Coupled UASB-activated sludge process for COD and nitrogen removals in municipal sewage treatment in warm climate

2009 ◽  
Vol 60 (11) ◽  
pp. 2829-2839 ◽  
Author(s):  
Ye Shi Cao ◽  
Chee Meng Ang
Keyword(s):  
Activated Sludge ◽  
Sewage Treatment ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Municipal Sewage ◽  
Anaerobic Sludge ◽  
Activated Sludge Process ◽  
Warm Climate ◽  
Mass Load ◽  
Final Effluent

A laboratory-scale system consisting of an upflow anaerobic sludge blanket (UASB) reactor followed by a modified Ludzack-Ettinger (MLE) activated sludge process was adopted to investigate COD and nitrogen removals in municipal sewage treatment in warm climate. The COD, SCOD, acetic acid (HAc), NH4+-N and PO43−-P conversions in the UASB reactor were investigated. A 35% reduction in volatile suspended solid (VSS) was achieved in the UASB process. The net methane (CH4) production was 0.06 l (g CODremoved)−1. Acids accumulation was not observed. In the MLE activated sludge process, nitrification was almost complete while denitrification was modest. Little excess sludge was produced as the bulk of the COD was removed in the UASB reactor, which reduced the COD mass load to the activated sludge process. The average COD and SCOD of the final effluent of the activated sludge process were 51 and 25 mg l−1, respectively and the average NH4+-N concentration of the final effluent was 3.1 mg N l−1. The results illustrated that the coupled process is feasible for COD and nitrogen removals in municipal sewage treatment in warm climate. However, the low pH of the final effluent (<6 on average) remains an issue to be solved.

Impact of microaeration bioreactor on dissolved sulfide and methane removal from real UASB effluent for sewage treatment

2020 ◽  
Vol 81 (9) ◽  
pp. 1951-1960 ◽  
Author(s):  
C. S. Cabral ◽  
A. L. Sanson ◽  
R. J. C. F. Afonso ◽  
C. A. L. Chernicharo ◽  
J. C. Araújo
Keyword(s):  
Sewage Treatment ◽  
Oxygen Demand ◽  
Post Treatment ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Sulfide Removal ◽  
Dissolved Sulfide ◽  
Removal Efficiencies ◽  
Anaerobic Sludge Blanket

Abstract Two bioreactors were investigated as an alternative for the post-treatment of effluent from an upflow anaerobic sludge blanket (UASB) reactor treating domestic sewage, aiming at dissolved sulfide and methane removal. The bioreactors (R-control and R-air) were operated at different hydraulic retention times (HRT; 6 and 3 h) with or without aeration. Large sulfide and methane removal efficiencies were achieved by the microaerated reactor at HRT of 6 h. At this HRT, sulfide removal efficiencies were equal to 61% and 79%, and methane removal efficiencies were 31% and 55% for R-control and R-air, respectively. At an HRT of 3 h, sulfide removal efficiencies were 22% (R-control) and 33% (R-air) and methane removal did not occur. The complete oxidation of sulfide, with sulfate formation, prevailed in both phases and bioreactors. However, elemental sulfur formation was more predominant at an HRT of 6 h than at an HRT of 3 h. Taken together, the results show that post-treatment improved the anaerobic effluent quality in terms of chemical oxygen demand and solids removal. However, ammoniacal nitrogen was not removed due to either the low concentration of air provided or the absence of microorganisms involved in the nitrogen cycle.

Comparison of simple, small, full-scale sewage treatment systems in Brazil: UASB–maturation ponds–coarse filter; UASB–horizontal subsurface-flow wetland; vertical-flow wetland (first stage of French system)

2014 ◽  
Vol 71 (3) ◽  
pp. 329-337 ◽  
Author(s):  
M. von Sperling
Keyword(s):  
Sewage Treatment ◽  
Subsurface Flow ◽  
Full Scale ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Plant Management ◽  
Anaerobic Sludge ◽  
Vertical Flow ◽  
Coarse Filter ◽  
Horizontal Subsurface Flow

This paper presents a comparison between three simple sewage treatment lines involving natural processes: (a) upflow anaerobic sludge blanket (UASB) reactor–three maturation ponds in series–coarse rock filter; (b) UASB reactor–horizontal subsurface-flow constructed wetland; and (c) vertical-flow constructed wetlands treating raw sewage (first stage of the French system). The evaluation was based on several years of practical experience with three small full-scale plants receiving the same influent wastewater (population equivalents of 220, 60 and 100 inhabitants) in the city of Belo Horizonte, Brazil. The comparison included interpretation of concentrations and removal efficiencies based on monitoring data (organic matter, solids, nitrogen, phosphorus, coliforms and helminth eggs), together with an evaluation of practical aspects, such as land and volume requirements, sludge production and handling, plant management, clogging and others. Based on an integrated evaluation of all aspects involved, it is worth emphasizing that each system has its own specificities, and no generalization can be made on the best option. The overall conclusion is that the three lines are suitable for sewage treatment in small communities in warm-climate regions.

Performance of UASB based sewage treatment plant in India: polishing by diffusers an alternative

2011 ◽  
Vol 63 (4) ◽  
pp. 680-688 ◽  
Author(s):  
R. Walia ◽  
P. Kumar ◽  
I. Mehrotra
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Total Coliform ◽  
Point Of View ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Detention Ponds ◽  
One Year

In India, recently, upflow anaerobic sludge blanket (UASB) based sewage treatment plants (STPs) have come up in a big way. Sequence adopted: screens- grit chambers- UASB reactors followed by one-day detention ponds (DP). Performance of DPs located at five STPs (27–70 ML/d) was evaluated over a period of one year from July 2004 to July 2005. The installation of these non-algal ponds reduced land requirement, but from treatment point of view it at best offered only removal of solids washed out of the UASB reactor. Total coliform count in the effluent from ponds ranging from 106 to 109 MPN/100 mL is more than the maximum permissible limit of 10,000 MPN/100 mL. A need has, therefore, been felt to evaluate the possibility of aerating the effluent from UASBR. During aeration, ORP and DO increase, whereas COD and BOD decrease. In a continuous aeration ~50% reduction in COD and nearly 50% increase in DO saturation (DO/DOs) can be achieved by increasing ORP from −100 to 122 mV. Regression equation established between ORP and COD/CODi & DO/DOs may find wide application.

Low temperature treatment of domestic sewage in upflow anaerobic sludge blanket and anaerobic hybrid reactors

1999 ◽  
Vol 39 (5) ◽  
pp. 177-185 ◽  
Author(s):  
Tarek A. Elmitwalli ◽  
Marcel H. Zandvoort ◽  
Grietje Zeeman ◽  
Harry Bruning ◽  
Gatze Lettinga
Keyword(s):  
Low Temperature ◽  
Sewage Treatment ◽  
Average Diameter ◽  
Anaerobic Treatment ◽  
Domestic Sewage ◽  
Cod Removal ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Removal Efficiencies

The treatment of sewage at a temperature of 13°C was investigated in three reactors (each 3.84 litre) a UASB and two anaerobic hybrid (AH) reactors with small sludge granules with an average diameter of 0.73 mm. The media used in the AH reactors were vertical polyurethane foam sheets. The reactors were operated at a HRT of 8 h. The use of small sludge granules and operating the reactors at low upflow velocity (1.8 m/d) improved suspended COD removal efficiencies for the UASB reactor. Moreover, the use of sheets in the AH reactors significantly increased suspended COD removal efficiencies as compared to the UASB and reached to 87% for pre-settled sewage treatment. The treatment of pre-settled sewage instead of raw sewage in AH reactors significantly increased colloidal and dissolved COD removal efficiencies with 13% and 12% respectively and colloidal COD removal efficiency for the UASB reactor with 13%. At ‘steady state’ for pre-settled sewage treatment, the AH reactors removed 64% of the total COD which is significantly higher by 4% than the UASB reactor. Therefore, the anaerobic treatment of domestic sewage at low temperature can be improved by treating pre-settled sewage in shallow AH reactors containing small sludge granules.

Association of a UASB reactor and a submerged aerated biofilter for domestic sewage treatment

1998 ◽  
Vol 38 (8-9) ◽  
pp. 189-195 ◽  
Author(s):  
Ricardo Franci Gonçalves ◽  
Vera Lúcia de Araújo ◽  
Carlos Augusto L. Chernicharo
Keyword(s):  
Granular Media ◽  
Sewage Treatment ◽  
Experimental Period ◽  
Domestic Sewage ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Hydraulic Load ◽  
Reactor Operating ◽  
Anaerobic Sludge Blanket

This paper presents exploratory results on the association of an Upflow Anaerobic Sludge Blanket - UASB reactor (46 L) and a submerged aerated biofilter – BF (6.3 L) for domestic sewage treatment. The experimental period extended for 322 days, during which the hydraulic and organic loads were gradually increased in both reactors. Having the UASB as a reference, the following hydraulic loads were tested: 0.4 m3/m2.h (θ = 16 h); 0.6m3/m2.h (θ = 10h); 0.8 m3/m2.h (θ = 8 h); 1.0 m3/m2.h (θ = 6 h) and 1.45 m3/m2.h (θ = 4h). During the experiments carried out with the UASB reactor operating at a hydraulic detention time of 6 hours, related to a θ < 11′ in the granular media of the BF, the mean removal efficiency in terms of SS, BOD5 and COD, in both reactors, were respectively 94%, 96% and 91%. The final effluent, related to the BF effluent, presented the following mean characteristics: SS = 10 mg/L, BOD5 = 9 mg/L and COD = 38 mg/L. The results obtained in the last phase of the experiments, when the hydraulic load in the UASB reactor reached 1.45 m3/m2.h (θ = 4h), were similar to those obtained in the previous phase. These results demonstrate that submerged aerated biofilters can be considered a viable alternative for the post-treatment of effluents from UASB reactors treating domestic sewage. These reactors are capable of being operated with very short hydraulic detention times.

scholarly journals On-Site Blackwater Treatment Fosters Microbial Groups and Functions to Efficiently and Robustly Recover Carbon and Nutrients

2020 ◽  
Vol 9 (1) ◽  
pp. 75
Author(s):  
Eiko E. Kuramae ◽  
Mauricio R. Dimitrov ◽  
Gustavo H. R. da Silva ◽  
Adriano R. Lucheta ◽  
Lucas W. Mendes ◽  
...  
Keyword(s):  
Microbial Community ◽  
Renewable Resource ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Human Pathogens ◽  
Shotgun Metagenomics ◽  
Microbial Groups ◽  
And Function ◽  
Final Effluent

Wastewater is considered a renewable resource water and energy. An advantage of decentralized sanitation systems is the separation of the blackwater (BW) stream, contaminated with human pathogens, from the remaining household water. However, the composition and functions of the microbial community in BW are not known. In this study, we used shotgun metagenomics to assess the dynamics of microbial community structure and function throughout a new BW anaerobic digestion system installed at The Netherlands Institute of Ecology. Samples from the influent (BW), primary effluent (anaerobic digested BW), sludge and final effluent of the pilot upflow anaerobic sludge blanket (UASB) reactor and microalgae pilot tubular photobioreactor (PBR) were analyzed. Our results showed a decrease in microbial richness and diversity followed by a decrease in functional complexity and co-occurrence along the different modules of the bioreactor. The microbial diversity and function decrease were reflected both changes in substrate composition and wash conditions. Our wastewater treatment system also decreased microbial functions related to pathogenesis. In summary, the new sanitation system studied here fosters microbial groups and functions that allow the system to efficiently and robustly recover carbon and nutrients while reducing pathogenic groups, ultimately generating a final effluent safe for discharge and reuse.

Evaluation of sludge properties in a pilot-scale UASB reactor for sewage treatment in a temperate region

2011 ◽  
Vol 64 (10) ◽  
pp. 1959-1966 ◽  
Author(s):  
K. Syutsubo ◽  
W. Yoochatchaval ◽  
I. Tsushima ◽  
N. Araki ◽  
K. Kubota ◽  
...  
Keyword(s):  
Suspended Solids ◽  
Sewage Treatment ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Methanogenic Activity ◽  
Working Volume ◽  
Anaerobic Sludge Blanket

In this study, continuous operation of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor for sewage treatment was conducted for 630 days to investigate the physical and microbial characteristics of the retained sludge. The UASB reactor with a working volume of 20.2 m3 was operated at ambient temperature (16–29 °C) and seeded with digested sludge. After 180 days of operation, when the sewage temperature had dropped to 20 °C or lower, the removal efficiency of both total suspended solids (TSS) and total biochemical oxygen demand (BOD) deteriorated due to washout of retained sludge. At low temperature, the cellulose concentration of the UASB sludge increased owing to the rate limitation of the hydrolytic reaction of suspended solids in the sewage. However, after an improvement in sludge retention (settleability and concentration) in the UASB reactor, the process performance stabilized and gave sufficient results (68% of TSS removal, 75% of total BOD removal) at an hydraulic retention time (HRT) of 9.7 h. The methanogenic activity of the retained sludge significantly increased after day 246 due to the accumulation of Methanosaeta and Methanobacterium following the improvement in sludge retention in the UASB reactor. Acid-forming bacteria from phylum Bacteroidetes were detected at high frequency; thus, these bacteria may have an important role in suspended solids degradation.

Development and Evaluation of a Partitioned Upflow Anaerobic Sludge Blanket (UASB) Reactor for the Treatment of Domestic Sewage from Small Villages

1999 ◽  
Vol 40 (8) ◽  
pp. 107-113 ◽  
Author(s):  
Carlos Augusto L. Chernicharo ◽  
Marcílio dos Reis Cardoso
Keyword(s):  
Rural Areas ◽  
Low Cost ◽  
Sewage Treatment ◽  
Field Evaluation ◽  
Domestic Sewage ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Attractive Alternative ◽  
Improved Performance

This paper presents the development and field evaluation of a partitioned UASB reactor, conceived for the treatment of domestic sewage from small villages and areas with large variation of the daily flowrate. In such situations, conventional single compartment UASB reactors are submitted to very extreme hydraulic conditions, that can disturb the behaviour of the treatment system. In the partitioned reactor, which is constituted of three digestion compartments, three gas separation devices and a single settler compartment, an adequate distribution of the variable incoming wastewater into one, two or three digestion chambers, allows the establishment of more stable up flow velocities and less occurrence of dead zones. As a result, a better contact between substrate and biomass can be achieved and an improved performance of the system can be expected. The partitioned UASB reactor was evaluated during a period of 16 months of continuous operation. The system presented a vary good performance during most of the operational period, showing very high efficiencies when the reactor was operated at a HRT of 7.5 hours. In this phase, the unit presented COD removal efficiencies around 80% and an average SS concentration in the final effluent of 32 mgSS/L. The research is still going on, focussing on the evaluation of the system under higher hydraulic loads and on the assessment of sludge activity and dehydration potential. Due to the operational simplicity and low cost of the system, it is believed that this type of reactor can become a very attractive alternative for domestic sewage treatment in small villages, particularly in Brazil where the number of rural areas with wastewater treatment is negligible.

Domestic sewage treatment in an upflow anaerobic sludge blanket - sequencing batch reactor system

1996 ◽  
Vol 33 (3) ◽  
pp. 73-84 ◽  
Author(s):  
J. T. de Sousa ◽  
E. Foresti
Keyword(s):  
Organic Matter ◽  
Batch Reactor ◽  
Sewage Treatment ◽  
Domestic Sewage ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Excess Sludge ◽  
Aerobic System ◽  
Anaerobic Sludge Blanket

Domestic sewage treatment in up-flow anaerobic sludge blanket (UASB) reactors has presented significant results in tropical regions. This reactor configuration has proven to be efficient in removing organic matter and total suspended solids as well as in producing smaller amounts of excess sludge than conventional aerobic reactor. On the other hand, its effluent often requires to be post-treated in order to achieve the emission standards. This paper is concerned with the alternative proposed here for treating domestic sewage in a combined anaerobic-aerobic system composed of an UASB reactor followed by sequencing batch aerobic reactors (SBR). In such a system, the UASB reactor removes considerable fraction of the influent organic matter, while the SBRs oxidize part of the remaining organic matter and ammonium nitrogen. A proper system operation would also permit the removal of nutrients (N and P). In order to investigate on the performance of this system for sewage treatment, a bench scale installation fed with synthetic substrate simulating domestic sewage was operated continuously during 38 weeks. The results permit to confirm the hypothesis proposed, since the system has consistently produced high quality effluents (BOD5 and VSS lower than 10 mg.L-1). The results also indicate that such combined anaerobic-aerobic system compete favorably with conventional aerobic systems in three essential cost features: energy consumption, excess sludge production and nutrient removal.

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