Starvation And Reactivation Of Partial Nitrifying Bacteria, Comparison Between Floccular And Granular Biomass

In this study, nitrogen was removed from wastewater via partial nitrification using both floccular and granular biomass. The purpose of this study is to investigate the effect of starvation on nitrogen removing bacteria, changes of biomass in term of structure during starvation, and recovery ability of biomass. 2 Sequencing Batch Reactor (SBR) with working volume of 8L were operated to enrich floccular and granular biomass. Both floccular and granular biomass were cultivated using high strength synthetic wastewater in SBR operating under similar parameters except height/diameter (H/D) ratio and settling time. The height/diameter ratio of SBR used to cultivate granular biomass was 10 which was higher than floccular biomass (5). The settling period of granular biomass was stepwise decreased from 5 to 1 minute for the enhancement of granulation. The cultivated granular biomass has an average diameter of 2mm. The long term performance of floccular and granular biomass were consistent and the results showed that partial nitrification was achieved for both floccular and granular biomass. Comparison was made between floccular and granular biomass in starvation, reactivation and energy distribution. Starvation studies (carbon starvation and energy starvation) were carried out on both floccular and granular biomass. The starvation studies showed that carbon starvation (absence of carbon source, only energy source is provided) has lesser impacts in the activity of both floccular and granular biomass as compared to energy starvation (absence of energy source, only carbon source is provided). Granular biomass was found to be more resilient to the starvation as compared to floccular biomass due to slower rate of reduction in ammonium uptake. Furthermore, recovery study was carried out on both floccular and granular biomass after certain period of starvations (both carbon and energy starvations). The recovery study results showed that carbon starved biomass were able to recovery easily as compared to energy starved biomass. Carbon starved granular biomass was found to be more responsive to the recovery as compared to carbon starved floccular biomass. Prolonged recovery was required for energy starved biomass to reactivate. Energy starved granular biomass required shorter period to recover as compared to energy starved floccular biomass. Maintenance energy distribution study was carried out on both carbon starved floccular biomass and granular biomass. It was found out that granular biomass has higher maintenance energy distribution (89%) during normal condition as compared to floccular biomass (69%). The maintenance energy distribution of both floccular and granular biomass were not affected by the starvation (70%). However, it was believed that the disintegration of the granular structure after starvation induced similar behaviour to the floccular biomass, which was probably the reason behind the similar maintenance energy distribution after starvation

Cold adaptation and replicable microbial community development during long-term low temperature anaerobic digestion treatment of synthetic sewage

The development and, activity of a cold-adapting microbial community was monitored during low temperature anaerobic digestion (LtAD) treatment of wastewater. Two replicate hybrid anaerobic sludge bed-fixed-film reactors treated a synthetic sewage wastewater at 12°C, at organic loading rates of 0.25–1.0 kg Chemical Oxygen Demand (COD) m−3 d−1, over 889 days. The inoculum was obtained from a full-scale AD reactor, which was operated at 37˚C. Both LtAD reactors readily degraded the influent with COD removal efficiencies regularly exceeding 78% for both the total and soluble COD fractions. The biomass from both reactors was sampled temporally and tested for activity against hydrolytic and methanogenic substrates at 12˚C and 37˚C. Data indicated that significantly enhanced low-temperature hydrolytic and methanogenic activity developed in both systems. For example, the hydrolysis rate constant (K) at 12°C had increased 20–30-fold by comparison to the inoculum by day 500. Substrate affinity also increased for hydrolytic substrates at low temperature. Next generation sequencing demonstrated that a shift in community structure occurred over the trial, involving a 1-log-fold change in 25 SEQS (OTU-free approach) from the inoculum. Microbial community structure changes and process performance were replicable in the LtAD reactors

Efficient and automated start-up of a pilot reactor for nitritation of reject water : from batch granulation to high rate continuous operation

An automated sequencing batch reactor operation based on online measurement of the ammonium concentration was investigated as a tool for improving the start-up of a nitrifying granular airlift reactor. The effectiveness of this start-up procedure was verified with the characteristics of the developed granular sludge but also the improvement of the start-up was confirmed when comparing with the results achieved with two continuous-mode start-up strategies. Once a stable granular biomass was obtained, the reactor started to operate in continuous mode during more than 100 days, maintaining the characteristics of the granular biomass and achieving a nitrogen loading rate of 1.75 g N L⁻¹ d⁻¹. The intermittent recirculation of small flocs of nitrifying biomass was explored as an alternative to increase the biomass concentration in the reactor and consequently, to increase the treated loading rate

Granular biomass technology for providing drinking water: microbial versatility and nitrate performance in response to carbon source

AL and RVV are supported by the funds of European Commission through the "European funds for regional development" (EFRE) as well as by the regional Ministry of Economy, Science and Digitalization of Saxony-Anhalt as part of the "Autonomy in old Age" (AiA) research group for "LiLife" Project (Project ID: ZS/2018/11/95324). Authors thank to Mrs. Ilka Kramer for her technical support in sequencing. BMP is supported by the funds of Ministerio de Universidades (Spain Government) and the European Union -NextGenerationEU. The authors would like to acknowledge the support given by the funding proving by LIFE16 ENV/ES/000196 and the RMN270 research group, which was essential for the realization of this research.The aerobic granular biomass technology was optimized for treating nitrate-polluted groundwater based on the biological denitrification processes in order to provide drinking water. Reactors inoculated with granular biomass were operated at progressively lower C/N rate using acetate and methanol to encourage heterotrophic denitrification, in order to meet the recommended requirements described by European Drinking Water Framework Directive. The granulation and long-term stability of granular biomass under low C/N were successful for all stages, demonstrated compactness of granules and absence of filamentous microorganisms. The nitrate removal was similar in methanol- and acetate-fed reactors, occurring in both cases nitrate removal ratios > 80%, and fact allows the selection of one of both depending groundwater polluted case. Also, feeding reactors with 2 C/N ratio showed nitrate removal values of & GE; 95%, treating highly polluted groundwater (100 mg & BULL;L-1). The microbial diversity was higher in the methanol-fed reactor with representative phylotypes as Flavobacterium, Cytophagaceae, NS9 marine group, while species richness was higher in the acetate-fed reactor, which was mainly represented by Flavobacterium genus. Statistical analyses revealed the higher resilience of bacterial population on granules fed with acetate, showing more resistance under drop C/N ratio. Oscillating pollution in groundwater during seasonal periods should be treated using acetate as carbon source for denitrification carried out by granular biomass, while stable pollution concentrations over time allow the use of methanol as a carbon source since the greater microbial diversity allows the elimination of other contaminants present in groundwater.European Union (EU)Regional Ministry of Economy, Science and Digitalization of Saxony-Anhalt ZS/2018/11/95324Ministerio de Universidades (Spain Government)LIFE16 ENV/ES/000196RMN270European Union -NextGenerationE

Biological decolorization of xanthene dyes by anaerobic granular biomass

Biodegradation of a xanthene dyes was investigated for the first time using anaerobic granular sludge. On a first screening, biomass was able to decolorize, at different extents, six azo dye solutions: acid orange 7, direct black 19, direct blue 71, mordant yellow 10, reactive red 2 and reactive red 120 and two xanthene dyes—Erythrosine B and Eosin Y. Biomass concentration, type of electron donor, induction of biomass with dye and mediation with activated carbon (AC) were variables studied for Erythrosine B (Ery) as model dye. Maximum color removal efficiency was achieved with 4.71 g VSS L−1, while the process rates were independent of the biomass concentration above 1.89 g VSS L−1. No considerable effects were observed when different substrates were used as electron donors (VFA, glucose or lactose). Addition of Ery in the incubation period of biomass led to a fivefold increase of the decolorization rate. The rate of Ery decolorization almost duplicated in the presence of commercial AC (0.1 g L−1 AC0). Using different modified AC samples (from the treatment of AC0), a threefold higher rate was obtained with the most basic one, \textAC\textH2ACH2, as compared with non-mediated reaction. Higher rates were obtained at pH 6.0. Chemical reduction using Na2S confirmed the recalcitrant nature of this dye. The results attest that decolorization of Ery is essentially due to enzymatic and adsorption phenomena.This work was supported by the PTDC/AMB/69335/2006 project grants (Fundacao para a Ciencia e Technologia, FCT, Portugal), BRAIN project (ID 6681, European Social Found and Romanian Government and the grant of the Romanian National Authority for Scientific Research, CNCS-UEFISCDI, project number PN-II-ID-PCE-2011-3-0559, Contract 265/2011

Partial nitritation and o-cresol removal with aerobic granular biomass in a continuous airlift reactor

Several chemical industries produce wastewaters containing both, ammonium and phenolic compounds. As an alternative to treat this kind of complex industrial wastewaters, this study presents the simultaneous partial nitritation and o-cresol biodegradation in a continuous airlift reactor using aerobic granular biomass. An aerobic granular sludge was developed in the airlift reactor for treating a high-strength ammonium wastewater containing 950+/-25 mg N-NH⁺₄ L⁻¹. Then, the airlift reactor was bioaugmented with a pnitrophenol-degrading activated sludge and o-cresol was added progressively to the ammonium feed to achieve 100 mg L⁻¹. The results showed that stable partial nitritation and full biodegradation of o-cresol were simultaneously maintained obtaining a suitable effluent for a subsequent anammox reactor. Moreover, two o-cresol shock-load events with concentrations of 300 and 1000 mg L⁻¹ were applied to assess the capabilities of the system. Despite these shock load events, the partial nitritation process was kept stable and o-cresol was totally biodegraded. Fluorescence in situ hybridization technique was used to identify the heterotrophic bacteria related to o-cresol biodegradation and the ammonia oxidising bacteria along the granules

Fundamental studies of anaerobic biosorption in wastewater treatment

The potential for sorption of soluble organic matter on anaerobic biomass is currently under investigation by the author and coworkers at Iowa State University. Biosorption is defined as the uptake or accumulation of particulates and chemicals by microbial biomass. The anaerobic biosorption process utilizes the sorption capabilities of active biomass for the treatment of wastewater. Biosorption is a rapid process. About 40% removal of organic matter was obtained in only 15 minutes after the substrate was brought in contact with the biomass;This dissertation presents the results of preliminary investigations on the effects of various factors on the biosorption process. The primary objective of this research was to determine the applicability of anaerobic biomass as a potential sorbent for organic matter and to quantify the results in terms of isotherms. The effects of mixing times, temperature, substrate concentration, biomass concentration, and granular biomass particle size were also studied;Anaerobic biomass was grown at 35°C in 10-liter source reactors, operated as anaerobic sequencing batch reactors (ASBR). Biosorption experiments were performed with active biomass in two liter batch reactors on a synthetic milk waste. The particle size distributions of the granular biomass were determined using an Automatic Image Analysis system. Temperature studies were significant. Better removals were obtained at higher temperature than at lower temperature. It was observed that wastes at temperatures as low as 7°C could be treated without the application of external heat;Higher removals were obtained with the small granular biomass than with the large granules. Increasing the biomass concentration resulted in a significant increase in the percentage removal of organic matter. Another method of improving biosorption was to operate a number of sorption reactors in series. High overall COD removals were obtained in a series of three reactors. The results were expressed in terms of adsorption isotherms. The data conformed well to both the Freundlich and the Langmuir adsorption models

Monitoring the stability of aerobic granular sludge using fractal dimension analysis

Cyclic episodes of granules formation and disintegration took place in two lab-scale aerobic granular sludge sequencing batch reactors, one fed with synthetic wastewater (COD: 0.6 g L−1 and NH4+–N:0.06 g L−1) and operated at a constant organic loading rate (2.5 g COD per L d), and the other fed with real wastewater (soluble COD: 0.27–1.37 and NH4+–N:0.02–0.16 g L−1) and with a variable loading rate (between 1.1 and 5.5 g CODsoluble per L d). The sludge volume index, density and diameter (mean value and relative standard deviation) of the granular biomass showed great fluctuations, without any clear tendency during the operational period. However, changes in granules fractal dimension values (both mean and relative standard deviation) matched with the formation and disintegration dynamics of the granular biomass. Statistical data analysis showed that the relative standard deviation of the granules fractal dimension could be a useful parameter for monitoring the granules status. Indeed, an increase of its value during the maturation or steady-state granulation stages is an early warning of disintegration episodes. A control strategy to maintain granules integrity based on this parameter is proposedThis work was funded by the Chilean Government through projects FONDECYT 1180650, FONDECYT 11181107, ANID/ FONDAP/15130015 and ANID PIA/BASAL FB0002, and by the Spanish Government through TREASURE [CTQ2017-83225-C2-1-R] and GRANDSEA [CTM2014-55397-JIN] projects. The authors from Universidade de Santiago de Compostela belong to CRETUS Strategic Partnership [ED431E 2018/01] and to the Galician Competitive Research Group [GRC ED431C 2017/29]. All the Spanish programs are co-funded by FEDER (EU)S

Biodegradation of a high-strength wastewater containing a mixture of ammonium, aromatic compounds and salts with simultaneous nitritation in an aerobic granular reactor

Long-term operation (390 days) of a continuous airlift reactor with aerobic granular biomass was successfully applied to treat a highly complex wastewater composed of: ammonium (1000 mg N L⁻¹), o-cresol (100 mg L⁻¹), phenol (100 mg L⁻¹, quinoline (50 mg L⁻¹) and salts (16 g salts L⁻¹). High nitrogen loading rate (1.1 g N L⁻¹ d⁻¹) and organic loading rate of 0.7 (g COD L⁻¹ d⁻¹) were achieved for the simultaneous nitritation and complete biodegradation of the aromatic compounds. The successful operation of the granular airlift reactor can be related to (i) the growth of specialized microorganisms in the aerobic granules and (ii) the continuous feeding regime. Aerobic granules were maintained stable in spite of the high salinity conditions. Dissolved oxygen (DO) concentration and DO/ammonium concentrations ratio were the key parameters to select a suitable effluent for anammox or heterotrophic denitrification via nitrite. Besides, nitrous oxide emissions were related to the DO concentration in the reactor

Effect of Coagulant-Flocculant Reagents on Aerobic Granular Biomass

This is the post-print reviewed version of the following article: Val del Río, A., Morales, N., Figueroa, M., Mosquera-Corral, A., Campos, J.L., Méndez, R. 2012. Effect of coagulant-flocculant reagents on aerobic granular biomass. Journal of Chemical Technology and Biotechnology, 87(7), 908-913, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/jctb.3698/full. This article may be used for non-commercial purposesBACKGROUND: Technologies based on aerobic granular biomass are presented as a new alternative for its application to the wastewater treatment due to its advantages in comparison with the conventional activated sludge ones. However the properties of the aerobic granules can be influenced by the presence of residual amounts of coagulant-flocculant reagents, frequently used as pre-treatment before the biological process. In this work the effect of these compounds on aerobic granular biomass development was tested. RESULTS: The presence of coagulant-flocculant reagents led to a worse biomass retention capacity with a lower VSS concentration compared to a control reactor (4.5 vs. 7.9 g VSS/L) and with a higher SVI (70 vs. 40 mL/g TSS) and diameter (5.0 vs. 2.3 mm). These reagents also caused a decrease in the maximum oxygen consumption rate, but the removal efficiencies of organic matter (90%) and nitrogen (60%) achieved were similar than the control reactor. CONCLUSION: The continuous presence of residual levels of coagulant-flocculant reagents from the pre-treatment unit negatively affected the formation process and the physical properties of the aerobic granules, however the removal of organic matter and nitrogen were not affectedThis work was funded by the Spanish Government (TOGRANSYS CTQ2008-06792-C02-01, NOVEDAR_Consolider CSD2007-00055) and Ministry of Education of Spain (FPU AP2006-01478).S