RESUMEN
Achieving consistent ammonia removal in post-lagoon processes faces two major challenges impacting nitrifiers due to the unique seasonal variation of lagoon-based systems: summer to winter temperature drop and summer to fall ammonia starvation period while lagoon is removing ammonia. The objective of this study was to follow microbial diversity and define conditions that could overcome these challenges in a post-lagoon moving bed biofilm reactor (MBBR) operated at an initial surface area loading rate (SALR) of 0.3 g-NH4-N m-2d-1 from mesophilic (20 °C) to psychrophilic (4 °C). Initially the temperature was maintained at 20 °C and decreased to 10 °C until steady state was achieved. During starvation conditions (i.e., continuous, intermittent and no aeration without inflow; decanted media; and intermittent and continuous ammonia supplement) the temperature was decreased by 2 °C per week until 4 °C. The results indicated that operational procedures, such as intermittent ammonia supplement with SALR of 0.15 g-NH4-N m-2d-1 could improve performance with 80% ammonia removal achieved immediately after starvation period. Intermittent ammonia supplement had produced the greatest biofilm preservation comparable to the initial load with the highest specific and surface area removal rates. In the recovery phase (initial load restoration) 10 days were required to reestablish performance above 95% ammonia removal. When temperature was decreased from mesophilic to psychrophilic, the microbial diversity was found higher when starving biofilm compared to the control operated at the initial load while it converged to a similar population over recovery. The main actors associated to nitrification enriched at psychrophilic conditions were Proteobacteria and Bacteriodotes at phyla level. Ammonia oxidation to nitrite was mainly driven by the order Burkholderiales and nitrite oxidation to nitrate by Pseudomonadales. This procedure should be considered in the implementation of full-scale post-lagoon MBBR technologies to ensure reliable, robust, and consistent performance despite the inherent seasonal variability of lagoon-based processes.
Asunto(s)
Biopelículas , Reactores Biológicos , Amoníaco , Nitrificación , NitritosRESUMEN
Controlling biofilm retention time in moving bed biofilm reactor (MBBR) and maintaining its performance for A-stage carbon redirection requires a reliable method to use as side stream biocarriers treatment. This paper investigates biofilm detachment and residual biofilm activity under multiple physicochemical treatment scenarios aiming to provide an applicable technique for control of biofilm retention time. Different mixing intensities (i.e. 30-120 rpm), filling fractions (i.e. 20%-100%), and pH (i.e. 2-12) were evaluated. Two continuously operating MBBRs were subjected to pH shocks of 2 and 12 to evaluate the impact of residual acidic or alkaline compounds on performance. The highest solids detachment (i.e. 70 ± 5%) was found in alkaline conditions and independent of mixing intensity and filling fraction. Biofilm detachment test revealed that alkaline shock produced higher detachment levels in a longer exposure time when compared to acidic conditions. The kinetic tests revealed 60% and 90% of the residual biofilm activity was lost at pH 12 and 2. The continuously operating MBBRs subjected to pH shocks of 2 and 12 demonstrated a 50% loss of soluble COD removal capability within one hydraulic retention time. Extracellular polymeric substances changes in its structure and surface properties influencing the degree of biofilm detachment and its solubilization properties leading to differences in biofilm resilience. The findings have shown that by applying a side stream alkali treatment it could be possible to control biofilm retention time ensuring its detachment up to 70% and a reduced impact on the residual biofilm activity returning to the reactor.
Asunto(s)
Biopelículas , Eliminación de Residuos Líquidos , Reactores Biológicos , Carbono , Propiedades de Superficie , Eliminación de Residuos Líquidos/métodos , Aguas ResidualesRESUMEN
The performance, kinetics, and stoichiometry of three high-rate moving bed biofilm reactors (MBBRs) were evaluated. A constant surface area loading rate (SALR) and three different hydraulic retention times (HRTs) were utilized to create scenarios where the attached and suspended biomass fractions would differentiate, despite the main design parameter remaining constant. Performance was simulated using BioWin™ 6.0 software. The objective was to evaluate whether a calibrated/validated model could accurately predict experimental results. Initially, a sensitivity analysis was performed to determine influential parameters. The calibration/validation of influential parameters was then conducted via steady-state simulations for two base cases: 1) highest HRT; and 2) lowest HRT. Both sets of calibrated/validated parameters were substantiated using: 1) steady-state simulations at the other HRTs; and 2) dynamic simulations to evaluate the kinetic rates of attached and suspended biomass fractions at all HRTs. Results demonstrated that the model could be calibrated/validated for a single HRT, but could not accurately predict the performance, kinetics, or stoichiometry at other HRTs.
Asunto(s)
Biopelículas , Reactores Biológicos , Biomasa , Eliminación de Residuos LíquidosRESUMEN
In this study, three different aerobic granular sludge (AGS) reactors fed with anaerobically pre-treated brewery wastewater were studied. The AGS reactors were operated under different conditions including organic loading rates (OLR) between 0.8 and 4.1 kg COD m-3 d-1, C:N:P ratios (100:10:1 and 100:6:1) and food to microorganism ratios (F/M) between 0.8 ± 0.6 and 1.2 ± 0.5 and 0.9 ± 0.3 kg-TCOD kg-VSS-1d-1. Stable granulation was achieved within two weeks and the size of the granules increased according to the OLR applied. The results indicated that low C:N:P and F/M ratios were favorable to achieve stable aerobic granules in the long term. The carbon removal rate was load-independent in the range examined (TCOD removal >80%), whereas TN removals were inversely proportional to the OLRs. Overall, a longer aeration reaction time with a lower OLR was beneficial to granular structure, which exhibited a compact and defined architecture. Performance results within the other conditions studied further indicated that the microbial community and its complex functionality in nutrient removal was efficient at operational parameters of OLR at 0.8 ± 0.2 kg-TCOD m-3d-1 and F/M ratio at 0.5 ± 0.2 kg-TCOD VSS-1d-1. Moreover, the protein to polysaccharide ratio increased as OLR decreased, leading to a stable granular structure.
Asunto(s)
Microbiota , Aguas del Alcantarillado , Aerobiosis , Reactores Biológicos , Eliminación de Residuos Líquidos , Aguas ResidualesRESUMEN
The A-stage of the AB process can minimize carbon oxidation by redirecting carbon to side-stream processes for harvesting carbon as energy and/or bioproduct. The redirection/harvesting of carbon has been studied in systems which utilize suspended biomass cultures. The potential of high-rate moving bed biofilm reactors, however, has not been explored. This study sought to control the biofilm solids retention time in a high-rate moving bed biofilm reactor operated at 17 ± 4 g-bCOD m-2d-1. Biofilm solids retention time was controlled by one of two strategies (i.e., 100% and 60% effective biofilm removal) that targeted several nominal biofilm solids retention times (i.e., 8, 6, 4, and 2 days) by employing different biocarrier replacement times. The results demonstrated that the suspended solids activity could be reduced by decreasing the nominal biofilm solids retention time. Using the 60% biofilm removal strategy, the actual biofilm solids retention time with a nominal biofilm solids retention time of 2 days was 12 h. When utilizing the 100% biofilm removal strategy, an actual biofilm solids retention time of less than 3 h was achieved with a nominal biofilm solids retention time of 2 days. The control reactor, which was a conventional moving bed biofilm reactor with no biocarrier replacement, was estimated to have a biofilm solids retention time of 2 days. Overall, the biofilm removal strategies favored carbon redirection and maximized the biomass yield at 1.1 ± 0.3 g-TSS g-COD-1 removed.
Asunto(s)
Carbono , Eliminación de Residuos Líquidos , Biopelículas , Biomasa , Reactores BiológicosRESUMEN
The objective of the study was to investigate the nitrification process, as well as the bio-chemical removal of cyanate and thiocyanate, while treating gold mining wastewater using an aerobic up-flow SAGR. A total of six SAGRs, each packed with locally sourced pea gravel (estimated specific surface area of 297 m-2 m-3), were operated at various HRTs and tested on both low- and high-strength gold mining wastewaters. The two sets of three SAGRs were operated at HRTs of 0.45 days, 1.20 days, and 2.40 days. Nitrification was successfully achieved in all six SAGRs regardless of the wastewater strength or HRT examined. The steady-state, 20 °C surface area loading rate was determined to be 1.2 g-TAN m-2 d-1 in order to comply with an effluent discharge limit at 10 mg-TAN L-1 (i.e., with the wastewater sources examined). At all ammonia loading rates, thiocyanate was successfully removed, and residual concentrations were below 2 mg-SCN-N L-1. Cyanate appeared to be hydrolyzed and subsequently nitrified. Acute toxicity tests conducted on both daphnia and trout revealed the effluent to be safe for direct discharge.
Asunto(s)
Amoníaco/aislamiento & purificación , Cianatos/aislamiento & purificación , Nitrificación , Tiocianatos/aislamiento & purificación , Aguas Residuales/química , Reactores Biológicos/normas , Cianatos/química , Oro , Minería , Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodosRESUMEN
Three parallel reactors (i.e. R1-R3) were operated with 340â mg-CODâ L-1, 42â mg-TNâ L-1, and 7â mg-TPâ L-1 at 20 ± 1°C. A mature granular sludge developed in 40â d and was stable for the 120â d experimentation period at an average food to microorganism ratio of 0.25 ± 0.08â g-CODâ g-VSS-1â d-1. Reactor biomass had higher inorganic content (i.e. 0.78-0.80â g-VSSâ g-TSS-1) than effluent biomass (i.e. 0.88-0.92â g-VSSâ g-TSS-1). Average granule diameter was 0.7-1.0â mm. Maximum phosphorus uptake and release rates averaged 4 ± 3 and 4 ± 2â mg-Pâ g-VSS-1â h-1, respectively. Maximum observed nitrification rates averaged 1.9 ± 0.6â mg-Nâ g-VSS-1â h-1. Phosphorus kinetics were similar between R1-R3 (i.e. P = 0.5309-0.6870) while nitrification kinetics varied significantly (i.e. P = 0.0002) even though conditions were the same. Effluent phosphate was on average 0.2 ± 0.4â mg-Pâ L-1 while total inorganic nitrogen removal averaged 60 ± 10% resulting in an average effluent of 17â mg-Nâ L-1. Aerobic granular sludge was capable of reliable nutrient removal from low-strength wastewater without volatile fatty acid source and at high dissolved oxygen concentrations.
Asunto(s)
Aguas del Alcantarillado , Aguas Residuales , Reactores Biológicos , Cinética , Nitrificación , Nitrógeno , Oxígeno , Fósforo , Eliminación de Residuos LíquidosRESUMEN
A novel partial nitritation-anammox (PNA) reactor configuration was piloted for 250â¯days. Primary effluent from full-scale municipal wastewater treatment plant was treated in a two-stage biofilm system incorporating innovative process control for cold partial nitritation. Partial nitritation was combined with carbon removal in a moving bed biofilm reactor (MBBR) to achieve high-rate treatment and nitritation was obtained with dissolved oxygen to total ammonium nitrogen (DO/TAN) ratio control and free ammonia (FA) for inhibition of nitratation. Effluent from MBBR was directed to an integrated fixed-film activated sludge (IFAS) reactor where nitrogen was removed via anammox. MBBR achieved partial nitritation at 2.0⯱â¯0.3â¯g-Nâ¯m-2â¯d-1 and nitrogen removal in the IFAS reactor reached 0.45⯱â¯0.1â¯g-Nâ¯m-2â¯d-1 (55â¯g-Nâ¯m-3â¯d-1). The process performed well at 19⯱â¯3⯰C with an average effluent total inorganic nitrogen (TIN) concentration of 11⯱â¯4â¯mgâ¯L-1.
Asunto(s)
Biopelículas , Nitrógeno/metabolismo , Aguas del Alcantarillado , Aguas Residuales/química , Amoníaco/metabolismo , Compuestos de Amonio/metabolismo , Reactores Biológicos , Desnitrificación , Oxidación-Reducción , Oxígeno/metabolismo , Proyectos PilotoRESUMEN
The review encompasses the development of municipal wastewater treatment process using MBBR from early stages, established application, and recent advancements. An overview of main drivers leading to the MBBR technology development over its early stage is discussed. Biocarriers types and features together with biofilm development and role of extracellular polymeric substances (EPS) are presented, ultimately, addressing the challenge in decreasing startup time required for full operation. Furthermore, the review investigates the state of the art of MBBR technology for nutrient removal (i.e., COD and BOD, nitrogen and phosphorus) through process functionality and configuration of established (e.g., IFAS) and under development (e.g. PN/A) applications. Reactor operational characteristics such as filling fractions, mixing properties, dissolved oxygen requirements, and loading rates are presented and related to full scale examples. Current literature discussing the most recent studies on MBBR capability in reduction and removal of chemicals of emerging concern (CEC) released is presented. Ultimately, high rate carbon and nitrogen removal through A/B stage process are examined in its main operational parameters and its application towards energy neutrality suggesting novel MBBR application to further reduce energy requirements and plant footprint.
Asunto(s)
Biopelículas , Aguas Residuales , Reactores Biológicos , Nitrógeno , Aguas del Alcantarillado , Eliminación de Residuos LíquidosRESUMEN
Mainstream partial nitritation was studied at 10⯰C in a moving bed biofilm reactor treating synthetic wastewater containing both nitrogen (≈40â¯mgâ¯L-1) and organic carbon at COD/N ratio ranging from 1.3 to 2.2. Three different control strategies were investigated to achieve partial nitritation. Initially, biofilm age was controlled by incorporating a media replacement strategy. Next, separately from the media replacement, oxygen limited conditions were investigated and finally pH control was incorporated together with oxygen limitation. Successful partial nitritation was achieved only by combining oxygen limitation with pH control. The average NH4-N concentration was equal to 16.0⯱â¯1.6â¯mgâ¯L-1 and average NO2-N concentration was equal to 15.7⯱â¯2.4â¯mgâ¯L-1 during steady state partial nitritation. The average residual NO3-N concentration was equal to 2.6⯱â¯2.2â¯mgâ¯L-1. The results obtained from this study prove for the first time that partial nitritation can be successfully controlled in a biofilm reactor treating wastewater with low nitrogen concentration, relatively high COD/N ratio and at low temperature. An algorithm for dynamic process control of partial nitritation has been also developed.
Asunto(s)
Algoritmos , Reactores Biológicos , Frío , Nitrificación , Aguas Residuales/química , Biopelículas , Concentración de Iones de Hidrógeno , Nitrógeno/análisis , Oxígeno/análisisRESUMEN
Results obtained from three aerobic granular sludge reactors treating brewery wastewater are presented. Reactors were operated for 60d days in each of the two periods under different cycle duration: (Period I) short 6h cycle, and (Period II) long 12h cycle. Organic loading rates (OLR) varying from 0.7kgCODm-3d-1 to 4.1kgCODm-3d-1 were tested. During Period I, granules successfully developed in all reactors, however, results revealed that the feast and famine periods were not balanced and the granular structure deteriorated and became irregular. During Period II at decreased 12h cycle time, granules were observed to develop again with superior structural stability compared to the short 6h cycle time, suggesting that a longer starvation phase enhanced production of proteinaceous EPS. Overall, the extended famine conditions encouraged granule stability, likely because long starvation period favours bacteria capable of storage of energy compounds.