Sludge accumulation rates in septic tanks used as part of the on-site treatment of domestic wastewater in a northern maritime temperate climate

Although the septic tank is the most applied on-site system for wastewater pre-treatment, limited research has been performed to determine sludge accumulation and biogas production in the tank. Therefore a dynamic mathematical model based on the Anaerobic Digestion Model No. 1 (ADM1) was developed for anaerobic digestion of the accumulated sludge in a septic tank treating domestic wastewater or black water. The results showed that influent chemical oxygen demand (COD) concentration and hydraulic retention time (HRT) of the tank mainly control the filling time with sludge, while operational temperature governs characteristics of the accumulated sludge and conversion to methane. For obtaining stable sludge and high conversion, the tank needs to be operated for a period more than a year without sludge wasting. Maximum conversion to methane in the tank is about 50 and 60% for domestic wastewater and black water, respectively. The required period for sludge wasting depends on the influent COD concentration and the HRT, while characteristics of the wasted sludge are affected by operational temperature followed by the influent COD concentration and the HRT. Sludge production from the tank ranges between 0.19 to 0.22 and 0.13 to 0.15 L/(person.d), for the domestic wastewater and black water, respectively.

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Temperature effect on UASB reactor operation for domestic wastewater treatment in temperate climate regions

Water Science & Technology ◽

10.2166/wst.2003.0151 ◽

2003 ◽

Vol 48 (3) ◽

pp. 25-30 ◽

Cited By ~ 24

Author(s):

B. Lew ◽

M. Belavski ◽

S. Admon ◽

S. Tarre ◽

M. Green

Keyword(s):

Methane Production ◽

Domestic Wastewater ◽

Cod Removal ◽

Upflow Anaerobic Sludge Blanket ◽

Uasb Reactor ◽

Temperate Climate ◽

Anaerobic Sludge ◽

Biological Degradation ◽

Domestic Wastewater Treatment ◽

Anaerobic Sludge Blanket

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.

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CFD analysis of sludge accumulation and hydraulic performance of a waste stabilization pond

Water Science & Technology ◽

10.2166/wst.2012.450 ◽

2012 ◽

Vol 66 (11) ◽

pp. 2370-2377 ◽

Cited By ~ 19

Author(s):

Andres Alvarado ◽

Esteban Sanchez ◽

Galo Durazno ◽

Mehul Vesvikar ◽

Ingmar Nopens

Keyword(s):

Time Distribution ◽

Tracer Experiment ◽

Cfd Modeling ◽

Cfd Analysis ◽

Accumulation Rates ◽

Waste Stabilization Ponds ◽

Waste Stabilization Pond ◽

Waste Stabilization ◽

Rtd Analysis ◽

Sludge Accumulation

Sludge management in waste stabilization ponds (WSPs) is essential for safeguarding the system performance. Sludge accumulation patterns in WSPs are strongly influenced by the pond hydrodynamics. CFD modeling was applied to study the relation between velocity profiles and sludge deposition during 10 years of operation of the Ucubamba WSP in Cuenca (Ecuador). One tracer experiment was performed and three sludge accumulation scenarios based on bathymetric surveys were simulated. A residence time distribution (RTD) analysis illustrated the decrease of residence times due to sludge deposition. Sludge accumulation rates were calculated. The influence of flow pattern on the sludge deposition was studied, enabling better planning of future pond operation and desludging.

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Sustainable Sanitation as a Part of an IWRM in the Karst Area of Gunung Kidul: Community Acceptance and Opinion

Water Practice & Technology ◽

10.2166/wpt.2010.104 ◽

2010 ◽

Vol 5 (4) ◽

Cited By ~ 1

Author(s):

S. Nayono ◽

M. Singer ◽

H. Lehn ◽

J. Kopfmüller

Keyword(s):

Low Income ◽

Low Cost ◽

Domestic Wastewater ◽

Karst Area ◽

Septic Tanks ◽

Community Acceptance ◽

Hygiene Practices ◽

The People ◽

Sanitation And Hygiene ◽

Composting Toilets

To overcome the problem of water scarcity in a rural karst area located in Gunung Sewu, Yogyakarta, Indonesia, water from an underground cave (Bribin Cave) is pumped and distributed to the people. Since karst aquifers are often considered as highly vulnerable to contamination from human activities, potential problems caused by current sanitation and hygiene practices in the recharge region must be anticipated. About 90% of the people in the recharge area use pour flush syphon toilets with poorly designed septic tanks and the rest have simple pit latrines. However, the existing septic tanks are very poorly designed and are actually only improved infiltration pits. One possible option to reduce the risk of aquifer contamination is to promote sustainable sanitation, which combines hygienic aspects with recycling of nutrients from human feces and urine. Sustainable sanitation comprises different technologies including low cost technology, which can be afforded by the community and provide economic benefit to the low income inhabitants in Gunung Sewu. The technology proposed is urine diverting and composting toilets. This paper presents the existing condition of rural domestic wastewater treatment and the opinion/ acceptance of the community in karst area of Gunung Sewu towards urine diverting and composting toilets. The results of the survey shows that although the acceptance of using the composting toilet is not high (25% to 43%), the interest of the community in using the end product is relatively high. While the acceptance of composting fertilizer from feces (humanure) ranges from 37% to 57%, urine fertilizer attracts 42%-71% respondents' interest.

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Sludge accumulation in an anaerobic pond and viability of helminth eggs: a case study in Burkina Faso

Water Science & Technology ◽

10.2166/wst.2010.959 ◽

2010 ◽

Vol 61 (4) ◽

pp. 919-925 ◽

Cited By ~ 5

Author(s):

Y. Konate ◽

A. H. Maiga ◽

J. Wethe ◽

D. Basset ◽

C. Casellas ◽

...

Keyword(s):

Public Health ◽

Burkina Faso ◽

Average Rate ◽

Dry Weight ◽

Average Concentration ◽

Egg Viability ◽

Accumulation Rates ◽

Helminth Eggs ◽

Sludge Accumulation

Accumulation rates and pathogen concentrations in primary stabilization pond sludges in developing countries are important parameters for adequate sludge management and the safeguarding of public health with sludge reuse in agriculture. An anaerobic pond has been investigated for sludge accumulation rates and helminth egg viability after four years of operation in Burkina Faso. The rate of sludge accumulation was measured at 0.037 m3/capita-year or 2.26 kg dry weight/capita-year. An equation describing vertical distribution of total solids in the accumulated sludge was found to be adequately represented by a regression equation. Influent helminth egg concentrations were reduced on average by 90% in the anaerobic pond effluent. Ascaris lumbricoides and Ancylostoma sp. were the most common eggs present in the sludge after four years of operation. The average concentration of helminth eggs in pond sludge was 536 eggs/g TS, and the percentages of viability ranged from 10.8% (47 viable eggs/g TS) to 57.2 (1,772 viable eggs/g TS, with an average rate of 36% (336 viable eggs/g TS). From a sludge depth and section study, egg viability was found to be randomly distributed in the sludge layer.

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Improving phosphorus removal of conventional septic tanks by a recirculating steel slag filter

Water Quality Research Journal ◽

10.2166/wqrjc.2015.045 ◽

2015 ◽

Vol 50 (3) ◽

pp. 211-218 ◽

Cited By ~ 10

Author(s):

Dominique Claveau-Mallet ◽

Félix Lida ◽

Yves Comeau

Keyword(s):

Total Phosphorus ◽

Phosphorus Removal ◽

Steel Slag ◽

Domestic Wastewater ◽

Septic Tank ◽

Retention Capacity ◽

Septic Tanks ◽

P Retention

The objective of this project was to increase the phosphorus (P) retention capacity of a conventional septic tank by adding a recirculating slag filter. Two recirculation modes and recirculation ratios from 5 to 50% were tested in the laboratory with reconstituted domestic wastewater. The best system was recirculation from the end to the inlet of the second compartment of a septic tank with a 50% recirculation ratio in the slag filter, achieving 4.2 and 1.9 mg P/L at the effluent for total phosphorus (TP) and orthophosphate (o-PO4), respectively, and a pH of 8.8. The calculated size of the slag filter for a two-bedroom house application was 1,875 kg for an expected lifetime of 2 years. The 1 mg P/L level goal was not reached, but P precipitation may be favoured by the relatively high effluent pH reaching the infiltration bed.

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