, comparison of simulated sunlight inactivation efficacy in maturation ponds under different design decisions showed that reducing pond depth can increase the log inactivation at the cost of larger land area, but increasing hydraulic retention time by adding ponds in series yielded greater improvements in inactivation.

Advancing Sustainable Sanitation and Agriculture through Investments in Human-Derived Nutrient Systems.

The sixth Sustainable Development Goal seeks to achieve universal sanitation, but a lack of progress due to inhibiting factors (e.g., limitations in financial resources, sociocultural conditions, household decision-making) demands innovative approaches to meet this ambitious goal. Resource recovery may generate income to offset sanitation costs while also enhancing agriculture through increased access to agricultural nutrients. The objective of this work was to determine if resource recovery sanitation can be a profitable business model in a specific context (Kampala, Uganda) and to explore the potential for this approach to translate to other Sub-Saharan African contexts. A techno-economic analysis was performed to evaluate the financial viability of two nutrient recovery systems and business models in urban communities in Kampala under two financing scenarios: (1) Startup relying on partial sanitation aid, and (2) Self-sustaining without philanthropic financing. Results show profitability can be achieved at a nutrient selling price at or below fertilizer market value in Uganda. Recoverable nutrients from the total population without at least basic sanitation services, in 10 Sub-Saharan African countries, are the same magnitude as nutrients distributed in subsidy programs (30-450% of distributed nutrients), indicating a potential to offset inorganic fertilizer consumption or increase nutrient availability. This research makes a case to support innovative sanitation strategies and the development and financial support of human-derived fertilizer markets in areas with poor fertilizer and sanitation access.

Navigating Multidimensional Social-Ecological System Trade-Offs across Sanitation Alternatives in an Urban Informal Settlement.

Urban growth in low- and middle-income countries has intensified the need to expand sanitation infrastructure, especially in informal settlements. Sanitation approaches for these settings remain understudied, particularly regarding multidimensional social-ecological outcomes. Guided by a conceptual framework (developed in parallel with this study) re-envisioning sanitation as a human-derived resource system, here we characterize existing and alternative sanitation scenarios in an informal settlement in Kampala, Uganda. Combining two core research approaches (household survey analysis, process modeling), we elucidate factors associated with user satisfaction and evaluate each scenario's resource recovery potential, economic implications, and environmental impacts. We find that existing user satisfaction is associated with factors including cleaning frequency, sharing, and type of toilets, and we demonstrate that alternative sanitation systems may offer multidimensional improvements over existing latrines, drying beds, and lagoons. Transitioning to anaerobic treatment could recover energy while reducing overall net costs by 26-65% and greenhouse gas emissions by 38-59%. Alternatively, replacing pit latrines with container-based facilities greatly improves recovery potential in most cases (e.g., a 2- to 4-fold increase for nitrogen) and reduces emissions by 46-79%, although costs increase. Overall, this work illustrates how our conceptual framework can guide empirical research, offering insight into sanitation for informal settlements and more sustainable resource systems.

Laboratory Demonstration and Preliminary Techno-Economic Analysis of an Onsite Wastewater Treatment System.

Providing safe and reliable sanitation services to the billions of people currently lacking them will require a multiplicity of approaches. Improving onsite wastewater treatment to standards enabling water reuse would reduce the need to transport waste and fresh water over long distances. Here, we describe a compact, automated system designed to treat the liquid fraction of blackwater for onsite water reuse that combines cross-flow ultrafiltration, activated carbon, and electrochemical oxidation. In laboratory testing, the system consistently produces effluent with 6 ≤ pH ≤ 9, total suspended solids (TSS) < 30 mg L-1, and chemical oxygen demand (COD) < 150 mg L-1. These effluent parameters were achieved across a wide range of values for influent TSS (61-820 mg L-1) and COD (384-1505 mg L-1), demonstrating a robust system for treating wastewater of varying strengths. A preliminary techno-economic analysis (TEA) was conducted to elucidate primary cost drivers and prioritize research and development pathways toward commercial feasibility. The ultrafiltration system is the primary cost driver, contributing to >50% of both the energy and maintenance costs. Several scenario parameters showed an outsized impact on costs relative to technology parameters. Specific technological improvements for future prototype development are discussed.

Re-Envisioning Sanitation As a Human-Derived Resource System.

Sanitation remains a global challenge, both in terms of access to toilet facilities and resource intensity (e.g., energy consumption) of waste treatment. Overcoming barriers to universal sanitation coverage and sustainable resource management requires approaches that manage bodily excreta within coupled human and natural systems. In recent years, numerous analytical methods have been developed to understand cross-disciplinary constraints, opportunities, and trade-offs around sanitation and resource recovery. However, without a shared language or conceptual framework, efforts from individual disciplines or geographic contexts may remain isolated, preventing the accumulation of generalized knowledge. Here, we develop a version of the social-ecological systems framework modified for the specific characteristics of bodily excreta. This framework offers a shared vision for sanitation as a human-derived resource system, where people are part of the resource cycle. Through sanitation technologies and management strategies, resources including water, organics, and nutrients accumulate, transform, and impact human experiences and natural environments. Within the framework, we establish a multitiered lexicon of variables, characterized by breadth and depth, to support harmonized understanding and development of models and analytical approaches. This framework's refinement and use will guide interdisciplinary study around sanitation to identify guiding principles for sanitation that advance sustainable development at the nature-society interface.

Technoeconomic Analysis of Brackish Water Capacitive Deionization: Navigating Tradeoffs between Performance, Lifetime, and Material Costs.

Capacitive deionization (CDI), a class of electrochemical separation technologies, has been proposed as an energy-efficient brackish water desalination method. Previous studies have focused on improving capacity and energy consumption through material (e.g., ion-selective membranes [IEMs], charged carbon) and operational modifications, but there has been no analysis that directly links lab-scale experimental performance to capital and operating costs of full-scale water production. In this study, we developed a parameterized process model and technoeconomic analysis framework to project capital and operating costs at the million gallon per day scale based on reported material and operational characteristics for constant current CDI with and without low ($20 m-2)- and high-cost ($100 m-2) IEMs. Using this framework, we conducted global sensitivity and uncertainty analyses for water price across the reported CDI design space. Our results show that the operating constraints of brackish water desalination lead to capital costs 2-14 times greater than operating costs (particularly for MCDI). While MCDI outperforms CDI, IEM prices dictate the threshold at which MCDI is more cost-effective. The high relative capital costs highlight the importance of achieving system lifetimes at 2 years or beyond. Last, we set performance and areal cost benchmarks for material-based CDI performance and lifetime improvements.

Global Sensitivity Analysis To Characterize Operational Limits and Prioritize Performance Goals of Capacitive Deionization Technologies.

Capacitive deionization (CDI) technologies couple electronic and ionic charge storage, enabling improved thermodynamic efficiency of brackish desalination by recovering energy released during discharge. However, insight into CDI has been limited by discrete experimental observations at low desalination depths (Δ c, typically reducing influent salinity by 10 mM or less). In this study, the performance and sensitivity of three common CDI configurations [standard CDI, membrane CDI (MCDI), and flowable electrode CDI (FCDI)] were evaluated across the operational and material design landscape by varying eight common input parameters (electrode thickness, influent concentration, current density, electrode flow rate, specific capacitance, contact resistance, porosity, and fixed charge). All combinations of designs were evaluated for two influent concentrations with a calibrated and validated one-dimensional (1-D) porous electrode model. Sensitivity analyses were carried out via Monte Carlo and Morris methods, focusing on six performance metrics. Across all performance metrics, high sensitivity was observed to input parameters which impact cycle length (current, resistance, and capacitance). Simulations demonstrated the importance of maintaining both charge and round-trip efficiencies, which limit the performance of CDI and FCDI, respectively. Accounting for energy recovery, only MCDI was capable of operating at thermodynamic efficiencies similar to reverse osmosis.

Microbial Source Tracking Using 16S rRNA Amplicon Sequencing Identifies Evidence of Widespread Contamination from Young Children's Feces in an Urban Slum of Nairobi, Kenya.

Child exposure to fecal contamination remains common in low- and middle-income countries after sanitation interventions. Unsafe disposal of children's feces may contribute to this continued exposure, but its relative importance to domestic fecal contamination is not well understood. To address this gap, we interviewed and collected environmental samples (drinking water, caregiver hands, child hands, surfaces, soil, open drainage ditches, standing water, streams) from 40 households in Kibera, an urban slum in Nairobi, Kenya. To track young children's feces (<3 years old) separately from other human-associated fecal sources, we validated distance-based and Bayesian (SourceTracker) microbial source tracking methods using amplicon-based sequencing of the 16S rRNA gene. Contamination by young children's feces could be identified and distinguished separately from older child/adult feces with high sensitivity and specificity in water and soil. Among environmental samples, young children's feces were almost always identified as the dominant source of human fecal contamination inside households (hands, surfaces) whereas older children/adult feces were often identified as the dominant source outside households (standing water, streams, soil). Markers for young children's feces were also detected in standing water and streams, and markers for both fecal sources were equally likely to be dominant in open ditches. These results establish motivation for sanitation interventions that directly address child feces management.

Aligning Product Chemistry and Soil Context for Agronomic Reuse of Human-Derived Resources.

Recovering human-derived nutrients from sanitation systems can offset inorganic fertilizer use and improve access to agricultural nutrients in resource-limited settings, but the agronomic value of recovered products depends upon product chemistry and soil context. Products may exacerbate already-compromised soil conditions, offer benefits beyond nutrients, or have reduced efficacy depending on soil characteristics. Using global spatial modeling, we evaluate the soil suitability of seven products (wastewater, sludge, compost, urine, ammonium sulfate, ammonium struvite, potassium struvite) and integrate this information with local recovery potential of each product from sanitation systems that will need to be installed to achieve universal coverage (referred to here as "newly-installed sanitation"). If product recovery and reuse are colocated, the quantity and suitability of nutrient reuse was variable across countries. For example, alkaline products (e.g., struvite) may be particularly beneficial when applied to acidic soils in Uganda but potentially detrimental in the southwestern United States. Further, we illustrate discrepancies across soil data sets and highlight the need for locally accurate data, knowledge, and interpretation. Overall, this study demonstrates soil context is critical to comprehensively characterize the value proposition of nutrient recovery, and it provides a foundation for incorporating soil suitability into local and global sanitation decision-making.

Mainstream Ammonium Recovery to Advance Sustainable Urban Wastewater Management.

Throughout the 20th century, the prevailing approach toward nitrogen management in municipal wastewater treatment was to remove ammonium by transforming it into dinitrogen (N2) using biological processes such as conventional activated sludge. While this has been a very successful strategy for safeguarding human health and protecting aquatic ecosystems, the conversion of ammonium into its elemental form is incompatible with the developing circular economy of the 21st century. Equally important, the activated sludge process and other emerging ammonium removal pathways have several environmental and technological limitations. Here, we assess that the theoretical energy embedded in ammonium in domestic wastewater represents roughly 38-48% of the embedded chemical energy available in the whole of the discharged bodily waste. The current routes for ammonium removal not only neglect the energy embedded in ammonium, but they can also produce N2O, a very strong greenhouse gas, with such emissions comprising the equivalent of 14-26% of the overall carbon footprint of wastewater treatment plants. N2O emissions often exceed the carbon emissions related to the electricity consumption for the process requirements of WWTPs. Considering these limitations, there is a need to develop alternative ammonium management approaches that center around recovery of ammonium from domestic wastewater rather than deal with its "destruction" into elemental dinitrogen. Current ammonium recovery techniques are applicable only at orders of magnitude above domestic wastewater strength, and so new techniques based on physicochemical adsorption are of particular interest. A new pathway is proposed that allows for mainstream ammonium recovery from wastewater based on physicochemical adsorption through development of polymer-based adsorbents. Provided adequate adsorbents corresponding to characteristics outlined in this paper are designed and brought to industrial production, this adsorption-based approach opens perspectives for mainstream continuous adsorption coupled with side-stream recovery of ammonium with minimal chemical requirements. This proposed pathway can bring forward an effective resource-oriented approach to upgrade the fate of ammonium in urban water management without generating hidden externalized environmental costs.

Comparable Nutrient Uptake across Diel Cycles by Three Distinct Phototrophic Communities.

The capacity of microalgae to advance the limit of technology of nutrient recovery and accumulate storage carbon make them promising candidates for wastewater treatment. However, the extent to which these capabilities are influenced by microbial community composition remains poorly understood. To address this knowledge gap, 3 mixed phototrophic communities sourced from distinct latitudes within the continental United States (28° N, Tampa, FL; 36° N, Durham, NC; and 40° N, Urbana, IL) were operated in sequencing batch reactors (8 day solids residence time, SRT) subjected to identical diel light cycles with media addition at the start of the nighttime period. Despite persistent differences in community structure as determined via 18S rRNA (V4 and V8-V9 hypervariable regions) and 16S rRNA (V1-V3) gene amplicon sequencing, reactors achieved similar and stable nutrient recovery after 2 months (8 SRTs) of operation. Intrinsic carbohydrate and lipid storage capacity and maximum specific carbon storage rates differed significantly across communities despite consistent levels of observed carbon storage across reactors. This work supports the assertion that distinct algal communities cultivated under a common selective environment can achieve consistent performance while maintaining independent community structures and intrinsic carbon storage capabilities, providing further motivation for the development of engineered phototrophic processes for wastewater management.