Pilot-scale fluoride-containing wastewater treatment by the ballasted flocculation process

2013 ◽  
Vol 68 (1) ◽  
pp. 134-143 ◽  
Author(s):  
Bin-yuan Wang ◽  
Zhong-lin Chen ◽  
Jia Zhu ◽  
Ji-min Shen ◽  
Ying Han
Keyword(s):  
Calcium Fluoride ◽  
Fluoride Concentration ◽  
Pilot Scale ◽  
Fluoride Removal ◽  
Turbidity Removal ◽  
Factors Affecting ◽  
Flocculation Efficiency ◽  
Sludge Recycling ◽  
Efficiency Factors ◽  
Flocculation Process

A pilot-scale ballasted flocculation system was used to remove fluoride from one type of industrial wastewater. The system included the formation of calcium fluoride (CaF2) using calcium hydroxide followed by coagulation sedimentation. Calcium fluoride was recycled as nuclei for enhancing CaF2 precipitation and as a ballasting agent for improving fluoride removal and flocculation efficiency. Factors affecting fluoride and turbidity removal efficiencies, including pH in the CaF2-reacting tank and coagulation-mixing tank, sludge recycling ratio, and dosages of FeCl3 and polyacrylamide (PAM), were investigated in the pilot-scale system. The recycled CaF2 precipitates improved CaF2 formation kinetics, enhanced fluoride removal and flocculation performance. Under the optimized condition, the ballast flocculation process reduced fluoride concentration from 288.9 to 10.67 mg/L and the turbidity from 129.6 NTU to below 2.5 NTU.

Fluoride removal from drinking water in Senegal: laboratory and pilot experimentation on bone char-based treatment

2011 ◽  
Vol 1 (4) ◽  
pp. 213-223 ◽  
Author(s):  
Sabrina Sorlini ◽  
Daniela Palazzini ◽  
Carlo Collivignarelli
Keyword(s):  
Drinking Water ◽  
Dental Fluorosis ◽  
Low Cost ◽  
Fluoride Concentration ◽  
Pilot Scale ◽  
Appropriate Technology ◽  
World Health ◽  
Fluoride Removal ◽  
Process Conditions ◽  
Bone Char

In Senegal there are four regions where fluoride concentration in drinking water exceeds the World Health Organization guide value of 1.5 mg/L. This generates permanent damages to the teeth (dental fluorosis) and to the skeleton (skeletal fluorosis). A safe, efficient, simple and low-cost effective defluoridation technique is not available yet and needs to be developed in order to prevent the occurrence of fluorosis. This experimental research was carried out in order to define an appropriate technology for fluoride removal from groundwater in Senegal. Batch tests and filtration tests at laboratory and pilot scale were carried out using animal bone char as adsorbent material for fluoride removal. Possible influencing parameters, such as specific ions in Senegalese drinking water, were investigated and the best process conditions were defined for the application in Senegal. The results attest to the efficacy of bone char in removing fluoride from Senegalese water: at pilot scale the mean specific adsorption was 2.7 mg F−/g of bone char, corresponding to a total treated volume of 4,000 L and a filter life of nearly three months.

Numerical Modeling and Experimental Study of the Mechanical Flocculation Process

2011 ◽  
Author(s):  
Bipeng Yan ◽  
Feng Shen
Keyword(s):  
Numerical Modeling ◽  
Flow Characteristics ◽  
Factors Affecting ◽  
Rotating Speed ◽  
Flocculation Efficiency ◽  
Four Corners ◽  
Hydraulic Conditions ◽  
Tank Design ◽  
Turbulent Momentum ◽  
Flocculation Process

Flow characteristics are one of the main factors affecting the flocculation process. The flow field in the flocculation tank was numerically modeled using the κ-ε turbulent flow model by considering different hydraulic conditions such as the flow rate, paddle rotating speed, dimension and its installation positions. The numerical modeling and experiment observation indicates that the turbulent momentum κ and effective energy consumption ε can be used as an indicator of flocculation efficiency. The rectangular shaped flocculation tank can dampen the flow effectively, but in the four corners there is a lack of mixing, which can be solved by installing baffles to promote the flocs growth. A proper paddle rotating speed can increase the collisions between particles in the main flocculation area; while still keep the formatted flocs from being damaged by shear force. Increasing the paddle service range appropriately can enlarge the main flocculation area. The paddle installation height should consider the turbulent conditions in both the upper and lower part of the flocculation tank. A set of parameters was recommended for the mechanical flocculation tank design.

Effects of operational parameters on defluoridation efficiency using electrocoagulation process

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
M. Behbahani ◽  
M.R. Alavi Moghaddam ◽  
M. Arami
Keyword(s):  
Reaction Time ◽  
Anode Material ◽  
Removal Efficiency ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Operational Parameters ◽  
Applied Current ◽  
Initial Ph ◽  
Electrocoagulation Process ◽  
Electrode Connection

The aim of this study is to examine the effect of operational parameters on fluoride removal using electrocoagulation method. For this purpose, various operational parameters including initial pH, initial fluoride concentration, applied current, reaction time, electrode connection mode, anode material, electrolyte salt, electrolyte concentration, number of electrodes and interelectrode distance were investigated. The highest defluoridation efficiency achieved at initial pH 6. In the case of initial fluoride concentration, maximum removal efficiency (98.5%) obtained at concentration of 25mg/l. The increase of applied current and reaction time improved defluoridation efficiency up to 99%. The difference of fluoride removal efficiencies between monopolar and bipolar series and monopolar parallel were significant, especially at reaction time of 5 min. When aluminum used as anode material, higher removal efficiency (98.5%) achieved compared to that of iron anode (67.7%). The best electrolyte salt was NaCl with the maximum defluoridation efficiency of 98.5% compared to KNO3 and Na2SO4. The increase of NaCl had no effect on defluoridation efficiency. Number of electrodes had little effect on the amounts of Al3+ ions released in the solution and as a result defluoridation efficiency. Almost the same fluoride removal efficiency obtained for different interelectrode distances.

scholarly journals Characterisation of smectite-rich clay soil: Implication for groundwater defluoridation

2016 ◽  
Vol Volume 112 (Number 11/12) ◽  
Author(s):  
Rabelani Mudzielwana ◽  
Mugera W. Gitari ◽  
Titus A.M. Msagati ◽  
◽  
◽  
...  
Keyword(s):  
South Africa ◽  
Rural Areas ◽  
Contact Time ◽  
Clay Soil ◽  
Dental Fluorosis ◽  
Fluoride Concentration ◽  
Limpopo Province ◽  
World Health ◽  
Fluoride Removal ◽  
X Ray

Abstract Groundwater is a widely used and affordable source of drinking water in most of the rural areas of South Africa. Several studies have indicated that groundwater in some boreholes in South Africa has a fluoride concentration above the level recommended by the World Health Organization (1.5 mg/L). Fluoride concentrations above the permissible limit (>1.5 mg/L) lead to dental fluorosis, with even higher concentrations leading to skeletal fluorosis. In the present work, we evaluate the application of smectite-rich clay soil from Mukondeni (Limpopo Province, South Africa) in defluoridation of groundwater. The clay soil was characterised by mineralogy using X-ray diffraction, by elemental composition using X-ray fluorescence and by morphology using scanning electron microscopy. Surface area and pore volume was determined by the Brunauer–Emmett–Teller surface analysis method. Cation exchange capacity and pHpzc of the soil were also evaluated using standard laboratory methods. Batch experiments were conducted to evaluate and optimise various operational parameters such as contact time, adsorbent dose, pH and initial adsorbate concentration. It was observed that 0.8 g/100 mL of smectite-rich clay soil removed up to 92% of fluoride from the initial concentration of 3 mg/L at a pH of 2 with a contact time of 30 min. The experimental data fitted well to a Langmuir adsorption isotherm and followed pseudo second order reaction kinetics. Smectite-rich clay soil showed 52% fluoride removal from field groundwater with an initial fluoride concentration of 5.4 mg/L at an initial pH of 2 and 44% removal at a natural pH of 7.8. Therefore smectite-rich clay soil from Mukondeni has potential for application in defluoridation of groundwater. Chemical modification is recommended to improve the defluoridation capacity.

Treatment of Textile Wastewater using Biodegradable Flocculants of Chitosan and Extracted Pandan Leaves

2013 ◽  
Vol 64 (1) ◽  
Author(s):  
Norzita Ngadi ◽  
Nor Aida Yusoff
Keyword(s):  
Solvent Extraction ◽  
Extraction Method ◽  
Textile Wastewater ◽  
Settling Time ◽  
Turbidity Removal ◽  
Test Experiment ◽  
Jar Test ◽  
Solvent Extraction Method ◽  
Flocculation Process

The study investigated the performance of chitosan and extracted pandan leaves towards treatment of textile wastewater by using flocculation process. Pandan leaves were extracted by using solvent extraction method. Flocculation process was conducted using a Jar test experiment. The effect of dosage, pH, and settling time on reduction of COD, turbidity and color of textile wastewater was studied. The results obtained found that chitosan was very effective for reduction of COD, turbidity, color and indicator for color. The best condition for COD and turbidity removal was achieved at 0.2 g dosage, pH 4 and 60 minutes of settling time. Under this condition, about 58 and 99% of COD and turbidity was removed, respectively. However, the results obtained using extracted pandan was opposite compared to the chitosan. Extracted pandan was not able to remove both COD and turbidity of the waste. 

scholarly journals Biosorption of Fluoride from Synthetic and Ground Water Using Chlorella vulgaris Immobilized in Calcium Alginate Beads in an Upflow Packed Bed Column

2017 ◽  
Vol 61 (3) ◽  
pp. 188 ◽  
Author(s):  
Poornima G. Hiremath ◽  
Thomas Theodore
Keyword(s):  
Experimental Data ◽  
Ground Water ◽  
Chlorella Vulgaris ◽  
Water Samples ◽  
Packed Column ◽  
Fluoride Concentration ◽  
Fixed Bed ◽  
Fluoride Removal ◽  
Fluoride Ions ◽  
Fluoride Adsorption

The potential of immobilized Chlorella vulgaris to remove fluoride from synthetic and real ground water samples in a fixed bed was investigated. The effect of important kinetic parameters including column bed height, feed flow rate and influent fluoride concentration of solution on fluoride removal was studied. Thomas, Yoon-Nelson, and BDST models were used to analyze the experimental data and understand the influence on biosorption performance. The models’ predictions were in good agreement with the experimental data for all the process parameters studied, indicating that the models were suitable for fixed-bed column design. Fluoride adsorption was reversible. Desorption of fluoride ions was accomplished by pumping 0.1 N HCl solution. The reusability of adsorbent was studied by subjecting column to repeated cycles of fluoride adsorption and desorption. The suitability of immobilized C. vulgaris adsorbent for fluoride removal from ground water samples of Pavagada taluk, Tumakuru district was studied in the packed column.

scholarly journals Column Efficiency of Fluoride Removal Using Quaternized Palm Kernel Shell (QPKS)

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Ayu Haslija Abu Bakar ◽  
Luqman Chuah Abdullah ◽  
Nur Amirah Mohd Zahri ◽  
Ma’an Alkhatib
Keyword(s):  
Fluoride Concentration ◽  
Fixed Bed ◽  
Palm Kernel ◽  
Fluoride Removal ◽  
Trimethylammonium Chloride ◽  
Transfer Resistance ◽  
Adsorption Models ◽  
Palm Kernel Shell ◽  
Bed Height ◽  
Fixed Bed Adsorption

In this research, the adsorption potential of quaternized palm kernel shell (QPKS) to remove F− from aqueous solution was investigated using fixed-bed adsorption column. Raw palm kernel shell waste was reacted with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHMAC) in order to modify the surface charge. The effects of inlet F− concentrations (2–12 mg/l) and QPKS bed height (2–10 cm) with optimum pH (pH = 3) on the breakthrough characteristics of the adsorption system were determined. In the fixed-bed column, breakthrough time increases with increasing bed height due to increasing amount of active site on adsorbents to adsorb the fluoride ion. Decreasing trend of breakthrough values was obtained with increasing initial fluoride concentration due to greater driving force for the transfer process to overcome the mass transfer resistance in the column. The adsorptions were fitted to three well-established fixed-bed adsorption models, namely, Thomas, Yoon–Nelson, and Adams–Bohart models. The results fitted well to the Thomas and Yoon–Nelson models with correlation coefficient, R2 ≥ 0.96.

scholarly journals FLOCCULANTS OPTIMIZATION IN HARVESTING FRESHWATER MICROALGAE Haematococcus pluvialis

2020 ◽  
Vol 5 (1) ◽  
pp. 49
Author(s):  
Dina Soes Putri ◽  
Desy Ambar Sari ◽  
Lulu Diani Zuhdia
Keyword(s):  
Large Scale ◽  
Haematococcus Pluvialis ◽  
Freshwater Microalgae ◽  
Filtration Method ◽  
Microalgae Culture ◽  
Flocculation Efficiency ◽  
Harvesting Efficiency ◽  
Harvesting Process ◽  
Flocculation Process

Microalgae-based researches are one of the interesting topics to date due to its wide applications for commercial industries. One of the vital issues that remain in the production of large-scale microalgae is the harvesting process of microalgae culture. There are several techniques that can be used in harvesting microalgae and each algae will be showing a different result. In this research, the microalgae Haematococcus pluvialis were harvested using flocculation-filtration method. Alum in different dosages, range from 0.25-2 g/L, was used as flocculants and the mixing duration was investigated to seek out the best harvesting efficiency. Based on the research, it can be concluded that the optimum flocculation process was alum addition of 1 g/L culture that continuously stirring for 5 minutes long. In which the flocculation efficiency reaches 94.5%.

Regeneration Effect of Fluoride-Rich Granular Activated Alumina on Desorption Regent NaOH Solution

2013 ◽  
Vol 316-317 ◽  
pp. 653-656
Author(s):  
Bai Jie Niu ◽  
Wen Ming Ding ◽  
Dan Dang
Keyword(s):  
Adsorption Capacity ◽  
Sodium Hydroxide Solution ◽  
Fluoride Concentration ◽  
Column Experiment ◽  
Fluoride Removal ◽  
Activated Alumina ◽  
Optimal Method ◽  
Column Adsorption ◽  
Naoh Solution ◽  
Regeneration Effect

As an effective adsorbent, granular activated alumina (GAA) has been widely used in defluoridation. In order to reduce cost and operate environment-friendly, the adsorbent should be regenerated. In this paper, column experiment was done to characterize the fluoride removal properties and to develop an optimal method to regenerate fluoride-rich modified activated alumina (MGAA). The MGAA can be regenerated by utilizing sodium hydroxide solution desorption, deionized water washing and ferric sulfate reactivation and then used for futher defluoride operation. The influence of the concentration of desorption agent (NaOH solution) and desorbing time on desorption rate and the adsorption capacity of regenerated MGAA were studied. The optimal desorption condition was: 1% NaOH solution for desorption agent, desorbing time in 1.5h.In addition, when the regenerated MGAA was used again for column adsorption test, its adsorption capacity reached 94% of that of original sorbent in 1mg/L outlet fluoride concentration.

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