Biological removal processes in aerobic granular sludge exposed to diclofenac

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 0.03 mM (9.54 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.info:eu-repo/semantics/acceptedVersio

ARTICLE Kinetic Modeling of Phototrophic Biofilms: The PHOBIA Model

ABSTRACT: A kinetic model for mixed phototrophic biofilms is introduced, which focuses on the interactions between photoautotrophic, heterotrophic, and chemoautotrophic (nitrifying) functional microbial groups. Biofilmspecific phenomena are taken into account, such as extracellular polymeric substances (EPS) production by phototrophs as well as gradients of substrates and light in the biofilm. Acid-base equilibria, in particular carbon speciation, are explicitly accounted for, allowing for the determination of pH profiles across the biofilm. Further to previous models reported in literature, the PHOBIA model combines a number of kinetic mechanisms specific to phototrophic microbial communities, such as internal polyglucose storage under dynamic light conditions, phototrophic growth in the darkness using internally stored reserves, photoadaptation and photoinhibition, preference for ammonia over nitrate as N-source and the ability to utilize bicarbonate as a carbon source in the absence of CO 2 . The sensitivity of the PHOBIA model to a number of key parameters is analyzed. An example on the potential use of phototrophic biofilms in wastewater polishing is discussed, where their performance is compared with conventional algal ponds. The PHOBIA model is presented in a manner that is compatible with other reference models in the area of water treatment. Its current version forms a theoretical base which is readily extendable once further experimental observations become available

Experimental assessment of substrate storage yield

Çevre biyoteknolojisindeki son gelişmeler doğrultusunda aktif çamur sistemlerinde substrat depolama kavramı önemli bir proses olarak kabul edilmektedir. Substrat depolama kavramı, aktif çamur modellemesine, Aktif Çamur Modeli No.3 (ASM3) ve saf substratlar için önerilen biyokimyasal modellerle dâhil edilmiştir. Depolama kavramının ortaya konması, modele çok fazla serbestlik derecesi sağlayarak, modeli daha karmaşık bir hale getiren pek çok kinetik ve stokiyometrik katsayının da eklenmesine yol açmıştır. Substrat depolama dönüşüm oranı, YSTO, ASM3 modelindeki en önemli parametrelerden biridir. Depolama dönüşüm oranı, substratın stokiyometrik olarak ne kadarının depolama ürünlerine dönüşeceğini belirleyen etkin bir model bileşenidir. Bu çalışma, ASM3 modelinde tanımlanan substrat depolama dönüşüm oranının (YSTO), deneysel olarak belirlenmesini amaçlamaktadır. Önerilen yöntem, atıksularda depolama ürünlerinin miktarlarının belirlenmesini gerektirmeyen, respirometrik bir prosedürdür. Yöntemde, model simulasyonlarından yararlanılarak, depolama prosesi için tüketilen oksijen miktarının oksijen tüketim hızı (OTH) eğrisi üzerinde belirlenmesinin esasları ortaya konmuştur. Önerilen yaklaşım kesikli deneylerle elde edilen oksijen tüketim hızına (OTH) dayanmaktadır. Yöntem substrat depolaması için kullanılan oksijen miktarının hesaplanması için grafiksel bir metot tanımlamaktadır. Yöntemin değerlendirilmesi için farklı deneysel başlangıç koşullarının kullanıldığı model simülasyonlarından yararlanılmıştır. Önerilen yöntem ile YSTO değeri %2’den daha düşük hata oranları ile belirlenebilmiştir. Deneysel yöntem ile, asetat, glikoz ve evsel atıksuyun kullanıldığı ve farklı F/M oranlarında yürütülen respirometrik testler sonucunda, depolama dönüşüm oranları, asetat için 0.78 gKOİ/gKOİ, glikoz için 0.87 gKOİ/gKOİ ve evsel atıksu için 0.96 gKOİ/gKOİ olarak belirlenmiştir. Anahtar Kelimeler: Asetat, Aktif Çamur Modeli No.3, evsel atıksu, glikoz, respirometri, depolama.Substrate storage under dynamic conditions is recently regarded as a significant process for activated sludge systems. The dynamic conditions and substrate gradients convey activated sludge cultures to develop a storage response when external substrate is present in the system. Substrate storage is incorporated into activated sludge modeling with Activated Sludge Model No. 3 (ASM3) and with biochemical models for pure substrates. ASM3 has been proposed for activated sludge systems both for aerobic and anoxic conditions. Introducing storage phenomena has also introduced a number of stoichiometric and kinetic coefficients making the model rather complicated with many degrees of freedom. Some default values have been proposed, but calibration of kinetic and stoichiometric parameters is needed for various applications. The storage yield (YSTO) is one of the most important parameters of the model, since it represents the stoichiometric amount of substrate converted into storage products, which are subsequently utilized for growth. The assessment of YSTO is therefore crucial for the accurate estimation of the overall electron acceptor utilization and sludge production. The information on the magnitude of the storage yield was mostly derived from pure culture studies. ASM3 suggested value of YSTO as 0.85 mgCOD/mgCOD under aerobic  conditions for domestic sewage. An experimental procedure was developed for the respirometric determination of bacterial storage yield (YSTO) as defined in the Activated Sludge Model No. 3. The proposed approach is based on the oxygen utilization rate (OUR) profile obtained from a batch test and correlates the area under the OUR curve to the amount of oxygen associated with substrate storage. The procedure is based on respirometry and does not involve measurement of storage products, as it will not always be possible or reliable to determine the amount of all the storage products when a complex substrate such as domestic sewage is concerned. It is theoretically possible to compute substrate storage yield (YSTO) if the oxygen used for the storage of a known amount of readily biodegradable COD can be determined by means of respirometric measurements. Such measurements however only provide the total oxygen utilization rate (OUR) of the system and not the OUR specific for the process of interest alone. Thus, it is necessary to understand and interpret the components of a total OUR versus time curve associated with the utilization of a readily biodegradable substrate. Model simulation was used to evaluate the procedure for different initial experimental conditions. Obtained results indicated that the proposed procedure was quite consistent with model-input values, involving an error of less than 2%, aside from analytical errors associated with standard COD measurements, for tests to be conducted with feeding (F/M) ratios over 0.1 gCOD/g cellCOD. The procedure was used to determine the storage yield, YSTO, associated with acetate, glucose and domestic sewage, together with mixtures of acetate/glucose and acetate/domestic sewage at different initial F/M ratios. YSTO was calculated as 0.78 gCOD/gCOD for acetate, 0.87 gCOD/gCOD for glucose and 0.96 gCOD/gCOD for domestic sewage. The high YSTO level related to domestic sewage, consistently obtained for a wide range of initial F/M ratios, challenges the validity of the concept of SS in ASM3, which is defined as the biodegradable fraction of the soluble substrate and tested in the study. The assumption introduced with ASM3 that the entire soluble biodegradable COD could be regarded as readily biodegradable substrate, although valid for pure substrates, requires, as in this case, careful evaluation for wastewaters with more complex substrate compositions. If readily biodegradable substrate is actually less, the corresponding oxygen consumption can only be interpreted with a superficially higher YSTO. The experiments conducted on substrate mixtures confirmed the validity of YSTO values calculated for individual substrates, yielding a transient pattern reflecting the character of the dominant substrate fraction in the mixture. For glucose/acetate mixtures, they provided a clear indication of a faster storage rate for glucose as compared to acetate. The proposed procedure may also be used to calculate initial readily biodegradable COD concentration, SS1, for a generally adopted YSTO value, as it defines a stoichiometric procedure between the storage yield and the available readily biodegradable substrate. Keywords: Acetate, Activated Sludge Model No.3, domestic sewage, glucose, respirometry, storage

Bioaugmentation of Aerobic Granular Sludge with specialized degrading granules treating 2-fluorophenol wastewater

The industry growth has been accompanied by an increase in the amount of industrial chemicals being released into the environment. Indigenous microbial communities in wastewater biotreatment processes are not always effective in removing xenobiotics. This work aimed to evaluate the efficiency of a new bioaugmentation strategy in an aerobic granular sludge sequencing batch reactor (AGS-SBR) system fed with 2-fluorophenol (2-FP). Bioreactor performance in terms of phosphate and ammonium removal, 2-FP degradation and chemical oxygen demand (COD) was evaluated. The new bioaugmentation strategy consisted in producing granules using extracellular polymeric substances (EPS) extracted from AGS as a carrying matrix and a 2-FP degrading strain, Rhodococcus sp. FP1. The produced granules were used for the bioaugmentation of a reactor fed with 2-FP. Shortly after bioaugmentation, the produced granules broke down into smaller fragments inside the bioreactor, but 2-FP degradation occurred. After 8 days of bioaugmentation, 2-FP concentration inside the reactor started to decrease, and stoichiometric fluorine release was observed 35 days later. Phosphate and ammonium removal also improved after bioaugmentation, increasing from 30% to 38% and from 20 to 27%, respectively. Complete ammonium removal was only achieved when 2-FP feeding stopped, and phosphate removal was not recovered during operation time. COD removal also improved after the addition of the produced granules. The persistence of Rhodococcus sp. FP1 in the reactor was followed by qPCR. Rhodococcus sp. FP1 was detected 1 day after in the AGS and up to 3 days after bioaugmentation at the effluent. Nevertheless, the 2-FP degradative ability remained thereafter in the granules. Horizontal gene transfer could have happened from the 2-FP degrading strain to indigenous microbiome as some bacteria isolated from the AGS, 3 months after bioaugmentation, were able to degrade 2-FP. This study presents a promising and feasible bioaugmentation strategy to introduce specialized bacteria into AGS systems treating recalcitrant pollutants in wastewater.N/

Effect of different salt adaptation strategies on the microbial diversity, activity, and settling of nitrifying sludge in sequencing batch reactors

The effect of salinity on the activity of nitrifying bacteria, floc characteristics, and microbial community structure accessed by fluorescent in situ hybridization and polymerase chain reaction–denaturing gradient gel electrophoresis techniques was investigated. Two sequencing batch reactors (SRB1 and SBR2) treating synthetic wastewater were subjected to increasing salt concentrations. In SBR1, four salt concentrations (5, 10, 15, and 20 g NaCl/L) were tested, while in SBR2, only two salt concentrations (10 and 20 g NaCl/L) were applied in a more shock-wise manner. The two different salt adaptation strategies caused different changes in microbial community structure, but did not change the nitrification performance, suggesting that regardless of the different nitrifying bacterial community present in the reactor, the nitrification process can be maintained stable within the salt range tested. Specific ammonium oxidation rates were more affected when salt increase was performed more rapidly and dropped 50% and 60% at 20 g NaCl/L for SBR1 and SBR2, respectively. A gradual increase in NaCl concentration had a positive effect on the settling properties (i.e., reduction of sludge volume index), although it caused a higher amount of suspended solids in the effluent. Higher organisms (e.g., protozoa, nematodes, and rotifers) as well as filamentous bacteria could not withstand the high salt concentrations

Increased extracellular polymeric substances production contributes for the robustness of aerobic granular sludge during long-term intermittent exposure to 2-fluorophenol in saline wastewater

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 (1.41â6.46 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.The authors wish to thank the company Aguas ´ do Tejo Atlantico, S.A. for supplying the granules. This work was financed by Fundação para a Ciência e Tecnologia (FCT, Portugal) under the project AGeNT - PTDC/ BTA-BTA/31264/2017 (POCI-01-0145-FEDER-031264). We would like to thank the scientific collaboration of CBQF under the FCT project UID/Multi/50016/2019 and NORTE-08-5369-FSE-000007 and CEB under the FCT project UID/BIO/044697/2019 and BioTecNorte operation (NORTE-01-0145-FEDER-000004).info:eu-repo/semantics/publishedVersio

Extraction and characterization of extracellular polymeric substances from aerobic granular sludge from a full-scale sequencing batch reactor in Portugal

Microbiotec'17 - Congress of Microbiology and Biotechnology 2017Background: Aerobic granular sludge (AGS) is a recently developed technology for wastewater treatment. This system is able to manage higher amounts of wastewater and requires less surface area than conventional systems. The granules consist of microorganisms embedded in a self-produced extracellular polymeric substances (EPS) matrix. EPS are high molecular weight polymers, which can be metabolic products of microorganisms (e.g. proteins, polysaccharides, humic substances, nucleic acids) or be due to cell lyses. Accumulation on the cells surface of such EPS forms a protective barrier for the cells from the external environment. This work focus on the extraction and quantification of EPS from AGS from a large scale bioreactor in Portugal, during approximately 4 months. Given the environmental and chemical differences that these granules are subjected to one of the goals was to assess variability in the EPS production and characterize the granules morphology and composition in a large scale environment.The authors thank the company SIMTEJO for supplying the granules, and the financial support of European Social Fund, under Programa Operacional under the project NORTE-08-5369-FSE-000007 and BioTecNorte operation (NORTE-010145-FEDER-000004). This work was also supported by Portuguese Funds from FCT - Fundação para a Ciência e a Tecnologia through the strategic funding of UID/Multi/50016/2013 and UID/BIO/04469/2013 units and COMPETE 2020 (POCI-01-0145-FEDER-006684). C.L. Amorim wishes to acknowledge the research grant from FCT (SFRH/BPD/96481/2013).info:eu-repo/semantics/publishedVersio

2-Fluorophenol degradation by aerobic granular sludge in a sequencing batch reactor

Aerobic granular sludge is extremely promising for the treatment of effluents containing toxic compounds, and it can economically compete with conventional activated sludge systems. A laboratory scale granular sequencing batch reactor (SBR) was established and operated during 444 days for the treatment of an aqueous stream containing a toxic compound, 2-fluorophenol (2-FP), in successive phases. Initially during ca. 3 months, the SBR was intermittently fed with 0.22 mM of 2-FP added to an acetate containing medium. No biodegradation of the target compound was observed. Bioaugmentation with a specialized bacterial strain able to degrade 2-FP was subsequently performed. The reactor was thereafter continuously fed with 0.22 and 0.44 mM of 2-FP and with 5.9 mM of acetate (used as co-substrate), for 15 months. Full degradation of the compound was reached with a stoichiometric fluoride release. The 2-FP degrading strain was successfully retained by aerobic granules, as shown through the recovering of the strain from the granular sludge at the end of the experiment. Overall, the granular SBR has shown to be robust, exhibiting a high performance after bioaugmentation with the 2-FP degrading strain. This study corroborates the fact that bioaugmentation is often needed in cases where biodegradation of highly recalcitrant compounds is targeted.info:eu-repo/semantics/publishedVersio

The substrate storage concept and the modelling applications for tannery wastewater

Son yıllarda aktif çamur arıtma sistemlerinin tasarımında IWA Çalışma Grubu tarafından önerilen en son model olan ASM3 ile substratın depolama polimerlerine dönüştükten sonra heterotrofik biyokütle tarafından tüketildiği varsayımı dikkate alınmaktadır. Ancak bu yaklaşım uygulama kolaylıkları getirmekle birlikte gerçeği yansıtamamakta ve kolay ayrışan substratın (SS) tanımı uygulamalarda zorluk yaratmaktadır. Bu çalışmada, daha gerçekçi bir yaklaşım olan, substratın kısmen çoğalma kısmen de depolama ürünleri oluşumu ile tüketildiği görüşü deri atıksuyu için uygulanmıştır. Dinamik koşullar altında, farklı modeller olan ASM1, ASM3 ve ASM3’ün simültane çoğalma ve depolamayı içeren versiyonları hazırlanarak elde edilen simülasyon sonuçları birbirleri ve literatür verileri ile karşılaştırılmıştır. Anahtar Kelimeler: Aktif çamur modellemesi, simultane çoğalma ve depolama kavramı, ASM1, ASM3, OTH.Consumption of substrate firstly in the form of stored polymers and subsequent use of the stored polymers by heterotrophic biomass recently introduced in the activated sludge system design by IWA Task Group with ASM3. Although this approach brings ease of application in calculations, it dose not reflect the reality and the definition of readily biodegradable substrate (SS) causes problems in applications. A more realistic approach, that is the simultaneous growth and storage concept on external substrate has been presented and applied for tannery wastewater. Different models, namely, ASM1, ASM3 and modified versions of ASM3 involving simultaneous growth and storage have been investigated under dynamic conditions. The simulation results were compared with each other and literature data. Model simulation results for ASM1 were quite consistent with literature but the results have shown that ASM3 modeling results gave better descriptions of the OUR response compared to ASM1. The comparison of the simulation results lead to the conclusion that the possibility of describing the real case increases, as the model gets more detailed. Observations suggest that the relative weight of biochemical reactions such as growth and storage shifts as the feeding pattern fluctuates between feast and famine conditions and models with a single mechanism like ASM1, although convenient from a practical viewpoint may become insufficient for a consistent explanation when the feeding rate (F/M ratio) changes. Keywords: Activated sludge modelling, simultaneous growth and storage concept, ASM1, ASM3, OUR

Ammonia removal from thermal hydrolysis dewatering liquors via three different deammonification technologies

The benefits of deammonification to remove nitrogen from sidestreams, i.e., sludge dewatering liquors, in municipal wastewater treatment plants are well accepted. The ammonia removal from dewatering liquors originated from thermal hydrolysis/anaerobic digestion (THP/AD) are deemed challenging. Many different commercial technologies have been applied to remove ammonia from sidestreams, varying in reactor design, biomass growth form and instrumentation and control strategy. Four technologies were tested (a deammonification suspended sludge sequencing batch reactor (S-SBR), a deammonification moving bed biofilm reactor (MEDIA), a deammonification granular sludge sequencing batch reactor (G-SBR), and a nitrification suspended sludge sequencing batch reactor (N-SBR)). All technologies relied on distinct control strategies that actuated on the feed flow leading to a range of different ammonia loading rates. Periods of poor performance were displayed by all technologies and related to imbalances in the chain of deammonification reactions subsequently effecting both load and removal. The S-SBR was most robust, not presenting these imbalances. The S-SBR and G-SBR presented the highest nitrogen removal rates (NRR) of 0.58 and 0.56 kg N m−3 d−1, respectively. The MEDIA and the N-SBR presented an NRR of 0.17 and 0.07 kg N m−3 d−1, respectively. This study demonstrated stable ammonia removal from THP/AD dewatering liquors and did not observe toxicity in the nitrogen removal technologies tested. It was identified that instrumentation and control strategy was the main contributor that enabled higher stability and NRR. Overall, this study provides support in selecting a suitable biological nitrogen removal technology for the treatment of sludge dewatering liquors from THP/A