Extended Aeration System

This invention relates to the field of wastewater treatment, specifically an improved Extended Aeration (EA) process with the inclusion of a Primary Settling Tank (PST) to enhance treatment efficiency, reduce system footprint, and lower operational costs. Background of the Invention: Extended Aeration (EA) is a widely used modification of the Activated Sludge Process (ASP) for wastewater treatment. However, conventional EA systems do not include a primary settling stage, requiring larger aeration tanks and higher energy consumption due to the presence of high Total Suspended Solids (TSS) and Biochemical Oxygen Demand (BOD). In high-strength wastewater applications, these limitations lead to increased capital and operational costs. This invention introduces a Primary Settling Tank (PST) before the aeration stage to reduce solids loading, optimize aeration efficiency, and improve overall performance.

Dissolved oxygen content is the most critical factor in intensive fish culture and it significantly affects the production of fish. Application of huge amount of fertilizers and fish feeds in heavily stocked fish ponds upsets the dynamics of dissolved oxygen. This becomes more pronounced in the early morning hours and on cloudy days resulting in severe depletion of dissolved oxygen of pond water. In addition to the problem of dissolved oxygen, toxic intermediates formed in the transformation of organic matter also inhibit growth of fish. These two factors which limit the production of fish in intensive culture, can be effectively controlled by the use of artificial aeration. Pond aeration systems were developed to sustain large quantities of fish and biomass materials. Aerator test results can assist in aerator design, aid aqua culturists in selecting aerators and provide a basis for estimating the amount of aeration required in specific situations. In the present study, four differ...

RESUMEN: Muchas de las áreas turísticas se caracterizan, a menudo, por una demanda estacional de agua. La influencia de la estacionalidad en la gestión de los recursos hídricos es más intensiva en el contexto de la escasez. Es por ello que el uso de fuentes alternativas de agua en estas áreas se convierte en un aspecto clave. En este sentido, la gestión eficiente, tanto en términos técnicos como económicos favorece las posibilidades de reutilización de agua y, por tanto, aumenta el suministro de los recursos llamados no convencionales. En las zonas turísticas, la estacionalidad es un factor determinante en la eficiencia de las plantas de tratamiento de aguas residuales (EDARs), ya que estas operan a plena capacidad sólo durante la temporada de verano, mientras que el resto del año tienen problemas de infrautilización. A través de la metodología Free Disposal Hull (FDH), este trabajo analiza las diferencias de eficiencia entre las EDAR´s ubicadas en zonas turísticas con fuerte estacionalidad, en relación con las situadas en las zonas no turísticas. Asimismo, con el objetivo de identificar qué tecnología se encuentra más afectada por la estacionalidad, se han diferenciado las EDARs cuyo proceso es aireación prolongada de aquellas cuya tecnología es fangos activados.

This study evaluated the performance of a rainwater utilization system. Excess rainwater is drained from rooftops into an underground container from which the water infiltrates from the base and sides into the surrounding soil of a vadose zone. The saturated hydraulic conductivity of the soil where this system was used was very low at the surface and higher in the deeper layer where the container was located. A simple method was proposed to estimate the steady recharge rate of excess rainwater from the buried container into the surrounding soil of the vadose zone. By modifying the steady recharge equation, which is widely used in the theory of the Guelph Permeameter, a steady recharge rate from the container was calculated from the measured value of saturated hydraulic conductivity and the size of the container.

Laboratory and field ponded infiltration tests in quasi-saturated soils (containing entrapped air) exhibit the same three-stage temporal variability for the flow rate and hydraulic conductivity. However, the values for the hydraulic conductivity may differ by as much as two orders of magnitude due to differences in the geometry and physics of flow when different

The showering aeration system (SAS) was designed and its performance was evaluated by conducting the aeration experiments in a tank of dimension 2 × 4 × 1.5 m. Initially, the aeration experiments were conducted to optimize the radius of curvature of the SAS with different values, such as = 0, 5, 10, 15, and 20 mm, and maintain other geometric parameters, i.e. number of holes in the shower (); height of water fall (H); diameter of the shower hole (d); volume of water under aeration (V) and water flow rate (Q) as constants. The optimum radius of curvature () was found to be 10 mm. The aeration experiments were further conducted with four different non-dimensional geometric parameters such as the number of holes , the ratio of the height of water fall to the length of shower arm the ratio of the diameter of the hole to the length of shower arm and the ratio of the volume of water to the cube of the length of shower arm The Response Surface Methodology and Box–Behnken Design were used t...

Surface aeration systems viz., paddle wheel and spiral aerators are the most commonly used aeration systems in intensive aquaculture practices. Use of aerators in intensive aquaculture is important for ensuring better survival, optimal oxygen supply, higher production, and disease free environment. Hence, selection of properly designed and high efficient aerators is necessary to maintain adequate and continuous supply of dissolve oxygen (DO) in semi-intensive and intensive aquaculture and keep the energy consumption (operating cost) to minimum. Paddle wheel and spiral aeration systems have advantage of cost effectiveness, low maintenance and easy availability. In the present study a review on previous studies related to standard aeration efficiency (SAE) and standard oxygen transfer rate (SOTR) of paddle wheel and spiral aeration systems has been discussed.

Aeration experiments were conducted on original and modified submersible aerator to evaluate its performance and to optimize the aeration efficiency. The angular position of the propeller (α) and submergence depth of the propeller (d) were varied to study their effects on standard aeration efficiency (SAE). Pre-performance evaluation of the original design without having a provision to vary α and d was done and resulted in an SAE of 0.320 kg O2/ kWh. The aerator was modified to have a provision to change α and d of the aerator. To evaluate the optimum α, experiments were conducted at different α: 0°, 15°, 30°, 45°, 60°, 75°, keeping the rotational speed (N) = 2900 rpm and d = 450 mm as constants. The optimized α was 75°. In the same way to optimize d, experiments were conducted at different d: 300, 350, 400, 450, 500, 550, and 600 mm, keeping N = 2900 rpm and α = 75° as constants. The optimized d was 350 mm. Finally the optimized value of SAE of 0.616 kg O2/ kWh was achieved at α = ...

The conventional extended aeration (EA) method has been considered as an effective method of secondary wastewater treatment in various installations around the world. The membrane bioreactor (MBR) method has been promoted by membrane manufacturers over the past decade as the most efficient treatment method in the industry. Research has shown the higher quality of MBR effluent compared with that of EA, but the comparison has seldom included the financial aspects. If the effluent quality from both methods is acceptable for a given reuse application, then a major consideration in adopting either method must be financial (i.e., the capital expenditure (CAPEX) and operating expenses (OPEX) involved in their deployment). In this study, simulation of both methods is conducted for domestic wastewater treatment plants using the biological and financial models of CAPDETWorks TM. The CAPEX and OPEX findings from the simulation were re-based to October 2019 using global price indices. Hydraulic loads from 500 to 5,000 m 3 /d were considered for three influent strengths: weak, medium, and strong. It is found that the EA method is less costly in meeting the effluent-quality requirements of certain reuse applications, while the MBR is recommended for the extra strong-strength influent especially for units smaller than 500 m 3 /d, due to both effluent quality and lifetime cost.

Aeration test was conducted in a brick masonry tank of dimension 5 m × 3 m × 1.5 m to evaluate the optimum geometric condition of Propeller-aspirator pump aerator, i.e., positional angle of propeller shaft () and dynamic condition, i.e., rotational speeds of propeller shaft (N) and submergence depth of propeller shaft (d). The results indicated a maximum SAE at  = 75°. Keeping the geometric condition constant ( = 75°), aeration experiments were further conducted at different rotational speeds of propeller shaft, N ranging from 1420 to 2840 rpm with an interval of 355 rpm and different values of submergence depth, d from 140 to 460 mm with an interval of 80 mm to evaluate the effect of dynamic conditions on aeration characteristics. Non-dimensional numbers related to standard aeration efficiency (SAE) and wire power (P) termed as E and Ne respectively, were introduced. It was found that E and Ne could be well correlated with Froude number (Fr) and Reynolds number (Re) respectively. Power consumption and Standard oxygen transfer rate (SOTR) of Propeller-aspirator pump aerator were evaluated at optimum geometric condition ( = 75°) and optimum dynamic conditions (N = 2840 rpm and d = 0.14 m). Further, aeration cost (Rs. 37.73 / kg O 2) of propeller-aspirator pump aerator was estimated for tank volume of 100 m 3. Index Terms-Aeration cost, dimensionless numbers, positional angle, standard oxygen transfer rate. I. INTRODUCTION Dissolved oxygen (DO) is considered to be the most vital water quality parameter in water and wastewater treatment. Atmospheric oxygen gets dissolved in water through diffusion process. As diffusion is a very slow process, aerators are generally used to maintain desired level of DO in water body. The aerators consume around 60% of the total energy consumption in a typical activated sludge wastewater treatment plant [1]. Presently diffused-air and surface aerators are being popularly used in wastewater treatment plants as well as in lakes and aquacultural ponds. Various types of aerators have been developed over the years to increase the dissolve oxygen (DO) concentration in the pond. Vertical pump sprayers, propeller-aspirator-pumps, paddle wheels, and diffused-air systems are probably the most widely used aerators in the field of waste water

Aeration test was conducted in a brick masonry tank of dimension 5 m × 3 m × 1.5 m to evaluate the optimum geometric condition of Propeller-aspirator pump aerator, i.e., positional angle of propeller shaft () and dynamic condition, i.e., rotational speeds of propeller shaft (N) and submergence depth of propeller shaft (d). The results indicated a maximum SAE at  = 75°. Keeping the geometric condition constant ( = 75°), aeration experiments were further conducted at different rotational speeds of propeller shaft, N ranging from 1420 to 2840 rpm with an interval of 355 rpm and different values of submergence depth, d from 140 to 460 mm with an interval of 80 mm to evaluate the effect of dynamic conditions on aeration characteristics. Non-dimensional numbers related to standard aeration efficiency (SAE) and wire power (P) termed as E and Ne respectively, were introduced. It was found that E and Ne could be well correlated with Froude number (Fr) and Reynolds number (Re) respectively. Power consumption and Standard oxygen transfer rate (SOTR) of Propeller-aspirator pump aerator were evaluated at optimum geometric condition ( = 75°) and optimum dynamic conditions (N = 2840 rpm and d = 0.14 m). Further, aeration cost (Rs. 37.73 / kg O 2) of propeller-aspirator pump aerator was estimated for tank volume of 100 m 3. Index Terms-Aeration cost, dimensionless numbers, positional angle, standard oxygen transfer rate. I. INTRODUCTION Dissolved oxygen (DO) is considered to be the most vital water quality parameter in water and wastewater treatment. Atmospheric oxygen gets dissolved in water through diffusion process. As diffusion is a very slow process, aerators are generally used to maintain desired level of DO in water body. The aerators consume around 60% of the total energy consumption in a typical activated sludge wastewater treatment plant [1]. Presently diffused-air and surface aerators are being popularly used in wastewater treatment plants as well as in lakes and aquacultural ponds. Various types of aerators have been developed over the years to increase the dissolve oxygen (DO) concentration in the pond. Vertical pump sprayers, propeller-aspirator-pumps, paddle wheels, and diffused-air systems are probably the most widely used aerators in the field of waste water

The objective of this paper is to present 3-D numerical and experimental study of the effect of blade angle on the cavitation phenomenon. The numerical computation in cavitating flow carried out using the Navier-Stokes code (CFD-ACE+ 2008) is presented. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-ε turbulence model to account for the turbulence effect. Pressure distribution and vapor volume fraction were obtained numerically at variable blade angles. Also the performance curve of the axial pump was obtained at variable blade angles 60°, 70° and 80°. The numerical and experimental results showed that the cavitation phenomenon appeared at blade angle 60° only. The computational code has been validated by comparing the predicted numerical results with the experimental ones. Besides, the predicted void growth and cavitation distribution on the impeller blade agreed with those visualized with high speed camera.

This paper presents an experimental and three-dimensional numerical study of unsteady, turbulent, void growth and cavitation simulation inside the passage of the axial flow pump. In this study a 3D Navier-Stokes code was used (CFDRC, 2008) to model the two-phase flow field around a four blades axial pump. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-e turbulence model to account for the turbulence effect. The numerical simulation of void growth and cavitation in an axial pump was studied under unsteady calculating. Pressure distribution and vapor volume fraction were completed versus time at different condition. The computational code has been validated by comparing the predicated numerical results with the experiment. The predicted of cavitation growth and distribution on the impeller blade also agreed with that visualized of high speed camera.

Exfiltration of waste water in sewer networks represents a potential danger for the soil and the aquifer. Various modelling approaches have been proposed to quantify sewerage exfiltration and its spatial and temporal variation. Common models are based on the law of Darcy, extended by a more or less detailed consideration of the expansion of leaks, the characteristics of the soil and the colmation layer. In the paper investigations are introduced, which are focused on the actual water content of the soil and its influence on exfiltration rates. Modelling results with HYDRUS 1D show, that under unsaturated conditions initial exfiltration rates are increased compared to saturated conditions. In experiments it was found, that the matrix potential increases the tightness of the colmation layer. Further a colmation model was deduced, which allows the calculation of the thickness and conductivity of the colmation layer.

The crucial phenomenon of air and water mixing together is called aeration. The venturi aeration is mainly responsible to transfer air directly through the atmosphere into the flowing water attribute to its simplicity and reliability. A water tank of 1000 litres capacity having dimensions 100 × 100 × 100 cm3 was used to conduct the experiments for aeration for the purpose of studying the characteristics of venturi aeration system design. Venturi having three significant sections i.e. inlet, constricted and outlet section, used as a differential pressure producer basis on Bernoulli’s theorem where the middle section of the venturi often called as constricted section is responsible for the energy conversion, which transfers oxygen by aspirating air into the constricted section and producing interfacial area between the air and water. On the basis of dimensional analysis, non-dimensional numbers associated with geometric, dynamic and process parameters were analysed. The non-dimensiona...

Aeration test was conducted in a brick masonry tank of dimension 5 m × 3 m × 1.5 m to evaluate the optimum geometric condition of Propeller-aspirator pump aerator, i.e., positional angle of propeller shaft () and dynamic condition, i.e., rotational speeds of propeller shaft (N) and submergence depth of propeller shaft (d). The results indicated a maximum SAE at  = 75°. Keeping the geometric condition constant ( = 75°), aeration experiments were further conducted at different rotational speeds of propeller shaft, N ranging from 1420 to 2840 rpm with an interval of 355 rpm and different values of submergence depth, d from 140 to 460 mm with an interval of 80 mm to evaluate the effect of dynamic conditions on aeration characteristics. Non-dimensional numbers related to standard aeration efficiency (SAE) and wire power (P) termed as E and Ne respectively, were introduced. It was found that E and Ne could be well correlated with Froude number (Fr) and Reynolds number (Re) respectively. Power consumption and Standard oxygen transfer rate (SOTR) of Propeller-aspirator pump aerator were evaluated at optimum geometric condition ( = 75°) and optimum dynamic conditions (N = 2840 rpm and d = 0.14 m). Further, aeration cost (Rs. 37.73 / kg O 2) of propeller-aspirator pump aerator was estimated for tank volume of 100 m 3. Index Terms-Aeration cost, dimensionless numbers, positional angle, standard oxygen transfer rate. I. INTRODUCTION Dissolved oxygen (DO) is considered to be the most vital water quality parameter in water and wastewater treatment. Atmospheric oxygen gets dissolved in water through diffusion process. As diffusion is a very slow process, aerators are generally used to maintain desired level of DO in water body. The aerators consume around 60% of the total energy consumption in a typical activated sludge wastewater treatment plant [1]. Presently diffused-air and surface aerators are being popularly used in wastewater treatment plants as well as in lakes and aquacultural ponds. Various types of aerators have been developed over the years to increase the dissolve oxygen (DO) concentration in the pond. Vertical pump sprayers, propeller-aspirator-pumps, paddle wheels, and diffused-air systems are probably the most widely used aerators in the field of waste water

According to this study, an extended aeration system can be upgraded by adding surface turbine aerators to the tanks and building new primary sedimentation tanks. Moreover, the biochemical oxygen demand (BOD 5), chemical oxygen demand (COD), and total suspended solids (TSS) were also observed to be 440, 682, and 212 mg/L after primary settling, respectively. These values represent the removal of about 35% of the organic load and about 68% of the suspended solids, which reduces the organic load and sediments entering the secondary treatment. Furthermore, effluent BOD 5 , COD, and TSS values were 30, 47, and 32 mg/L respectively, while those permitted values are 60 mg/L of BOD 5 , 80 mg/L of COD, and 50 mg/L of TSS reflecting the success of the upgrading work.

The objective of this paper is to present 3-D numerical and experimental study of the effect of blade angle on the cavitation phenomenon. The numerical computation in cavitating flow carried out using the Navier-Stokes code (CFD-ACE+ 2008) is presented. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-ε turbulence model to account for the turbulence effect. Pressure distribution and vapor volume fraction were obtained numerically at variable blade angles. Also the performance curve of the axial pump was obtained at variable blade angles 60°, 70° and 80°. The numerical and experimental results showed that the cavitation phenomenon appeared at blade angle 60° only. The computational code has been validated by comparing the predicted numerical results with the experimental ones. Besides, the predicted void growth and cavitation distribution on the impeller blade agreed with those visualized with high speed camera.

This paper presents an experimental and three-dimensional numerical study of unsteady, turbulent, void growth and cavitation simulation inside the passage of the axial flow pump. In this study a 3D Navier-Stokes code was used (CFDRC, 2008) to model the two-phase flow field around a four blades axial pump. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-e turbulence model to account for the turbulence effect. The numerical simulation of void growth and cavitation in an axial pump was studied under unsteady calculating. Pressure distribution and vapor volume fraction were completed versus time at different condition. The computational code has been validated by comparing the predicated numerical results with the experiment. The predicted of cavitation growth and distribution on the impeller blade also agreed with that visualized of high speed camera.

Various types of microbubble generators for use in aquaculture facilities for aeration. The aeration system is essential for high-density shrimp cultivation. However, there is a blockage in the microbubble generator aeration system, and generally, aeration at high densities requires considerable electrical power. In this study, modifications were made to various diameter nozzles and various pump power for microbubble generators. This research was conducted to determine the best microbubble by comparing the nozzle diameter and pump power. To achieve this goal, three diameter nozzles are combined with three different powers with an airflow rate of 2.5 LPM. The best combination of 32.5 mm nozzle diameter and 160-watt pump power. Produce bubbles ranging from 5.6 – 82 μm, with an increased oxygen concentration time of 60 minutes.

The objective of this paper is to present 3-D numerical and experimental study of the effect of blade angle on the cavitation phenomenon. The numerical computation in cavitating flow carried out using the Navier-Stokes code (CFD-ACE+ 2008) is presented. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-ε turbulence model to account for the turbulence effect. Pressure distribution and vapor volume fraction were obtained numerically at variable blade angles. Also the performance curve of the axial pump was obtained at variable blade angles 60°, 70° and 80°. The numerical and experimental results showed that the cavitation phenomenon appeared at blade angle 60° only. The computational code has been validated by comparing the predicted numerical results with the experimental ones. Besides, the predicted void growth and cavitation distribution on the impeller blade agreed with those visualized with high speed camera.

This paper presents an experimental and three-dimensional numerical study of unsteady, turbulent, void growth and cavitation simulation inside the passage of the axial flow pump. In this study a 3D Navier-Stokes code was used (CFDRC, 2008) to model the two-phase flow field around a four blades axial pump. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-e turbulence model to account for the turbulence effect. The numerical simulation of void growth and cavitation in an axial pump was studied under unsteady calculating. Pressure distribution and vapor volume fraction were completed versus time at different condition. The computational code has been validated by comparing the predicated numerical results with the experiment. The predicted of cavitation growth and distribution on the impeller blade also agreed with that visualized of high speed camera.

The objective of this paper is to present 3-D numerical and experimental study of the effect of blade angle on the cavitation phenomenon. The numerical computation in cavitating flow carried out using the Navier-Stokes code (CFD-ACE+ 2008) is presented. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-ε turbulence model to account for the turbulence effect. Pressure distribution and vapor volume fraction were obtained numerically at variable blade angles. Also the performance curve of the axial pump was obtained at variable blade angles 60°, 70° and 80°. The numerical and experimental results showed that the cavitation phenomenon appeared at blade angle 60° only. The computational code has been validated by comparing the predicted numerical results with the experimental ones. Besides, the predicted void growth and cavitation distribution on the impeller blade agreed with those visualized with high speed camera.

This paper presents an experimental and three-dimensional numerical study of unsteady, turbulent, void growth and cavitation simulation inside the passage of the axial flow pump. In this study a 3D Navier-Stokes code was used (CFDRC, 2008) to model the two-phase flow field around a four blades axial pump. The governing equations are discretized on a structured grid using an upwind difference scheme. The numerical simulation used the standard K-e turbulence model to account for the turbulence effect. The numerical simulation of void growth and cavitation in an axial pump was studied under unsteady calculating. Pressure distribution and vapor volume fraction were completed versus time at different condition. The computational code has been validated by comparing the predicated numerical results with the experiment. The predicted of cavitation growth and distribution on the impeller blade also agreed with that visualized of high speed camera.

Inadequate wastewater treatment facilities and a general lack of data on hygienic aspects of treated wastewater have hampered the successful implementation of effluent reuse schemes at the national level; in addition, illegal irrigation practices with partially treated effluent impose serious health hazards and environmental problems. The main objective of this research is to investigate the pathogens removal in Upflow Anaerobic Sludge Blanket (UASB)-septic tanks and Albireh wastewater treatment plant (AWWTP). The UASBseptic tanks, located at AWWTP, were fed continuously with raw municipal wastewater from the aerated grit chamber of AWWTP. The two pilot scale UASB-septic tanks (R1 and R2) were operated at two different hydraulic retention times (HRT) of 2 and 4 days for R1 and R2, respectively. At AWWTP, as an extended aeration system with aerobic sludge stabilization, the HRT was about one day. Both raw wastewater and treated effluent were tested for microbial pathogens, including indicator bacteria, protozoa and trophozoite using microscopic and specific culture media. The removal efficacies of R1 and R2 were 15.5% and 15% for fecal coliform and 6.9% and 11% for fecal streptococcus, respectively, while the removal efficacy of the oxidation ditch was 38% for fecal coliform and 16% for fecal streptococcus. Though Salmonellae was detected in 30% of analyzed influent samples, it was not detected in any sample of the effluent of both treatment systems. Also, the treated effluent of R1, R2 and oxidation ditch was parasite-(cysts or trophoziote) free. This information can assist municipalities and village councils in the implementation of rational and efficient treatment strategies for sustainable effluent reuse. Finally, the installation of post treatment stages, including filtration and disinfecting units, is recommended in order to comply with prescribed national guidelines for effluent reuse.

According to this study, an extended aeration system can be upgraded by adding surface turbine aerators to the tanks and building new primary sedimentation tanks. Moreover, the biochemical oxygen demand (BOD 5), chemical oxygen demand (COD), and total suspended solids (TSS) were also observed to be 440, 682, and 212 mg/L after primary settling, respectively. These values represent the removal of about 35% of the organic load and about 68% of the suspended solids, which reduces the organic load and sediments entering the secondary treatment. Furthermore, effluent BOD 5 , COD, and TSS values were 30, 47, and 32 mg/L respectively, while those permitted values are 60 mg/L of BOD 5 , 80 mg/L of COD, and 50 mg/L of TSS reflecting the success of the upgrading work.

The conventional extended aeration (EA) method has been considered as an effective method of secondary wastewater treatment in various installations around the world. The membrane bioreactor (MBR) method has been promoted by membrane manufacturers over the past decade as the most efficient treatment method in the industry. Research has shown the higher quality of MBR effluent compared with that of EA, but the comparison has seldom included the financial aspects. If the effluent quality from both methods is acceptable for a given reuse application, then a major consideration in adopting either method must be financial (i.e., the capital expenditure (CAPEX) and operating expenses (OPEX) involved in their deployment). In this study, simulation of both methods is conducted for domestic wastewater treatment plants using the biological and financial models of CAPDETWorks TM. The CAPEX and OPEX findings from the simulation were re-based to October 2019 using global price indices. Hydraulic loads from 500 to 5,000 m 3 /d were considered for three influent strengths: weak, medium, and strong. It is found that the EA method is less costly in meeting the effluent-quality requirements of certain reuse applications, while the MBR is recommended for the extra strong-strength influent especially for units smaller than 500 m 3 /d, due to both effluent quality and lifetime cost.

Urban wastewater systems (WWS) comprising of municipal sewage collection, treatment, and disposal play a vital role in alleviating urban water pollution and maintaining overall public health and sanitation. WWS forms one of the most energy-intensive components of the urban water cycle and requires huge financial investment for its construction, operations, and management. The financial burden of WWS operations can be subsided to a significant extent by implementing strategies for energy reduction, optimization as well as energy production and recovery from wastewater. However, developing an energy-neutral or energypositive WWS is a challenging task, requiring the application of several interdependent energy pathways. In this chapter, comprehensive energy analysis of WWS is carried out, considering the available routes for reducing, optimizing, producing, and recovering energy from wastewater. Alongside this, available approaches for assessing the total energy consumption and energy efficiency of the WWS have also been evaluated. The use of indicators and indices can be particularly effective to both quantify and compare energy efficiency within different components of a WWS or among different WWS. The diagnostic potential of energy efficiency indices (EEIs) proposed specifically for WWS has been comparatively evaluated in this study. Such an index-based energy evaluation can conveniently characterize the energy efficiency of WWS and facilitating energy benchmarking of systems.

Aeration cost is the third largest cost in intensive aquaculture system after post larvae and feed cost representing about 15% of total production cost. Therefore, selection of aerators plays a major role in maximizing the profit in such system. Over the years, various types of aerators have been developed specifically to enhance the production of aquatic species. The performances of these aerators are generally compared in terms of standard aeration efficiency. However, suitability of a particular aerator at different pond sizes and water quality conditions can best be determined in terms of aeration cost per unit time of operation. In the present study, economic performance of five different aeration systemscircular stepped cascade (CSC), pooled circular stepped cascade (PCSC), 1-hp paddle wheel, 2-hp paddle wheel and propeller aspirator pump were evaluated and compared at different pond sizes, initial DO concentrations of pond and operating hours of aerators; assuming a typical Indian major carp (IMC) culture with commonly practiced stocking density and feeding. Both CSC and PCSC aerators were found to be suitable for pond size less than 1000 m 3. However, for pond sizes more than 5000 m 3 , 1-hp paddle wheel and 2-hp paddle wheel aerators were found to be efficient.

Inadequate wastewater treatment facilities and a general lack of data on hygienic aspects of treated wastewater have hampered the successful implementation of effluent reuse schemes at the national level; in addition, illegal irrigation practices with partially treated effluent impose serious health hazards and environmental problems. The main objective of this research is to investigate the pathogens removal in Upflow Anaerobic Sludge Blanket (UASB)-septic tanks and Albireh wastewater treatment plant (AWWTP). The UASBseptic tanks, located at AWWTP, were fed continuously with raw municipal wastewater from the aerated grit chamber of AWWTP. The two pilot scale UASB-septic tanks (R1 and R2) were operated at two different hydraulic retention times (HRT) of 2 and 4 days for R1 and R2, respectively. At AWWTP, as an extended aeration system with aerobic sludge stabilization, the HRT was about one day. Both raw wastewater and treated effluent were tested for microbial pathogens, including indicator bacteria, protozoa and trophozoite using microscopic and specific culture media. The removal efficacies of R1 and R2 were 15.5% and 15% for fecal coliform and 6.9% and 11% for fecal streptococcus, respectively, while the removal efficacy of the oxidation ditch was 38% for fecal coliform and 16% for fecal streptococcus. Though Salmonellae was detected in 30% of analyzed influent samples, it was not detected in any sample of the effluent of both treatment systems. Also, the treated effluent of R1, R2 and oxidation ditch was parasite-(cysts or trophoziote) free. This information can assist municipalities and village councils in the implementation of rational and efficient treatment strategies for sustainable effluent reuse. Finally, the installation of post treatment stages, including filtration and disinfecting units, is recommended in order to comply with prescribed national guidelines for effluent reuse.

Various types of microbubble generators for use in aquaculture facilities for aeration. The aeration system is essential for high-density shrimp cultivation. However, there is a blockage in the microbubble generator aeration system, and generally, aeration at high densities requires considerable electrical power. In this study, modifications were made to various diameter nozzles and various pump power for microbubble generators. This research was conducted to determine the best microbubble by comparing the nozzle diameter and pump power. To achieve this goal, three diameter nozzles are combined with three different powers with an airflow rate of 2.5 LPM. The best combination of 32.5 mm nozzle diameter and 160-watt pump power. Produce bubbles ranging from 5.6 -82 µm, with an increased oxygen concentration time of 60 minutes.

The crucial phenomenon of air and water mixing together is called aeration. The venturi aeration is mainly responsible to transfer air directly through the atmosphere into the flowing water attribute to its simplicity and reliability. A water tank of 1000 litres capacity having dimensions 100 × 100 × 100 cm3 was used to conduct the experiments for aeration for the purpose of studying the characteristics of venturi aeration system design. Venturi having three significant sections i.e. inlet, constricted and outlet section, used as a differential pressure producer basis on Bernoulli’s theorem where the middle section of the venturi often called as constricted section is responsible for the energy conversion, which transfers oxygen by aspirating air into the constricted section and producing interfacial area between the air and water. On the basis of dimensional analysis, non-dimensional numbers associated with geometric, dynamic and process parameters were analysed. The non-dimensiona...

Filamentous sludge bulking and foaming problems are common operational problems of activated sludge systems worldwide. The Kuwait Institute for Scientific Research (KISR) has recently conducted a study to identify the filamentous bacteria proliferating Kuwait activated sludge systems. Weekly grab samples were collected from Riqqa and Umm Al-Haiman activated sludge systems. To accurately identify the dominant filaments, a modern molecular biology technique was used, namely, Vermicon Identification Technology (VIT). Obtained results indicated that the dominant filamentous bacteria are: N. limicola II, Type 1851, H. hydrossis and Nacordioform. Results of the assessment of systems' performance indicated that the Riqqa system was heavily impacted by the excessive growth of filamentous bacteria.

The showering aeration system (SAS) was designed and its performance was evaluated by conducting the aeration experiments in a tank of dimension 2 × 4 × 1.5 m. Initially, the aeration experiments were conducted to optimize the radius of curvature of the SAS with different values, such as = 0, 5, 10, 15, and 20 mm, and maintain other geometric parameters, i.e. number of holes in the shower (); height of water fall (H); diameter of the shower hole (d); volume of water under aeration (V) and water flow rate (Q) as constants. The optimum radius of curvature () was found to be 10 mm. The aeration experiments were further conducted with four different non-dimensional geometric parameters such as the number of holes , the ratio of the height of water fall to the length of shower arm the ratio of the diameter of the hole to the length of shower arm and the ratio of the volume of water to the cube of the length of shower arm The Response Surface Methodology and Box–Behnken Design were used t...

The study was carried out for identifying microorganisms present in the extended aeration activated sludge process at Common Effluent Treatment Plant (CETP), Thane. The stabilization of biological foams results from production of extra cellular materials like lipids, peptides, proteins and carbohydrates which have the properties of surface active agents and bulking phenomenon has been recognized for a long time and is known to be caused by at least 14 types of filamentous microorganisms. The microbial population from treated sludge was isolated on nutrient medium, MacConkey’s agar and Sabauroud’s agar using streak plate method. The isolated colonies were then Gram stained and isolates were used further for biochemical tests to confirm the organism upto probable genus level. Diverse microflora was observed in the water sample collected from aeration tank at CETP. The microscopic examination of water samples showed the presence of Diatoms (Bacillariophycophyta), Paramoecium species, V...

This paper reviews the problem of foaming associated with the activated sludge process and its control using various physical, chemical and biological methods. Activated sludge process is widely used for treatment of every type of wastewater like industrial, domestic and municipal wastewater. This process is driven by a complex microbial population, among which some mycolic acid containing bacteria leads to the stable foam formation which ultimately results in poor efficiency of the plants and leading to major environmental, operational, and health problems. A number of researches provide the evidences of foaming in wastewater treatment plants and its control using physical, chemical and biological methods. Current approaches for controlling foam includes operational adjustments, additional structures, controlling dissolved oxygen levels, water sprays, steam application, polymer addition, chlorination and a novel and ecofriendly approach that is treatment of filamentous bacteria wit...

The paper presents methods for measuring the dissolved oxygen concentration in water; the electrical method is presented by presenting an experimental installation designed and built in the laboratories of POLITEHNICA University in Bucharest. For the creation of fine air bubbles, a bubble generator with 0.1 mm orifices processed by spark-erosion was used. The results of the experimental researches on the measurement of dissolved oxygen in water are presented.

The paper presents an original solution of a fine air bubble generator (FBG) that is used for water aeration. The calculation of the oriffices number and their diameter is indicated, orifices appearing in the perforated plate to be mounted on the fine bubble generator. The constructive solution of the fine bubble generator is presented, and the results of the experimental researches on water aeration using this fine bubble generator are presented.

Filamentous bulking can be controlled by specific and/or non-specific methods. Specific methods intend to recognize and resolve the major causes of filamentous bacterial proliferation and are preferred because they are selective for the target microorganism and cause limited damage to the remaining biomass. In what concerns non-specific methods, chlorination was one of the first methods to be used to control filamentous bulking and is still used, but its action is only temporary and tend to damage flocforming bacteria, leading to floc and process breakdown [1]. The use of alternative biocides has attracted the attention of wastewater treatment technicians and researchers for the potential of its use in the control of filamentous overgrowth (ability to induce filamentous cell lysis) and is presently one of the most commonly used methods for the control of filamentous bulking under critical conditions [2]. Triclosan, cetyltrimethyl ammonium bromide (CTAB) and glutaraldehyde were used ...

Aeration experiments were conducted in a masonry tank to study the effects of operating parameters on the standard aeration efficiency (SAE) of a propeller diffused aeration (PDA) system. The operating parameters included the rotational speed of shaft (N), submergence depth (h), and propeller angle (α). The response surface methodology (RSM) and an artificial neural network (ANN) were used for modelling and optimizing the standard aeration efficiency (SAE) of a PDA system. The results of both approaches were compared for their modelling abilities in terms of coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE), computed from experimental and predicted data. ANN models were proved to be superior to RSM. The results indicate that for achieving the maximum standard aeration efficiency (SAE), N, h and α should be 1,000 rpm, 0.50 m, and 12°, respectively. The maximum SAE was found to be 1.711 kg O2/ kWh. Cross-validation results show that best a...

Aeration helps improve water quality and make it favorable to fish. SPFTAS was designed based on the environment and characteristics of freshwater ponds. SPFTAS consist of floating platform, power source, sensors, signaling and aeration system. It functions to disperse and increase dissolved oxygen (DO). It possessed capability to monitor real time condition of water, store data and send it through short messaging service (SMS). The SPFTAS oxygen transfer rate was 0.07 kg of oxygen using four diffusers and the standard aeration efficiency of 0.2710 kg oxygen/hp-hr. The standard oxygen transfer efficiency was 0.36 at 18 kg of oxygen transferred. SPFTAS increased DO level to 1.32 ppm and rated highly effective during the test. DO levels using 1, 2, 3 and 4 diffusers at different depths, distances and time results were significantly different. The DO level using different diffusers at time intervals was highest at 7.16 ppm in three hours operation. The total cost of automated SPFTAS was ₱170,385.75. The cost analysis of using the machine indicated a breakeven point of 1,440 hours per year. The annual operation expected save ₱32,737.39 and expected recover the investment in 5.33 years. Finally, machine was found beneficial to increase DO concentration in fishponds.

Aeration experiments were conducted in a masonry tank to study the effects of operating parameters on the standard aeration efficiency (SAE) of a propeller diffused aeration (PDA) system. The operating parameters included the rotational speed of shaft (N), submergence depth (h), and propeller angle (α). The response surface methodology (RSM) and an artificial neural network (ANN) were used for modelling and optimizing the standard aeration efficiency (SAE) of a PDA system. The results of both approaches were compared for their modelling abilities in terms of coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE), computed from experimental and predicted data. ANN models were proved to be superior to RSM. The results indicate that for achieving the maximum standard aeration efficiency (SAE), N, h and α should be 1,000 rpm, 0.50 m, and 12°, respectively. The maximum SAE was found to be 1.711 kg O2/ kWh. Cross-validation results show that best a...

Low-cost aerators relying on the venturi principle to entrain air into flowing water have the notable advantage of contributing both to water mixing and oxygen transfer, making them attractive for wastewater treatment in low-resource settings. This study aimed to characterize the performance of such aerators by describing the impact of different design characteristics, including water flow rate, the number of nozzles used, and the nozzle depth. The study also explored the effect on aeration performance of temperature, total dissolved solids (TDS) concentration, and addition of the archetypal surfactant sodium dodecyl sulphate (SDS). Tests were conducted in a 200 L reactor with 2, 3 or 4 nozzles, at depths of 20, 40 or 60 cm, while circulating water through the aeration device at a rate of 400, 600 or 800 L/h. The configuration that yielded the highest mass transfer coefficient (KLa20 of 20.8 h-1) had both the highest flow rate (800 L/h) and the smallest number of nozzles (2). Nozzle...

Background: The main objective of the study was the assessment of the prevalence and the identification of species of human gastrointestinal parasites as an indicator of the pollution of the seashore of Gaza City. Methods: The investigation was conducted by analysis of the parasitic contamination of seawater along the study area. A total of 52 samples of seawater were analyzed during the summer period; from June to October 2011. The study area was divided into six zones (A, B, C, D, E and F) according to specific criteria such as the presence of the wastewater discharge points and other geographical characteristics. Results: The results show that about 48% of the seawater samples from the shoreline region of Gaza City were contaminated with parasites. Zones A, B and D (mouth of Wadi Gaza, Al Sheikh Ejleen discharge and Al Shalehat discharge points respectively) have the highest level of parasitic contamination, while, zones C and E (From Al-Baydar restaurant to Khalel Alwazer Mosque and the basin of the Gaza marina respectively) had a lower level of contamination and zone F (From the northern part of the Gaza marina to the Intelligence Building) was uncontaminated. The parasitic species found were: Ascaris lumbricoides, Giardia lamblia, Strongyloides stercoralis, Hymenolepis nana, Entamoeba histolytica/dispar and Cryptosporidium parvum. Conclusions: The present study revealed a high level of contamination with parasites at most of the points which were investigated along the Gaza City coast line.

This study is conducted to investigate the characteristics of outflow wastewater of the 1 m 3 on-site wastewater treatment unit on the basis of the testing and measurement data of the samples that were taken during the study monitored period (August 2017 to January 2018). For this purpose, samples were taken on a weekly basis from the treated wastewater effluent and five quality parameters (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH, E-coli counts) were monitored and measured. The average values of the five parameters were compared with the Jordanian standard maximum values, and water reuse in irrigation of plants classifications have been assessed and investigated. Average values of BOD, COD, TSS, pH, and E-coli in treated wastewater were 11 mg/L, 104 mg/L, 15 mg/L, 7.51, and 387 counts, respectively. The installation of in-line ultraviolet (UV) unit in recirculating delivery system played a vital role in the reduction of counts far below the permissible maximum level (1000 counts). Based on national and international standards and criteria, results showed that the treated wastewater is suitable for the irrigation of two classifications of plants: (i) Fruit trees, road-green sides outside cities, and green landscape; (ii) Crops, commercial crops, and forest trees. Hence, such very low water flow rate treatment system can be utilized in refugees' camps and water scarce residential areas in Jordan.

This study is conducted to investigate the characteristics of outflow wastewater of the 1 m 3 on-site wastewater treatment unit on the basis of the testing and measurement data of the samples that were taken during the study monitored period (August 2017 to January 2018). For this purpose, samples were taken on a weekly basis from the treated wastewater effluent and five quality parameters (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH, E-coli counts) were monitored and measured. The average values of the five parameters were compared with the Jordanian standard maximum values, and water reuse in irrigation of plants classifications have been assessed and investigated. Average values of BOD, COD, TSS, pH, and E-coli in treated wastewater were 11 mg/L, 104 mg/L, 15 mg/L, 7.51, and 387 counts, respectively. The installation of in-line ultraviolet (UV) unit in recirculating delivery system played a vital role in the reduction of counts far below the permissible maximum level (1000 counts). Based on national and international standards and criteria, results showed that the treated wastewater is suitable for the irrigation of two classifications of plants: (i) Fruit trees, road-green sides outside cities, and green landscape; (ii) Crops, commercial crops, and forest trees. Hence, such very low water flow rate treatment system can be utilized in refugees' camps and water scarce residential areas in Jordan.

Inadequate wastewater treatment facilities and a general lack of data on hygienic aspects of treated wastewater have hampered the successful implementation of effluent reuse schemes at the national level; in addition, illegal irrigation practices with partially treated effluent impose serious health hazards and environmental problems. The main objective of this research is to investigate the pathogens removal in Upflow Anaerobic Sludge Blanket (UASB)-septic tanks and Albireh wastewater treatment plant (AWWTP). The UASBseptic tanks, located at AWWTP, were fed continuously with raw municipal wastewater from the aerated grit chamber of AWWTP. The two pilot scale UASB-septic tanks (R1 and R2) were operated at two different hydraulic retention times (HRT) of 2 and 4 days for R1 and R2, respectively. At AWWTP, as an extended aeration system with aerobic sludge stabilization, the HRT was about one day. Both raw wastewater and treated effluent were tested for microbial pathogens, including indicator bacteria, protozoa and trophozoite using microscopic and specific culture media. The removal efficacies of R1 and R2 were 15.5% and 15% for fecal coliform and 6.9% and 11% for fecal streptococcus, respectively, while the removal efficacy of the oxidation ditch was 38% for fecal coliform and 16% for fecal streptococcus. Though Salmonellae was detected in 30% of analyzed influent samples, it was not detected in any sample of the effluent of both treatment systems. Also, the treated effluent of R1, R2 and oxidation ditch was parasite-(cysts or trophoziote) free. This information can assist municipalities and village councils in the implementation of rational and efficient treatment strategies for sustainable effluent reuse. Finally, the installation of post treatment stages, including filtration and disinfecting units, is recommended in order to comply with prescribed national guidelines for effluent reuse.