Percorrer por autor "Loosdrecht, Mark van"
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- Enhancing maize growth and reducing irrigation needs with extracellular polymeric substances and microbial inoculantsPublication . Overall, Alexandra; Moreira, Helena; Sousa, Ana S. S.; Wilfert, Philipp; Loosdrecht, Mark van; Castro, Paula M. L.; Pereira, Sofia I. A.Soil amendments and microbial inoculants can affect plant growth, water retention, and crop resilience. This study investigated the effects of two amendments, extracellular polymeric substances (EPS) and biochar, with and without bacterial inoculation, on maize (Zea mays) growth, irrigation needs, and physiological responses. Maize was cultivated in soil with 2.5 % and 5 % (w/w) of wet EPS (Kaumera®) or biochar and inoculated with a bacterial consortium consisting of Arthrobacter nicotinovorans EAPPA and Rhodococcus sp. EC35. EPS-treated plants exhibited significantly higher shoot biomass, larger stem thickness, while soil plant analysis development (SPAD) values suggest improved nutrient availability and photosynthetic efficiency. In non-inoculated plants, EPS supplementation increased shoot dry biomass by 78 % and stem thickness by 9 % compared to control plants grown without amendments. This enhancement strongly correlated with nutrient uptake, especially in plants supplemented with 5 % of EPS. Particularly, Mg and Ca concentrations increased by 195 % and 73 %, respectively, compared to non-amended controls. Inoculation further amplified these benefits, underscoring its key role in plant development and resilience. In contrast, biochar-treated plants exhibited reduced growth, suggesting stress effects at the tested addition doses. Electrolyte leakage, a key indicator of plant stress, was significantly lower in soils amended with EPS, suggesting that EPS provides a protective effect to the plants. EPS also demonstrated remarkable water retention benefits, reducing irrigation requirements by 30 % with 5 % of EPS application, compared to 9 % reduction with biochar. The use of EPS, combined with microbial inoculants, represents a sustainable agricultural strategy for optimizing maize production in water-limited environments.
- Enhancing photosynthetic efficiency and nutrient uptake in Maize (Zea mays L.) using extracellular polymeric substances recovered from waste sludgePublication . Amorim, Catarina L.; Pereira, Sofia I. A.; Sousa, Ana S. S.; Wilfert, Philipp; Loosdrecht, Mark van; Martins, António; Castro, Paula M. L.; Miranda, CatarinaExtracellular polymeric substances (EPS) can be recovered from waste aerobic granular sludge (AGS) generated during biological wastewater treatment. These biopolymers are rich in organic carbon and nutrients and can improve the water-holding capacity of soils, making them suitable for agricultural applications.
- Enhancing photosynthetic efficiency and nutrient uptake in Maize (Zea mays L.) using extracellular polymeric substances recovered from waste sludgePublication . Amorim, Catarina L.; Pereira, Sofia I. A.; Sousa, Ana S. S.; Wilfert, Philipp; Loosdrecht, Mark van; Martins, António; Castro, Paula M. L.; Miranda, CatarinaExtracellular polymeric substances (EPSs) are biopolymers that can be recovered from waste aerobic granular sludge (AGS) generated in wastewater treatment plants (WWTPs). These biopolymers represent a valuable resource with attractive attributes, making them suitable for applications across different sectors. In agriculture, EPSs have attracted growing interest, although their beneficial effects are still underexplored. In a 7-week greenhouse experiment, the effects of EPSs recovered from waste AGS sourced from two WWTPs (Utrecht (EPS_U) and Faro (EPS_F)) and a lab-scale reactor (EPS_R) on maize growth, photosynthetic efficiency, and nutrient uptake and use efficiency were explored. EPSs were incorporated into the soil at doses of 0.5% and 1% (w/w), and their effects were evaluated against equivalent doses of vermicompost and non-amended soil (control). EPS incorporation, especially with 1% EPS_R, enhanced stem thickness and shoot fresh weight, whereas lower doses of other EPS sources and vermicompost had only marginal effects. Additionally, EPSs, regardless of their source, markedly enhanced the chlorophyll content compared to plants grown in non-amended soils, demonstrating their role in enhancing nutrient availability and maize photosynthetic efficiency. Moreover, the incorporation of EPS_R_1% and EPS_F_1% markedly increased the Mg and K uptake by 46% and 34%, respectively, compared to the control. Some EPS treatments were also able to increase the use efficiency of Ca, K, Na, and Zn, compared to plants in vermicompost-treated soils. As such, EPSs can effectively enhance the availability, uptake, and use of nutrients in maize. The study highlights the potential of waste-derived biopolymers to enhance maize nutritional traits and physiological responses while promoting sustainable agricultural practices and resource recovery strategies.
- Increased extracellular polymeric substances production contributes for the robustness of aerobic granular sludge during long-term intermittent exposure to 2-fluorophenol in saline wastewaterPublication . Oliveira, Ana S.; Amorim, Catarina L.; Mesquita, Daniela P.; Ferreira, Eugénio C.; Loosdrecht, Mark van; Castro, Paula M. L.Industrial effluents often contain organic pollutants and variable salinity levels, making their treatment challenging. The high content of extracellular polymeric substances (EPS) in the aerobic granular sludge (AGS) is thought to protect the microbial communities from stressful conditions. Ammonium and phosphate removal, EPS production, and granular morphology were assessed in a lab-scale AGS reactor operated during 138 days at continuous low or moderate salinity levels (1.41–6.46 g/L of NaCl) and intermittent short-term loadings of a fluoroorganic pollutant, 2-fluorophenol (2-FP, 20 mg/L). 2-FP was not degraded throughout operation. Ammonium removal efficiency was drastically affected whenever 2-FP stressor was present, decreasing from 99 % to non-detectable conversion levels, but completely recovering after 2-FP feeding ceased. Phosphate removal, initially disturbed by exposure to stress conditions, recovered with time, even when stressors were still present. Complete phosphate removal did not occur in periods when nitrite temporarily accumulated after nitrification started to recover. EPS composition and concentration in AGS varied during operation, initially decreasing from 133 to 34 mg/g VSS of AGS, during the stress phases but recovering thereafter to 176 mg/gVSS of AGS. Breakage of granules into smaller ones occurred at two different operational moments due to stressors presence. The presence of 2-FP and moderate salinity levels in wastewater had more immediate detrimental effects on nutrients removal than on EPS production. The AGS system capacity to recover the nutrient removal performance and EPS production, after the withdrawal of 2-FP from the inlet stream reinforced its robustness to deal with industrial wastewaters.
- Recovered granular sludge extracellular polymeric substances as carrier for bioaugmentation of granular sludge reactorPublication . Oliveira, Ana S.; Amorim, Catarina L.; Zlopasa, Jure; Loosdrecht, Mark van; Castro, Paula M. L.An increasing amount of industrial chemicals are being released into wastewater collection systems and indigenous microbial communities in treatment plants are not always effective for their removal. In this work, extracellular polymeric substances (EPS) recovered from aerobic granular sludge (AGS) were used as a natural carrier to immobilize a specific microbial strain, Rhodococcus sp. FP1, able to degrade 2-fluorophenol (2-FP). The produced EPS granules exhibited a 2-FP degrading ability of 100% in batch assays, retaining their original activity after up to 2-months storage. Furthermore, EPS granules were added to an AGS reactor intermittently fed with saline wastewater containing 2-FP. Degradation of 2-FP and stoichiometric fluorine release occurred 8 and 35 days after bioaugmentation, respectively. Chemical oxygen demand removal was not significantly impaired by 2-FP or salinity loads. Nutrients removal was impaired by 2-FP load, but after bioaugmentation, the phosphate and ammonium removal efficiency improved from 14 to 46% and from 25 to 42%, respectively. After 2-FP feeding ceased, at low/moderate salinity (0.6–6.0 g L−1 NaCl), ammonium removal was completely restored, and phosphate removal efficiency increased. After bioaugmentation, 11 bacteria isolated from AGS were able to degrade 2-FP, indicating that horizontal gene transfer could have occurred in the reactor. The improvement of bioreactor performance after bioaugmentation with EPS immobilized bacteria and the maintenance of cell viability through storage are the main advantages of the use of this natural microbial carrier for bioaugmentation, which can benefit wastewater treatment processes.
- Unveiling the agronomic potential of extracellular polymeric substances recovered from aerobic granular sludge on maizePublication . Amorim, Catarina L.; Pereira, Sofia I.A.; Sousa, Ana S. S.; Wilfert, Philipp; Loosdrecht, Mark van; Martins, António; Castro, Paula M. L.; Miranda, CatarinaBackground: Extracellular polymeric substances (EPS) recovered from waste aerobic granular sludge (AGS) generated during wastewater treatment represent a promising route for resource recovery. As valuable biopolymers, EPS have garnered special attention across multiple sectors, particularly agriculture, although their benefits in this field remain understudied. This study assessed the agronomic potential of EPS recovered from three AGS sources, including two full-scale wastewater treatment plants in Utrecht (EPS_U) and Faro (EPS_F), and a laboratory-scale reactor (EPS_R), as soil amendments. Methods: A greenhouse pot experiment was conducted to evaluate the effects of two EPS doses (0.5% and 1% w/w) on maize growth, nutrient uptake, and soil enzyme activities, compared with vermicompost at the same doses and a non-amended soil (control). Results: Both the source and dose of EPS strongly influenced their performance, with EPS often outperforming vermicompost. Notably, application of 1% of EPS, regardless of the source, markedly enhanced maize chlorophyll content, with EPS_R at 1% increasing it by 62% compared to 1% vermicompost and by 105% compared to the control. Similarly, applying 1% of EPS_R significantly increased shoot fresh weight and stem thickness. Nutritionally, 1% of EPS_R and 1% of EPS_F enhanced magnesium and potassium contents in shoots by 46% and 34%, respectively. Regarding soil enzymatic, EPS_U_1% greatly stimulated urease activity and fluorescein diacetate hydrolysis, while EPS_R_1% maximized acid phosphatase activity, underscoring the role of EPS in fostering a healthy rhizosphere. Conclusions: Using EPS as soil amendments offers a viable alternative to conventional fertilizers, while their recovery for agricultural use supports circular economy principles within the water sector.
- Variability in the composition of extracellular polymeric substances from a full-scale aerobic granular sludge reactor treating urban wastewaterPublication . Oliveira, Ana S.; Amorim, Catarina L.; Ramos, Miguel A.; Mesquita, Daniela P.; Inocêncio, Paulo; Ferreira, Eugénio C.; Loosdrecht, Mark van; Castro, Paula M. L.Within the framework of the circular economy, there is a need for waste management alternatives that promote the reuse of materials produced in wastewater treatment plants (WWTP). An interesting option is the recovery of extracellular substances from sludge. The variability of characteristics of potential recovered bioproducts has to be assessed in full scale operational settings. In this study, aerobic granular sludge (AGS) from a full-scale WWTP treating urban wastewater was regularly collected for 4 months to assess variability in extracellular polymeric substances (EPS) composition and in granular morphology. Variations in the EPS composition occurred with time. Proteins and humic substances were the main EPS components (329–494 and 259−316 mg/g VSS of AGS, respectively), with polysaccharides and DNA representing minor components. The application of an extra purification step after extraction to obtain a purer EPS led to a decrease in the yield of each EPS component, particularly pronounced for the polysaccharides. The final product had a rather constant composition for the monthly samples. The granules showed morphological stability throughout the sampling period and the yield of EPS was correlated to the size of the granules, higher when there was a higher content of small granules (Deq<150 μm) comparing to intermediate (150 ≤ Deq<1500 μm) or large granules (Deq≥1500 μm). This is the first time that a potential valorization strategy for surplus AGS biomass is studied in a full-scale environment. Knowledge on yield and product homogeneity is important as these features are essential for downstream application of the recovered EPS.