Enhancement of a UASB-septic tank performance for decentralised treatment of strong domestic sewage

2011 ◽  
Vol 64 (4) ◽  
pp. 923-929 ◽  
Author(s):  
Nidal Mahmoud ◽  
Jules B. van Lier
Keyword(s):  
Domestic Sewage ◽  
Cod Removal ◽  
Septic Tank ◽  
Anaerobic Sludge ◽  
Reactor Performance ◽  
Removal Efficiencies ◽  
The Difference ◽  
Long Term Performance ◽  
Term Performance

The possibility of enhancing the process performance of the UASB-septic tank for treating strong sewage in Palestine by means of inoculating the reactor with well adapted anaerobic sludge and/or adding a packing media to the upper part of the reactor, creating an anaerobic hybrid (AH)-septic tank, was investigated. To achieve these objectives, two community onsite UASB-septic tank and AH-septic tank were operated in parallel at 2 days HRT for around 8 months overlapping the cold and hot periods of the year in Palestine. The achieved removal efficiencies of CODtot in the UASB-septic tank and AH-septic tank during the first months of operation, coinciding with the cold period and the subsequent hot period, were respectively 50(±15)% and 48(±15)% and 66(±8)% and 55(±8)%. This shows that the UASB-septic tank performed significantly better (p < 0.05) than the AH-septic tank after rather long periods of operation. The difference in the CODtot removal efficiency was mainly due to the better CODss removal efficiencies in the UASB-septic tank. The removal efficiencies over the last 50 days of operation for CODtot, CODsus, CODcol and CODdis were 70, 72, 77 and 55% and 53, 54, 78 and 45% for the UASB-septic tank and AH-septic tank, respectively. Comparing the here achieved COD removal efficiencies with previously reported efficiencies of UASB-septic tanks operated in Palestine shows that the reactor performance in terms of COD removal and conversion, during the first 8 months of operation, has improved substantially by being started with well adapted anaerobic sludge, simulating and predicting long-term performance. Adding packing media did not lead to an improvement.

scholarly journals Enhancement of a UASB-Septic Tank Performance for Decentralised Treatments of Storng Domestic Sewage

2017 ◽  
pp. 363-374
Author(s):  
Nidal Mahmoud
Keyword(s):  
Removal Efficiency ◽  
Domestic Sewage ◽  
Septic Tank ◽  
Anaerobic Sludge ◽  
Process Performance ◽  
Reactor Performance ◽  
Septic Tanks ◽  
Long Period ◽  
Removal Efficiencies ◽  
The Difference

The possibility of enhancing the process performance of the UASB-septic tank for treating strong sewage in Palestine by the means of inoculating the reactor with well adopted anaerobic sludge and/or adding a packing media to the upper part of the reactor, thus becoming an AH-septic tank, was investigated. To achieve those objectives, two community onsite UASB-septic tank and Anaerobic Hybrid (AH)-septic tank were operated in parallel at 2 days HRT for around eight months overlapping the cold and hot periods of the year, Palestine. The achieved removal efficiencies of CODtot in the UASB-septic tank and AHseptic tank during the first months of operation, coinciding the cold period and the subsequent months coinciding the hot periods were respectively “50(15) and 48(15)” and “66(8) and 54.73(7.9)”. This shows that the UASB-septic tank performed significantly better (p<0.05) than the AH septic tank after rather long period of operation. The difference in the CODtot removal efficiency was mainly due to the better CODss removal efficiencies in the UASBseptic tank. The removal efficiencies over the last 50 days of operation for CODtot, CODsus, CODcol and CODdis were “70, 72, 77 and 55%” and “53, 54, 78 and 45%” for the UASBseptic tank and AH-septic tank, respectively. Comparing the here achieved COD removal efficiencies with previously reported efficiencies of UASB-septic tanks operated in Palestine shows that the reactor performance has improved substantially by being started with well adopted anaerobic sludge but not by adding a packing media.

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.

scholarly journals Long-Term Performance Evaluation of Main Cable for Large Span Suspension Bridge Based on ARIMA Model

2021 ◽  
Author(s):  
Shiqiao Xu ◽  
Rujin Ma ◽  
Chuanjie Cui
Keyword(s):  
Time Series ◽  
Performance Evaluation ◽  
Arima Model ◽  
Engineering Research ◽  
Large Span ◽  
Main Cable ◽  
The Difference ◽  
Long Term Performance ◽  
Term Performance

Main cables are major load-bearing components and play a decisive role in the long-term performance of suspension bridges. In particular, the wide application of health monitoring systems in large-span bridges facilitates a new channel for the performance evaluation of bridges. Under this context, Xihoumen Bridge is taken as the engineering research background. The long-term performance of the bridge’s main cable was evaluated by analyzing the main cable strand force data from January 2015 to October 2020, which was collected by the anchor rope meter. Firstly, the difference calculation was performed on the basis of the modeling theory of stationary time series to realize the stationary process of the original time series. Then, the Autoregressive Integrated Moving Average (ARIMA) model is established to predict the main cable strand force of the Xihoumen Bridge by model order estimation and parameter identification. Finally, the load degree index is defined in the discussion part to evaluate the long-term performance and determine the performance grading of the main cable.

Low temperature anaerobic biotreatment of priority pollutants

2008 ◽  
Vol 57 (4) ◽  
pp. 499-503 ◽  
Author(s):  
R. M. McKeown ◽  
G. Collins ◽  
F. A. Chinalia ◽  
T. Mahony ◽  
V. O'Flaherty
Keyword(s):  
Loading Rate ◽  
Operating Temperature ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Stable Operation ◽  
Reactor Performance ◽  
Loading Rates ◽  
Removal Efficiencies ◽  
Hybrid Reactors

The effect of low operating temperature and pollutant concentration on the performance of five anaerobic hybrid reactors was investigated. Stable and efficient long-term (&gt;400 days) treatment of a cold (6–13°C), volatile fatty acid (VFA)-based, wastewater was achieved at applied organic loading rates (OLRs) of 5 kg chemical oxygen demand (COD) m−3 d−1 with COD removal efficiencies c. 84% at 6°C (sludge loading rate (SLR) 1.04–1.46 kg COD kg [VSS]−1 d−1). VFA-based wastewaters, containing up to 14 g pentachlorophenol (PCP) m−3 d−1 or 155 g toluene m−3 d−1 were successfully treated at applied OLRs of 5–7 kg COD m−3 d−1. Despite transient declines in reactor performance in response to increasing toxicant loading rates, stable operation (COD removal efficiencies &gt; 90%) and satisfactory toxicant removal efficiencies (&gt;88%) were demonstrated by the systems.

scholarly journals ‘Solar septic tank’: evaluation of innovative decentralized treatment of blackwater in developing countries

2020 ◽  
Vol 10 (4) ◽  
pp. 828-840
Author(s):  
Thammarat Koottatep ◽  
Stephanie Connelly ◽  
Tatchai Pussayanavin ◽  
Sopida Khamyai ◽  
Wattanapong Sangchun ◽  
...  
Keyword(s):  
Chemical Oxygen Demand ◽  
Biochemical Oxygen Demand ◽  
Oxygen Demand ◽  
Total Solid ◽  
Septic Tank ◽  
Log Reduction ◽  
Removal Efficiencies ◽  
Decentralized Wastewater Treatment System ◽  
Long Term Performance ◽  
Term Performance

Abstract An innovative decentralized wastewater treatment system, namely the ‘Solar Septic Tank (SST)’, was constructed and tested at the household scale in a community in central Thailand. This study aimed to investigate the long-term performance of the SST in treating blackwater subject to year-round variation. Results of the 3-year continuous operation and monitoring showed significant improvement in the SST effluent quality with the potential to minimize environmental problems and public health risks. The SST achieved significantly higher total chemical oxygen demand, soluble chemical oxygen demand, total biochemical oxygen demand (TBOD), soluble biochemical oxygen demand, total kjeldahl nitrogen, total solid and total volatile solid removal efficiencies than a conventional septic tank (CST). The average TBOD concentration of the SST effluent was 150 ± 75 mg/L, meeting the Thai discharge standard (less than 200 mg/L of TBOD), while the average TBOD concentration of the CST was 240 ± 140 mg/L, higher than the Thai discharge standard. The Escherichia coli inactivation in the SST was 1–2 log reduction more than that in the CST. The removal efficiencies of TBOD and pathogens exhibited positive correlation with the ratios of the SST temperature.

Parsing on the Processing Methods of Seamline for Concrete Bridgewith Seamless Broaden Technology

2014 ◽  
Vol 587-589 ◽  
pp. 1581-1585 ◽  
Author(s):  
Fang Yuan Li ◽  
Xiao Shuai Guo
Keyword(s):  
Driving Safety ◽  
Prestress Loss ◽  
Shrinkage Temperature ◽  
Long Term Effect ◽  
Rigid Connection ◽  
The Difference ◽  
Long Term Performance ◽  
Term Performance ◽  
Creep And Shrinkage

In view of the difference in design, construction and the usage of the old and the new bridges, there are always stress defects in seamline because of the concrete creep and shrinkage, temperature effect and prestress loss, which seriously affect the service and driving safety. The current ways in foreign and domestic, such as plant steel and semi-rigid connection method, are passive processing based on structure, can’t ensure the long-term performance. According to the three direction stress existing in the seamline, this paper decomposes the material contribution and structure influence, putting forward respectively using material and structure to overcome the adverse situation, using material to remove partial long-term effect, and through the sensitivity analysis of related parameters, to make the structure bearing the rest adverse effect, ensuring the long-term performance of seamline. The relevant conclusion can provide reference for the design and construction of the concrete bridge seamline.

Long Term Performance of a Septic Tank - Rock Filter System

2002 ◽  
Vol 2002 (10) ◽  
pp. 111-122
Author(s):  
D. M. Griffin ◽  
X. Yan ◽  
H. Xiang ◽  
C Fletcher ◽  
R. Crawford
Keyword(s):  
Septic Tank ◽  
Filter System ◽  
Long Term Performance ◽  
Term Performance
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