Loading...
5 results
Search Results
Now showing 1 - 5 of 5
- 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.; InocĆŖncio, Paulo; Ferreira, EugĆ©nio 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 (329ā494 and 259ā316āÆmg/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<150āÆĪ¼m) comparing to intermediate (150āÆā¤āÆDeq<1500āÆĪ¼m) or large granules (Deqā„1500āÆĪ¼m). 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.
- Intermittent load of 2-fluorophenol in saline wastewater shapes aerobic granular sludge microbiome and reactor performancePublication . Oliveira, Ana S.; Amorim, Catarina L.; Loosdrecht, Mark C. M. van; Castro, PaulaIndustrial effluents often contain organic pollutants and variable salinity levels, making their treatment challenging. Aerobic granular sludge (AGS) is an innovative and compact wastewater treatment technology for the treatment of domestic and industrial water streams. The high content of extracellular polymeric substances (EPS) in AGS composition is thought to protect , to some extent, the microbial communities from stressful conditions in external environment. This work aimed to evaluate the robustness of AGS systems in terms of nutrient removal performance and to unravel the protective role of EPS towards transient feeding with a toxic pollutant (2-fluorophenol - 2-FP) in saline wastewater. Moreover, the taxonomic and functional patterns of the AGS microbiome were characterized and linked with nutrient removal performance and EPS production. In order to mimic transient states of composition typical of industrial effluents, the reactor inlet medium periodically varied regarding to 2-FP presence and salt concentration.
- Biological removal processes in aerobic granular sludge exposed to diclofenacPublication . Bessa, VĆ¢nia S.; Moreira, Irina S.; Loosdrecht, Mark C. M. van; Castro, Paula M. L.Diclofenac is a worldwide consumed drug included in the watch list of substances to be monitored according to the European Union Water Framework Directive (Directive 2013/39/EU). Aerobic granular sludge sequencing batch reactors (AGS-SBR) are increasingly used for wastewater treatment but there is scant information on the fate and effect of micropollutants to nutrient removal processes. An AGS-SBR fed with synthetic wastewater containing diclofenac was bioaugmented with a diclofenac degrading bacterial strain and performance and microbial community dynamics was analysed. Chemical oxygen demand, phosphate and ammonia removal were not affected by the micropollutant at 0.03ā mM (9.54ā mg L-1). The AGS was able to retain the degrading strain, which was detected in the sludge throughout after augmentation. Nevertheless, besides some adsorption to the biomass, diclofenac was not degraded by the augmented sludge given the short operating cycles and even if batch degradation assays confirmed that the bioaugmented AGS was able to biodegrade the compound. The exposure to the pharmaceutical affected the microbial community of the sludge, separating the two first phases of reactor operation (acclimatization and granulation) from subsequent phases. The AGS was able to keep the bioaugmented strain and to maintain the main functions of nutrient removal even through the long exposure to the pharmaceutical, but combined strategies are needed to reduce the spread of micropollutants in the environment.
- Simultaneous nitrification and phosphate removal by bioaugmented aerobic granules treating a fluoroorganic compoundPublication . Duque, Anouk F.; Bessa, VĆ¢nia S.; Dongen, Udo van; Kreuk, Merle K. de; Mesquita, Raquel B. R.; Rangel, Antonio O. S. S.; Loosdrecht, Mark C. M. van; Castro, Paula M. L.The presence of toxic compounds in wastewater can cause problems for organic matter and nutrient removal. In this study, the long-term effect of a model xenobiotic, 2-fluorophenol (2-FP), on ammonia-oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and phosphate accumulating organisms (PAO) in aerobic granular sludge was investigated. Phosphate (P) and ammonium (N) removal efficiencies were high (>93%) and, after bioaugmentation with 2-FP degrading strain FP1, 2-FP was completely degraded. Neither N nor P removal were affected by 50 mg Lā1 of 2-FP in the feed stream. Changes in the aerobic granule bacterial communities were followed. Numerical analysis of the denaturing gradient gel electrophoresis (DGGE) profiles showed low diversity for the ammonia monooxygenase (amoA) gene with an even distribution of species. PAOs, including denitrifying PAO (dPAO), and AOB were present in the 2-FP degrading granules, although dPAO population decreased throughout the 444 days reactor operation. The results demonstrated that the aerobic granules bioaugmented with FP1 strain successfully removed N, P and 2-FP simultaneously.
- 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 (0.6ā6.0 g Lā1 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.