An official website of the United States government
Abstract Sensor driven aeration control strategies have recently been developed as a means to efficiently carry out biological nutrient removal (BNR) and reduce aeration costs in wastewater treatment plants. Under load-based aeration control, often implemented as ammonia-based aeration control (ABAC), airflow is regulated to meet desired effluent standards without specifically setting dissolved oxygen (DO) targets. Another approach to reduce aeration requirements is to constantly maintain low DO conditions and allow the microbial community to adapt to the low-DO environment. In this study, we compared the performance of two pilot-scale BNR treatment trains that simultaneously used ABAC and low-DO operation to evaluate the combination of these two strategies. One pilot plant was operated with continuous ABAC while the other one used intermittent ABAC. Both processes achieved greater than 90% total Kjehldal nitrogen (TKN) removal, 60% total nitrogen removal, and nearly 90% total phosphorus removal. Increasing the solids retention time (SRT) during the period of cold (∼12 °C) water temperatures helped maintain ammonia removal performance under low-DO conditions. However, both processes experienced poor solids settling characteristics during winter. While settling was recovered under warmer temperatures, improving settling quality remains a challenge under low-DO operation.
more »
« less
This content will become publicly available on March 1, 2026
Evaluation of biofilm scouring methods on the nitrification efficiency in a pilot‐scale membrane‐aerated biofilm reactor
Membrane‐aerated biofilm reactors (MABRs) are being increasingly being implemented at full‐scale for domestic wastewater treatment and effective biofilm control is critical to their performance. This study investigated the impact of three biofilm scouring strategies on nitrogen removal performance of a pilot‐scale MABR operated in Houston, TX: (1) regular air scouring, (2) high intensity air scouring, and (3) high liquid flow scouring. Normal and high intensity air scouring regimes and a high liquid flow scour (10× baseline flow) were each tested sequentially. High NH4+‐N removal efficiency of 52% in flow‐through mode was observed post‐high liquid flow scouring, which was comparable to the performance during the intense scouring regime. The absolute abundance ofamoAgene for ammonia oxidizing bacteria (AOB) increased significantly by over 200%, between pre‐ and post‐high liquid flow scouring. The energy consumption was 43% lower for the combination of high liquid flow scouring with regular air scouring as compared to the intense air scouring. This study showed that high liquid flows may be utilized as an energy‐efficient biofilm control strategy in nitrifying MABR systems. Practitioner PointsPilot‐scale MABR reactors were operated with different scouring settings: regular aeration, intense aeration, and high liquid flow.High liquid flow scouring improved nitrification efficiency, comparable to intense scouring.High liquid flow scouring selected for nitrifiers as seen by an increase in AOB quantified asamoAgene abundance.Using high liquid flow with regular aeration scouring reduces electrical energy consumption by 43% as compared to intense aeration scouring.High liquid flows may be used as an energy‐efficient biofilm control strategy to improve nitrification performance in MABR systems.
more »
« less
- Award ID(s):
- 1932000
- PAR ID:
- 10584959
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Water Environment Research
- Volume:
- 97
- Issue:
- 3
- ISSN:
- 1061-4303
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract The Twin Falls, Idaho wastewater treatment plant (WWTP), currently operates solely to achieve regulatory permit compliance. Research was conducted to evaluate conversion of the WWTP to a water resource recovery facility (WRRF) and to assess the WRRF environmental sustainability; process configurations were evaluated to produce five resources—reclaimed water, biosolids, struvite, biogas, and bioplastics (polyhydroxyalkanoates, PHA). PHA production occurred using fermented dairy manure. State‐of‐the‐art biokinetic modeling, performed using Dynamita's SUMO process model, was coupled with environmental life cycle assessment to quantify environmental sustainability. Results indicate that electricity production via combined heat and power (CHP) was most important in achieving environmental sustainability; energy offset ranged from 43% to 60%, thereby reducing demand for external fossil fuel‐based energy. While struvite production helps maintain a resilient enhanced biological phosphorus removal (EBPR) process, MgO2production exhibits negative environmental impacts; integration with CHP negates the adverse consequences. Integrating dairy manure to produce bioplastics diversifies the resource recovery portfolio while maintaining WRRF environmental sustainability; pilot‐scale evaluations demonstrated that WRRF effluent quality was not affected by the addition of effluent from PHA production. Collectively, results show that a WRRF integrating dairy manure can yield a diverse portfolio of products while operating in an environmentally sustainable manner. Practitioner pointsWastewater carbon recovery via anaerobic digestion with combined heat/power production significantly reduces water resource recovery facility (WRRF) environmental emissions.Wastewater phosphorus recovery is of value; however, struvite production exhibits negative environmental impacts due to MgO2production emissions.Bioplastics production on imported organic‐rich agri‐food waste can diversify the WRRF portfolio.Dairy manure can be successfully integrated into a WRRF for bioplastics production without compromising WRRF performance.Diversifying the WRRF products portfolio is a strategy to maximize resource recovery from wastewater while concurrently achieving environmental sustainability.more » « less
-
van_Kessel, Julia C (Ed.)ABSTRACT Bacterial motility plays a crucial role in biofilm development, yet the underlying mechanism remains not fully understood. Here, we demonstrate that the flagellum-driven motility ofPseudomonas aeruginosaenhances biofilm formation by altering the orientation of bacterial cells, an effect controlled by shear stress rather than shear rate. By tracking wild-typeP. aeruginosaand its non-motile mutants in a microfluidic channel, we demonstrate that while non-motile cells align with the flow, many motile cells can orient toward the channel sidewalls, enhancing cell surface attachment and increasing biofilm cell density by up to 10-fold. Experiments with varying fluid viscosities further demonstrate that bacterial swimming speed decreases with increasing fluid viscosity, and the cell orientation scales with the shear stress rather than shear rate. Our results provide a quantitative framework to predict the role of motility in the orientation and biofilm development under different flow conditions and viscosities.IMPORTANCEBiofilms are ubiquitous in rivers, water pipes, and medical devices, impacting the environment and human health. While bacterial motility plays a crucial role in biofilm development, a mechanistic understanding remains limited, hindering our ability to predict and control biofilms. Here, we reveal how the motility ofPseudomonas aeruginosa, a common pathogen, influences biofilm formation through systematically controlled microfluidic experiments with confocal and high-speed microscopy. We demonstrate that the orientation of bacterial cells is controlled by shear stress. While non-motile cells primarily align with the flow, many motile cells overcome the fluid shear forces and reorient toward the channel sidewalls, increasing biofilm cell density by up to 10-fold. Our findings provide insights into how bacterial transition from free-swimming to surface-attached states under varying flow conditions, emphasizing the role of cell orientation in biofilm establishment. These results enhance our understanding of bacterial behavior in flow environments, informing strategies for biofilm management and control.more » « less
-
Abstract Producer–decomposer interactions within aquatic biofilms can range from mutualistic associations to competition depending on available resources. The outcomes of such interactions have implications for biogeochemical cycling and, as such, may be especially important in northern peatlands, which are a global carbon sink and are expected to experience changes in resource availability with climate change. The purpose of this study was to evaluate the effects of nutrients and organic carbon on the relative proportion of primary producers (microalgae) and heterotrophic decomposers (bacteria and fungi) during aquatic biofilm development in a boreal peatland. Given that decomposers are often better competitors for nutrients than primary producers in aquatic ecosystems, we predicted that labile carbon subsidies would shift the biofilm composition towards heterotrophy owing to the ability of decomposers to outcompete primary producers for available nutrients in the absence of carbon limitation.We manipulated nutrients (nitrate and phosphate) and organic carbon (glucose) in a full factorial design using nutrient‐diffusing substrates in an Alaskan fen.Heterotrophic bacteria were limited by organic carbon and algae were limited by inorganic nutrients. However, the outcomes of competitive interactions depended on background nutrient levels. Heterotrophic bacteria were able to outcompete algae for available nutrients when organic carbon was elevated and nutrient levels remained low, but not when organic carbon and nutrients were both elevated through enrichment.Fungal biomass was significantly lower in the presence of glucose alone, possibly owing to antagonistic interactions with heterotrophic bacteria. In contrast to bacteria, fungi were stimulated along with algae following nutrient enrichment.The decoupling of algae and heterotrophic bacteria in the presence of glucose alone shifted the biofilm trophic status towards heterotrophy. This effect was overturned when nutrients were enriched along with glucose, owing to a subsequent increase in algal biomass in the absence of nutrient limitation.By measuring individual components of the biofilm and obtaining data on the trophic status, we have begun to establish a link between resource availability and biofilm formation in northern peatlands. Our results show that labile carbon subsidies from outside sources have the potential to disrupt microbial coupling and shift the metabolic balance in favour of heterotrophy. The extent to which this occurs in the future will probably depend on the timing and composition of bioavailable nutrients delivered to surface waters with environmental change (e.g. permafrost thaw).more » « less
-
Abstract Enhanced biological phosphorus removal (EBPR) can recover significant quantities of wastewater phosphorus. However, this resource recovery process realizes limited use largely due to process stability concerns. The research evaluated the effects of anaerobic HRT (τAN) and VFA concentration—critical operational parameters that can be externally controlled—on EBPR performance. Evaluated alone, τAN(1–4 h) exhibited no statistical effect on effluent phosphorus. However, PHA increased with VFA loading and biomass accumulated more phosphorus. Regarding resiliency, under increasing VFA loads PAOs hydrolyzed more phosphorus to uptake/catabolize VFAs; moreover, PHA synthesis normalized to VFA loading increased with τAN, suggesting fermentation. Kinetically, PAOs exhibited a Monod‐like relationships for qPHAANand qVFAANas a function of anaerobic P release; additionally, qPAEexhibited a Monod‐like relationship with end‐anaerobic PHA concentration. A culminating analysis affirmed the relationship between enhanced aerobic P uptake, and net P removal, with a parameter (phosphorus removal propensity factor) that combines influent VFA concentration with τAN. Practitioner pointsEvaluated alone τANexhibits no statistical effect on effluent phosphorus in an EBPR configuration.Increased PHA synthesis, associated with increased VFAs and/or extended τAN,enhances aerobic phosphorus removal.PHA synthesis normalized to VFA loading increased with τAN, suggesting fermentation in the EBPR anaerobic zone.Aerobic phosphorus uptake increases linearly with anaerobic phosphorus release, with the slope exceeding unity.Increased VFAs can be substituted for shorter anaerobic HRTs, and vice versa, to enhance EBPR performance.more » « less
