Nutrient Removal Research Articles

Arbuscular mycorrhizal fungi improve treatment performance and vegetative resilience in constructed wetlands exposed to microplastics.

Microplastics are increasingly present in municipal wastewater and wastewater treatment plant effluent, prompting the use of constructed wetlands (CWs) for additional treatment. Enhancing CWs with arbuscular mycorrhizal fungi (AMF), known to aid nutrient removal and alleviate plant pollution stress, is gaining interest. This study is the first to examine the influence of two microplastic polymers (polyethylene microspheres and polyester microfibers) at concentrations of 0.1 and 1 mg/L on nutrient removal, plant health, and microbial composition in AMF-inoculated CWs. The results indicate that AMF inoculation combined with microplastic treatments significantly enhances nutrient removal in wetlands, achieving a 45.7% increase in total nitrogen removal and a 25.3% increase in phosphate removal. The effects of microplastics on plant health vary depending on the inoculation status, with an increase in lipid peroxidation (73.4% ± 25.4), and a decrease in the effective quantum yield of PSII (13.4% ± 5) observed in all treatments. High concentrations of polyester microfibers significantly altered the microbial community, increasing AMF colonization frequency and microbial richness, decreasing evenness and the abundance of denitrifying genera, and creating distinct clusters in beta diversity analysis. AMF inoculation maintained higher species richness and evenness, contributing to the resilience of CWs to microplastic pollution. Overall, AMF-inoculated wetlands and plants showed superior treatment performance, highlighting the successful bio-augmentation potential of this approach.

Feasibility and efficiency of microalgae cultivation for nutrient recycling and energy recovery from food waste filtrate.

With the continuous growth of economic and population, the generation of food waste has significantly increased in recent years. The disposition of food waste, typically through incineration or landfill, can lead to severe health and environmental problems, accompanied by high additional costs. However, the leachate produced from food waste during collection, transportation and landfill operations predominantly contains high levels of nutrients necessary for microalgae growth. The integration of microalgae cultivation into waste treatment for nutrient recycling presents a potential route for energy recovery from food waste. Therefore, this study was conducted to evaluate the feasibility of microalgae cultivation for food waste filtrate treatment. In addition, the optimal cultivation conditions and nutrient removal efficiency for microalgae in food waste filtrate treatment were investigated. The results indicated that Cyanobacterium aponinum exhibited the highest growth rate (0.530 cells d-1) and maximum cell density (9.6 × 106 cells mL-1) among eight potential microalgal species in 10% food waste filtrate treatment under 10,000 lux and 32°C. It was also observed that C. aponinum had significantly higher biomass productivity and nutrient removal efficiency under a 5% CO2 concentration. The successful cultivation of C. aponinum demonstrated that food waste filtrate could be a promising growth medium, reducing the high cost of cultivation with synthetic medium. However, further efforts should be made to utilize microalgae in food waster filtrate treatment, transitioning from laboratory condition to a pilot scale.

Use of Membrane Techniques for Removal and Recovery of Nutrients from Liquid Fraction of Anaerobic Digestate

This review focuses on the use of membrane techniques to recover nutrients from the liquid fraction of digestate (LFD) and emphasizes their role in promoting the principles of the circular economy. A range of membrane separation processes are examined, including microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), membrane distillation (MD) and new tools and techniques such as membrane contactors (MCs) with gas-permeable membranes (GPMs) and electrodialysis (ED). Key aspects that are analyzed include the nutrient concentration efficiency, integration with biological processes and strategies to mitigate challenges such as fouling, high energy requirements and scalability. In addition, innovative hybrid systems and pretreatment techniques are examined for their potential to improve the recovery rates and sustainability. The review also addresses the economic and technical barriers to the full-scale application of these technologies and identifies future research directions, such as improving the membrane materials and reducing the energy consumption. The comprehensive assessment of these processes highlights their contribution to sustainable nutrient management and bio-based fertilizer production.

Intensifying intermittent aeration for optimizing nutrient and hormone removal in vertical-flow constructed wetlands filled with aerated concrete.

Operational strategies have been applied in constructed wetlands to optimize the removal of nutrients and hormones that are still a concern in wastewater treatment. The strategy of intensifying intermittent aeration was investigated in two microcosm-scale vertical-flow constructed wetlands (VFCWs) planted with Eichhornia crassipes onto autoclaved aerated concrete (AC) in the removal of nutrients, estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2). CW-1 (2.4 LO2 min-1) and CW-2 (1.4 LO2 min-1) were fed with synthetic wastewater in sequencing-batch mode (cycles 48-48-72h) and intermittently aerated for 1h, followed by 7h without aeration for 377 days. Combined with the intensification strategy, the use of planted free-floating macrophytes and concrete-based material (emergent) as filtering media stand out as the innovation and originality aspects of this study. Despite the hormone addition, intensifying aeration enhanced the efficiencies since CW-1 achieved the highest removals with 91% COD, 77% TN, 74% TAN, 60% nitrate, and 97% TP in Stage I (no hormone addition) and 90% COD, 80% TN, 93% TAN, 63% nitrate, and 82% TP in Stage II (with hormone addition). CW-1 achieved the highest removal efficiencies of E1 (84%), E2 (95%), and EE2 (73%). Conversely, the efficiencies decreased under the lower aeration rate (in CW-2) for all parameters. Macrophyte uptake and adsorption stood out for TN (>60.25%) and TP (>27.6%) removal as the main mechanisms in the VFCWs. The characteristics of AC favored ion exchange and precipitation, reinforcing the potential of this material as filtering media in VFCWs. Intensification of intermittent aeration combined with hormone addition diverse and riched the microbial community with the presence of Thauera, Lentimicrobium (denitrification), Candidatus Accumulibacter (phosphorus removal), Pseudomonas, Fusibacter, and Azoarcus (EE2 degradation). Intensifying intermittent aeration was an important strategy to enhance the simultaneous removal of nutrients and hormones in the VFCWs under the evaluated operational conditions.

Feasibility of using lipid-rich mutant microalgae in wastewater cultivation: Biochemical changes, nutrient removal, and lipid analysis

Feasibility of using lipid-rich mutant microalgae in wastewater cultivation: Biochemical changes, nutrient removal, and lipid analysis

Simultaneous Organic and Nutrient Removal in Wastewater Using a Revolving Algae Biofilm Reactor

This study focused on a revolving algae biofilm (RAB) reactor for the efficient removal of nutrients from synthetic wastewater. Chlorella vulgaris algae species were used in this study. The study examined the reactor performance across various hydraulic retention times (HRTs) ranging from 60 to 30hours, revealing crucial insights into its operational efficiency. The results demonstrate that HRT significantly influences key performance indicators, including removal rates, removal efficiencies, biomass growth rate, and complete nitrification. Among the tested configurations, HRT-30h emerged as the optimal parameter, exhibiting impressive removal rates of 108mg/L/day for COD, 35mg/L/day for ammonia nitrogen, and 1.8mg/L/day for phosphorus. Furthermore, it achieved the highest levels of suspended and harvested biofilm mass, measuring 1.07g/L and 7g, respectively. Notably, HRT-30h displayed exceptional biomass growth rate, reaching up to 3.77g/m2/day. Therefore, it underscores the promising potential of the RAB reactor as an efficient and adaptable technology for nutrient removal in wastewater treatment. Further exploration and refinement of operational parameters hold the key to harnessing the full capabilities of this innovative wastewater treatment technology.

Stormwater ponds: Unaccounted environmental challenges of a widely-adopted best management practice in urban landscapes.

Stormwater ponds (SWPs) are an increasingly common management tool for flood control and water quality protection in urban areas. They are designed to buffer the impacts to downstream environments caused by altered hydrologic, chemical, biological, and ecological processes in developed watersheds. While small in size, they can have disproportionately large impacts on watersheds because they store, transform, and release inputs of carbon (C) and nutrients, mainly nitrogen (N) and phosphorus (P). In this review, we discuss how SWPs are not passive conveyances of nutrients and C, where minimal internal processing occurs. Rather, they are active hotspots of biogeochemical processing, with implications for downstream water quality protection. We highlight how processes of assimilation, sedimentation, erosion, filtration, remineralization and remobilization, gaseous transformations, and the activities of living organisms all transform nutrients and C in SWPs, sometimes making ponds net exporters of nutrients, rather than net sinks or removers, as is often believed. There are numerous unaccounted challenges in SWP management, such as in-pond processes that decouple pond effluent and influent quality; that sedimentation often fails as a proxy indicator for nutrient removal; how optimizing for removal of one nutrient (nitrogen or phosphorus) may reduce removal efficiencies of the other; or how nutrient removal strategies may be at odds with strategies to mitigate greenhouse gas emissions from SWPs. Our goal is to show that SWPs play large roles in constraining and mediating the fluxes of materials and energy in urban ecosystems and that their effluent water quality is driven not only by inflowing water quality but largely also by in-pond processes that warrant increased future research.

Nutrient removal performance and microbial community analysis in an integrated wastewater treatment system with macroalgae (U. meridionalis) and Bacillus

Nutrient removal performance and microbial community analysis in an integrated wastewater treatment system with macroalgae (U. meridionalis) and Bacillus

Stories of biologically enhanced carbon diversion technology in the age of biological nutrient removal process – Origin, evolution and milestones

Stories of biologically enhanced carbon diversion technology in the age of biological nutrient removal process – Origin, evolution and milestones

Nutrient removal performance of novel Filamentous Algae Nutrient Scrubber (FANS) configurations

Nutrient removal performance of novel Filamentous Algae Nutrient Scrubber (FANS) configurations

Genera complying denitrifying phosphorus removal community contribute excellent SND-PR in a pilot cyclic SBR: Effect of DO, settling and recirculation rate on process performance.

This work investigated the role of operational conditions and typical functional microbes to maximize the nutrient removal efficiency of a pilot-scale sequencing batch reactor (SBR) system (100 m3/d) that treated municipal wastewater. The pilot system was operated in five phases, including start-up and four runs at variable cycle times (2.0, 1.5, 1.7, 2.0, and 3.0h) with an average readily biodegradable chemical oxygen demand (rbCOD) to chemical oxygen demand (COD) ratio of ∼15.3%. The best TN removal 'ηmax' of 75.6 ± 5.6% (TNinfluent= 27.5 ± 6.5 mg/L, TNeffluent ≤5.9 mg/L) and TP removal 'pmax' 77.9 ± 6.3% (TPinfluent= 3.8 ± 1.3 mg/L, TPeffluent ≤1.0 mg/L) along with the COD, biochemical oxygen demand (BOD), and total suspended solids (TSS) removal efficiencies of 87.3 ± 4.5%, 92.7 ± 2.8%, 92.0 ± 3.5%, respectively, were observed during run 3 (2h cycle) at settling/ total cycle times ratio (S/T) of 0.33 and recirculation/ total cycle times ratio (R/T) of 0.017 (6.4%), and operating DO of 0.5-2.5 mg/L. The denitrifying polyphosphate accumulating organisms 'DPAOs' of Burkholderia (17.0%), Rhodocyclales (6.1%), and Flavobacterium (8.7%) classes, and Nitrifiers of Nitrospira (5.4%) and Nitrosomonas (5.4%) classes were dominant in accomplishing simultaneous nitrification, denitrification, and phosphorus removal (SND-PR) in the pilot system.

Optimization of AAO process for reduced N2O emissions and enhanced nitrogen removal in municipal wastewater treatment: Exploring carbon supplementation and DO control strategies.

The anaerobic/anoxic/oxic (AAO) process remains a common nutrient removal process in municipal wastewater treatment, yet research focusing on concurrent optimization of process performance and N2O emissions reduction is scarce. This study aimed to investigate the mitigation of N2O emissions and enhance nitrogen removal efficiency in an AAO system treating low C/N domestic wastewater by establishing a fully enclosed gas-collecting continuous flow reactor and implementing carbon supplementation and dissolved oxygen (DO) control strategies. The results indicated that carbon supplementation in the anoxic zone effectively reduced nitrate concentrations and mitigated the accumulation of dissolved N2O below 0.1 mgN/L. The moderate DO control (1-2 mg/L) could ensure the nitrification efficiency while reducing the gaseous N2O emission rate to 63.48 mgN/d, and decreasing the dissolved N2O concentration in the effluent to below 0.01 mgN/L. Both too high and too low DO levels were detrimental to N2O emission mitigation. The optimized AAO process achieved a significant reduction in the N2O emission factor to 0.85 % and an increase in nitrogen removal efficiency to 81.81 %. Additionally, the enrichment of anammox bacteria, Candidatus brocadia (0.15 %), positively contributed to the improvement in nitrogen removal efficiency. In conclusion, this study provides valuable insights into optimizing AAO process to mitigate N2O emissions, enhance nitrogen removal, and lower carbon footprints associated with wastewater treatment.

Fabrication and Optimization of Alginate Membranes for Improved Wastewater Treatment

Alginate, a naturally occurring biopolymer extracted from brown algae, presents a promising avenue for developing sustainable and efficient membranes for wastewater treatment. This review comprehensively examines recent advancements in the fabrication, modification, and application of alginate-based membranes for effective water purification. The paper delves into various fabrication techniques, including casting, electrospinning, and 3D printing, which influence the structural and functional properties of the resulting alginate membranes. To enhance performance, strategies such as crosslinking, incorporation of porogens, and surface functionalization are employed. These modifications optimize crucial properties like mechanical strength, porosity, selectivity, and antifouling resistance. Furthermore, Response Surface Methodology (RSM) has emerged as a valuable tool for systematically optimizing fabrication parameters, enabling researchers to identify optimal conditions for achieving desired membrane characteristics. The integration of alginate membranes with biological treatment processes, such as phycoremediation (utilizing microalgae) and mycoremediation (employing fungi), offers a synergistic approach to enhance wastewater treatment efficiency. By immobilizing these microorganisms within the alginate matrix, their bioremediation capabilities are amplified, leading to improved pollutant degradation and nutrient removal. In conclusion, alginate-based membranes demonstrate significant potential as a sustainable and effective technology for wastewater treatment. Continued research and development, focusing on optimizing fabrication processes and exploring innovative integration strategies with biological systems, will further advance the application of alginate membranes in addressing the pressing global challenge of water pollution.

Removal of antibiotics and their impact on growth, nutrient uptake, and biomass productivity in semi-continuous cultivation of Auxenochlorella protothecoides.

The prevalence of antibiotics in wastewater poses risks to human and animal health, contributing to antimicrobial resistance. Although various antibiotic removal methods exist, microalgae-based technology presents a cost-effective and eco-friendly alternative; however, limited research on its long-term integration in semi-continuous wastewater treatment trials hinders our understanding of its potential effectiveness. This investigation explored the antibiotic removal capabilities of the microalga Auxenochlorella protothecoides in photobioreactors with synthetic wastewater under semi-continuous conditions over one month. Additionally, the study assessed the impact of seven commonly used antibiotics (ciprofloxacin, clarithromycin, erythromycin, metronidazole, ofloxacin, sulfamethoxazole, and trimethoprim) on the microalgal system regarding growth, nutrient removal, and biomass productivity. The microalga effectively removed antibiotics, achieving maximum removal efficiencies ranging from 45.8% to 70.1% over 3-4 days of exposure. Remarkably, antibiotics stimulated algal growth, resulting in an 11.0% increase in biomass. Nutrient removal also improved significantly; ammonium removal rose from 78.0% to 86.4%, and phosphate removal increased from 85.1% to 90.3%. Furthermore, the biomass composition showed notable enhancements, with increases in pigments (12.9%), lipids (20.6%), proteins (45.8%), and carbohydrates (50.6%). These findings highlight the potential applicability of A. protothecoides as a valuable addition to conventional wastewater treatment plants. The study emphasises the importance of considering antibiotic presence in microalgae-based wastewater treatment technologies, as these compounds can have a stimulatory effect that enhances both growth and nutrient removal efficiency. Overall, this research contributes to the development of more effective strategies for managing antibiotic pollution in wastewater.

Cyanobacterial phycoremediation: a sustainable approach to dairy wastewater management

ABSTRACT The dairy industry is a significant sector within the food industries, known for its high-water consumption and consequent generation of dairy wastewater (DWW), which is rich in pollutants like Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). Improper disposal of DWW poses serious environmental challenges, including eutrophication and highlighting the need for sustainable biological treatment methods. This study investigates the potential of indigenous cyanobacterial strains Oscillatoria pseudogeminata, Oscillatoria proteus, Oscillatoria trichoides, and Lyngbya ceylanica for the bioremediation of DWW. Under controlled laboratory conditions, these strains were assessed for their uptake capabilities for 15 days. Results indicated that L. ceylanica significantly reduced (approx. 70%, P < .05) in key pollutants such as ammonia, nitrate, and phosphate compared to other strains. Biochemical analyses indicated a decrease in biomass, chlorophyll a, carotenoids, proteins, and carbohydrates in DWW relative to the growth of cyanobacteria in BG 11 media. This decline may hinder the effectiveness of cyanobacterial in wastewater remediation. The findings highlight the efficacy of selected cyanobacteria in nutrient removal from DWW, emphasizing their dual role in nutrient uptake through biosorption mechanism and biomass generation. The results pave the way for innovative biotechnological applications such as biofertilizers and feedstock for bioethanol/ biodiesel production, thus promoting more sustainable management practices within the dairy industry.

Enhancing Wastewater Treatment Efficiency Using MBBR: A Media Selection Approach

Background: Wastewater treatment is a critical environmental challenge, and moving bed biofilm reactor (MBBR) technology is an effective solution. The selection of appropriate biofilm media significantly impacts treatment efficiency, particularly in terms of organic matter and nutrient removal. This study aims to optimize media selection for MBBR systems to improve wastewater treatment. Methods: Three biofilm media types-K3, MB3, and K5-were evaluated based on key properties such as specific surface area (SSA), porosity, buoyancy, and economic feasibility. The analytical hierarchy process (AHP) was employed to assess and prioritize these criteria. Expert Choice software facilitated the analysis, followed by a laboratory-scale investigation to assess pollutant removal efficiency. Results: K5 media outperformed K3 and MB3 in terms of nitrogen removal (90%), chemical oxygen demand (COD) reduction (90%), biochemical oxygen demand (BOD) elimination (95%), and TSS removal (89%). K5 also demonstrated superior efficiency in pollutant removal while maintaining consistent pH regulation. K3 and MB3 displayed relatively lower performance, especially in nitrogen and COD removal. Conclusion: The study confirms that K5 media, selected using the AHP method, provides the highest treatment efficiency in MBBR systems. The AHP-based media selection process enhances the decision-making process, ensuring that economic and performance factors are adequately considered. Future studies should focus on scaling up the MBBR system with K5 media to further evaluate its long-term performance in real-world conditions.

National scale evaluation of nutrient purification capacity in marine sediments along the coast of South Korea: A mesocosm study based in situ assessment.

The ecosystem regulating services from tidal flats, such as removal of organic pollutants, provided by natural tidal flats are being increasingly recognized, yet quantitative evaluation remains limited. Here we evaluated a nationwide capacity of natural purification in tidal flats. Using in situ sediments from five along the Korean coast (Incheon, Gunsan, Sinan, Gwangyang, and Busan), we applied a mesocosm system informed by 18years of riverine monitoring data from national surveys. In particular, we adopted an integrated approach, analyzing nutrient fluxes, removal rates, and their economic value. The results indicated that in all regions, the water-sediment fluxes of all nutrients showed negative values, indicating the migration of nutrients from the overlying water to the sediment. A significant (p<0.01) difference among regions of water-sediment fluxes was primarily due to exposed nutrient concentrations. Notably, the presence of greater total nitrogen (TN) and total phosphorus (TP) purification capacities in Incheon and Nakdong sediments reflected in remaining loads of river-estuarine continuum. Nationwide, the nutrient purification capacities of Korean tidal flats (2491km2) were estimated at 0.29 Tg N yr-1 and 0.15 Tg P yr-1, equating to economic values of 8.26 billion USD yr-1 and 8.21 billion USD yr-1, respectively. Scaling globally, the economic values for TN and TP removal by tidal flats (124,921km2) reached 414 billion USD yr-1 and 412 billion USD yr-1. Overall, the integrated approach successfully provided the first national-scale evaluation of nutrient removal capacity in tidal flats across Korea, addressing the ecological and economic significance of tidal flats, while underscoring the need for their conservation and management strategies of coastal areas globally.

Efficiency of Microalgae Employment in Nutrient Removal (Nitrogen and Phosphorous) from Municipal Wastewater

Growing population, industrialisation, and demand for resources put pressure on the delicate balance of the planet’s ecosystems. From alternative sources of energy, healthier foods, cleaner water, and an overall more sustainable economy, the integration of microalgae in various industries, that otherwise are based on practices that hurt the environment, could be a successful solution. To reach that goal, further research is required on the complex relationship between microalgae and growth parameters (temperature, light intensity and spectrum, nutrient distribution, inhibiting factors, and so on). The scientific community successfully used microalgae to produce healthier foods, pigments, biofuel, animal fodder, methods for sequestering heavy metals, toxic compounds from water, and much more. In this review article, we approach the use of microalgae in municipal wastewater treatment, mainly for using nitrogen and phosphorous present in water as nutrients. Data were collected from articles published in the last 7 years (2018–2024). The results show that microalgae are very efficient at using N and P compounds from wastewater, as well as carbon, converting them in high-value substances (proteins, lipids, carbohydrates, etc.) with further applications in multiple industries.

The new urban wastewater treatment directive from the perspective of the receiving rivers’ quality

BackgroundThe European Union is reformulating key water management directives: the Urban Wastewater Treatment Directive (UWWTD) and the Water Framework Directive. The UWWTD update mandates extended removal of nutrients and stricter limits on micropollutants, primarily at wastewater treatment plants with a constructed capacity above 10 000 population equivalents. The revised Environmental Quality Standards Directive expands the list of regulated pollutants and lowers permissible concentrations for priority substances, including pharmaceuticals. The present study, applied for the Central-European country Hungary as a pilot, examines the impact of the UWWTD recast on receiving water quality. Employing a mixing model to assess the impact of municipal wastewater treatment plant emissions on regional waters, the research aims to optimize resource allocation for plant improvements and enhance risk area designation methods.ResultsBased on the evaluation of 886 river water bodies, it was found that wastewater plant effluents explain most of the current river impairment. Stricter nitrogen and phosphorus standards foreseen in the UWWTD recast will reduce the fraction of water bodies failing to achieve good ecological status by ~ 10%. The introduction of the new environmental quality standards for pharmaceuticals, in particular clarithromycin and diclofenac, will reveal that almost half of the river water bodies fail to achieve the good chemical status. Even after the implementation of micropollutant removal at the largest plants, as required by the recast, this number will not improve substantially.ConclusionsThe UWWTD recast’s stricter effluent standards for nutrients are projected to remarkably reduce the number of water bodies failing to achieve good ecological status, particularly in lowland rivers. However, the chemical status for pharmaceuticals like diclofenac remains concerning, with more than 40% of streams expected to fail under the revised limits. To overcome this, it is suggested to revise how the implementation of micropollutant removal at plants is prioritized. In addition to plant constructed capacity, the receiving water’s dilution capacity is to be considered at the prioritization and the designation of areas at risk.

Nitrogen and phosphorus-related functional genes enhance nutrient removal in the integrated aquaculture wastewater bioremediation system in the presence of photosynthetic bacteria

Nitrogen and phosphorus-related functional genes enhance nutrient removal in the integrated aquaculture wastewater bioremediation system in the presence of photosynthetic bacteria