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Conventional biological nitrogen removal (BNR) processes for mainstream municipal wastewater (MMW) treatment have high energy and chemical costs. Partial nitritation/anammox (PN/A) has the potential to reduce the carbon footprint of BNR; however, its implementation for MMW treatment has been limited by the low ammonium and high organic matter concentrations in MMW, which prevent suppression nitrite oxidizing bacteria (NOB) and heterotrophic denitrifiers. In this study, after organic carbon diversion, ammonium was separated from MMW in a novel bench-scale sequencing batch biofilm reactor (SBBR) containing chabazite, a natural zeolite mineral with a high ammonium ion exchange (IX) capacity. After breakthrough, chabazite was bioregenerated by PN/A biofilms. Recirculation was applied from the bottom to the top of the column to create an aerobic zone (top) for ammonia-oxidizing microorganisms (AOM) and an anoxic zone (bottom) for anammox bacteria. Rapid IX-PN/A SBBR startup was observed after inoculation with PN/A enrichments. The time required for bioregeneration decreased with increasing recirculation rate, with high total inorganic nitrogen (TIN) removal efficiency (81 %) and ammonium removal rate (0.11 g N/L/day) achieved at recirculation velocity of 1.43 m/h. The core microbiome of the IX-PN/A SBBR contained a high abundance of bacteria of the phylum Pseudomonadota (15.27–20.62 %), Patescibacteria (12.38–20.05 %), Chloroflexota (9.36–14.23 %), and Planctomycetota (7.55–12.82 %), while quantitative PCR showed the highest ammonia monooxygenase (amoA, 2.0 × 102) and anammox copy numbers (amx, 1.0 × 104) in the top layers. The single-stage IX-PN/A SBBR achieved stable BNR for >two years without chemical inputs, media replacement or brine waste production. 

Tourism offers many economic benefits but can have long-lasting ecological effects when improperly managed. Tourism can cause overwhelming pressure on wastewater treatment systems, as in Belize, where some of the over 400 small islands (cayes) that were once temporary sites for fishermen have become popular tourist destinations. An overabundance of nitrogen, in part as a result of incomplete wastewater treatment, threatens human health and ecosystem services. The tourism industry is a complex and dynamic industry with many sectors and stakeholders with conflicting goals. In this study, a systems thinking approach was adopted to study the dynamic interactions between stakeholders and the environment at Laughing Bird Caye National Park in Belize. The project centered on nutrient discharges from the caye’s onsite wastewater treatment system. An archetype analysis approach was applied to frame potential solutions to nutrient pollution and understand potential behaviors over time. “Out of control” and “Underachievement” were identified as system archetypes; “Shifting the Burden” and ‘‘Limits to Success’’ were used to model specific cases. Based on these results, upgrading of the wastewater treatment system should be performed concurrently with investments in the user experience of the toilets, education on the vulnerability of the treatment system and ecosystem, and controls on the number of daily tourists. 

Nitrogen and fecal indicator bacteria (FIB) in runoff from concentrated animal feeding operations (CAFOs) can impair surface and groundwater quality. Bioretention systems are low impact nature-based technologies that can effectively treat CAFO runoff if modified with an internal water storage zone (IWSZ) or amended with biochar. In this study, the performances of four pilot-scale modified bioretention systems were compared to assess the impacts of (1) amending bioretention media with biochar and (2) planting the systems with Muhlenbergia. The system with both plants and biochar amendment had the best performance, with an average of 5.58 log reduction in E. coli and 98% removal of total nitrogen (TN). All systems treated the first pore volume well as new runoff flushed the treated water from the IWSZ. Biochar improved TN and FIB removal due to its high capacity to adsorb or retain ammonium (NH4+), dissolved organic nitrogen, dissolved organic carbon, and E. coli. Planting improved performance, possibly by increasing rhizosphere microbial activity. 

Interest in craft beers is increasing worldwide due to their flavor and variety. However, craft breweries have high water, energy, and carbon dioxide (CO2) demands and generate large quantities of high-strength waste and greenhouse gases. While many large breweries recover energy using anaerobic digestion (AD) and recapture CO2 from beer fermentation, little is known about the economic feasibility of applying these technologies at the scale of small craft breweries. In addition, compounds in hops (Humulus lupulus), which are commonly added to craft beer to provide a bitter or “hoppy” flavor, have been shown to adversely affect anaerobic microbes in ruminant studies. In this study, biochemical methane potential (BMP) assays and anaerobic sequencing batch reactor (ASBR) studies were used to investigate biomethane production from high-strength craft brewery waste, with and without hop addition. A spreadsheet tool was developed to evaluate the economic feasibility of bioenergy and CO2 recovery depending on the brewery’s location, production volume, waste management, CO2 requirement, energy costs, and hop waste addition. The results showed that co-digestion of yeast waste with 20% hops (based on chemical oxygen demand (COD)) resulted in slightly lower methane yields compared with mono-digestion of yeast; however, it did not significantly impact the economic feasibility of AD in craft breweries. The use of AD and CO2 recovery was found to be economically feasible if the brewery’s annual beer production is >50,000 barrels/year.