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Influence of superficial liquid velocity on maximum bed contact time between sludge and liquid under unfluidization state
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Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor (SAB) were performed based on bed expansion ratio (E), maximum bed sludge content (V(pmax)), and maximum bed contact time between sludge and liquid (tau(max)). Bed expansion behavior models were established under bed unfluidization, fluidization, and transporta...
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... When a natural wetland is receiving wastewater, there is an opportunity for environmental enhancement and significant cost savings [25][26][27]. Among different wastewater treatment technologies such as Waste Stabilization Pond (WSP), Activated Sludge Process (ASP), Trickling Filters, and Sequential Batch Reactor (SBR); natural wetland has been considered as most sustainable and efficient in terms of land area requirement, cost effectiveness and removal efficiency [28][29][30]. Therefore, this research focuses on the efficiency of natural wetlands as an effluent polishing step in removing phosphorus from wastewater in the northern continental environment. ...
This study focuses on understanding the role of passive wastewater treatment (wastewater lagoon plus wetland) in reducing the phosphorus discharge levels in a northern small community in Manitoba, Canada. The facultative lagoon system of that small community treats domestic wastewater and seasonally discharges effluent into a wetland that connects to Lake Manitoba. This research assesses phosphorus removal efficiency through the natural wetland during the vegetation growing season. The average total phosphorus (TP) concentration reduction for the observed treatment area of 1.3 ha was more than 70%, achieving the desired TP discharge concentration below 1 mg/l. Data analysis showed that the main accumulation of TP occurred at the 21-40 cm soil depth, which indicates the potential of natural wetland treatment applications under cold continental climate conditions as an effluent polishing step to satisfy regulatory requirements for phosphorus reduction.
... Langmuir and Freundlich models were used to fit the adsorption isotherm data and pseudo-first-order and pseudo-second-order models were used to fit the adsorption kinetics data by Origin 2019b (Foo and Hameed, 2010;Tan and Hameed, 2017). The removal processes of Cu 2+ and Zn 2+ were fitted with the first-order kinetic model and the sensitivity analysis was referred to Chen et al. (2010). XPS spectra were analyzed by using XPS Peak 4.1. ...
Copper and zinc are often used as feed additives and frequently detected in swine wastewater. Anaerobic granular sludge (AnGS) plays an important role in high-rate anaerobic methanation biotechnologies which are widely applied to treat swine wastewater. The removal of Cu²⁺ and Zn²⁺ by AnGS was investigated in the batch and continuous systems. The results of batch experiments showed the adsorption by AnGS could be a significant method for Cu²⁺ and Zn²⁺ removal with efficiencies of 99% and 49% respectively. The sulfide precipitation mediated by AnGS could be another significant pathway for Zn²⁺ removal with efficiency of 18-27% in Protein/M²⁺ experiments and 16-46% in SO4²⁻/M²⁺ experiments (M²⁺ represents the total concentration of Cu²⁺ and Zn²⁺). The results of continuous experiment showed, with SO4²⁻/M²⁺ larger than 1.5, the influent Cu²⁺ and Zn²⁺ could be effectively removed in an anaerobic methanation bioreactor and its effluent Cu²⁺and Zn²⁺concentrations were below 1 mg/L and 2 mg/L separately. The main removal mechanism of Cu²⁺and Zn²⁺ in the anaerobic methanation system was that the biological production of sulfide from sulfate was followed by chemical precipitation and reduction. It is helpful for the removal of Cu²⁺ and Zn²⁺ with organic pollutants simultaneously to eliminate environmental risk of swine wastewater.
... As shown in Figure 10, we compared the bed height calculated by the drag model and Wen-Yu model. It can be seen that, compared with Wen-Yu model, the bed height calculated by the drag coefficient model obtained in this study was closer to the actual situation [25]. The maximum deviation between the calculated results and the experimental results was reduced from 8.7% (Wen-Yu) to 4.8% (this study). ...
An internal circulation (IC) anaerobic reactor is widely used in the treatment of municipal and industrial wastewater with high volumetric loading rates. The performance of an IC reactor is closely related with hydrodynamic behaviors of anaerobic granules. Typically, anaerobic granules work in swarms and the settling behavior of a granule is disturbed by other granules. However, the research on anaerobic granule swarms is insufficient. In this work, Computational Fluid Dynamics (CFD) method was employed to study the hydrodynamic behaviors of anaerobic granule swarms with various voidages. The simulated results showed that the average velocity inside granules increased significantly as the voidage of granule swarm decreased and as the Reynolds number increased. The maximum shear stress on the granule’s surface increased with decreasing voidage and increasing Reynolds number. Based on the hydrodynamic behaviors of anaerobic granule swarms, an improved model of drag force coefficient for granule swarms was developed. The predicted expanded height, using the improved model, gives better consistency with experimental results. The improved model can embed in CFD code to improve the precision of the description of the IC reactor model and provide valuable information for designing and operating an IC reactor.
... In case of sewage, the OLR usually is applied in the range of 1.0-2.0 KgCOD/m 3 ⋅day [42,101]. UASB reactor is preferred for its potential to treat wastewater having low content of suspended solids and gives higher methane yield [27]. ...
The upflow anaerobic sludge blanket (UASB) reactor has been recognized as an important wastewater treatment technology among anaerobic treatment methods. The objective of this study was to perform literature review on the treatment of domestic sewage using the UASB reactor as the core component and identifying future areas of research. The merits of anaerobic and aerobic bioreactors are highlighted and other sewage treatment technologies are compared with UASB on the basis of performance, resource recovery potential, and cost. The comparison supports UASB as a suitable option on the basis of performance, green energy generation, minimal space requirement, and low capital, operation, and maintenance costs. The main process parameters such as temperature, hydraulic retention time (HRT), organic loading rate (OLR), pH, granulation, and mixing and their effects on the performance of UASB reactor and hydrogen production are presented for achieving optimal results. Feasible posttreatment steps are also identified for effective discharge and/or reuse of treated water.
... At the industrial scale a range of high-rate anaerobic fluidized-bed (AFB) reactors such as upflow anaerobic sludge blanket (UASB), upflowstaged sludge bed (USSB), expanded granular sludge bed (EGSB), internal circulation (IC), and inverse anaerobic fluidized bed (IAFB) reactors can bear very high loading rates, up to 40 kg COD/(m 3 ⋅d) [41]. The organic loading rate (OLR) and volumetric biogas production (VBP) of the spiral automatic circulation (SPAC) reactor in our laboratory could reach up to 306 kg COD/(m 3 ⋅d) [41][42][43]. ...
... At the industrial scale a range of high-rate anaerobic fluidized-bed (AFB) reactors such as upflow anaerobic sludge blanket (UASB), upflowstaged sludge bed (USSB), expanded granular sludge bed (EGSB), internal circulation (IC), and inverse anaerobic fluidized bed (IAFB) reactors can bear very high loading rates, up to 40 kg COD/(m 3 ⋅d) [41]. The organic loading rate (OLR) and volumetric biogas production (VBP) of the spiral automatic circulation (SPAC) reactor in our laboratory could reach up to 306 kg COD/(m 3 ⋅d) [41][42][43]. Several authors reported that up to a certain limit, the treatment efficiency of complex wastewaters, for example, potato maize, slaughterhouse, in high rate anaerobic reactors increases with increase in OLR. ...
The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB), namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT), Organic Loading Rate (OLR), and sludge retention time (SRT) were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive.
... Fixed film or attached growth reactors are often considered to be susceptible to bio-film surface area limitations. In this respect, Chen et al. [63] concluded that the bed expansion ratio of a super-high rate anaerobic bioreactor correlated positively with superficial gas and liquid velocities, while maximum bed sludge content and maximum bed contact time between sludge and liquid correlated negatively. Ganesh et al. [3] addressed the effect of media design on treatment performance and stated that physical parameters, like the type of media, its size and shape, affect the performance of waste treatment. ...
This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB) reactor, hybrid systems etc.; operational challenges, mass transfer considerations, energy production estimation, toxicity, modeling, technology assessment and recommendations for successful operation.
... could be calculated using Eq. (17) in the following form (Chen et al., 2010a): ...
... could be calculated using Eq. (17) in the following form (Chen et al., 2010a): ...
BACKGROUND: Specific energy dissipation rate (ϕ) is an important performance parameter of the super-high-rate anaerobic bioreactor (SAB) and is closely linked with power matching and operation optimization. The ϕ value was investigated for a SAB using anaerobic granular sludge and simulating gas production. The ϕ models for separation, reaction and water distribution units were established.
RESULTS: Experimental results showed that the model predictions agreed well with the experimental data and, thus, they may be used for power matching and operation optimization of similar high-rate anaerobic bioreactors. The ϕ value for the separation unit was so low as to be neglected. The maximum ϕ values for the reaction unit during nonfluidization, granular sludge agglomeration, liquid-solid two-phase fluidization and gas-liquid-solid three-phase fluidization states were 0.143 W m−3, 4.449 W m−3, 2.173 W m−3 and 11.132 W m−3, respectively. The maximum ϕ value for the water distribution unit was 8.37 W m−3. ϕ for the reaction unit was significantly influenced by ρp, ul and Vp, ug and dp.
CONCLUSION: The maximum ϕ value of 11.132 W m−3 was the basic parameter for power matching for the SAB. Some measures were introduced to reduce the ϕ values based on parametric sensitivity analyses. The present investigation will further assist in optimizing the operation and design of SABs. Copyright
... The performances reported for laboratory-scale high-rate anaerobic reactors were very promising. For example, the volumetric loading rate of super-high-rate anaerobic bioreactor (SAB) developed in our laboratory reached up to 306 g CODÁL À1 Ád À1 with volumetric hydraulic loading rate (HLR) of 15.3 LÁL À1 Ád À1 with COD volumetric removal rate of 240 g CODÁL À1 Ád À1 , and volumetric biogas production rate (BPR) of 131 LÁL À1 Ád À1 (Chen et al., 2008aChen et al., , 2010). One of the main characteristics of SAB was the setting of spiral board in reaction zone, which optimized the flow patterns and improved the volumetric efficiency (Chen et al., 2008b; Zheng et al., 2008). ...
The super-high-rate anaerobic bioreactor (SAB) possesses outstanding potential to treat concentrated wastewater. The flow patterns of SAB were investigated through tracer pulse stimulus–response technique and cold-model tests. The flow patterns were demonstrated to be analogous to plug flow at low loading rate and to completely mixed flow at super-high loading rate. Mean dead spaces of SAB caused by biomass and hydraulic behavior were 6.98 % and 21.01 %, respectively. The relationship among the hydraulic dead spaces (Vh), the volumetric hydraulic loading rate (L) and the volumetric biogas production rate (G) was represented by: Vh = 0.7603 L + 0.1627 G − 4.0620. The Vh was greatly influenced by G over L value. The volumetric efficiency could further be improved when SAB was operated at super-high loading rate. The volume ratio of VN and V1 decreased as N increased and the optimum N was 3.00 or so.
The performance of constructed wetland depends upon the types of constructed wetland, vegetation, applied hydraulic load, and media used in the bed. This paper describes the review of constructed wetland on type, technology and treatment of various types of wastewater generated such as textile waste, dairy waste, industrial waste, piggery waste, tannery waste, petrochemical waste, municipal waste, etc. The review summarizes the types of constructed wetlands considering media, vegetation, removal efficiency, construction cost, maintenance cost and land area requirement using life cycle cost analysis. The review compares how and why constructed wetland is a better option as per treatment efficiency, their payback period and cost-effective with the other wastewater treatment technologies. Further, there is no proper guidelines for the selection of media and vegetation in the constructed wetland. It is found that Typha Latifolia and Phragmites Australis have a better removal efficiency than other species. Lightweight Expanded Clay Aggregate (LECA), saw dust, zero-valent iron and gravels can be effectively used as a media for the removal of organic matter, phosphorus, sulphate and arsenate. Constructed wetland with low Hydraulic Loading Rate (HLR) performs exceptionally well and can remove 80%–91% Biochemical Oxygen Demand (BOD), 60%–85% Chemical Oxygen Demand (COD) and 80%–95% Total Suspended Solids (TSS). It requires a very low operation and maintenance than others. This review on constructed wetland further suggests research and development related to land area, media, plants, engineering design and automation of treatment units.
