Feasibility of the UASB/AF system for domestic sewage treatment in developing countries

1998 ◽  
Vol 38 (8-9) ◽  
pp. 325-332 ◽  
Author(s):  
C. A. L. Chernicharo ◽  
R. M. G. Machado
Keyword(s):  
Developing Countries ◽  
Sewage Treatment ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
Treatment Unit ◽  
Promising Alternative ◽  
Operational Conditions ◽  
Belo Horizonte ◽  
Final Effluent ◽  
Bod Removal

This paper presents the results of three pilot units comprising one UASB reactor followed by two anaerobic filters (AFs) operating in parallel (upflow and downflow modes). The UASB reactor had a volume of 416 litres, being operated at hydraulic retention times (HRT) of 6 and 4 hours. The anaerobic filters had total volumes of 102 litres (32 litres of packing material), being operated at HRT varying from 24 to 1.5 hours (upflow velocities varying from 0.06 to 1.44 m/h). These different operational conditions characterised seven phases of research. Both reactors were fed with domestic sewage pumped directly from the main interceptor of Belo Horizonte city – Brazil. After almost one year of continuous monitoring, the UASB/AF system produced very good results in terms of COD and BOD removal, and also very low solids concentration in the final effluent. The average results of COD and BOD removal varied from 85 to 95%, sufficient to maintain the COD concentration in the final effluent in the range of 60 to 90 mg/l and the BOD values systematically below 40 mg/l. The overall averages of SS in the final effluent were kept below 25 mg/l. The UASB/AF system could become a very promising alternative for the treatment of domestic sewage in developing countries, since the system can be designed at very short hydraulic retention times (6 hours for the UASB reactor and 3 to 4 hours for the AF), resulting in a very compact and low cost treatment unit. Besides, there is no energy consumption and the labour costs are minimum.

Feasibility of a pilot-scale UASB/trickling filter system for domestic sewage treatment

2001 ◽  
Vol 44 (4) ◽  
pp. 221-228 ◽  
Author(s):  
C.A.L. Chernicharo ◽  
M.C.P. Nascimento
Keyword(s):  
Sewage Treatment ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
Trickling Filter ◽  
Treatment Unit ◽  
Promising Alternative ◽  
Operational Conditions ◽  
Belo Horizonte ◽  
Final Effluent ◽  
Bod Removal

This paper presents the results of pilot system comprised of one UASB reactor followed by one trickling filter (TF). The UASB reactor had a volume of 416 litres, being operated at an average hydraulic retention time (HRT) of 4 hours. The trickling filter had a useful volume of 60 litres, being operated at hydraulic and organic loading rates varying from 3.4 to 30.6 m3/m2.d and 0.3 to 3.9 kgBOD/m3.d, respectively. These different operational conditions characterised eight research phases. Both reactors were fed with domestic sewage pumped directly from the main interceptor of Belo Horizonte City, Brazil. After almost 16 months of continuous monitoring, the UASB/TF system produced very good results in terms of COD and BOD removal, and also very low solids concentration in the final effluent. The average results of COD and BOD removal varied from 74 to 88% and from 80 to 94%, respectively, sufficient to maintain the COD concentration in the final effluent in the range of 60 to 120 mg/L and the BOD values systematically below 60 mg/L. The overall averages of SS in the final effluent were kept below 30 mg/L. The UASB/TF system is a very promising alternative for the treatment of domestic sewage in Brazil and other developing countries, since the system can be designed with very short hydraulic retention times, resulting in a very compact and low cost treatment unit. Besides, the energy consumption and the labour costs are minimal.

Post-Treatment of Effluents from Anaerobic Reactor Treating Domestic Sewage by Dissolved-Air Flotation

1999 ◽  
Vol 40 (8) ◽  
pp. 137-143 ◽  
Author(s):  
R. G. Penetra ◽  
M. A. P. Reali ◽  
E. Foresti ◽  
J. R. Campos
Keyword(s):  
Scale Up ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
Dissolved Air Flotation ◽  
Operational Conditions ◽  
Apparent Color ◽  
Air Flotation ◽  
Dissolved Air

This paper presents the results of a study performed with a lab-scale dissolved-air flotation (LSDAF) unit fed with previously coagulated effluent from a pilot scale up-flow anerobic sludge blanket (UASB) reactor treating domestic sewage. Physical operational conditions for coagulation (rapid mix) and flocculation/flotation were maintained constant. Chemical (FeCl3) dosages ranged from 30 to 110 mg.l−1. The effect of pH was also verified in the range of 5.1 to 7.6 for each dosage. Best results were achieved for 65 mg.l−1 of FeCl3 and pH values between 5.3 and 6.1. For these conditions, the removal efficiencies obtained in the LSDAF unit were: between 87% and 91% for chemical oxygen demand (COD), between 95% and 96% for total phosphate (TP), 94% for total suspended solids (TSS), between 96% and 97% for turbidity (TU), between 90% and 93% for apparent color (AC) and more than 96% for sulfide (S). For the UASB-DAF system, global efficiencies would be around 98% for COD, 98% for TP, 98.4% for TSS, 99.3% for TU and 98% for AC. The stripped gases treatment is desirable.

The effect of operational conditions on the sludge specific methanogenic activity and sludge biodegradability

2009 ◽  
Vol 59 (9) ◽  
pp. 1847-1853 ◽  
Author(s):  
R. C. Leitão ◽  
S. T. Santaellla ◽  
A. C. van Haandel ◽  
G. Zeeman ◽  
G. Lettinga
Keyword(s):  
Municipal Wastewater ◽  
Pilot Scale ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Treatment Unit ◽  
Methanogenic Activity ◽  
Operational Conditions ◽  
Anaerobic Reactors ◽  
Specific Methanogenic Activity

The effects of hydraulic retention time (HRT) and influent COD concentration (CODInf) on Specific Methanogenic Activity (SMA) and the biodegradability of an anaerobic sludge need to be elucidated because of the discordant results available in literature. This information is important for the operation of anaerobic reactors and design of the sludge post-treatment unit. For this study, sludge samples obtained from eight pilot-scale Upflow Anaerobic Sludge Blanket (UASB) reactors were tested. The reactors were fed with municipal wastewater and operated with different sets of HRT and influent concentrations until the steady state was established. The results show that at a lower HRT, sludge with relatively higher SMA develops. A slight trend of declining SMA at increasing CODInf was found for reactors operated at longer HRTs; however, further experiments are necessary for more definitive conclusions. The sludge from reactors operated at longer HRTs and with lower CODInf resulted in lower biodegradability. Results also showed that it is ineffective to design a UASB reactor with a longer HRT to cope with organic shock loads.

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.

Development of Technology for the Use of the UASB Reactor in Domestic Sewage Treatment

1986 ◽  
Vol 18 (12) ◽  
pp. 109-121 ◽  
Author(s):  
Sonia M. M. Vieira ◽  
Marcos E. Souza
Keyword(s):  
Steady State ◽  
Ambient Temperature ◽  
Initial Phase ◽  
Hydraulic Retention Time ◽  
Sewage Treatment ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
Technical Feasibility ◽  
Feasible Option ◽  
The Cost

The lack of a simple and economic option for the treatment of sewage created the need to develop and make the UASB reactor adequate for low strength wastes. Thus a UASB reactor with 106 ℓ capacity was built, which was specially designed for sewage treatment. Several treatability tests were conducted with raw and settled domestic sewage, with only A hours of hydraulic retention time. This proved the reactor's technical feasibility in treating raw sewage at ambient temperature in São Paulo. Based on these experiments, the reactor was scaled up to 120 m3 and built for the treatment of raw sewage at ambient temperature. The operation is in its initial phase, and good COD removals are already being observed, although steady state has not been achieved yet. Since the cost of the system was extremely low, it is a feasible option to be applied in this country.

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.

Domestic Sewage Treatment Using an Anaerobic Biofilter with an Aerobic Biofilter

1986 ◽  
Vol 18 (7-8) ◽  
pp. 209-216 ◽  
Author(s):  
Y. Inamori ◽  
R. Sudo ◽  
T. Goda
Keyword(s):  
Water Temperature ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Sewage Treatment ◽  
Domestic Sewage ◽  
Circulation Ratio ◽  
Low Strength ◽  
Bod Removal ◽  
Organic Wastewater

The purpose of this study was to assess the applicability of the anaerobic biofilter process to treat low strength organic wastewater such as domestic sewage. It was found that when the influent BOD was approximately 200 mg/l, water temperature and BOD loading, under a hydraulic retention time (HRT) of 30 hrs, were 20°C and 0.2 kg/m3.day respectively, a BOD removal of at least 70% was attained, and the ratio of sludge produced to BOD removed in the anaerobic biofilter was as low as 0.1. Furthermore it was also found that 75% of nitrogen (N) could be removed in the anaerobic-aerobic biofilter process when the circulation ratio was more than 1:2.

Potential of resource recovery in UASB/trickling filter systems treating domestic sewage in developing countries

2017 ◽  
Vol 75 (7) ◽  
pp. 1659-1666 ◽  
Author(s):  
T. Bressani-Ribeiro ◽  
E. M. F. Brandt ◽  
K. G. Gutierrez ◽  
C. A. Díaz ◽  
G. B. Garcia ◽  
...  
Keyword(s):  
Developing Countries ◽  
Sewage Treatment ◽  
Resource Recovery ◽  
Domestic Sewage ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Flow Sheet ◽  
Trickling Filters ◽  
Recovery Potential ◽  
Anaerobic Sludge Blanket

This paper aims to present perspectives for energy (thermal and electric) and nutrient (N and S) recovery in domestic sewage treatment systems comprised of upflow anaerobic sludge blanket (UASB) reactors followed by sponge-bed trickling filters (SBTF) in developing countries. The resource recovery potential was characterized, taking into account 114 countries and a corresponding population of 968.9 million inhabitants living in the tropical world, which were grouped into three desired ranges in terms of cities’ size. For each of these clusters, a technological arrangement flow-sheet was proposed, depending on their technical and economic viability from our best experience. Considering the population living in cities over 100, 000 inhabitants, the potential of energy and nutrient recovery via the sewage treatment scheme would be sufficient to generate electricity for approximately 3.2 million residents, as well as thermal energy for drying purposes that could result in a 24% volume reduction of sludge to be transported and disposed of in landfills. The results show that UASB/SBTF systems can play a very important role in the sanitation and environmental sector towards more sustainable sewage treatment plants.

Application of an innovative methodology to improve the starting-up of UASB reactors treating domestic sewage

2001 ◽  
Vol 44 (4) ◽  
pp. 295-303 ◽  
Author(s):  
J. A. Rodríguez ◽  
M. R. Peña ◽  
V. Manzi
Keyword(s):  
Sewage Treatment ◽  
Quality Parameters ◽  
Domestic Sewage ◽  
Design Flow ◽  
Uasb Reactor ◽  
Removal Mechanisms ◽  
Start Up ◽  
Innovative Methodology ◽  
Valle Del Cauca ◽  
Positive Evolution

This study shows the results obtained during the starting-up evaluation of an UASB reactor treating domestic sewage. It is located in the municipality of Ginebra, Valle del Cauca region in Colombia. Its design flow is 7.5 l/s with a maximum capacity of 10 l/s. The reactor was seeded with a deficient quality inoculum which accounted for 20% of the total reactor volume. The starting-up methodology comprised the sequential washing of the sludge (inoculum) by applying three different upflow velocities. This procedure resembles what other authors term the “selective pressure method”. Once the sludge was washed, the reactor was started-up with an initial hydraulic retention time (HRT) of 24.9 hours, which was steadily reduced down to 6.7 hours in the final stage. Along the starting-up phase, there was a positive evolution in terms of quantity, quality and spatial distribution of the sludge. Consequently, there was a positive evolution in organic matter removal mechanisms. For HRT above 14 hours, the removal mechanisms were mainly physical whilst for HRT below 9 hours the removal mechanisms were mostly biological. Based on the above considerations and on the water quality parameters measured, it may be concluded that the start-up of an UASB reactor for domestic sewage treatment seeded with a low quality inoculum can be done with HRT as low as 15 or 12 hours. In this way, it is possible to reduce the starting-up period of these reactors down to 4 to 6 weeks, provided that the starting-up methodology is properly applied.

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