Separation Of Suspended Solids Research Articles

An amphiphilic flocculant with a lignin core for efficient separation of suspended solids

The synthesis and application of conventional polymeric flocculants suffer from low flocculation efficiency and toxic residues; therefore, there is an urgent need to develop green and efficient flocculants and corresponding technologies. An amphiphilic copolymer (NPL) was synthesized by a “grafting to” strategy, using acrylamide, 3-chloro-2-hydroxypropyltrimethylammonium chloride, and kraft lignin. NPL consists of a lignin core that is attached to a polyacrylamide branched chain and a cationic group, and has the properties of an amphoteric polyelectrolyte. This structure demonstrates superior flocculation performance on suspended solids. Two typical clay suspensions, kaolin and bentonite, were selected to evaluate the flocculation performance of NPL. The results showed that the turbidity of kaolin and bentonite could be reduced to 2.08 NTU and 0.31 NTU, respectively, by using NPL in combination with polymeric aluminum chloride. The synergistic effect of charge neutralization and bridging was confirmed as the main mechanism of flocculation on the two clay suspensions by a series of characterization techniques, such as zeta potential determination, particle size analysis, and focused beam reflectance measurement. The treatment of high-turbidity wastewater/feedwater with NPL was investigated, and was found to significantly improve the effluent quality. The use of NPL is efficient, environmentally friendly, and technically feasible, and shows excellent potential for the treatment of wastewater.

Progress of Ultrafiltration-Based Technology in Ion Removal and Recovery: Enhanced Membranes and Integrated Processes

Toxic ions from industrial wastewater entail important challenges to the environment. Ultrafiltration (UF) with low operation pressure and high permeability has been widely used for macromolecules and suspended solids separation. However, UF cannot be directly used to separate ions from wastewater due to the large pore size of UF membranes. Recently, the design of enhanced UF membrane structures and UF-based integrated processes expands the application of UF for ion removal. This review aims to summarize the latest developments of UF membranes preparation as well as integrated UF processes in ion removal. First, the advanced materials for UF membranes preparation are discussed, with specific attention on active nanomaterials including inorganic materials, organic materials, and biomaterial-based materials. The design principles such as pore size control and composite thin layer fabrication of enhanced UF-based membranes for ion removal are illustrated. Next, integrated processes such as micellar-enhanced UF, polymer-enhanced UF, electro-driven UF, and other UF-based combined processes are reviewed. Finally, current application limitations and future perspectives in the enhanced UF membrane for ion removal are discussed. This review presents potential approaches for the preparation and application of enhanced UF membranes in sustainable ion removal from wastewaters.

High suspended solids removal of Indian drain water with a down-scaled Dissolved Air Flotation (DAF) for water recovery. Assessing water-type dependence on process control variables

The Barapullah drain crosses through New Delhi, India, and transports millions of cubic meters of stormwater, municipal sewage and industrial sewage to the Yamuna River. Seasonal variations and ambiguous annual discharges cause 20-fold fluctuations in hydraulic flows, pollutants type and concentration. Furthermore, New Delhi is among the most densely populated areas on the planet, with limited surface area and high water stress. Dissolved Air Flotation (DAF) units are known to be highly compact, robust, and an efficient suspended solids separation technology that enables further water recovery in a treatment train. Thus, a down-scaled column DAF was designed and used to determine the total suspended solids removal efficiencies, under different influent conditions. Three influents that resemble the Barapullah drain seasonal variations in composition, and a fourth that imitates the feed of DAF when located after an anaerobic bioreactor were tested. A total of 60 batch DAF experiments were completed and used to assess seven independent control variables for DAF operation, which are influent Total Suspended Solids (TSS), pH, temperature, DAF particles residence time, white water pressure, coagulants and flocculants concentration, and coagulation and flocculation time. Results showed that the down-scaled DAF could be steered from low to high removal efficiencies, comparable to full-scale systems. Maximum TSS removal varied between 92 and 96%. The effect and statistical relevance of the different performance variables on the measured separation efficiencies depended on the influent type. All variables, except temperature and pH, had a significant performance effect with a p-value below 0.1, for at least one influent. Pressure had a positive effect on separation efficiency, due to its importance in bubble formation. Moreover, the down-scaled DAF system had low removal efficiency for particles with spherical shapes, and diameters below 10 µm. Based on the high TSS removal for all tested influents, and the effect of the studied control variables, a full-scale DAF could efficiently remove the suspended solids of the Barapullah drain. The unit robustness for different flows and pollutant concentrations, and small footprint, show DAF suitability as part of a treatment train for water recovery, in densely populated areas.

3D-printing has the potential to deliver ceramic membranes with transformational performance gains

In the UK, Evove is working with a company that specialises in 3D printing to develop a way of producing ceramic membranes using additive manufacturing. It says the work marks a milestone in the commercialisation of additive manufacturing of membranes and anticipates it will result in a transformational increase in performance for water purification and suspended solids separation, as this brief focus article reveals.

Denitrification process and suspended solids separation in deep-bed two-media down-flow filters

A denitrification process with simultaneous suspended solids separation and denitrification was studied in pilot-scale filters. Denitrification rates for the total, upper, middle, and lower layer of the filter bed were 21.3, 79.0, 27.8, and 21.9 g (NO3+NO2)-N m−3 filter bed h−1 (g NOx-N m−3 h−1), respectively. The biofilm on the grains showed denitrification rates for not backwashed grains and grains backwashed once of 8.8 and 7.8 g NOx-N m−3 h−1, respectively, indicating a robust biofilm. Construction and operation strategies of full-scale filters were done based on the pilot-scale study results. For further optimization of the denitrification process, 1 of 60 filters in operation was chosen for a full-scale study. The denitrification rates for the total layer, upper layer, middle layers, and lower layer of the filter bed were 12.7, 15.6, 27.3, 27.9, 27.8, and 14.0 g NOx-N m−3 h−1, respectively. The rate of 27.8 g NOx-N m−3 h−1 was obtained for a middle layer in both filters. The amount of nitrogen possible to reduce in the full-scale filters was calculated to 8.8 mg N L−1 or 2403 kg N d−1. This paper presents results of denitrification rates, reaction orders, rate constants, and suspended solids separation.

Model-based analysis and optimization of a full-scale industrial high-rate anaerobic bioreactor.

The objective of this paper is to present the model-based optimization results of an anaerobic granular sludge internal circulation reactor. The International Water Association Anaerobic Digestion Model No. 1 extended with phosphorus (P), sulfur (S), and ethanol is used to describe the main biological and physico-chemical processes. The high-rate conditions within the reactor are simulated using a flow + reactor model comprised of a series of continuous stirred tank reactors followed by an ideal total suspended solids separation unit. Following parameter estimation by least squares on the measured data, the model had a relative mean error of 13 and 15% for data set #1 and data set #2, respectively. Response surfaces show that the reactor performance index (a metric combining energy recovery in the form of heat and electricity, as well as chemicals needed for pH control) could be improved by 45% when reactor pH is reduced down to 6.8. Model-based results reveal that influent S does not impose sufficient negative impacts on energy recovery (+5.7%, in MWh/day,+0.20 M€/year when influent S is removed) to warrant the cost of its removal (3.58 M€/year). In fact, the process could handle even higher S loads (ensuring the same degree of conversion) as long as the pH is maintained above 6.8. Nevertheless, a higher S load substantially increases the amount of added NaOH to maintain the desired operational pH (>25%) due to the acidic behavior of HS - . CO 2 stripping decreases the buffer capacity of the system and hence use of chemicals for pH control. Finally, the paper discusses the possibilities and limitations of the proposed approach, and how the results of this study will be put into practice.

Optimizing electrospinning parameters for piezoelectric PVDF nanofiber membranes

In this study, nanofiber membranes were fabricated using electrospinning to induce piezoelectric properties. Optimization of the piezoelectric properties was achieved using the Taguchi design method to systematically vary the electrospinning parameters (acetone fraction, tip-to-collector distance (TCD), flow rate, and voltage setting). The optimized settings for piezoelectric properties were a solvent ratio of 60 v% DMF/40 v% acetone, a TCD of 16 cm, a flow rate of 0.8 mL/h, and a voltage setting of 14 kV. Additionally, the effect of three solvents (dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide) on fiber formation and piezoelectric properties was compared; dimethylformamide (DMF) created the smallest fiber diameter and highest piezoelectric properties. During filtration of a synthetic solution mimicking biofouling, severe fouling was observed for both the commercial flat-sheet PVDF microfiltration membranes and unactivated electrospun membranes, although fouling occurred at different times for the electrospun membranes fabricated with different solvents. Little to no flux decline or increase in TMP was observed for the piezoelectrically activated nanofiber membranes. Total suspended solids removal of anaerobic digester mixed liquor for the electrospun membranes were comparable to the commercial PVDF microfiltration membrane. The results demonstrate that piezoelectrically activated nanofiber membranes have the potential to mitigate fouling in water treatment applications, particularly for systems with high levels of biofouling that require suspended solids separation (i.e., membrane bioreactors).

The effect of temperature on the efficiency of aerobic biodegradation of sugar beet distillery stillage: Removal of pollution load and biogens

Abstract Beet stillage is a high-strength effluent from the production of ethanol from sugar beet. A large annual volume of sugar beet stillage requires finding new effective ways for its utilization. The aim of the study was to investigate the effect of temperature on the efficiency of aerobic biodegradation of beet stillage. Biodegradation was carried out for 168 hours in a stirred-tank reactor with a working volume of 5 L at 27°C, 36°C, 45°C, 54°C and 63°C. All experiments were performed at uncontrolled pH, aeration of 1.0 vvm and of 900 rpm. The effectiveness of biodegradation was determined by the extent of removal of SCODsum (COD determined after suspended solids separation and theoretical COD of betaine), BOD5 and TOC. Studies have shown that, under mesophilic conditions, the extents of reduction of SCODsum, BOD5 and TOC were statistically significantly (p≤0.05) higher than under thermophilic conditions. Within the range of 27-36°C, the highest reduction in SCODsum (79.2-79.9%), BOD5 (98.4-99%) and TOC (76.1-77.3%) was obtained. Additionally, at the temperature of 36°C, the highest reduction in total nitrogen (56.4%) and total phosphorus (58%) was achieved. Aerobic biodegradation allows for efficient treatment of sugar beet distillery stillage (preferably at 36°C).

Efficiency of aerobic biodegradation of beet molasses vinasse under non-controlled pH: conditions for betaine removal / Efektywność tlenowej biodegradacji buraczanego wywaru melasowego przy nieregulowanym pH podłoża: określenie warunków usunięcia betainy

Abstract The aim of the study was to establish such conditions that would provide high-efficiency aerobic biodegradation of beet molasses vinasse with a mixed culture of thermo- and mesophilic bacteria of the genus Bacillus in batch processes without controlling the pH of the medium. Particular consideration was given to the betaine removal (the main pollutant of vinasse), which accounted for as much as 37.6% of total organic carbon. Biodegradation was performed in a stirred tank reactor at 27-63°C with initial pH (pH0) of 6.5 and 8.0. Efficiency of biodegradation was expressed in terms of reduction in SCODsum, which is a sum of SCOD (soluble chemical oxygen demand, i.e. COD determined after suspended solids separation) and theoretical COD of betaine. The values achieved at 27 and 36°C with pH0 = 8.0 exceeded 77.7%, whereas those obtained at 36 and 45°C with pH0 = 6.5 were higher than 83.6%. The high biodegradation efficiency obtained in the four processes is attributable to the betaine removal by the bacterial strains used in the study. Maximal extent of reduction in SCODsum (85.41%), BOD5 (97.91%) and TOC (86.32%), and also the fastest rate of biodegradation (1.17 g O2/l∙h) was achieved at 36°C and pH0 = 8.0

Permeability of porous ceramic based on calcium carbonate as pore generating agent

This study concerns the processing and characterization of porous ceramics based on low cost mineral raw materials for environmental applications. Three formulations were tested with calcium carbonate as pore generating agent and different proportions of kaolin, potassic feldspar, albite, quartz and white clay. Ceramic bodies were formed by pressing, heat treated up to 1180°C and characterized for porosity, flexural strength, air permeability and microstructural aspects. The resulting bodies displayed apparent porosity (28–32%), flexural strength (7–29MPa), permeability coefficients (k1≅10−15m2 and k2≅10−11m) and average pore size (0.706–1.137μm) suitable for membrane separations. The formulation containing 50% kaolin, 20% limestone, 10% potassic feldspar, 10% albite and 10% quartz (dry basis) was considered the most suitable for separation of suspended solids from liquid suspensions (microfiltration).

A New Protocol for the Analysis of Pharmaceuticals, Pesticides, and Hormones in Sediments and Suspended Particulate Matter From Rivers and Municipal Wastewaters

We developed a protocol to quantify 12 emerging contaminants (ECs) (pharmaceuticals and hormones) and pesticides extracted from suspended particulate matter (SPM) of river water and municipal wastewaters samples as well as river sediments. The separation of suspended solids was realized using filtration of water samples. We tested a series of six different filter types. The effect of filtration on the concentrations of dissolved contaminants was evaluated to minimize losses of target compounds. The river sediment samples were lyophilized, and both SPM and sediment samples were subjected to ultrasonic extraction combined with C18 cartridge clean-up. Quantifications were realized using mass spectrometry. The method recoveries of all compounds ranged from 38 to 112 % in all studied matrices; poorer recoveries were achieved for sulfamethoxazole and diclofenac (as low as 38 %), whereas the recoveries for all other compounds in the wastewater treatment plant (WWTP) samples were between 68 and 111 %. The detection limits in sediments and SPM from river samples for the 12 analytes varied from 0.7 to 9.4 ng g(-1) and from 21 to 92 ng g(-1) for WWTP SPM samples. All targeted ECs were detected with concentrations ranging from 3 to 5,440 ng g(-1) in the studied matrices with the highest concentrations observed in WWTP SPM samples. A significant portion of the contaminants in a water sample is clearly associated with the suspended particulates. Optimization of water-treatment processes and environmental fate must absolutely consider the fraction of contaminants that is particulate-bound if one hopes to have a reasonable mass balance.

Submicron capsules extracted from rapeseed as novel flocculant agents for the treatment of turbid water

Flocculation is an important step in water treatment as it is responsible for the separation of suspended solids and colloids. The currently used flocculants have certain limitations with respect to environmental impact and disposal as well as potentially being harmful to human health, which has encouraged the study of natural flocculants originating from oleaginous plants. Oil-bodies are individual small organelles in which oleaginous seeds store triacylglycerols reserves. In this article, the flocculant properties of oil-bodies have been investigated. Oil-bodies flocculate at pH 5, 7 and 9 and high ionic strength (100 mM NaCl) and it was demonstrated that their intact structure is necessary for the flocculation activity as treatment with protease K and diethyl ether, that remove the protein coat and the oil-core, respectively, dramatically decreased the flocculation activity. This study shows that oil-bodies have the potential to be novel, natural, sustainable, environmentally friendly and biodegradable flocculant candidates for water treatment.

Investigation of residence time distribution and local mean age of fluid to determine dead-zones in flow field

Residence time and local mean age of flare important parameters of the fl uid fl ow, with which we are able to detect the functioning and non-functioning zones. It is a novel approach to estimate the effect of dead-zones on chemical and biological processes. In this paper, we introduce a numerical tracer study, which is calibrated by fi measurements and which is applied in different cases such as settling tank and aeration tank of wastewater treatment. Using an advective-diffusive passive scalar transport equation, the age of the fl uid can be calculated. It also shows the short-circuits and dead-zones of the fl uid and this corresponds with our observations. This method helps eliminate potential hydraulic problems at the early stage of design. Settling tanks in the wastewater treatment have a key role in the separation of suspended solids and sludge fl ocks. The design of these tanks is based on the ATV-A131 standard (1), which takes into account only the global parameters of the fl ow, e.g. average residence time, but in many cases the inequalities inside the tank may have serious effect on effl uent quality. In this paper, we are fi rst and foremost interested in the detection of dead-zones, where the mixing is adverse due to low velocity, high residence time and fl uid age. In aeration tanks, for example, anaerobic zones may develop because microorganisms consume the oxygen. There is mass transfer between the fl ow and dead-zone because of the presence of turbulence; how- ever, this is much less than the effect of convective transport. On the other hand, hydraulically inactive zones are redundant and these increase the cost of operation. Computational fl uid dynamics is widely applied in wastewater treatment tank design (2-4)) because with the knowledge of hydraulic phenomena, the understanding of biochemical processes could be improved. One signifi cant linking parameter between the hydraulics and biology is residence time; therefore, it is essential to know the precise value for every point. Residence time dis- tribution (RTD) can be measured experimentally (5). In pulse experiment, the tracer is mixed in a small volume of fl which is introduced to the reactor in a very short time interval (Dirac-delta function) and the response function is measured at the outlet. The tracer should be a conservative material without any background concentration of the wastewater. The response function shows the changes in tracer concentration in the course of time, from which we can estimate the hydraulic behavior of the tank. RTD calculations can be performed numerically, and they can be compared to the results of the fi eld measurement. This paper deals with circular fl ow reactors, one aeration tank and one radial fl ow settling reactor. The fi rst is designed as a fully mixed reactor, but the RTD investigation demonstrated that there is a short-circuit, where the nutrients could fl ow through the reactor rapidly and did not have enough time for biodegradation. Circular radial fl ow settling tanks generally have problems with short-circuiting and the wind also could have an infl uence on the fl ow regimes.

Technologies Used in the Wastewater Treatment for Nutrient Removal

In this paper will be showed some techniques employed effectively in wastewater treatment for nutrient removal. The results concerning biological phosphorus and nitrogen removal, from an anaerobic expanded bed reactor (AEBR), treating domestic wastewater, in an Intermittent Aeration Reactor (IAR) followed by dissolved air flotation (DAF); aiming to remove chemical oxygen demand (COD), nitrogen and phosphorus on the same unit. The DAF was used for separation of suspended solids. Conditions to obtain nitrification were assessed, denitrification and phosphorus removal in a reactor operated with alternate aerobic and anaerobic periods. The intermittent aeration system was operated with hydraulic detention time (θh) of 8 hour and 6 hours. The system with intermittent aeration (θh:6hr) showed stable results and presented average COD removal of 92% (90 to 94%) and average phosphorus removal of 90% (82 to 96%). For hour detention time, the average orthophosphate (PO4 -3-P) removal was: 84% (60 to 94%) for raw samples and 94% (60 to 98%) for filtered samples (filter: 0.45 µm). Neither the use of the external carbon source nor pH correction was necessary.

Pilot-scale studies on the treatment of tannery effluents by electroflotation

A pilot-scale electroflotation system with a treatment capacity of 0.8 m³ per hour has been designed and built. The system is equipped with a conditioning tank, a rectifier, flow meters, an energy meter and pumps. Iron, aluminium and titanium coated with oxides of tantalum, ruthenium and iridium were used as electrodes. The system was installed within the premises of the Common Effluent Treatment Plant (CETP), which receives effluents from nearly 200 tanneries. The effectiveness of electroflotation for the separation of suspended solids, sulphur species, chromium and other chemicals contributing to COD and BOD were studied. The separation of suspended solids and chromium by electroflotation was nearly complete (>95%) and their concentration in the processed samples can be maintained well below the discharge limits. The removal of COD was observed to be 15?20% greater than with conventional chemical coagulation. Furthermore, the entire spectrum of pathogenic bacteria was eliminated to the extent of 99.97% by subjecting the effluent to electroflotation.

Combination of computational techniques - evaluation of CSO efficiency for suspended solids separation

During the last two decades, the use of simulation models has played an increasingly important role in the evaluation of the dynamic behaviour of sewer systems. One of the basic characteristics of these models is the number of dimensions taken into account during simulation. This paper demonstrates the benefits of the combination of two models with a different number of dimensions included. The evaluation of separation efficiency of suspended solids in the combined sewer overflow (CSO) was the basic objective of the project. Two simulation models have been used for the evaluation. The 1D model output was the CSO inflow hydrograph, which was used as an input for the 3D model. With the help of the 3D model, the water flow inside the CSO was simulated. This paper includes the results of case study documenting the proposed methodology. Charts of concentration dynamics of suspended solids on the CSO inflow, outflow and overflow are presented (for particles with different characteristics).

SOLID–LIQUID SEPARATION OF FLUSHED SWINE MANURE WITH PAM: EFFECT OF WASTEWATER STRENGTH

Organic polymers are useful to increase separation of suspended solids and reduced carbon compounds from liquid swine manure. Along with the solids, there is a capture of the nutrients associated with small particles typical of these wastes. The combined effect increases the amount of materials available for value–added products, reduces the size of process units necessary to treat the liquid, and provides needed alternatives to land application. In this work, we evaluated the effect of solids strength typical of flushing systems on optimum polymer dose requirement and chemical use efficiency. Seven flush samples of varied strength were obtained two weeks apart during a three–month period in a feeder–to–finish operation (22.7 to 100 kg weight) in Bladen County, North Carolina. Treatments consisted of eight rates (0 to 140 mg L–1) of polyacrylamide (PAM) followed by screening. Manure samples were characterized for solids, nutrients, and oxygen–demanding compounds amenable for separation. Their concentration varied greatly: 0.4% to 2.5% total solids (TS), 0.1% to 1.6% total suspended solids (TSS), 5.9 to 31.3 g L–1 chemical oxygen demand (COD), 0.7 to 10.6 g L–1 biochemical oxygen demand (BOD5), 749 to 2442 mg total Kjeldahl (TKN) L–1, and 96 to 585 mg total phosphorus (TP) L–1. About 87% of P and 45% of N were organic forms, and 80% of TSS were volatile (VSS). Separation by screening alone was not effective; efficiencies were <20% TSS and VSS, <10% COD and BOD5, and <15% N and P. Mixing with PAM before screening substantially increased separation; efficiencies using 140 mg L–1 rate were 95% TSS and VSS, 69% COD, 59% BOD5, and 67% carbonaceous BOD5. Inorganic P and N were not reduced by treatment. However, PAM significantly enhanced removal of both organic P and N (92% and 85%, respectively). For every 100 g of TSS removed, there was a 1.32–g reduction of COD, 3.32–g reduction of organic P, and 7.26–g reduction of organic N. The N:P nutrient ratio was improved from 4.79 to 12.11, resulting in a more balanced effluent for crops. It was more economical to treat flushed manure with the higher strength. Changes in optimum PAM rate were small (70 to 110 mg L–1) and, consequently, polymer usage rate based on solids produced decreased significantly (from 5.34 to 0.75 g PAM/100 g dry solids separated) with increased wastewater strength. Therefore, reduction of total water volume to clean the houses can result in significant savings (about 700%) in total polymer cost. Chemical cost to capture 95% of the suspended solids was estimated to be $1.37 to $1.27 per finished pig for liquid waste containing 2% to 2.5% TS, respectively. Our results indicate that PAM technology can be enhanced for better liquid manure handling systems and associated management of nutrients.

Retention of Pesticides in Filter Membranes

AbstractThe objective of this work was to determine the retention of pesticides in membrane filters used for the separation of suspended solids from solutions. Five types of filter materials were tested: cellulose acetate, nylon, polyethersulfone, polyvinylidene fluoride (PVDF), and polytetra‐fluorethylene (PTFE). Five aqueous solutions of pesticides with initial concentrations of 9.5 μg/L were studied: atrazine (6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine), isoproturon (3‐(4‐isopropylphenyl)‐1,1‐dimethylurea), mecoprop ((RS)‐2‐(4‐chloro‐o‐tolyloxy)‐propionic acid), 2,4‐D ((2,4‐dichlorophenoxy)acetic acid), and bentazone (3‐isopropyl‐1H‐2,1,3‐benzothiadiazin‐4‐(3H)‐one 2,2‐dioxide). Detectable losses of pesticides were measured on all the tested filter materials. Cellulose acetate filter, nylon filter, and polyethersulfone filter retained between 3 and 90% of all five tested pesticides. On PVDF filter and PTFE filter the retention was limited, as only two (isoproturon and mecoprop) out of five pesticides was retained with a maximum retention of 4.2% for isoproturon on the PVDF filter. In the present study no correlation between retention by filters and pesticide solubility in water was observed. The results also demonstrate that pesticides with relatively high solubility and low octanol‐water partition coefficient (Kow values) can be strongly retained by synthetic filter materials.

Operational and control practices to improve the performance of small wastewater treatment plants in Catalonia

Observations during routine wastewater treatment plants (WWTP) controls in Catalonia suggest that in small Activated Sludge (AS) plants suspended solids separation problems could reach a special intensity. In order to evaluate their incidence, filamentous scums, clarifier floating solids, rising sludge, deflocculation and bulking incidences occurring in 34 small WWTP were controlled for a year. To improve the efficiency of these plants, analyses of mainly suspended solids separation problems were systematically performed.

Field testing CFD-based predictions of storage chamber gross solids separation efficiency

The use of computational fluid dynamics-based techniques for predicting the gross solids and finely suspended solids separation performance of structures within urban drainage systems is becoming well established. This paper compares the result of simulated flow patterns and gross solids separation predictions with field measurements made in a full size storage chamber. The gross solids retention efficiency was measured for six different storage chambers in the field and simulations of these chambers were undertaken using the Fluent computational fluid dynamics software. Differences between the observed and simulated flow patterns are discussed. The simulated flow fields were used to estimate chamber efficiency using particle tracking. Efficiency results are presented as efficiency cusps, with efficiency plotted as a function of settling velocity. The cusp represents a range of efficiency values, and approaches to the estimation of an overall efficiency value from these cusps are briefly discussed. Estimates of total efficiency based on the observed settling velocity distribution differed from the measured values by an average of ±17%. However, estimates of steady flow efficiency were consistently higher than the observed values. The simulated efficiencies agreed with the field observations in identifying the most efficient configuration.