Septic Tank Sludges: Accumulation Rate and Biochemical Characteristics

Philip, H.; Maunoir, S.; Rambaud, Alfred; Philippi, Luiz Sérgio

doi:10.2166/wst.1993.0205

Cited by 30 publications

(10 citation statements)

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“…It was reported that the concentration of effluent solids increases as sludge accumulates in the tank (Philip et al (1993); Nnaji & Agunwamba (2012). Accordingly, the effluent concentration from a septic tank can be related to the sludge accumulation in the tank by:…”

Section: Mathematical Model Formulationmentioning

confidence: 99%

Mathematical model for predicting sludge accumulation in septic tanks based on operational parameters: effect of hydraulic mixing

Momani

2015

Water & Environment J

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Reporting sludge accumulation in septic tanks as a constant rate is no longer accepted, and there is a need for a model that predicts sludge accumulation in septic tanks taking into consideration the continuous consumption of sewage solids by microorganisms. This study presents the development of mathematical model that predicts sludge accumulation in septic tanks and to investigate the effect of mixing on solids digestion. The mathematical model takes into consideration the effect of different operational parameters (influent and effluent) as well as the bacterial kinetics in predicting the sludge accumulation in septic tanks. The model predicts with R 2 > 0.88 the sludge accumulation rate in standard septic tank calculated by empirical models developed by Weibel in 1955, and by Bounds in 1995. The model was also used to estimate the typical pump-out interval for different tank volumes and the sludge accumulation inside septic tanks at different operational parameters.

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Section: Mathematical Model Formulationmentioning

confidence: 99%

Mathematical model for predicting sludge accumulation in septic tanks based on operational parameters: effect of hydraulic mixing

Momani

2015

Water & Environment J

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“…However, anecdotally it is known that a lot of the septic tanks across the country are desludged by local farmers who then spread the waste onto their land as a fertiliser. Studies on septic tanks in temperate climates have shown average accumulation rates of sludge of between 0.18 to 0.34 L/ca.day within the tank, with rates typically higher in the first year and dropping thereafter [27][28][29]. Using 0.25 L/ca.day with the population served by septic tanks in Ireland would equate to an annual sludge production of 2854 t/year, assuming the concentration of sludge in the tanks is 24,500 mg/L [30].…”

Section: Sludgementioning

confidence: 99%

Application of On-Site Wastewater Treatment in Ireland and Perspectives on Its Sustainability

Dubber

Gill

2014

Sustainability

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Abstract:The wastewater of one third of Ireland's population is treated on-site using domestic treatment systems (DWWTSs) that usually consist of a septic tank and soil attenuation system. Within the past four years, the legislative framework for these systems has undergone a major change with a registration and inspection regime being introduced to identify legacy sites that will require remediation work, particularly in areas of the country underlain by subsoils of very low permeability. Against this background this study aims to assess the overall sustainability of existing DWWTSs as well as alternative treatment and disposal options. The results show that main CO 2eq emissions are from the methane production in septic tanks. The reduced methane production in mechanically aerated secondary treatment systems was found to counterbalance the related emissions due to the additional energy requirements. In contrast, septic tank systems have the lowest construction and operational costs representing the most economically sustainable solution. Pressurised disposal systems are slightly more expensive but have the potential to reduce environmental impact on surface water and reduce greenhouse gas emissions. Clustered decentralised treatment solutions could be environmentally and economically sustainable but ownership, management and related financial and legal issues will need to be addressed and developed.

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“…To date there is a paucity of data for methane production from the literature, particularly with respect to start-up. Philip et al (1993) relate that to facilitate effective sludge breakdown in a septic tank, a 2-5 year acclimation period was required with similarly extended start-up periods reported for AWSP (Alexiou and Mara, 2003;Parker et al, 1959). In the present study, both liquid and gas phase measurements demonstrate the production of methane after a short start-up period and establish the potential for acclimation of anaerobic WSP treating northern European wastewater.…”

Section: Temperate Wastewater Treatment Using An Anaerobic Waste Stabmentioning

confidence: 99%

Waste stabilisation ponds for anaerobic wastewater treatment

McAdam¹,

Ansari²,

Cruddas³

et al. 2012

Proceedings of the Institution of Civil Engineers - Engineering

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1 2 3 4 5 6 7 8 An anaerobic waste stabilisation pond (AWSP) has been assessed to enable energy neutral wastewater treatment at decentralised works. During start-up, chemical oxygen demand (COD) removal efficiency was comparable to full-scale AWSPs operated in moderate climates, thereby establishing the potential for treating wastewater in the less conducive European climate. The linear relationship between COD removal and time demonstrated that the AWSP had not reached steady-state, indicating further improvement in COD removal is expected. Data modelled on a 10 000 population equivalent catchment indicated that integrating an AWSP upstream of trickling filters presented the optimum configuration to minimise on-site electrical demand. Anaerobic WSP can generate sufficient electricity onsite to offset electrical demand. Anaerobic WSP can generate sufficient electricity onsite to offset electrical demand, recording a net on-site energy balance of +379?5 kWhe d -1 . Using an AWSP for on-site sludge treatment also reduced exported sludge volume, markedly reducing the wastewater treatment total carbon dioxide equivalent emissions (carbon footprint) compared to conventional technologies. This study established AWSP as a significant future technology for sustainable decentralised wastewater treatment.

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Septic Tank Sludges: Accumulation Rate and Biochemical Characteristics

Cited by 30 publications

References 0 publications

Mathematical model for predicting sludge accumulation in septic tanks based on operational parameters: effect of hydraulic mixing

Mathematical model for predicting sludge accumulation in septic tanks based on operational parameters: effect of hydraulic mixing

Application of On-Site Wastewater Treatment in Ireland and Perspectives on Its Sustainability

Waste stabilisation ponds for anaerobic wastewater treatment

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