Re-engineering Domestic Septic Tanks into Biogas Tanks

2018 ◽  
Vol 2 (2) ◽  
pp. 54-62
Author(s):  
M. Modjinou, L. Darkwah
Keyword(s):  
Anaerobic Digestion ◽  
Environmental Protection Agency ◽  
Suspended Solids ◽  
Sea Water ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Domestic Sewage ◽  
Green Technology ◽  
Septic Tank ◽  
Septic Tanks

This study is to design a novel septic tank, named Anaerobic Upflow Domestic Septic Tank (AUDST) to recover biogas asenergy and treat domestic sewage. The green technology proposes alternate options to existing Domestic Septic Tanks (DST),encourages anaerobically pre-treatment to reduce bacteria, pollutants, Total Suspended Solids (TSS), Chemical oxygen demand(COD) and Biological oxygen demand (BOD) before the effluent is discharged or is removed by cesspit trucks. Studies haveshown that DST in homes partially treat or just store sewage. Again, these DST have to be emptied from time to time becauseit lack features that will sustain anaerobic activity and usually the sludge is disposed of directly into the sea, water bodies andeven into open places such as “Lavender Hills” without any treatment or disinfection. These practices cause severe public healthand environmental problems. To tackle the challenge at household level, DST are redesigned to treat domestic sewage with lessmanagement, low operating cost, low secondary discharge of pollutants. The proposed new design concept is operated throughthree (3) units: such as desilting, anaerobic digestion and facultative filtration units. The anaerobic digestion stage is made upof baffle and anaerobic filter for accommodating sludge and providing a more intimate contact between anaerobic biomass andsewage which improves treatment performance. The anaerobic unit is fitted with locally woven baskets prefilled with packingmaterials. The aim is to strengthen the biological treatment process at this stage. The Facultative Filtration unit of the model isalso packed with filtering media such as gravels (3-6mm in diameter) that is low in cost, and has a high durability to produceeffluent with lower pollutants and suspended solids content to meet Ghana’s Environmental Protection Agency (EPA) standardsfor the discharge of domestic effluents.

Re-engineering Domestic Septic Tanks into Biogas Tanks

2018 ◽  
Vol 2 (2) ◽  
pp. 54-62
Author(s):  
Mawufemo Modjinou
Keyword(s):  
Anaerobic Digestion ◽  
Environmental Protection Agency ◽  
Suspended Solids ◽  
Sea Water ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Domestic Sewage ◽  
Green Technology ◽  
Septic Tank ◽  
Septic Tanks

This study is to design a novel septic tank, named Anaerobic Upflow Domestic Septic Tank (AUDST) to recover biogas asenergy and treat domestic sewage. The green technology proposes alternate options to existing Domestic Septic Tanks (DST),encourages anaerobically pre-treatment to reduce bacteria, pollutants, Total Suspended Solids (TSS), Chemical oxygen demand(COD) and Biological oxygen demand (BOD) before the effluent is discharged or is removed by cesspit trucks. Studies haveshown that DST in homes partially treat or just store sewage. Again, these DST have to be emptied from time to time becauseit lack features that will sustain anaerobic activity and usually the sludge is disposed of directly into the sea, water bodies andeven into open places such as “Lavender Hills” without any treatment or disinfection. These practices cause severe public healthand environmental problems. To tackle the challenge at household level, DST are redesigned to treat domestic sewage with lessmanagement, low operating cost, low secondary discharge of pollutants. The proposed new design concept is operated throughthree (3) units: such as desilting, anaerobic digestion and facultative filtration units. The anaerobic digestion stage is made upof baffle and anaerobic filter for accommodating sludge and providing a more intimate contact between anaerobic biomass andsewage which improves treatment performance. The anaerobic unit is fitted with locally woven baskets prefilled with packingmaterials. The aim is to strengthen the biological treatment process at this stage. The Facultative Filtration unit of the model isalso packed with filtering media such as gravels (3-6mm in diameter) that is low in cost, and has a high durability to produceeffluent with lower pollutants and suspended solids content to meet Ghana’s Environmental Protection Agency (EPA) standardsfor the discharge of domestic effluents.

Sources of Pollution of the Estuary of the River Nervion, Spain – A Case Study

1984 ◽  
Vol 16 (5-7) ◽  
pp. 95-125 ◽  
Author(s):  
A Azkona ◽  
S H Jenkins ◽  
H M G Roberts
Keyword(s):  
Fresh Water ◽  
Hydrogen Sulphide ◽  
Industrial Wastewater ◽  
Industrial Effluent ◽  
Oxygen Demand ◽  
Industrial Effluents ◽  
Domestic Sewage ◽  
Septic Tank ◽  
Safety Level ◽  
Sulphide Concentration

This paper describes part of a comprehensive multidisciplinary study of the pollution of the estuary of the River Nervion, Bilbao, Spain. The objectives of the study were to determine the sources and loads of pollution from domestic sewage and industrial wastewater; provide information on the extent of pollution; formulate hydrodynamic and predictive models capable of forecasting the effects on the estuary of the anticipated growth of population and industry; determine the amount of polluting matter that would have to be removed in order to reach defined estuary water quality standards; arrive at suitable technical methods able to attain these standards at minimum cost; determine the treatability of wastewater discharges and recommend methods for controlling industrial wastewater. These objectives necessitated a survey of the pollution loads from domestic sources and industry which were discharged to the fresh water and tidal reaches of four major tributaries in addition to the main river Nervion; the results of this part of the survey are described in this paper. The presence of iron in discharges from iron ore mining and metal processing was found to aid flocculation of organic matter and the consequent deposition of sludge in the estuary. This action and the rate of oxygen uptake during the decomposition of such deposits are also described. The domestic sewage of the study area receives treatment in septic tanks before discharging to rivers or the estuary. In spite of free hydrogen sulphide and high concentrations being present in the septic tank effluents, odour nuisance does not occur, because, as is shown in the paper, of the formation of ferrous sulphide. The hydrogen sulphide concentration in the atmosphere at a pumping station was found to be above the safety level. The industrial load of impurity was estimated to be approximately 15% higher than the domestic load, but it is extremly difficult to find a rational basis on which comparisons may be made between domestic sewage and a mixture of industrial effluents containing substances inimical to biological activity. The industrial effluent was contained in a very large volume of water, much of it taken from the estuary for cooling or process water. It is calculated that if the industrial pollutants had been contained only in the fresh water used by industry the COD of the mixture would have been 1317 mg/l; the suspended solids 2143 mg/l; the ammonia nitrogen 191 mg/l; iron 1037 mg/l; other heavy metals 118 mg/l; fluoride as F 14.5 mg/l; cyanide as CN 8.1 mg/l; oil 196 mg/l; phenols 8.1 mg/l; mercury 0.13 mg/l; and the mixture would have had an excess of acidity of 5188 mg/l. An estimate of the load of substances having an oxygen demand indicated that of the total oxygen demand discharged to the system of rivers and estuary approximately 50% entered the estuary from the main tributaries, the remainder being discharged directly to the estuary. An outline is given of the methods that would be used to determine the treatability of industrial effluents which were rendered acceptable for discharge into public sewers.

Modeling of pathogen inactivation in thermal septic tanks

2013 ◽  
Vol 4 (1) ◽  
pp. 81-88 ◽  
Author(s):  
T. Koottatep ◽  
S. Phuphisith ◽  
T. Pussayanavin ◽  
A. Panuvatvanich ◽  
C. Polprasert
Keyword(s):  
Oxygen Demand ◽  
Weibull Model ◽  
Septic Tank ◽  
Most Probable Number ◽  
Pathogen Inactivation ◽  
Probable Number ◽  
E Coli ◽  
Septic Tanks ◽  
Log Reduction ◽  
Safe Level

Thermal application has been widely used for pathogen inactivation in various fields. The purpose of this research was to develop a model of pathogen inactivation in septic tanks operating at various temperatures. Four laboratory-scale septic tanks fed with septage were operated at temperatures of 30, 40, 50 and 60 °C and Escherichia coli (E. coli) was selected as the pathogenic indicator. The efficiencies of E. coli inactivation were found to increase with increasing temperatures, while the opposites were observed for chemical oxygen demand (COD) reduction. At 60 °C, the E. coli concentrations were reduced from 9.6 × 106 to about 10 most probable number (MPN)/100 mL or 6 log reduction. The kinetics of E. coli reduction followed a modified Weibull model which could be applied to septic tank design and operation. The percentage COD removal was found to be 93, 94, 89 and 84 at temperatures of 32, 40, 50 and 60 °C, respectively. The results of this study suggested that pathogenic microorganisms in septic tanks could be inactivated to be at a safe level with thermal application.

Engineered ecosystem for on-site wastewater treatment in tropical areas

2012 ◽  
Vol 66 (10) ◽  
pp. 2131-2137 ◽  
Author(s):  
André Luis de Sá Salomão ◽  
Marcia Marques ◽  
Raul Gonçalves Severo ◽  
Odir Clécio da Cruz Roque
Keyword(s):  
Wastewater Treatment ◽  
Aquatic Macrophytes ◽  
Suspended Solids ◽  
Treatment Options ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Septic Tank ◽  
Decentralized Wastewater Treatment ◽  
Tropical Areas ◽  
Aerated Filter

There is a worldwide demand for decentralized wastewater treatment options. An on-site engineered ecosystem (EE) treatment plant was designed with a multistage approach for small wastewater generators in tropical areas. The array of treatment units included a septic tank, a submersed aerated filter, and a secondary decanter followed by three vegetated tanks containing aquatic macrophytes intercalated with one tank of algae. During 11 months of operation with a flow rate of 52 L h−1, the system removed on average 93.2% and 92.9% of the chemical oxygen demand (COD) and volatile suspended solids (VSS) reaching final concentrations of 36.3 ± 12.7 and 13.7 ± 4.2 mg L−1, respectively. Regarding ammonia-N (NH4-N) and total phosphorus (TP), the system removed on average 69.8% and 54.5% with final concentrations of 18.8 ± 9.3 and 14.0 ± 2.5 mg L−1, respectively. The tanks with algae and macrophytes together contributed to the overall nutrient removal with 33.6% for NH4-N and 26.4% for TP. The final concentrations for all parameters except TP met the discharge threshold limits established by Brazilian and EU legislation. The EE was considered appropriate for the purpose for which it was created.

Sludge accumulation and conversion to methane in a septic tank treating domestic wastewater or black water

2013 ◽  
Vol 68 (4) ◽  
pp. 956-964 ◽  
Author(s):  
Tarek Elmitwalli
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Septic Tank ◽  
Black Water ◽  
Operational Temperature ◽  
Filling Time ◽  
Pre Treatment ◽  
Sludge Accumulation

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.

The role of pH in the organic material solubilization of domestic sludge in anaerobic digestion

2003 ◽  
Vol 48 (3) ◽  
pp. 143-150 ◽  
Author(s):  
C. Yangin Gomec ◽  
R.E. Speece
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Ph Control ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Soluble Chemical Oxygen Demand ◽  
Ph Controlled

The effect of pH on anaerobic solubilization of domestic primary sludge and activated sludge was investigated and compared. Anaerobic solubilization was carried out in continuously stirred anaerobic reactors at mesophilic temperature (35°C) and pH was fixed at 6.5 (pH-controlled). Many researches reported the serious effects of pH on the solubilization of organic materials. Thus, the aim of pH control in the reactors consisting of domestic primary and activated sludges, was the evaluation of retardation in hydrolysis/acidogenesis at low pH values. Since primary and activated sludges have different biodegradation characteristics, results were compared. Results indicated that the destruction of Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS) were better in the pH-controlled reactors. In both sludges, acetic acid was the main Volatile Fatty Acid (VFA) produced. In the pH-controlled reactors, VSS reduction was found to be 72% in about 20 days in the anaerobic digestion of activated sludge, whereas for the same interval VSS reduction could only be achieved by 32% in primary sludge at 35°C. When primary sludge was used as substrate, the pH-uncontrolled and the pH-controlled reactors removed VSS with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). However, production of VFAs and SCOD was ceased after 5 days in the pH-controlled reactor whereas VFAs and SCOD production continued after 5 days in the pH-uncontrolled reactor, which indicated that hydrolysis and fermentation did not complete and continued longer. On the other hand; in either the pH-uncontrolled or the pH-controlled reactor of activated sludge, VSS was not removed with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). It was apparent that solubilization was occurring, however this solubilization was not observed as VFA production. When total methane production and total COD (CODtot) removal were estimated using VSS removal in both types of sludges, results indicated that pH control enhanced biogas productions as well as CODtot removals.

scholarly journals Effect of Volume Loading Rate and C/N on Ship Domestic Sewage Treatment by Two Membrane Bioreactors

2019 ◽  
Vol 64 (3) ◽  
pp. 328-339
Author(s):  
Yuhang Cai ◽  
Asad A. Zaidi ◽  
Peiqi Sun ◽  
Yue Shi ◽  
Kun Zhang ◽  
...  
Keyword(s):  
Membrane Reactor ◽  
Urease Activity ◽  
Suspended Solids ◽  
Loading Rate ◽  
Sewage Treatment ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Domestic Sewage ◽  
Volume Loading ◽  
Interesting Phenomenon

Design of ship sewage treatment systems that not only satisfy the use of small space on board but also meets International Maritime Organisation (IMO) latest emission standards is still a challenging problem for ship industry. This study provides a comparative disquisition between two different MBR reactors i.e, air-lift multilevel circulation membrane reactor (AMCMBR) and anaerobic/anoxic/aerobic membrane reactor (AOA-MBR) for domestic sewage treatment. The influence of pollutants volume loading rate (VLR) and C/N on effluent chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and TN for marine domestic sewage was analyzed. The results revealed that AMCMBR showed better removal efficiencies for COD and TN than AOA-MBR. The volume of AMCMBR was only half of the AOA-MBR. In addition, high average value of mixed liquor volatile suspended solids (MLVSS)/mixed liquid suspended solids (MLSS) (i.e. 0.75) of AMCMBR indicated high biomass and good pollutants removal achieved by this reactor. An interesting phenomenon was found in the study regarding Urease activity for the two reactors. Urease activity for AMCMBR in different working conditions all exceeded AOA-MBR and there exist no clear difference of NR activities between AMCMBR and AOA-MBR except for low C/N ratio (i.e. 6 and 4). This phenomenon proved that AMCMBR has a greater performance for treating ship domestic wastewater.

Feasibility Study of Municipal Wastewater Treatment by a Subsurface Infiltration System in Northeast, China

2012 ◽  
Vol 610-613 ◽  
pp. 1774-1777
Author(s):  
Hai Bo Li ◽  
Ying Hua Li ◽  
Xin Wang ◽  
Tie Heng Sun
Keyword(s):  
Surface Water ◽  
Northeast China ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Surface Water Quality ◽  
Ammonia Nitrogen ◽  
Domestic Sewage ◽  
Municipal Wastewater Treatment ◽  
Surface Water Pollution

From October 2009 to September 2010, this study focused on investigation the performance of a subsurface wastewater infiltration (SWI) system in treating domestic sewage, and evaluated the potential of the surface water pollution by using the SWI system. The results showed the removal efficiencies were relatively high: for biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), ammonia nitrogen (NH3-N) and total phosphorus (TP) were 95.0, 89.1, 98.1 87.6 and 98.4%, respectively. Meanwhile, the monitoring of a nearby stream characteristic indicated the SWI system could not decrease the receiving surface water quality.

scholarly journals Water Contamination in Petroleum Refinery Processes

2021 ◽  
pp. 267-275
Author(s):  
Ibrahim M. Abou El Lei ◽  
Khaled M. Mezughi ◽  
Nuri M. Triki
Keyword(s):  
Environmental Protection Agency ◽  
Suspended Solids ◽  
Petroleum Refinery ◽  
Production Capacity ◽  
Oxygen Demand ◽  
Petroleum Products ◽  
High Concentration ◽  
Standard Values ◽  
Petroleum Refineries

<p>This study was conducted to assessment the environmental impacts in petroleum refineries due to the different processes. The paper presents the data obtained during a case study was achieved in Tobruk petroleum refinery. The main petroleum products of the refinery represented by diesel, light naphtha, heavy naphtha and kerosene with maximum production capacity concerning 21,500 bbl/day. The results of the study revealed that the waste water affected by high concentration of hydrocarbons. The heavy metals are also determined and represented by V, Fe, Ni and Cu with low contents in crude oil. Also the pollutants parameters in the disposal water e.g. biochemical oxygen demand, chemical oxygen demand, total organic carbon, suspended solids, phenols, ammonia and sulphides are determined, and the results are compared with other refinery types. The concentration of these parameters are higher than the standard values that recommended by Environmental Protection Agency (EPA), at the same time these values are less if they are compared with the other refinery types.</p>

Decentralised treatment of concentrated sewage at low temperature in a two-step anaerobic system: two upflow-hybrid septic tanks

2003 ◽  
Vol 48 (6) ◽  
pp. 219-226 ◽  
Author(s):  
T.A. Elmitwalli ◽  
S. Sayed ◽  
L. Groendijk ◽  
J. van Lier ◽  
G. Zeeman ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Low Temperature ◽  
Domestic Sewage ◽  
Septic Tank ◽  
Septic Tanks ◽  
Black Water ◽  
Short Run ◽  
One Step ◽  
The Mathematical Model ◽  
Anaerobic System

The decentralised treatment of concentrated sewage (about 3,600 mgCOD/l) at low temperature was investigated in a two-step anaerobic system: two-anaerobic hybrid (AH) septic tanks (each 0.575 m3). The two reactors were placed in a temperature controlled-room and the HRT was 2.5 days for each reactor. The system was fed with concentrated domestic sewage, mainly black water from about 40 toilets flushed with only 4 litre of water and a limited amount of grey water. The system showed high removal efficiency for the different COD fractions. Mean removal efficiencies in the two-step AH-septic tank at 5 days HRT and 13°C were 94, 98, 74 and 78% for total COD, suspended COD, colloidal COD and dissolved COD respectively. The results of short run experiments indicated that the presence of reticulated polyurethane foam (RPF) media in the AH-septic tank improved the removal of suspended COD by 22%. The first AH-septic tank was full of sludge after 4 months of operation due to the high removal of particulate COD and the limited hydrolysis at low temperature conditions. Therefore, a simple mathematical model was developed based on ADM1 (the IWA model in 2002). Based on the experimental results and the mathematical model, only a one-step AH septic tank is required. An HRT of 5.5-7.5 days is needed for that one-step AH septic tank to treat concentrated sewage at a low temperature of 13°C. Such a system can provide a total COD removal as high as 87% and will be full of sludge after a period of more than a year.

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