Influence of hydraulic retention time on UASB post-treatment with UF membranes

2011 ◽  
Vol 64 (11) ◽  
pp. 2299-2305 ◽  
Author(s):  
M. L. Salazar-Peláez ◽  
J. M. Morgan-Sagastume ◽  
A. Noyola

A pilot UASB reactor coupled with an external ultrafiltration (UF) membrane was operated under three different hydraulic retention times (HRT) for domestic wastewater treatment. The aim was to assess the HRT influence on system performance and fouling. The highest concentrations of COD, total solids, extracellular polymeric substances (EPS) and soluble microbial products (SMP) in UASB effluent and permeate were found when the UASB reactor was operated under the lowest HRT studied (4 hours); although the fulfillment of Mexican Standard for wastewater reclamation was not compromised. This fact could be attributed to the higher shear stress forces inside the UASB reactor when it was operated at low HRT, which promoted the release of biopolymeric substances in its effluent. Besides, the fouling propensity in the UASB effluent was worsened with HRT reduction, by increasing the fouling rate and the specific cake resistance. Based on these results, it is recommended to avoid operating the UASB reactor at low HRTs (less than 4 hours) in order to control SMP and EPS fouling potential. The results presented also suggest that HRT reduction has a detrimental effect on performance and fouling.

2003 ◽  
Vol 3 (5-6) ◽  
pp. 361-365 ◽  
Author(s):  
D. Abdessemed ◽  
G. Nezzal ◽  
R. Ben Aim

We considered the treatment of domestic wastewater by coagulation–adsorption–ultrafiltration, and a test of adsorption like pre-treatment to the membrane as an alternative for wastewater reclamation and reuse. The performances of two inorganic tubular membranes (M2 and M5 CARBOSEP with 15,000 Da and 10,000 Da MWCO) were studied. Powdered activated carbon was used as adsorbent agent and FeCl3 as a coagulant. Coupling adsorption and ultrafiltration resulted in satisfactory results: the efficiency of COD removal was increased by using PAC compared with results obtained when using only UF membranes.


1997 ◽  
Vol 61 (3) ◽  
pp. 239-245 ◽  
Author(s):  
E. Behling ◽  
A. Diaz ◽  
G. Colina ◽  
M. Herrera ◽  
E. Gutierrez ◽  
...  

2012 ◽  
Vol 455-456 ◽  
pp. 1030-1036
Author(s):  
Hui Zhou Yuan ◽  
Jian Bang Zhao ◽  
Shui Zhou Ke

This paper studied on the treatment of urban domestic wastewater with Anaerobic MBBR in the tropical and subtropical areas in the South of China. The emphasis focused on the effects of the Hydraulic Retention Time (HRT) and pH value to the CODCrconcentration and the NH3-N concentration of the outflow of the reactor. Moreover, the mechanism of denitrification was also explored. The results showed that the mechanism of denitrification of the reactor was found. When HRT was equal to or more than 8h, NH3-N was reduced mainly in the way of short-cut nitrification and denitrification. When HRT was less than 8h, the reactions of short-cut nitrification and denitrification & anaerobic ammonia oxidation both existed in the reactor.


2003 ◽  
Vol 48 (3) ◽  
pp. 25-30 ◽  
Author(s):  
B. Lew ◽  
M. Belavski ◽  
S. Admon ◽  
S. Tarre ◽  
M. Green

The performance of an upflow anaerobic sludge blanket (UASB) reactor was investigated for the treatment of domestic wastewater at different operational temperatures (28, 20, 14 and 10°C) and loading rates. For each temperature studied a constant CODt removal was observed as long as the upflow velocity was lower than 0.35 m/h: 82% at 28°C, 68% at 14°C and 44% at 10°C. At 20°C the COD removal increased with the HRT, reaching similar values as at 28°C for long HRT. At upflow velocities higher than 0.35 m/h, a reduction in total COD removal was observed due to washout of influent TSS. At 28°C, a constant 200 g sludge mass was observed and COD removal was attributed to biological degradation only. At lower temperatures, COD removal resulted from degradation and solids accumulation in the reactor. The increase in reactor sludge was greater as the temperature decreased and explains the similar overall COD removal efficiency at 28°C, 20°C and 14°C. During the transition from winter to summer conditions (10°C to 28°C), methane production initially increased due to the degradation of accumulated solids. Afterwards, methane production gradually declined and an increase in COD removal was observed, indicating that the TSS accumulated during the winter was exhausted and influent degradation remained.


2014 ◽  
Vol 955-959 ◽  
pp. 2526-2529 ◽  
Author(s):  
John Leju Celestino Ladu ◽  
Xi Wu Lu ◽  
Ahmed Mohammed Osman

This paper examined the treatment of rural domestic wastewater. Influent and effluent samples were experimented for Chemical oxygen demand (COD), NH4+-N, NO3--N and TP in the Taihu Lake Environmental laboratory of Southeast University in Wuxi. Different hydraulic retention time (HRT) and recycle ratios were applied to appraise their influence on removal efficiency. The wastewater temperature was controlled between 20 to 24°C and pH ranges 7.6 – 8.1. The result revealed average COD, NH4+-N, NO3--N and TP removal efficiencies of 77.2, 74.1, 94 and 83% with optimum HRT of 3hrs and recycle ratio of 2 respectively. The obtained results confirmed that, the integrated processes of anoxic/oxic bioreactor and artificial wetland was viable and proficient in domestic wastewater treatment.


Desalination ◽  
2009 ◽  
Vol 242 (1-3) ◽  
pp. 325-335 ◽  
Author(s):  
A. Moawad ◽  
U.F. Mahmoud ◽  
M.A. El-Khateeb ◽  
E. El-Molla

Author(s):  
Juliano Curi de Siqueira ◽  
Mateus Pimentel de Matos ◽  
Ivan Célio Andrade Ribeiro ◽  
Ronaldo Fia ◽  
Antonio Teixeira de Matos

Hen eggshell is a waste with high phosphorus (P) removal capacity from synthetic solutions. However, there is a lack of knowledge about how to use this material on P removal from real wastewater. The present study proposed to evaluate two types of system for P removal from wastewater using eggshells. On the first system, eggshells grinded, sieved in 0.425 mm, and contained in coffee filters, were fixed to baffles using calico cloth bags. On the second, the eggshells in the same conditions were attached to vertical wooden rods and distributed at different heights. For both systems, P concentration was daily monitored for four weeks, with and without medium acidification and hydraulic retention time of one day. The baffles system was more efficient, reaching a maximum removal of 15.93% in wastewater with pH 4.73. P removals did not differ significantly over the weeks; however, there is a tendency to vary the efficiencies according to the change in pH. The baffled tank, for presenting higher performance in P removal, is the most suitable for use in a domestic wastewater treatment system.


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