Hydraulic Flocculation Research Articles

Field Approach on the Effectiveness of Hydraulic Flocculator Followed By Sedimentation and Rapid Sand Filter

This research investigates the effectiveness of a hydraulic flocculator at the Kalanki Groundwater Treatment Project-Sipradi in Kalanki-Kathmandu. Hydraulic flocculation is a cost-effective alternative to mechanical flocculation, particularly beneficial for developing nations. The study involved determining the optimal Poly Aluminium Chloride (PACl) dosage through Jar Testing and assessing the flocculator's efficiency in the field with this dose. The research also analyzed other treatment units under various PACl doses to evaluate the Water Treatment Plant's operational conditions and the required PACl dose for efficient turbidity removal. The system included components like a deep well source, V-Notch weir tank, hydraulic flocculator, sedimentation tank, rapid sand filter (RSF), chlorinator, and clear water reservoir, with a 16-minute flocculator detention time. Baffle walls were strategically positioned at various intervals on-site. The study revealed that while sedimentation with coagulation achieved peak efficiency at a PACl dose of 80mg/l, it was less efficient than a 16-minute jar detention, likely due to sedimentation tank short-circuiting. Increasing the PACl dose from 20 mg/l to 80 mg/l improved overall unit efficiency, indicating the need for more mixing energy in the existing flocculator length for optimal results. The filter unit's efficiency remained consistent, whether with or without coagulation, at 57.69% and 54.10%, respectively. These results emphasize the importance of further investigation to enhance water treatment processes and coagulant dosages for improved effectiveness in this critical field.

Machine-learning based multi-objective optimization of helically coiled tube flocculators for water treatment

The limitations of water resources and their importance for human life necessitates special attention to water purification processes. Here, the flocculation process, in which unstable particles aggregate, have been considered. In particular, we focused on helically coiled tube flocculators (HCTFs), which have certain advantages over conventional hydraulic flocculators. The simulation of the flocculation process in HCFTs has been done using the computational fluid dynamics (CFD) to study the effect of different geometrical and hydrodynamic variables on the performance of HCTFs. Small variations of velocity gradient, Gˆp95, and particle’s residence time, MI, are considered as the performance parameters. CFD results show that the design variables can change the performance parameters up to 60% and 40%, respectively. Using CFD for the training of machine-learning regression models, multi-objective optimization of HCTFs is performed. Our results show that a helical pipe with the diameter of 8.35 mm, curvature radius of 42.5 mm, helical pitch of 62.1 mm, and flow rate of 1.08 L min−1 provides the best performance among the range of input variables, where both performance parameters are minimum. Moreover, it was shown that the optimum results can be generalized to other scales with less than 2% difference in outputs by using equal non-dimensional groups.

On the design of compact hydraulic pipe flocculators using CFD-PBE

Designing a compact hydraulic pipe flocculator is a common challenge for various water purification and wastewater processes where space is limited. Various geometrical parameters are analysed to identify the most important parameters when designing an efficient system for a Reynolds number of ReD = 20, 000. A coupled CFD-PBE model is applied to a total of 123 geometrical configurations to simulate particle aggregation and breakage due to the local velocity gradients in the configurations. The shear present in the 90∘ pipe bends is the dominating factor in the final aggregate size and therefore the most important geometrical factor is the bend radius. Secondly, it is observed that the primary length, L1, has the second-largest impact as a linearly increasing particle diameter is observed along the straight pipe. Helically coiled geometrical configurations with no straight sections, L1 = L2 = 0, and a bend radius of rb≥ 2dh result in large particles as a constant but moderate cross-sectionally averaged turbulent energy dissipation is observed throughout the pipe. The largest volume-averaged particle size is observed for a configuration with a primary length of L1 = 20dh, a secondary length of L2 = 0 and a bend radius of rb = 2.5dh.

Selection of Unit Design for Teluk Buyung 4 Water Treatment Plant (WTP), Bekasi City, West Java, Indonesia

The city of Bekasi is experiencing rapid development so the demand for water is increasing. To increase service coverage and meet the drinking water needs of the people of Bekasi City with a quality that meets the Minister of Health Regulation No. 492 of 2010, it is planned to up rate the capacity that the Teluk Buyung 4 WTP has a capacity of 300 L/second with a raw water source, namely the West Tarum Secondary Channel. The Teluk Buyung 4 WTP is planned to use the design criteria from the Equivalent WTP evaluation, namely Teluk Buyung 3 WTP and literature studies. Teluk Buyung 4 WTP uses processing units, intake unit, hydraulic coagulation, hydraulic flocculation, plate settler sedimentation, rapid sand filtration, disinfection, and reservoir. The data used in the planning process is divided into two, namely primary data and secondary data. The intake unit has several components, namely a barscreen, sluice gate, carrier channel, and collecting well. The pre-sedimentation unit consists of 2 tanks and is channeled to a collection well and then pumped to the WTP. The coagulation unit uses hydraulic coagulation with a plunge of 1 tub. The coagulant used was PAC at a dose of 25 mg/L. The flocculation unit uses hydraulic flocculation with up and down flow with 2 tubs. The sedimentation unit uses a plate settler with 2 tanks. The filtration unit uses a rapid sand filter with dual media, namely anthracite media and sand media and has 7 tubs. Disinfection process uses NaOCl with a dose of 41.67 mg/L. The reservoir unit uses 1 tub with a ground reservoir type.

ANALISIS MULTI KRITERIA DALAM PEMILIHAN UNIT PENGOLAHAN AIR IPA CIAWI, KECAMATAN MEGAMENDUNG, KABUPATEN BOGOR

To increase service coverage and meet the increasing demand for drinking water, PDAM Tirta Kahuripan plans to build a Ciawi WTP in Megamendung District with a processing capacity of 165 L/second using the Sukabirus River as a raw water source. The purpose of this study was to determine the processing units in the design of the Ciawi WTP using multi-criteria analysis. Based on the results of the analysis of raw water quality, there were several parameters that do not meet the drinking water quality standards according to the Minister of Health Regulation No. 492 of 2010 and PPRI No. 82 of 2001, namely turbidity, Fecal coliform, total coliform, TSS, BOD, COD, and DO. There were three alternative processing circuits used. Alternative I consists of intake, hydraulic coagulation, up-down flow hydraulic flocculation, plate settler sedimentation, rapid sand filtration, disinfection, and reservoir. Alternative II consists of intake, hydraulic coagulation, vertical-shaft paddle wheel mechanical flocculation, tube settler sedimentation, rapid sand filtration, disinfection, and reservoir. Alternative III consists of intake, in-line static mixers coagulation, horizontal-shaft paddle wheel mechanical flocculation, plate settler sedimentation, rapid sand filtration, disinfection, and reservoir. There are other factors that must be considered in the selection of treatment units, namely contaminant removal, reliability, flexibility, construction, land requirements, ease of operation, maintenance, cost, and environmental compatibility. Based on multi-criteria analysis, the percentage of suitability for alternative I is 78%, Alternative II is 63%, and Alternative III is 48%. From this assessment, it can be said that alternative I is the best alternative.

Design Algorithm for Vertically-Baffled Flocculators

To date, design guidance for hydraulic flocculators has been limited, with several articles focusing on the design of horizontally-baffled flocculators. In this article, a design algorithm for vert...

An Approximate Method of Determining the Velocity Gradient in Spiral Flocculation (Dept.C)

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Experimental investigation and modelling the effect of humic acid on coagulation efficiency for sludge blanket clarifier

The physicochemical process of coagulation has largely been used for turbidity removal for water treatment. However, lately, the intrusion of NOM (Natural organic matter) in the surface water sources due to climate change has impeded the dosing approaches and has presented a requirement to evaluate the effect of NOM on turbidity removal efficiency and the performance of coagulation reactors in general. In this work, a previously developed performance model for hydraulic flocculators was modified and tested for a sludge blanket clarifier (SBC) which is a type of hydraulic flocculator. The experimental runs were conducted by preparing synthetic sample waters by using humic acid (for NOM) and kaolin clay (for turbidity). PACl (Poly aluminium chloride) was used as a coagulant. The expression of attachment efficiency has been modified to include the interactions of humic acid (HA) and kaolin, which were not previously accounted for in the model. The coverage functions were used to calculate the attachment efficiency of HA-PACl and PACl-Clay. The standalone coverage function ГPACl-HA efficiently predicted the doses where the removal efficiency was maximum. However, the coverage function ГClay-PACl was impacted by the hydrodynamic conditions in SBC and over-speculated the Clay-PACl interactions. The RMSE value was low for the modified equation indicating that in SBC the interactions between the organic and inorganic impurities are significant. The HA-Kaolin interactions were found to be significant in the modified model in case of a low HA range of 4 and 8 mg/L of HA.

Removal of antibiotic-resistant bacteria (ARBs) by ultrafiltration membranes for Nervión river water potabilization

Ultrafiltration membranes associated with in-line coagulation and hydraulic flocculation were applied for antibiotic-resistant bacteria removal during Nervion river water potabilization. The study was conducted at pilot scale with an ultrafiltration module equipped with three hollow fibre polyvinylidenefluoride membranes (0.04 μm nominal pore size) with in-line precoagulation–flocculation. The system operated continuously with constant dose of 20 mg FeCl3/L and a stable production of 50 L/h (18.5 lmh), operating in vacuum. All physico-chemical water quality parameters analysed improved, but the yields were variable, highlighting the low capacity to remove organic matter, with a significant influence of influent concentration. A high capacity to retain bacteria was observed for ultrafiltration membranes with total absence of several faecal indicators in the effluent, but the presence of total aerobic bacteria and occasionally faecal coliform or even E. coli strains casts doubt on the microbiological quality of the treated water. Most of the isolated strains in effluent samples were antibiotic-resistant bacteria with a significant percentage of multi-antibiotic-resistant bacteria, which increase the one observed for the isolated strains from influent. Antibiotic-resistant bacteria to β-lactams, macrolide and the cotrimoxazole antibiotic groups were frequently detected in effluent samples.

Evaluation at Cibinong Water Treatment Plant (WTP) in Bogor District

Cibinong WTP using raw water sources from the Ciliwung River. Processed water from the Cibinong WTP serves 5 sub-districts, namely, Tajur Halang, Bojong Gede, Cibinong, Babakan Madang and Citereup districts. The research covered raw water quality, evaluation of the existing WTP condition and optimization of work of operation unit and process. Cibinong WTP consist of unit intake, hydraulic coagulation, hydraulic flocculation, sedimentation plate settler, rapid sand filtration, and ground reservoir. The coagulant used is 5% alum with a dose of 25 mg / L and disinfectants that use liquid gas and chlorine at a dose of 1.4 mg / L. Specifications for installation of drinking water installations use standards that are in accordance with SNI 6774 in 2008 concerning procedures for processing plant package units. Water quality in accordance with the Minister of Health Regulation 492 of 2010 concerning drinking water quality requirements. Cibinong WTP has several units that have not met the 2008 SNI 6774 standard but, the quality of the water already in accordance with the regulation of Minister of health no 492/2010.

Treatment of performance evaluation at Cisauk water treatment plant, Cisauk Sub-district, Tangerang

Cisauk Water Treatment Plant (WTP) is one of the water treatment plants operated by PDAM Tirta Kerta Raharja, Tangerang District, which supply drinking water for Sub districts of Cisauk and Suradita with a capacity of 50 L/sec. This research conducted to evaluate the treatment performance of each unit at Cisauk WTP and compare the quality of water produced with the drinking water standard of PERMENKES No. 492 of 2010. Evaluation of WTP process is conducted by analysing the quantity and quality of produced water, and then calculate of design parameter for each unit. The processing unit consists of intake, hydraulic coagulation, hydraulic flocculation, sedimentation, filtration and ground reservoir. The coagulant used was NUSACHEM with dose of 35 mg/L and the disinfectant used was gas and liquid chlorine with dose of 3-5 mg/L. Through the WTP evaluation of treatment, not all units fulfil the design criteria based on SNI 6774 of 2008. However, the quality of the water produced fulfil the drinking water quality requirements of PERMENKES No. 492 of 2010.

The Use of Multi-criteria Analysis in Selecting Water Treatment Units in Sadu Water Treatment Plant, Bandung District, West Java Province, Indonesia

Abstract: Increasing the number of residents and still not fulfilling the scope of drinking water services for resident of Bandung Regency, Tirta Raharja Regional Water Supply Company is developing in the field of drinking water supply. To improve community drinking water services in the Bandung Regency area, Tirta Raharja Water Supply Company plans to add a drinking water tratment plant with a capacity of 150 liters/second located in Sadu Village, Soreang District, Bandung Regency. In the planning of the Sadu WTP (Sdau Water Treatmnet Plant) was carried out several stages of planning, i.e. literature study, preliminary survey, data collection, alternative selection of treatment units using multi criteria analysis, and calculation of treatment unit dimensions. the parameters under review are those that exceed the standard of quality according to the Minister of Health Regulation No. 492 of 2010, i.e. turbidity, BOD, COD and fecal coliform. The selection of Sadu WTP units is based on parameters that exceed drinking water quality standards. There were two alternative proposed (Alternative I and Alternative II) in drinking water treatment, i.e. complete unit (Alternative I) consisting of intake; hydraulic coagulation; hydraulic flocculation; tube settler sedimentation; rapid sand filter; reservoir; disinfection; and sludge drying bed, and slow sand filter unit (Alternative II) consisting of intake, pre-sedimentation, slow sand filter, reservoir, disinfection, and sludge drying bed. The method to be used in determining the unit plan is multi-criteria analysis which refers to aspects based on Minister of Public Works Regulation No. 18/PRT/M/2007. Based on the results of the scoring obtained, the complete treatment unit has the highest score, i.e. 4.05, so the alternative treatment used in the Sadu WTP is the complete treatment unit (Alternative I).

Mathematical modelling and analysis of the flocculation process in low retention time hydraulic flocculators

This article aims to advance the understanding of particle interactions in low retention time flocculators and proposes a new flocculation model that appropriately considers the influence of retention time in flocculation processes. This consideration is important for units with flocculation time lower than 1 min, as seen in helically coiled tube flocculators (HCTFs), whose retention time is significantly lower than conventional flocculation units (about 30 min). With this, it was possible to obtain a more adherent model, reducing deviations between results obtained by physical modelling (using HCTFs, 48 tests) and those obtained with the proposed model, when compared with results obtained using the flocculation models commonly used for this purpose. The decreasing-rising behaviour presented by experimental data for process efficiency versus retention time, not verified in the benchmark models, was satisfactorily addressed by the proposed model. Furthermore, maximum and average absolute percentage deviations obtained using the model proposed in this study were less than or equal to the results obtained with the benchmark models and less for experimental uncertainty (10%). The results obtained indicate that this model can be a useful tool to support the rational design of low retention time units, including applications for the water industry and water recycling systems.

Optimal design parameters for hydraulic vertical flocculation in the package surface water treatment plant

After 2003, hundreds projects were completed to provide drinking water to rural areas in most governorates in Iraq. These projects consist of the package water treatment plant, which treats surface water from the Tigris and Euphrates rivers. All the package water treatment plant contains a mechanical flocculators, which suffers from continuous faults and needs periodic maintenance and needs electric energy to operate, which leads to an increase in the cost of water production and lack of quality of water produced. In this project, the possibility of changing the type of flocculators from mechanic to hydraulic was tested for a 100 m3·h–1 package water treatment plant in the Al-Eskan water treatment project in the south of Diwaniyah city in Iraq. There are many challenges facing the design involving findings ways to improve the effi ciency of the flocculation system. Computational Fluid Dynamics (CFD) package, ANSYS Fluent 16.1 software have been used to simulate turbulent fluid flow in hydraulic flocculators for Al-Eskan package water treatmen plants (EPWTP). The flocculator simulations in ANSYS Fluent are used to obtain turbulent kinetic energy dissipation rate to determine the distance between baffles, the quantity of baffles, velocity gradient, residence time, and flocculation performance. The results obtained from ANSYS Fluent simulation are used in designing a hydraulic flocculator, so our finding can be utilized to validate the hydraulic flocculator model. The results confi rmed that the method used to design certain parameters of the tank are fairly accurate. Overall the design of the flocculation tank produced reasonable results which match expected results of hydraulic fl occulation tanks found in literature. The results of the report suggest that a height to baffl e spacing ratio of 22.5 creates intersecting energy dissipation regions that produce the greatest formation of fl ocs per reactor volume.

A Hydrodynamic and Surface Coverage Model Capable of Predicting Settled Effluent Turbidity Subsequent to Hydraulic Flocculation

Abstract A widely applicable hydraulic flocculator design model would facilitate increased adoption of this sustainable technology. To this end, the authors previously proposed rate equations for t...

ANÁLISIS Y DISEÑO ASISTIDO POR CFD DE FLOCULADORES HIDRÁULICOS

In water treatment processes, the hydrodynamic behavior in a flocculation unit is critical in order to achieve flocs with appropriate characteristics that allow their subsequent separation. In this contribution computational fluid dynamics (CFD) was used to investigate the flow characteristics of a Cox type hydraulic flocculator at the water purification plant in Viterbo, Colombia. In order to improve the original design, the effect of the windows configurations and the inlet volumetric flow was investigated. For the configurations performance assessment, the local velocity gradient and residence time distribution were calculated. The simulation results indicate that the window position have a considerable effect on the velocity gradient and retention time distribution, while the number of windows showed a negligible effect on the retention time. It was possible to decrease the local gradient mean error between $10$ and $20 \%$ by employing $2$ windows instead of $1$. The best hydraulic performance was obtained by locating the windows horizontally aligned and using $2$ windows between chambers. These results are encouraging to systematically improve the plant design thus performance.

Numerical simulation and experimental study of electrocoagulation grid flocculation tank.

In recent years, electrocoagulation has been extensively studied on the removal of refractory pollutants. However, the application of electrocoagulation in actual flocculation tank is limited because of its high energy consumption, especially under the condition of large electrode plate spacing. In this study, the computational fluid dynamics (CFD) software - ANSYS Fluent had been used to simulate the flow state of grid flocculation tank, for the purposes of optimizing the design parameters. The simulation results showed that vortex velocity gradient was stronger, the grid plate spacing was smaller when the velocity was 0.13 m s-1, perforation size was 25 × 25 mm, porosity was 31.25%. And the optimal grid plate spacing was 250 mm. Moreover, in order to prove the reasonableness of simulation results, the humic acid wastewater was treated by electrocoagulation process in the specific device which was built based on simulation results. The results showed that the optimal condition of orthogonal test were as follows: the initial pH was 8, the concentration of sodium chloride was 5 mmol L-1, the voltage was 15 V; and the power time was 60 min. This study greatly narrowed the grid plate spacing, optimized design parameters under the circumstances of strong turbulent intensity and provided a theoretical basis for the combination of electrocoagulation and hydraulic flocculation.

Revisiting Coiled Flocculator Performance for Particle Aggregation.

This work summarizes recent studies evaluating the torsion and curvature parameters in flocculation efficiency using a hydraulic plug flow flocculator known as a Flocs Generator Reactor (FGR). Colloidal Fe(OH)3 and coal particles were used as suspension models and a cationic polyacrylamide was used for the flocculation. The effectiveness of the aggregation process (in the distinct curvature and torsion parameters, and hydrodynamic conditions) was evaluated by the settling rate of the Fe(OH)3 flocs, and flocs size by photographic analysis. As a result of curvature, a secondary flow is induced and the profiles of the flow quantities differ from those for a straight pipe. Results showed that the differences in the flocculator design influences the Fe(OH)3 flocs size and settling rates, reaching values of about 13 and 4 m/h, for the coiled and straight pipes respectively. Coal flocs generation was also shown to be dependent on the flocculator design and shear rate. Results showed that turbulent kinetic energy increases because of curvature when the torsion parameter is kept constant (pitch close to zero), enhancing the flocs formation.

Revisiting Hydraulic Flocculator Design for Use in Water Treatment Systems with Fluidized Floc Beds

In water treatment, flocculation creates aggregated particles or flocs large enough to be removed by downstream processes of sedimentation and filtration. Fluidized beds of flocs (floc blankets) are sometimes included in upflow sedimentation processes because they can significantly improve sedimentation tank particle removal when plate or tube settlers are used. Overall performance of a sedimentation tank containing a floc blanket is influenced by the characteristics of incoming flocs from the flocculator. Floc blankets provide an additional opportunity for aggregation of colloidal particles that enables a reduction in the size of the flocculators, while improving particle removal efficiency. In this study, laminar flow flocculators varying in velocity gradient (G) and residence time (θ) were tested in a laboratory scale water treatment system with a floc blanket. Results indicate that increasing G (range of 74–251 s−1), while decreasing residence time from 269 to 80 s, and maintaining a constant Gθ (∼20,000) improved particle removal. These results indicate that velocity gradients greater than existing design recommendations may be used to reduce flocculator residence times (and associated construction costs) when upflow sedimentation with a floc blanket and overlying lamellar plate or tube settlers are employed subsequent to flocculation. Further reduction of the residence time to 24 s with a G of 251 s−1 resulted in a settled water turbidity of 14 nephelometric turbidity unit (NTU). When varying θ at a constant G of 72 s−1, an apparent minimum in settled effluent turbidity at 0.15 NTU was observed at the middle residence time tested (θ = 211 s), suggesting that long hydraulic flocculator residence times may be suboptimal.

Theoretical Foundation and Test Apparatus for an Agent-Based Flocculation Model

Abstract A predictive, mechanistically based performance model for hydraulic flocculation could potentially enable improved design for hydraulic flocculators. Such a model would take characteristics of the flocculator and the suspension as inputs so that designers and operators could rationally consider effects of changing flocculator dimensions or influent water conditions on performance. A performance model exists for laminar flocculators, but a model applicable to turbulent flocculators is still needed, as real scale flocculators operate in the turbulent regime. This article outlines a theoretical approach that suggests the form of two dimensionless composite parameters that account for the influence of raw water turbidity, coagulant dose, flocculator hydraulic residence time, and energy dissipation rate on settled water turbidity. The utility of these parameters in describing turbulent flocculation will require testing and validation. Thus, this article also describes the design of a suitable laborato...