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Abstract Biomass washout from high-speed anaerobic suspended bed bio-reactors is still a challenge to their stable operation. Preserving active biomass to efficiently retain biomass in the reactor is one of the solutions to this problem. Herein, two carriers (polyvinyl alcohol/chitosan (PVA/CS) and PVA/CS/Fe gel beads) were prepared using the cross-linking method. The fourier transform infrared (FTIR) and 13C nuclear magnetic resonance (13C NMR) analyses showed that PVA/CS gel beads formed mainly through hydrogen-bonds (NH 2 OH-). Furthermore, FTIR, 13C NMR, energy dispersive spectrum (EDS), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed that PVA/CS/Fe gel beads formed mainly through chelate bond (NH 2 -FeM+ OH-). The scanning electron microscope (SEM) results affirmed that the gel beads had rough and well-developed porous structure for the attachment of microbes. Furthermore, the abilities of gel beads on the cultivation of granular sludge in an up-flow anaerobic sludge bed (UASB) reactor were effectively demonstrated while treating wastewater polluted with glucose and alkali lignin. The results showed that the gel beads-assisted reactors had a higher performance than those without the gel beads. The cultivation of granules in these reactors was accelerated, while the granules became bigger and exhibited better settling velocities. The reactor with gel beads was easier to withstand a higher organic loading rate due to dense microbial aggregates, which were caused by more humic-like substance. Particularly, the reactor with PVA/CS/Fe gel beads was able to improve the overall robustness of the system due to stronger mechanical properties of gel beads, and also prevented cells detachment. Highlights • Two carriers (PVA/CS and PVA/CS/Fe gel beads) were prepared by cross-linking method. • Possible cross-linking mechanism of PVA/CS and PVA/CS/Fe gel beads has been proposed. • The abilities of PVA/CS and PVA/CS/Fe gel beads in anaerobic granular sludge cultivation were successfully verified. [ABSTRACT FROM AUTHOR]

Abstract At least 11% of total nitrogen (TN) remains in the anammox effluent, making it difficult to meet increasingly stringent discharge standards. To overcome this bottleneck, an innovative process to achieve completely anaerobic ammonium removal over nitrite (CAARON) in one single up-flow anaerobic sludge blanket reactor was proposed in this study. The synchronous feeding of acetate at a C/N (nitrite) ratio of 0.6 significantly reduced the nitrogen removal capacity of anammox reactor by limiting the abundance and metabolism of anammox bacteria. In contrast, the asynchronous feeding of acetate optimized the partition of the reactor column into two specific compartments: the lower half favoring anammox and the upper half dominated by DEAMOX (DEnitrifying AMmonium Oxidation). A high TN removal efficiency of 96.2 ± 0.4% and a low effluent TN concentration of 9.3 ± 0.9 mg L−1 were obtained under a high TN loading rate of 9.0 kgN m−3 d−1. The dominant functional microbes in the CAARON process were identified as Candidatus Kuenenia and Thauera , which were responsible for the anammox and denitratation reactions, respectively. Overall, the results in this study provide valuable insight into the coupling of anammox with denitratation, which is a cost-efficient approach for treating ammonium-rich wastewaters. Graphical abstract Unlabelled Image Highlights • A novel CAARON process was achieved for complete ammonium removal over nitrite. • High total nitrogen removal efficiency of >95% was achieved in CAARON process. • High total nitrogen removal rate of 8.6 kgN m−3 d−1 was achieved in CAARON process. • The functional microbes responsible for the CAARON process were identified. [ABSTRACT FROM AUTHOR]

Aims: The phylum Chloroflexi is frequently found in high abundance in methanogenic reactors, but their role is still unclear as most of them remain uncultured and understudied. Hence, a detailed analysis was performed in samples from five up‐flow anaerobic sludge blanket (UASB) full‐scale reactors fed different industrial wastewaters. Methods and Results: Quantitative PCR show that the phylum Chloroflexi was abundant in all UASB methanogenic reactors, with higher abundance in the reactors operated for a long period of time, which presented granular biomass. Both terminal restriction fragment length polymorphism and 16S rRNA gene amplicon sequencing revealed diverse Chloroflexi populations apparently determined by the different inocula. According to the phylogenetic analysis, the sequences from the dominant Chloroflexi were positioned in branches where no sequences of the cultured representative strains were placed. Fluorescent in situ hybridization analysis performed in two of the reactors showed filamentous morphology of the hybridizing cells. Conclusions: While members of the Anaerolineae class within phylum Chloroflexi were predominant, their diversity is still poorly described in anaerobic reactors. Due to their filamentous morphology, Chloroflexi may have a key role in the granulation in methanogenic UASB reactors. Significance and Impact of the Study: Our results bring new insights about the diversity, stability, dynamics and abundance of this phylum in full‐scale UASB reactors which aid in understanding their function within the reactor biomass. However, new methodological approaches and analysis of bulking biomass are needed to completely unravel their role in these reactors. Combining all this knowledge with reactor operational parameters will allow to understand their participation in granulation and bulking episodes and design strategies to prevent Chloroflexi overgrowth. [ABSTRACT FROM AUTHOR]

Abstract Brazil is one of the world's largest rice producers with trends for the growth of this sector. During the processing of the grain, high amounts of husk are generated, corresponding to 22% of its weight. On the other hand, in the process of parboiling, in turn, the final result is considerable volumes of effluent rich in organic matter. Thereby, this study demonstrates in an energetic, economic and environmental way the possibilities of using these residues for power generation in the southern Brazilian rice parboiling industries. Two scenarios are presented: the first, with the use of biogas and the second, with the use of hydrogen-rich syngas. A case study was made in one of these industries, where it was discussed in detail the energy potential coming from systems operating with a CHP genset, using hydrogen-rich syngas from the rice husks and the biogas from the anaerobic treatment of the effluents. The results have shown that it is possible to produce more than 2,17E+04 MWh of electricity just considering the use of the biogas generated. On the other hand, the use of syngas generates enough thermal energy to operate the entire industrial process, with a surplus of 53,3% in MWh/year. Highlights • Potential production of methane and hydrogen-rich syngas in Brazilian rice industries. • 2,17E+04 MWh/year of electricity only with the use of the biogas generated. • 7,3E+05 MWh/year of electricity only with the use of the syngas generated. • NPV of R$1,245,370.00, with excellent return on invested capital. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental is the property of Revista Eletronica em Gestao, Educacao e Tecnologia Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anaerobic ammonium oxidation (Anammox) is considered as one of the high efficiency and low energy consumption processes, while excessive amounts of nitrate in effluents and delayed anammox bacterial growth have limited the use of the anammox process. We enhanced the nitrogen removal efficiency of the anammox process and expedited reactor start-up by utilizing gravel balls as innovative carriers. The total nitrogen removal efficiency was enhanced (93.11%) and the start-up time was shortened from 98 to 67 days. Moreover, microbial analysis revealed an increase in the microbial community's richness and diversity. High-throughput analysis indicated that gravel ball addition improved the relative abundance of the anammox bacteria Candidatus Kuenenia. Thus, this study offered new perspectives on how gravel ball addition affects the anammox process and provided a potential carrier for practical engineering-scale anammox reactors. [Display omitted] • A novel carrier for the anammox process was introduced. • Nitrogen removal performance enhanced with gravel balls. • The start-up time shortened from 98 days to 67 days used novel carrier reactor. • The presence of gravel balls enhanced the relative abundance of Candidatus Kuenenia. [ABSTRACT FROM AUTHOR]

Due to the high concentration of pollutants, swine wastewater needs to be treated prior to disposal. The combination of anaerobic and aerobic technologies in one hybrid system allows to obtain higher removal efficiencies compared to those achieved via conventional biological treatment, and the performance of a hybrid system depends on the microbial community in the bioreactor. Here, we evaluated the community assembly of an anaerobic-aerobic hybrid reactor for swine wastewater treatment. Sequencing of partial 16S rRNA coding genes was performed using Illumina from DNA and retrotranscribed RNA templates (cDNA) extracted from samples from both sections of the hybrid system and from a UASB bioreactor fed with the same swine wastewater influent. Proteobacteria and Firmicutes were the dominant phyla and play a key role in anaerobic fermentation, followed by Methanosaeta and Methanobacterium. Several differences were found in the relative abundances of some genera between the DNA and cDNA samples, indicating an increase in the diversity of the metabolically active community, highlighting Chlorobaculum, Cladimonas, Turicibacter and Clostridium senso stricto. Nitrifying bacteria were more abundant in the hybrid bioreactor. Beta diversity analysis revealed that the microbial community structure significantly differed among the samples (p < 0.05) and between both anaerobic treatments. The main predicted metabolic pathways were the biosynthesis of amino acids and the formation of antibiotics. Also, the metabolism of C5-branched dibasic acid, Vit B5 and CoA, exhibited an important relationship with the main nitrogen-removing microorganisms. The anaerobic-aerobic hybrid bioreactor showed a higher ammonia removal rate compared to the conventional UASB system. However, further research and adjustments are needed to completely remove nitrogen from wastewater. • A hybrid anaerobic-aerobic reactor was evaluated for swine wastewater treatment. • The hybrid reactor enhanced NH 4 + and P removal compared to a control UASB reactor. • Bacterial composition was significantly different from anaerobic-hybrid to the UASB reactor. • Methanosaeta was predominant in all samples, especially in the UASB. • The relative abundances of total and metabolically active genera differed. [ABSTRACT FROM AUTHOR]

En esta investigación se presenta la evaluación de un biorreactor de manto de lodo anaerobio de flujo ascendente (UASB) de 4.4 L durante un periodo de 90 días, el cual fue alimentado con vinazas de una empresa de bebidas fermentadas provenientes de Comitán, Chiapas. Se investigó principalmente la eficiencia de la remoción de la demanda química de oxígeno (DQO) y la estabilidad del reactor con respecto al factor alfa (α) y potencial de hidrógeno (pH). La eficiencia de remoción de la DQO fue de 90 %. Durante el estudio, se mantuvo un sistema estable con α =0.28 y pH=7.1.

A presente pesquisa objetivou avaliar o desempenho de sistemas anaeróbios quanto à concentração de sulfetos presentes no efluente de reatores UASB. Foram utilizados dois reatores UASB para comparação; em um foi inserido oxigênio na manta de lodo (0,6 a 1,2 mgO2 .L-1) e o outro apresentava características de um UASB sem modificações. Com os resultados obtidos, identificou-se que a adição de oxigênio na manta de lodo resultou em uma diminuição de sulfeto no efluente de 81%, garantindo uma concentração final no efluente de 12,09±3,22 mgS-SO4 2-.L-1 e 2,54±1,92 mgS-S2-.L-1, inibindo o mau cheiro e diversos problemas relacionados com a formação de sulfeto em reatores anaeróbios, além de remover uma parcela considerável do material orgânico em termos de DQO, 54% e 52% na primeira fase e 58% e 59% na segunda, para o UASB – O2 e UASB – Controle, respectivamente.

O trabalho objetiva analisar a potencialidade da espacialização de informações de SAAs por meio de SIG, a fim de facilitar o armazenamento, manipulação e monitoramento dos dados. Para isso, foram utilizados os softwares Excel 2010, da Microsoft, e ArcGIS 9.3, do ESRI, como também definidos os dados empregados no trabalho (etapa 1) e realizados o armazenamento e organização dos dados em SIG (etapa 2), tendo sido considerados os dados tabulares e cartográficos do SAA. Por fim, foram determinados e espacializados os indicadores de desempenho (etapa 3), tendo sido proposta a utilização de oito variáveis operacionais, 18 comerciais e dez de despesas de exploração e do limite de setores de abastecimento como unidade de gerenciamento, constituindo o banco de dados georreferenciado. Os indicadores de desempenho foram determinados por meio da ferramenta Field Calculator do ArcGIS 9.3, que relaciona as variáveis por meio de operações matemáticas, gerando novos resultados. Com isso, é possível analisar e monitorar o desempenho de SAAs, facilitando a tomada de decisão no gerenciamento desses sistemas.

The use of straw for biofuel production is encouraged by the European Union. A previous study showed the feasibility of producing biomethane in upflow anaerobic sludge blanket (UASB) reactors using hydrolyzed, steam-pretreated wheat straw, before and after dark fermentation with Caldicellulosiruptor saccharolyticus, and lucerne. This study provides information on overall microbial community development in those UASB processes and changes related to acidification. The bacterial and archaeal community in granular samples was analyzed using high-throughput amplicon sequencing. Anaerobic digestion model no. 1 (ADM1) was used to predict the abundance of microbial functional groups. The sequencing results showed decreased richness and diversity in the microbial community, and decreased relative abundance of bacteria in relation to archaea, after process acidification. Canonical correspondence analysis showed significant negative correlations between the concentration of organic acids and three phyla, and positive correlations with seven phyla. Organic loading rate and total COD fed also showed significant correlations with microbial community structure, which changed over time. ADM1 predicted a decrease in acetate degraders after a decrease to pH ≤ 6.5. Acidification had a sustained effect on the microbial community and process performance.

Up-flow anaerobic sludge blanket (UASB) reactor belongs to high-rate systems, able to perform anaerobic reaction at reduced hydraulic retention time, if compared to traditional digesters. In this review, the most recent advances in UASB reactor applications are critically summarized and discussed, with outline on the most critical aspects for further possible future developments. Beside traditional anaerobic treatment of soluble and biodegradable substrates, research is actually focusing on the treatment of refractory and slowly degradable matrices, thanks to an improved understanding of microbial community composition and reactor hydrodynamics, together with utilization of powerful modeling tools. Innovative approaches include the use of UASB reactor for nitrogen removal, as well as for hydrogen and volatile fatty acid production. Co-digestion of complementary substrates available in the same territory is being extensively studied to increase biogas yield and provide smooth continuous operations in a circular economy perspective. Particular importance is being given to decentralized treatment, able to provide electricity and heat to local users with possible integration with other renewable energies. Proper pre-treatment application increases biogas yield, while a successive post-treatment is needed to meet required effluent standards, also from a toxicological perspective. An increased full-scale application of UASB technology is desirable to achieve circular economy and sustainability scopes, with efficient biogas exploitation, fulfilling renewable energy targets and green-house gases emission reduction, in particular in tropical countries, where limited reactor heating is required.

The paper industry is an activity that have a large impact on the quality of natural resources. The large amount of water used has an impact on the wastewater generated. Untreated liquid waste can cause pollution in water bodies (rivers). Wastewater treatment with Up flow Anaerobic Sludge Blanket (UASB) is able to process wastes with high COD content in the paper industry. This paper provides a basic review and UASB research that has been carried out in the wastewater treatment of the paper industry.

Extraction of sugar from sugarcane produces a high volume of effluent carrying large amounts of organics and BOD5. Discharging the effluent into rivers and into the environment endangers the aquatic life and increases the risks of environmental pollution. This study was conducted in 2012 to determine the kinetic coefficients of the anaerobic treatment systems (UASB) at the wastewater treatment plant of Imam Khomeini Sugarcane Agro-industrial Plant in Shushtar. The parameters of BOD5, COD, and TSS were measured at the inlet and outlet of the WWTP. Subsequently, the operation and design parameters of the system were determined. Using the modified Monod Equations, the kinetic coefficients Ks, Y, Kd, μ max, and K max for employing the UASB process at the WWPT in question were calculated as 506.4mg/l, 0.11 g VSS/g COD, 0.0045 d-1, 0.0069 d-1, and 0.055 d-1, respectively. The kinetic coefficients obtained in this study can be used in the steering and operation as well as fundamental design of similar plants, especially in hot areas.

This study aimed to evaluate the start-up of a horizontal anaerobic fixed bed reactor (HAFBR) followed by an upflow anaerobic sludge blanket (UASB) for the slaughterhouse wastewater treatment. HAFBR was filled with bamboo rings and had 1.2 m in length, 0.10 m in diameter and volume of 7.5 L. The UASB had the volume of 15 L. The HAFBR and UASB operated at organic loading rate and hydraulic retention time average of 8.46 and 3.77 kg m-3 d-1 of COD and 0.53 and 0.98 days, respectively. During 150 days of monitoring system it was found pH 6.8, relatively high values of bicarbonate alkalinity (> 1000 mg L-1) and reduced values of volatile acids (70 to 150 mg L-1), which afforded average removal efficiencies of COD total and total suspended solids of the order of 31 and 23% in HAFBR and 79% and 63% in UASB. It can be concluded that the generation and consumption of bicarbonate alkalinity and total volatile acids, thereby maintaining the pH during the study indicated stable operation of the reactors. The COD removal in the reactors was satisfactory especially when it considers that the assessment was conducted in a period of adaptation of organisms to the effluent and also the high organic load applied during this period.

Anaerobic digestion of food waste still faces important challenges despite its world-wide application. An important fraction of food waste is composed of organic material having a low hydrolysis rate and which is often not degraded in digesters. The addition of this less hydrolysable fraction into anaerobic digesters requires a longer hydraulic residence time, and therefore leads to oversizing of the digesters. To overcome this problem, the conversion of the highly biodegradable liquid fraction from fruit and vegetable waste in a up-flow anaerobic sludge blanket (UASB) digester is proposed and demonstrated. The more easily biodegradable fraction of the waste is concentrated in the liquid phase using a 2-stage screw press separation. Then, this liquid fraction is digested in a 3.5 L UASB digester at a high organic loading rate. A good and stable performance was observed up to an organic loading rate (OLR) of 12 g COD/(Lrx.d), with a specific methane production of 2.6 L CH 4 /(Lrx.d) and a degradation of 85% of the initial total COD. Compared to the conversion of the same initial waste with a continuously stirred tank reactor (CSTR), this new treatment strategy leads to 10% lower COD degradation, but can produce the same amount of methane with a digester that is twice as small. The scale-up of this process could contribute to reduced costs related to the anaerobic digestion of food waste, while reducing management efforts associated with digestate handling and increasing process stability at high organic loading rates.

The activated sludge (AS) process has been the most widely used process for wastewater treatment despite it has several limitations for its further application and adoption worldwide, owing to unsustainable properties such as high-energy consumption and the production of large amount of excess sludge. To overcome the drawbacks of the AS process, the downflow hanging sponge (DHS) has been developed as an energy-saving and easy-to-maintain alternative. To date, six types of different sponge configurations have been developed and their performances have been evaluated in practical- to full-scale DHS reactors. A large number of studies have been carried out in order to enhance the performance and expand the application fields of the DHS. Transition of this process to the deployment and diffusion stage from the research and development phase is now ongoing in India and Egypt as well as in Japan. Under this situation, concise and state-of-the art review is important for enhancing DHS research and future applications. Herein, we summarize and present the DHS concerning the history of development, the mechanism of treatment, recent studies on its use in the field of wastewater treatment, and the features of microbial community structure. [ABSTRACT FROM AUTHOR]

Volatile fatty acids (VFA) production and degree of acidification (DA) were investigated in the anaerobic treatment of cheese whey by comparison of two processes: a continuous process using a laboratory upflow anaerobic sludge blanket (UASB) reactor and a discontinuous process using a sequencing batch reactor (SBR). The main purpose of this work was to study the organic loading rate (OLR) effect on the yield of VFA in two kinds of reactors. The predominant products in the acidogenic process in both reactors were: acetate, propionate, butyrate and valerate. The maximum DA obtained was 98% in an SBR at OLR of 2.7 g COD L−1 d−1, and 97% in the UASB at OLR at 15.1 g COD L−1 d−1. The results revealed that the UASB reactor was more efficient at a medium OLR with a higher VFA yield, while with the SBR reactor, the maximum acidification was obtained at a lower OLR with changes in the VFA profile at different OLRs applied. [ABSTRACT FROM AUTHOR]

Highlights • Three models were applied to identify the main fouling mechanisms in a UF membrane. • Surface fouling had the best fits for the blocking laws and combined models. • In all cases similar fits were obtained with both models when N 2 bubbling was applied. • There are clear differences between filtration runs with and without gas bubbling. • The resistance-in-series model identified a post-cake fouling mechanism. Abstract Three models (blocking laws, combined and resistance-in-series) were applied to identify the prevailing fouling mechanisms in a submerged membrane in an up-flow anaerobic sludge blanket reactor treating municipal wastewater. Experimental runs were carried out at lab-scale with filtration periods of 4 and 10 min, followed by relaxation periods of one minute with and without nitrogen bubbling. In all conditions excepting one (IF4R), the blocking laws model showed a predominance of cake formation. With the combined model, cake formation coupled with intermediate, standard and complete fouling had the better fits in all conditions, excepting IF4 and IF4R. When sewage was fed, both models pointed at intermediate fouling in the absence of gas bubbling. The resistance-in-series model identified the positive effect of gas bubbling and a post-cake fouling behavior, not shown by the other two models. This modeling approach could be applied for achieving longer filtration runs in submerged UF membranes. [ABSTRACT FROM AUTHOR]

Abstract Two bio-cathode microbial fuel cells (MFCs) with Upflow anaerobic sludge blanket (UASB) are integrated to construct a UASB-MFC dual sensors system, developed to solve the problems of low accuracy and less information about the single sensor system. The bio-cathode MFC is developed as the biosensor for UASB operation performance and online monitoring. Owing to the biosorption of anaerobic microbes, the MFC in the suspended layer is more suitable for effluent chemical oxygen demand (COD) real-time monitoring, and the MFC in the sludge layer is more suitable for total volatile fatty acid (TVFA) real-time monitoring. Electrochemical analysis discovers that the lower electron transfer resistance determines the higher sensitivity of MFC in the suspended layer. The difference in species abundance indicates that TVFA has a stronger inhibitory effect on MFC in the sludge layer. The novel UASB-MFC dual sensors system shows promising potential for COD and TVFA simultaneous online monitoring, which can enhance the reliability of anaerobic reaction. Graphical abstract Image 1 Highlights • A new type of UASB-MFC dual sensor system was developed for UASB operation performance online monitoring. • The MFC suspended layer for effluent COD monitoring and the MFC sludge layer for TVFA monitoring. • The adsorption saturation phenomenon of activated sludge was proved by three-dimensional fluorescence method. • The sensor's characteristics were investigated based on the electrochemical method and microbial community analysis. [ABSTRACT FROM AUTHOR]

Highlights • Mineralization of nutrient-rich sludge constitutes a solution for aquaculture waste treatment. • UASB reactors can break down sludge into bioavailable nutrients, which can be delivered to plants. • Results indicate that UASB reactors operating at low pH can contribute towards nutrient-recovery. Abstract There is a recognized need for mineralizing aquaculture-derived sludge in aquaponics systems in order to reduce waste production. Many recent studies of aquacultural waste treatment have focused only the production of biogas as opposed to the potential for mineralization of nutrient-rich sludge. Upflow anaerobic sludge blanket (UASB) reactors provide one possible solution for breaking down sludge into bioavailable nutrients that can subsequently be delivered to plants. As such, this study examines the mineralization performance of sequential UASB reactors that are designed with an expanded granular sludge bed (EGSB) and compared to standard aerobic and anaerobic batch reactors. Results of our experiments demonstrate that only chemical oxygen demand reduction is significantly different. An unexpected drop in pH of one of the three reactor systems revealed that a pH below 6 was able to significantly increase the mineralization and mobilization of nutrients. Approximately 25% of phosphorus, potassium, and calcium could also be recovered from the sludge under lower pH conditions, as compared to the mineralization performance of standard UASB reactors running at a higher pH. However, the opposite effect was observed with respect to organic sludge reduction, where diminished performance was observed in the low-pH reactor. The current study implies that anaerobic reactors operating at low pH can potentially contribute towards improved nutrient recovery in multi-loop aquaponics systems and reduction of additive agents for pH control of the hydroponic subsystem. [ABSTRACT FROM AUTHOR]

The competition between methane-producing archaea and sulfate-reducing bacteria is an important topic in anaerobic wastewater treatment. In this study, an Up-flow Anaerobic Sludge Blanket Reactor (UASB) was operated for 330 days to evaluate the treatment performance of sulfate-rich wastewater. The effects of competition change between methane production and sulfate reduction on the organic removal efficiency, methane production, and electrons allocation were investigated. Synthetic wastewater was composed of ethanol and acetate with a chemical oxygen demand (COD)/SO 4 2− of 1.0. As a result, the COD removal efficiency achieved in long-term treatment was higher than 90%. During the initial stage, methane production was the dominant reaction. Sulfate-reducing bacteria (SRB) could only partially oxidize ethanol to acetate, and methane-producing archaea (MPA) utilized acetate for methane production. Methane production declined gradually over the long-term operation, whereas the sulfate-reducing efficiency increased. However, UASB performed well throughout the experiment because there was no significant inhibition. After the complete reduction of the sulfate, MPA converted the remaining COD into methane. [ABSTRACT FROM AUTHOR]

The hydrodynamic characteristics of granular sludge is the key factor for efficient operation of up flow anaerobic sludge blanket (UASB) reactor, This research aims to evaluate the hydrodynamic characteristics of anaerobic sludge produced from five different pilot scale configurations, based on its settle ability, expansion characteristics and particle size distribution. An experimental set-up was established to determine the parameters required for settle ability and expandability equations. For particle size distribution, the proposed technique involves the determination of the settling velocities of a sludge sample then calculating the corresponding diameters using a mathematical approach. Results show that the hydrodynamic characteristics of different types of granular sludge have been determined using simple, flexible and low cost techniques. Results also indicated that sludge settling characteristics were not affected by adding supporting plastic media to the UASB reactor. On the contrary, the excess activated sludge returned to UASB reactor enhanced the sludge settling properties. The particle size distribution ranged from 0.06 to 1.1 mm and the corresponding Reynolds number (Re)for most sludge granules are from 0.1 to 50 which demonstrates that the settling process of the granules is in intermediate flow regime. [ABSTRACT FROM AUTHOR]

The up-flow anaerobic sludge blanket (UASB) system with graphene assisted was developed for coal gasification wastewater (CGW) treatment. Short-term results showed that optimal graphene addition (0.5 g/L) resulted in a more significant enhancement of methane production and chemical oxygen demand (COD) removal compared with that of the optimal activated carbon addition (10.0 g/L). Long-term results demonstrated that COD removal efficiency and methane production rate with graphene assisted achieved 64.7% and 180.5 mL/d, respectively. In addition, graphene could promote microbes accumulation and enzymes activity, resulting in higher extracellular polymeric substances (EPS) and coenzyme F 420 concentrations. X-ray Diffraction (XRD) analysis indicated that chemical of graphene changed insignificantly during the experiment. Meanwhile, with graphene assisted, cells were attached together to form microbial aggregates to facilitate sludge granulation process. Furthermore, the enriched Geobacter and Pseudomonas might perform direct interspecies electron transfer (DIET) with Methanosaeta via biological electrical connection, enhancing the anaerobic degradation of CGW. [ABSTRACT FROM AUTHOR]

Knowledge of leveraging biomass characteristics is essential for achieving a microbial community with a desired structure to optimize anaerobic bioreactor performance. This study investigates the successive granule transformations in a high-rate anaerobic system with intermittent gas sparging and sequential increases in organic loading rates (OLRs), by establishing the correlations between the granule microstructures and reactor operating parameters. Over the course of a 196-day lab-scale trial, the granules were visualized in various stages using scanning electron microscopy, and digital image processing was applied for further quantifying their surface properties. Correlation analyses revealed that irregularities of the granule microstructures (surface properties, specific surface area and pore volume) emerged at stage 4 when the OLR was 13.31 kg COD/m 3 ·day and in stage 5 in the absence of gas sparging. The loading ratio (substrate surface loading to upward velocity) was identified to be the main parameter controlling the granule transformations, and the surface structures were classified into three categories for further interpretation. Confocal laser scanning microscopy analyses showed that the granule core started to hollow out from stage 4. It is also found that a rough granule surface helped accelerate the growth of the granular diameter under gas sparging. Overall, this study not only establish quantitative correlations between the granules microstructures and reactor operating parameters, but also shed light on the use of intermittent gas sparging to control the surface properties of anaerobic granules in high-rate anaerobic bioreactors. [ABSTRACT FROM AUTHOR]

Phenols are industrially generated intermediate chemicals found in wastewaters that are considered a class of environmental priority pollutants. Up-flow anaerobic sludge blanket (UASB) reactors are used for phenolic wastewater treatment and exhibit high volume loading capability, favorable granule settling, and tolerance to impact loads. Use of support materials can promote biological productivity and accelerate start-up period of UASB. In the present study, turf soil was used as a support material in a mesophilic UASB reactor for the removal of phenols in wastewater. During sludge acclimatization (45–96 days), COD and phenols in the treatments were both reduced by 97%, whereas these contents in the controls were decreased by 81% and 75%, respectively. The phenol load threshold for the turf soil UASB reactor was greater (1200 mg/L, the equivalent of COD 3000 mg/L) in comparison with the control UASB reactor (900 mg/L, the equivalent of COD 2250 mg/L) and the turf soil UASB reactor was also more resistant to shock loading. Improved sludge settling, shear resistance, and higher biological activity occurred with the turf soil UASB reactor due to the formation of large granular sludge (0.6 mm or larger) in higher relative percentages. Granular sludge size was further enhanced by the colonization of filamentous bacteria on the irregular surface of the turf soil. [ABSTRACT FROM AUTHOR]

The influence of polarized electrodes on the methane production, which depends on the sludge concentration, was investigated in upflow anaerobic bioelectrochemical (UABE) reactor. When the polarized electrode was placed in the bottom zone with a high sludge concentration, the methane production was 5.34 L/L.d, which was 53% higher than upflow anaerobic sludge blanket (UASB) reactor. However, the methane production was reduced to 4.34 L/L.d by placing the electrode in the upper zone of the UABE reactor with lower sludge concentration. In the UABE reactor, the methane production was mainly improved by the enhanced biological direct interspecies electron transfer (bDIET) pathway, and the methane production via the electrode was a minor fraction of less than 4% of total methane production. The polarized electrodes that placed in the bottom zone with a high sludge concentration enhance the bDIET for methane production in the UABE reactor and greatly improve the methane production. [ABSTRACT FROM AUTHOR]

A lab-scale anammox up-flow anaerobic sludge blanket (UASB) reactor was run to investigate the influence of temperature on anammox performance and community structure. The anammox system had a higher substrate tolerance at 13 °C than at 18 °C. The adverse effects caused by the use of a lower temperature (8 °C) could be restored. The nitrogen removal rate (NRR) decreased with decreasing in situ specific anammox activity (SAA). Interestingly, the ex situ SAA acclimated at 23 °C, when exposed to ex situ temperatures of 33 and 28 °C, was higher than for those acclimated at 33 and 28 °C. No shift was observed in the optimum temperature for ex situ SAA in the whole lowering process of anammox UASB. More extracellular polymeric substances were produced in response to cooler conditions (18 °C and 13 °C). Ca. Kuenenia became much more abundant (55.18% of the microbial community) and had a competitive advantage over other anammox bacteria (AnAOB) at 13 °C. [ABSTRACT FROM AUTHOR]

Anaerobic co-digestion has made a greater impact on the biogas production from mixing different type of waste. In this research, sewage sludge (SS) and cow manure (CM), was used as a primary waste along with kitchen waste (KW), yard waste (YW), floral waste (FW) and dairy wastewater (DWW) as co-substrate for anaerobic digestion. Mixtures with a ratio of 1:2 ratio is fed into a single stage up-flow anaerobic sludge blanket (UASB) reactor. Digestion was carried out in a mesophilic temperature range for 20 days. pH and VFA were measured and ranged from 5 to 7.5 and 3500–500 mg/L, respectively, for all the mixtures throughout the digestion period. Percentage of COD removal efficiency after 20 days was found to be in the range of 76–86%. The maximum biogas production rate was found to be 4500 mL/day. Characterization of the final residue from each of the digesters was carried out by Scanning Electron microscope, Energy dispersive, thermogravimetric, FTIR Spectra, and Atomic microscope. Thermal analysis reveals that spent sludge can be potential waste energy sources. [ABSTRACT FROM AUTHOR]

This study examines the removal of micropollutants (MPs) in a hybrid process that combines anaerobic and aerobic redox conditions under different Organic Loading Rates (OLRs). A laboratory-scale pilot-plant composed of an Upflow Anaerobic Sludge Blanket reactor (UASB) combined with a membrane bioreactor (MBR) was operated. Six MPs were analyzed: the hormones estrone, 17-α-ethinyl estradiol and 17-β-estradiol, the plasticizer bisphenol A and the pharmaceuticals carbamazepine and diclofenac. In order to study its influence on removal efficiencies, the system was operated at three different OLRs: high (0.67 ± 0.15 kg COD/m3 d), medium (0.37 ± 0.06 kg COD/m3 d) and low (0.11 ± 0.02 kg COD/m3 d). The results demonstrated the synergistic effects due to the double biological treatment, with removal rates above 90% for the hormones and the plasticizer. Pharmaceuticals were the most resistant compounds, being only partially removed in the liquid phase. Removal rates of the MPs were higher at high OLR of the influent. [ABSTRACT FROM AUTHOR]

The severe environmental pollution in many countries is caused by indiscriminate discharge of large quantities of food waste (FW), fat oil and grease (FOG) and sewage sludge (SS) to the environment. There are many possible treatment routes, but anaerobic digestion (AD) is now well accepted for treating several kinds of organic wastes. But AD of FW alone presents some operational challenges because of substrates and variability. Anaerobic co-digestion of two or more substrates is better than single substrate digestion. This can use a plant’s unused capacity, in line with the trend to renewable energy. Co-digestion technology, although well established in many European countries, is still in its infancy in Ireland. There are problems with different regulatory arrangements. They should be resolved. The paper reviews anaerobic co-digestion technology is reviewed, with special focus on possible application in Ireland. [ABSTRACT FROM AUTHOR]

Effects of temperature variations from mesophilic to thermophilic on the performance of UASB reactors with glucose and ethanol as substrate were investigated. The reactor with ethanol as substrate had better resistance to temperature variations with over 93% COD degradation rate and 75% methane content. The conductivity of granular sludge that degraded ethanol was also considerably higher. High-throughput sequencing indicated that the abundance of Methanobacterium decreased, while Methanosaeta increased with increasing temperature. Moreover, the abundance of Geobacter and Methanosaeta were higher in the reactor with ethanol as substrate than that with glucose, whereas a higher abundance of Klebsiella was observed in the glucose reactor. More importantly, significant correlations were observed between granular sludge conductivity and COD removal rate (R 2  = 0.73), between the abundance of Geobacter and COD removal rate (R 2  = 0.895). These results indicate that the growth of Geobacter and Methanosaeta which promote transfer electrons in the manner of DIET in anaerobic methanogenic systems might alleviate the effect of temperature variation and facilitate reaction rate. [ABSTRACT FROM AUTHOR]

For enhanced dechlorination of 2,4-dichloronitrobenzene (2,4-DClNB), a coupled microbial electrosynthesis-upflow anaerobic sludge reactor (MES-UASB) was established, and the effect of cathode potential on the performance of combined process was investigated in this study. Results showed that a higher dechlorination efficiency of 78.5 ± 6.1% was achieved in the coupled MES-UASB at −660 mV, and the degradation rate of 4-chloroaniline (4-ClAn) reached 4.61 mg·L −1 ·d −1 within 120 h at −660 mV of cathode potential in batch experiments. The results of Illumina sequencing indicated that the biocathode operated at a lower potential favored the enrichment of dechlorination-related microbes such as Dehalobacter , Dehalococcoides and Anaeromyxobacter both in granular sludge and cathode biofilm. It could be speculated that a lower cathode potential is more feasible for the dechlorination of 2,4-DClNB due to the enrichment of dechlorination-related microbes as well as the production of electrons with higher energy for long-distance electron transfer (LDET). [ABSTRACT FROM AUTHOR]

The present study introduces a new technique using a combined up-flow anaerobic sludge bed (UASB) followed by innovative down-flow hanging non-woven fabric (DHNW) for the treatment of domestic wastewater. The aim of this work is to develop an innovative non-woven packing material that can be used to improve the performance of both UASB and DHNW and other similar techniques for the treatment of wastewater. The packing material could be produced from waste plastic bottles, thus considerable part of solid waste can be reduced, recycled and applied in wastewater treatment plant to produce treated reusable effluent. The primary treatment was carried out using packed and classical UASB reactor (in parallel manner). The quality of the packed UASB effluent was better than that of the classical UASB reactor. Consequently, the effluent of the packed UASB reactor was fed directly to the DHNW reactor. The source of wastewater was the domestic wastewater from Zeneen's wastewater treatment station. The hydraulic residence time (HRT) of the UASB reactors was 6 h. The performance of the combined packed UASB/DHNW showed reduction of COD, BOD and TSS from 349.6, 260.6 and 171.3 to 44, 24 and 27 mg/L, respectively. The fecal coliform (FC)count was reduced by 3 log units using the combined packed UASB/DHNW system. The results indicated that polyethylene terephthalate (PET) spun-bond non-woven fabric can offer a cost effective solution as well as durable and efficient packing material for wastewater treatment. [ABSTRACT FROM AUTHOR]

The effect of chitosan on the development of granular sludge in upflow anaerobic sludge blanket reactors (UASB) when treating wastewater polluted with the organic solvents ethanol, ethyl acetate, and 1-ethoxy-2-propanol was evaluated. Three UASB reactors were operated for 219 days at ambient temperature with an organic loading rate (OLR) of between 0.3 kg COD m −3 d −1 and 20 kg COD m −3 d −1 . One reactor was operated without the addition of chitosan, while the other two were operated with the addition of chitosan doses of 2.4 mg gVSS −1 two times. The three reactors were all able to treat the OLR tested with COD removal efficiencies greater than 90%. However, the time required to reach stable operation was considerably reduced in the chitosan-assisted reactors. The development of granules in the reactors with chitosan was accelerated and granules larger than 2000 μm were only observed in these reactors. In addition, these granules exhibited better physicochemical characteristics: the mean particle diameter (540 and 613 μm) was approximately two times greater than in the control reactor (300 μm), and the settling velocities exceeded 35 m h −1 . The extracellular polymeric substances (EPS) in the reactors with the chitosan was found to be higher than in the control reactor. The protein-EPS content has been correlated with the granule size. The analyses of the microbial communities, performed through denaturing gradient gel electrophoresis and high-throughput sequencing, revealed that the syntrophic microorganisms belonging to genus Geobacter and the hydrogenotrophic methanogen Methanocorpusculum labreanum were predominant in the granules. Other methanogens like Methanosaeta species were found earlier in the chitosan-assisted reactors than in the control reactor. [ABSTRACT FROM AUTHOR]

Up-flow anaerobic sludge blanket (UASB) has been in use since last few decades for the treatment of organic wastewaters. However, the performance of UASB reactor is quite low for treatment of low strength wastewaters (LSWs) due to less biogas production leading to poor mixing. In the present research work, a modification was done in the design of UASB to improve mixing of reactor liquid which is important to enhance the reactor performance. The modified UASB (MUASB) reactor was designed by providing a slanted baffle along the height of the reactor having an angle of 5.7° with the vertical wall. A two-dimensional computational fluid dynamics (CFD) simulation of three phase gasliquid- solid flow in MUASB reactor was performed and compared with conventional UASB reactor. The CFD study indicated better mixing in terms of vorticity magnitude in MUASB reactor as compared to conventional UASB, which was reflected in the reactor performance. The performance of MUASB was compared with conventional UASB reactor for the onsite treatment of domestic sewage as LSW. Around 16% higher total chemical oxygen demand removal efficiency was observed in MUASB reactor as compared to conventional UASB during this study. Therefore, this MUASB model demonstrates a qualitative relationship between mixing and performance during the treatment of LSW. From the study, it seems that MUASB holds promise for field applications. [ABSTRACT FROM AUTHOR]

With an increasing interest in using anaerobic reactors for treating domestic/industrial wastewater, posttreatment processes to upgrade the anaerobic effluents produced have also been investigated, although in many cases in very little depth. A few reviews have discussed the posttreatment of up-flow anaerobic sludge blanket (UASB) effluents; these systems generally improve the removal of organic matter, nutrients and pathogens to attain discharge standards, or reuse in agriculture. However, with the recent developments in anaerobic membrane bioreactors (AnMBR), advanced posttreatment technology can produce higher quality effluents that can ultimately be used for recycling. Hence, this paper will discuss the posttreatment methods for all anaerobic reactor types, while focussing on the UASB and AnMBR, which aim to remove organic compounds as well as nitrogen and phosphorus. With regards to the advanced treatment of organic compounds in anaerobic effluents, the removal of micropollutants such as pharmaceuticals and soluble microbial products (SMPs) will also be addressed. Finally, the removal of dissolved methane as well as the potential resource recovery of compounds such as nitrogen, phosphorus or dissolved methane will also be highlighted. [ABSTRACT FROM AUTHOR]

It is commonly accepted that high salt concentrations negatively affect microbial activity in biological wastewater treatment reactors such as upflow anaerobic sludge blanket (UASB) reactors. Microbial aggregation in such reactors is equally important. It is well documented that anaerobic granules, when exposed to high salinity become weak and disintegrate, causing wash-out, operational problems and decreasing process performance. In this research, the possibility of microbial granule formation from dispersed biomass was investigated at salinity levels of 5 and 20 g Na + /L. High removal efficiencies of soluble influent organics were achieved at both salinity levels and this was accompanied by fast and robust formation of microbial granules. The process was found to be stable for the entire operational period of 217 days. As far as we know this is the first time it has been demonstrated that stable granule formation is possible at a salinity level as high as 20 g Na + /L. Methanosaeta was identified as the dominant methanogen at both salinity levels. Streptococcus spp. and bacteria belonging to the family Lachnospiraceae were identified as the dominant microbial population at 5 and 20 and g Na + /L, respectively. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the efficiency of a full-scale treatment system effluent slaughterhouse. The full-scale Sewage Treatment Station was designed for a daily flow of 60 m³/d, corresponding to a slaughter of 60 cattle per day. The treatment system consists of a Parshall flume for flow measurement, followed by static sieve, gravimetric fat, sedimentation and anaerobic sludge blanket (UASB) box and it was monitored weekly from January to August. The following parameters were analyzed: pH, alkalinity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS), total suspended solids (TSS), ammonia nitrogen, and total nitrogen kjedhall. The average pH, COD and TSS in the UASB reactor effluent values were 6.96, 660 mg/L and 188 mg/L , respectively. The system proved to be efficient, with average removal of 96.40% to 89.92% for COD and TSS. The UASB reactor showed high performance in removing solids and organic load. Thus, this reactor becomes a viable alternative for treating wastewater slaughterhouse, offering good removal results and low cost of deployment.