Optimum Flocculation Conditions Research Articles

Preparation of a novel organic-inorganic composite sludge bioflocculant (SBF) from dewatered sludge as raw material: Characteristics, flocculation mechanism and application for domestic sewage

In this work, a green sludge bioflocculant (SBF) was prepared via chemical hydrolysis of dewatered sludge and applied to flocculation of domestic wastewater. The process parameters for the preparation of the SBF were 1.80 % hydrochloric acid concentration, 60 min extraction time, and 4000 r/min centrifugation speed. SBF is polymeric flocculant composed of organic and inorganic compounds. Flocculation efficiency reached 97.31 ± 0.26 % under optimal flocculation conditions. Charge neutralization promotes the surface adsorption, bridging and net trapping and sweeping of Fe (OH)3, Al (OH)3 and active functional groups OH/NH and C = O in SBF, which together achieve efficient flocculation reactions. SBF had high efficiency and stable flocculation performance for phosphorus in urban domestic wastewater, and the concentration of TP in effluent was lower than 0.30 mg/L. Therefore, SBF prepared from dewatered sludge has efficient flocculation properties and is suitable for removing pollutant phosphorus, which has good application prospects in the field of wastewater treatment.

Optimization of shrimp and crab shell as bio-flocculant for Chlorella pyrenoidosa harvesting using response surface methodology

The use of bio-flocculants in flocculation processes offers a feasible approach for separating solid and liquid phases, with a particular focus on microalgae harvesting. Critical parameters such as the dose of bio-flocculant, pH level, and dose of cationic inducer significantly impact the success of microalgae harvesting. This study aims to examine the efficacy of chitosan derived from shrimp shells and crab shells as bio-flocculants in microalgae harvesting, specifically Chlorella pyrenoidosa. Central Composite Design (CCD) and Response Surface Methodology (RSM) were employed in this study to attain optimal flocculation conditions, characterized by high flocculation efficiency and short settling time. The optimal harvesting condition using chitosan derived from shrimp shells was achieved at 0.499 g/L of bio-flocculant, pH 9.09, and 0.172 g/L of cationic inducer with 92.58% efficiency and 133.49 s settling time. Meanwhile, The optimal harvesting condition with chitosan derived from crab shells was achieved at 0.434 g/L of bio-flocculant, pH 8.96, and 0.168 g/L of cationic inducer. This resulted in an efficiency of 93.72% and a settling time of 117 s. Based on this fact, the potential of shrimp shells and crab shells as bio-flocculants for Chlorella pyrenoidosa harvesting is evident. Furthermore, the efficacy of flocculation and settling time are significantly influenced by variables such as the concentration of cationic inducers, the levels of bio-flocculants, and pH.

Using a novel bio-based cationic flocculant for food industry wastewater treatment

Wastewater from the food industry is considered harmful to human health and aquatic life, as well as polluting water and soil. This research is centered around finding an affordable and easy physicochemical method for dealing with waste generated by the food industry. To accomplish this goal, a new bio-based flocculant called 4-benzyl-4-(2-oleamidoethylamino-2-oxoethyl) morpholin-4-ium chloride was created using sustainable sources, specifically crude olive pomace oil. Its chemical structure was confirmed using various spectroscopic techniques such as FTIR, 1H-NMR, mass spectra, and 13C-NMR. This new bio-based cationic flocculant was combined with alum to act as a coagulant in the waste treatment process. Also, a study was conducted to determine the optimal conditions for the coagulation-flocculation process parameters, namely, pH and alum dosage, on COD and removal efficiency. The results showed that the optimal conditions for flocculation were achieved at pH 5.8, with 680 mg/L alum and 10 mg/L of commercial flocculant dose compared to only 5 mg/L of a new bio-based cationic flocculant. A comparison was made between the new bio-cationic flocculant and a commercial CTAB one for treating wastewater in the food industry. The study found that the new bio-based cationic flocculant was more effective in reducing the chemical oxygen demand, achieving a reduction of 61.3% compared to 54.6% for using a commercial cationic flocculant. Furthermore, using a new bio-based cationic flocculant costs only 0.49 $/g, which is less than the present cationic flocculant, which costs 0.93 $/g. The adoption of this new flocculant provides a sustainable alternative to existing industrial wastewater treatment processes

Acrylamide Cross‐Linked Psyllium Polysaccharide with Improved Flocculation Performance for the Removal of Microplastics from Water

AbstractThis article presents a novel material of acrylamide (AM) cross‐linked psyllium polysaccharides (PLP) derivative, PLP‐AM, which can be used as an effective polymeric flocculant for the removal of microplastics (MP) from water. PLP‐AM was produced by radical polymerization of PLP and AM using microwave irradiation instead of conventional radical initiators. The characterization of PLP‐AM was carried out by FT‐IR spectroscopy, elemental analysis, intrinsic viscosity measurement and thermogravimetric analysis (TG). Polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) were utilized to examine the flocculation performance of PLP‐AM. The optimum flocculation conditions were obtained by the comprehensive exploration of flocculant concentration, solution pH and temperature. In a solution with a pH 6 at 30 °C, the maximum removal percentages of PS and PVC by 60 mg/L of PLP‐AM were 92.55 % and 94.31 %, respectively, while 93.85 % of the maximum removal of PET percentage could be obtained by 80 mg/L of PLP‐AM. The results of zeta potential measurement revealed that there was adsorption electric neutralization between MP and PLP‐AM besides the adsorption bridging mechanism. These results suggest that PLP‐AM may bring an inspiration for the development of polymer flocculant to remove MP from water.

Bioflocculant Producing Bacillus megaterium from Poultry Slaughterhouse Wastewater: Elucidation of Flocculation Efficacy and Mechanism

The study focused on isolating bioflocculant-producing microorganisms from poultry slaughterhouse wastewater (PSW). Microorganisms (n = 20) were isolated, and the D2 isolate, identified as Bacillus megaterium using 16S rDNA and RpoD (sigma 70), had maximum flocculation activity. Furthermore, characteristics of the bioflocculant produced by B. megaterium were determined, and the optimum storage conditions, including the flocculation mechanism, were identified. The bioflocculant was composed mainly of polysaccharides and proteins and was better stored frozen in a crude form. Furthermore, the flocculation efficacy was assessed using response surface methodology at pH 4 (min) and 9 (max), bioflocculant dosage of 1% (min) and 3% (max, v/v), indicating pH 6.5 and dosage of 2% (v/v) as optimum flocculation conditions for floc formation under ambient temperature. These results were further confirmed with microscopy assessments with zeta potential measurements confirming that the bioflocculant was ionic, albeit charge neutralization was not the primary mechanism for floc agglomeration. Hydrogen bonding was predominant, indicative of a neutralization-bridging mechanism, an assertion also based on the functional groups prevalent in the isolate-B. megaterium. The results obtained indicate that bioflocculants can be used to treat isolates that are sourced from wastewater.

Flocculation behavior, mechanics, and optimization of tailings based on multi-objective: Insight into the concentration and time-dependent floc size

Tailings thickening is the primary link and key technology of cemented paste backfill (CPB) technology, in which flocculation conditions are important factors affecting the thickening effect. Conventional flocculation effects only consider macro indicators such as concentration and initial settling rate (ISR), ignoring the floc evolution and multi-objective optimization. Therefore, it leads to substandard underflow, frequent rake accidents, and untimely thickener regulation. In this study, the multi-objective optimization of the flocculation effect based on response surface methodology, Box-Behnken design, and the desirability function (RSM-BBD-DF) was carried out. Firstly, through the single-factor experiments, the sedimentation properties and floc size evolution under various influencing factors were analyzed. It is found that the evolution of floc size is time-dependent, which conforms to the asymmetric double sigmoidal (Asym2sig) model, and there is a linear relationship between test-ending floc size and ISR. The ISR increases with floc size. Through the RSM-BBD, the regression models of concentration and mean weighted chord length (MWCL) as response values were established. Multi-factor interaction found that the tailing feeding concentration (TFC) had the greatest influence on the concentration, and the shear rate (SR) had the greatest influence on the MWCL. The interaction between TFC and the flocculant solution concentration (FSC) influences the concentration most. The interaction between TFC and SR has the highest influence on the MWCL. By introducing the single desirability function and the overall desirability function, the optimization method based on RSM-BBD-DF obtained the optimal flocculation conditions (TFC is 17 wt%, FSC is 1 wt‱, SR is 160 r·min−1, and ST is 30 s), which were very close to the optimization results of the Design Expert, indicating that RSM-BBD-DF optimization method is reliable. Thus, RSM-BBD-DF has important application value for multi-objective optimization in mining and other industries,.Thus, RSM-BBD-DF provides a new approach for multi-objective optimization in mining and other industries, especially for intelligent control technology of thickening processes, which has important theoretical and practical value.

Study on Flocculation Characteristics of Potato Starch Wastewater

Herein, a chitosan film (CS) was modified using 2,3-epoxy-propyl trimethyl ammonium chloride (GTA) to flocculate granular pollutants in potato starch wastewater, aiming at the deficiencies of poor water solubility and weak electropositivity of the chitosan film. By examining the degree of substitution of chitosan film amino under different factors and different levels and response surface optimization tests, the optimum preparation conditions of chitosan film quaternary ammonium salt (HTCC) were obtained. Using scanning electron microscopy (SEM), Fourier infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and 1H-nuclear magnetic spectroscopy, the nucleophilic substitution reaction of the GTA molecule with the hydrogen atoms in the chitosan film amino group successfully improved the water solubility and electropositivity of the chitosan film. HTCC was used to treat potato starch wastewater, and the optimal flocculation conditions were obtained. The flocculation product was recovered, and the composition analysis of the flocculation product demonstrated that HTCC-potato protein flocculation precipitate was rich in high protein, which is a good choice of feed and can realize sustainable utilization of resources.

Flocculation performance of PCFA composite coagulant for removing nanoparticles

In this study, red mud was used as the main raw material to prepare polyaluminum-ferric chloride (PCFA) with high added value. The effects of the liquid–solid ratio, reaction temperature, reaction time, hydrochloric acid concentration during acid leaching, polymerization time, OH−/Fe molar ratio, and polymerization temperature on the preparation of PCFA were investigated and determined by conducting single-factor optimization experiments under optimal preparation conditions. Characterization results show that the surface of the PCFA flocculant has compact and dense porosity and a dense sheet-like structure, and PCFA contains hydroxyl-bridged iron–aluminum polymers. When the settling time was 30 min, the stirring intensity was 200 rpm; the initial concentration of Nano-titanium dioxide（TiO2-NPs） was 30 mg·L−1; the pH value was 7.0; the dosage of PCFA was 25 mg·L−1, and the optimum removal rates of TiO2-NPs and turbidity were 84.8% and 81.3%, respectively. The flocs produced by PCFA treatment of TiO2-NPs were large and dense. Under optimal flocculation conditions, the average particle size of PCFA-TiO2-NP flocs was 2.98 µm, and the fractal dimension was 1.66. Based on the abovementioned flocculation experimental data, a Grey correlation method was established to evaluate the degree of correlation among factors such as ionic strength, settling time, stirring strength, kaolin concentration, initial concentration, reaction pH value, and dosage and the performance of PCFA coagulation to remove TiO2-NP-containing wastewater. In the reaction system of the PCFA coagulation of TiO2-NPs, the dosage is the most important factor.

Optimizing the Flocculation Effect of Cationic Polyacrylamide Prepared with UV-Initiated Polymerization by Response Surface Methodology

Cationic polyacrylamide (CPAM) is a commonly used flocculant for water treatment. Factors that affect the flocculation effect and can be controlled manually include the type and dosage of CPAM, wastewater pH, stirring time and settling time, and their reasonable setting is critical to the flocculation effect of CPAM. In this paper, the optimal flocculation conditions of a novel CPAM were studied. First, single-factor tests were conducted to preliminarily explore the optimal range of factors that influence CPAM flocculation, and then response surface methodology (RSM) tests were performed to accurately determine the optimums of the influencing factors. The results showed that the flocculation effect was better when the intrinsic viscosity was larger or the cationic degree of CPAM was higher. The CPAM dosage, wastewater pH and stirring time significantly impacted the flocculation effect, and inflection points were observed. A model that could guide CPAM-8.14-40.2 flocculation was obtained by RSM tests. The model optimization showed that the optimal flocculation conditions of CPAM-8.14-40.2 for treating wastewater prepared with kaolin were as follows: the CPAM dosage, wastewater pH and stirring time were 5.83 mg·L−1, 7.28, and 5.95 min, respectively, and the turbidity of the treated wastewater was reduced to 6.24 NTU.

Assessing the effects of operating parameters on flocculation of Chlorella vulgaris using bioflocculants extracted from miscellaneous waste biomass

Harvesting of microalgae is one of the main challenges in the production of biodiesel due to the small cell size of microalgae cells. Chemical flocculants have been generally used in the harvesting of microalgae, but they are harmful to the environment and relatively costly. Therefore, the utilization of waste biomass in producing bioflocculants is the current research niche to introduce environmental-friendly harvesting method and to minimize the cost of biodiesel production. Thus, in the current work, flocculation Chlorella vulgaris using mild acid-extracted bioflocculants from miscellaneous waste biomass (cockle shell, peanut shell and banana peel) were conducted by varying the pH values, the dosage of bioflocculants and temperatures. Cockle shell bioflocculant demonstrated the best flocculation performance, with highest flocculation efficiency of 85.2% compared to the peanut shell bioflocculant with flocculation efficiency of 37% and banana peel bioflocculant with flocculation efficiency of 16.3%. The optimum flocculation conditions for cockle shell bioflocculant were determined as follow: pH 9, bioflocculant dosage of 140mg/L and temperature of 30oC. The findings herein presented practical applicability of bioflocculants extracted from cockle shell for safe, rapid and inexpensive microalgae harvesting.

Study of microwave‐template initiated copolymerization peculiarity and evaluation on the coal floc distinctive behavior and flocculation performance

AbstractCationic polyacrylamide (CPAM) contains a large number of acylamino and positively charged methyl ammonium chloride groups. It has the advantages of good water solubility, strong adsorption bridging ability, enhanced charge neutralization and destabilization performance, excellent flocculation effect, and wide application. Therefore, CPAM can be used in the treatment of coal washing wastewater, and the research and development of a new flocculant with high efficiency is a hot topic in this field. Template copolymer (TPADM) of methacryloyloxyethyl trimethyl ammonium chloride (DMC) and acrylamide (AM) was synthesized by microwave‐template initiated polymerization with sodium polyacrylate (PAAS) as template. The microwave‐template initiated polymerization is abbreviated as MW‐TP. By analyzing FTIR, 1H (13C) NMR and TG/DSC of TPADM, it was found that TPADM had obvious cationic fragment structure. In addition, the association constant (KM) and the kinetics of the template reaction showed that the MW‐TP was confirmed to be free radical initiated polymerization and I Zip‐up (ZIP) polymerization mechanism, which demonstrated the formation of the cationic fragment structure again. This new cationic fragment structure greatly enhanced the ability of charge neutralization, electrical patching and adsorption bridging, thus improving the flocculation performance. Compared with cationic P(AM‐DMC) (CPADM), Commercial cationic polypropanamide (CCPAM‐1 and CCPAM‐2), TPADM had better flocculation effect on coal washing wastewater. Under the optimum flocculation conditions (dosage = 16 mg/L, pH = 7.5), suspended solid (SS) concentration and turbidity of coal washing wastewater treated by TPADM reached 14.3 mg/L and 8.7 NTU, respectively. The floc formation, breakage, and regeneration analyses showed that the cationic fragment structure in TPADM could contribute to the formation of large and high density flocculation structure (d50 ≥ 245 μm, Df ≥ 2.05), and these coal flocs can regenerate rapidly after being broken. Finally, these large and compact flocs help to accelerate the flocs sedimentation and reduce the SS concentration and turbidity of coal washing wastewater, and enhance the effect of solid–liquid separation.

A review of nano-based materials used as flocculants for water treatment

In recent years, the development of nanoparticle materials for water treatment has received great attention. From an industrial technological view point, the application of nanomaterials in the twenty-first century for water treatment will be the focal point of advanced materials design, processing and progress. In this context, the potential utilisation of different types of flocculants to clean up contaminated water becomes important to address the tremendous increase of water pollution resulting from continued high-level global industrialisation. A number of researchers have investigated the effectiveness of various nanoflocculants for this purpose. Although these nanoflocculants have been reported to successfully treat contaminated water, their flocculation performances are different. To the best of our knowledge, there is no review article which summarises the application and performance of nanoflocculants in the treatment of water containing various types of contaminants. This review summarises the recent development of a wide range of nanoflocculants for the treatment of water polluted particularly by heavy metals, dyes and bacteria. The influence of physicochemical properties of nanoflocculants upon their performance and optimum flocculation conditions is discussed in detail. This review will provide a useful source of information for researchers working on the advancement of cost-effective and environmentally friendly nanoflocculants.

Isolation and Identification of a Bioflocculant-Producing Strain and Application in Rice Vinegar Clarification

A bioflocculant-producing bacterium S-3# was isolated from fresh sand bones 40-50 cm underground in the desert region of China’s Ningxia Province. It was identified as Paenibacillus sp. based on 16S rDNA sequence along with its biochemical and morphological characteristics. Chemical analysis found that the bioflocculant from S-3# is mainly composed of extracellular polysaccharide. Researchers observed no noticeable change (above 91%) in its flocculating activities in pH range 2.0-9.0 in kaolin suspensions and hypothesized that it could be useful in clarification of rice vinegar (pH 2.9-3.5). Using one-factor-at-a-time experiments, dosage of bioflocculant, temperature of flocculation system and metal cations were investigated for their efficacy on rice vinegar clarification. The Box-Behnken design, an experimental design for Response Surface Methodology (RSM), was also used to create a series of 17 runs to optimize the operating conditions. Quadratic regression models with estimated coefficients were developed to describe the suspended particle removals of rice vinegar. Results showed that the optimal flocculation conditions were 3.94 mg/L bioflocculant, 0.32 mM CaCl2 and flocculation system temperature of 41.5°C, respectively. These findings were in reasonable agreement with the modeled values. Under these conditions, the increase rate of transmittance (λ = 900 nm) of rice vinegar ranged over 240.63% under these conditions.

Describing Mining Tailing Flocculation in Seawater by Population Balance Models: Effect of Mixing Intensity

A population balance model (PBM) is used to describe flocculation of particle tailings in seawater at pH 8 for a range of mixing intensities. The size of the aggregates is represented by the mean chord length, determined by the focused beam reflectance measurement (FBRM) technique. The PBM follows the dynamics of aggregation and breakage processes underlying flocculation and provides a good approximation to the temporal evolution of aggregate size. The structure of the aggregates during flocculation is described by a constant or time-dependent fractal dimension. The results revealed that the compensations between the aggregation and breakage rates lead to a correct representation of the flocculation kinetics of the tailings of particles in seawater and, in addition, that the representation of the flocculation kinetics in optimal conditions is equally good with a constant or variable fractal dimension. The aggregation and breakage functions and their corresponding parameters are sensitive to the choice of the fractal dimension of the aggregates, whether constant or time dependent, however, under optimal conditions, a constant fractal dimension is sufficient. The model is robust and predictive with a few parameters and can be used to find the optimal flocculation conditions at different mixing intensities, and the optimal flocculation time can be used for a cost-effective evaluation of the quality of the flocculant used.

Harvesting of Chlorella Vulgaris Biomass by Using Different Bio-Flocculants: A Comparison Study

In the present study, several natural flocculants were extracted from natural resources to harvest Chlorella vulgaris. Jar tests were carried out to evaluate the flocculation efficiencies of the extracted flocculants in harvesting C. vulgaris cells. Chitosan and maize seeds were proven to be effective flocculants as they achieved more than 80 % efficiency after one(1) hour and four (4) hours of sedimentation time, respectively. Under the optimum flocculation conditions of pH 7, 2 mg/L dosage, 120 rpm of stirring speed for chitosan; and pH 3, 450 mg/L of dosage, 15 rpm of stirring speed for maize seeds flocculant; the flocculation efficiencies up to 97.9 % and 84.7 % are able to achieved, respectively. A scale-up study was done to test the flocculation ability of chitosan and maize seeds extracts to harvest 1 L of C. vulgaris. Approximately 97 % and 82 % of flocculation efficiencies were achieved by chitosan and maize seeds flocculants, respectively, under their optimum flocculation conditions. Comparatively, chitosan offer superiority in flocculating C. vulgaris than maize seeds extract in terms of floc size, dosage and sedimentation time.
 Keywords: natural flocculant, chitosan, maize seed, microalgae, harvest

Partial purification and characterization of a recombinant β-mannanase from Aspergillus fumigatus expressed in Aspergillus sojae grown on carob extract

Mannanases are of great importance as they are able to hydrolyze polysaccharides for industrial applications and can be easily produced by fermentation. Purification of a β-mannanase produced from carob extract in a bioreactor is of great importance in order to obtain information about its structural and functional features and to foresee its implementations. Therefore, the aims of this study were to purify a β-mannanase from Aspergillus fumigatus expressed in Aspergillus sojae grown on carob extract by implementation of various flocculant agents in the fermentation medium, followed by the determination of its physico-chemical, kinetic, and thermodynamic characteristics. Flocculants increase the visible size of the dispersed particles by agglomeration, simplifying the separation of solids and liquids, and thereby reducing process costs. Optimum flocculation conditions for chitosan- and PAC-PAM-implemented processes were determined as 40 mg/L of chitosan, 30 min of implementation time, no agitation and 3 g/L PAC-PAM, 30 min implementation time, and no agitation. Under these conditions, more than a 2-fold increase in the enzyme activity was achieved in both flocculation processes. Further investigations determined molecular weight, optimum pH, and temperature values of the produced β-mannanase to be 56–60 kDa, pH 6, and 60 °C, respectively. Additionally, Km and Vm determination of the enzyme for various substrates concluded that the β-mannanase showed the highest substrate specificity against locust bean gum among the substrates evaluated. Furthermore, experimental results for substrate specificity were further modeled and successfully represented by the Weibull model. In conclusion, this study provides valuable and important information about β-mannanase production and purification for industrial-scale applications.

Unravelling the Mechanism of Chitosan-Driven Flocculation of Microalgae in Seawater as a Function of pH

Chitosan is a nontoxic biobased polymer, attractive for the flocculation-based harvesting of microalgae. While it is generally effective to harvest algae in freshwater medium, its performance in seawater has been unpredictable. This study determined the optimal conditions for flocculation of the marine microalgae Nannochloropsis oculata using chitosan. Whereas in freshwater a low pH ( 7.5). The dosage of chitosan required for flocculation of Nannochloropsis in seawater (75 mg/L) was higher than the reported dose to flocculate the freshwater microalgae (±10 mg/L) reported in the literature. Experiments carried out in synthetic seawater with modified magnesium concentration indicated that flocculation induced by chitosan at varying pH was not related to precipitation of magnesium hydroxides (so-ca...

Magnetic flocculants synthesized by Fe3O4 coated with cationic polyacrylamide for high turbid water flocculation.

A novel magnetic flocculant (CPAMF) was synthesized by using Fe3O4 coated with cationic polyacrylamide (CPAM) for flocculation of high turbid water. The surface morphology and chemical structures of CPAMF were confirmed by Fourier transform infrared spectroscopy (FTIR) and thermo-gravimetric analysis (TGA). X-ray diffraction (XRD) was employed to verify the crystal structure of CPAMF. The magnetic property of CPAMF was compared with Fe3O4 in this study. The flocculation performance by using flocculants CPAMF was evaluated in high turbid water treatment. The maximum transmittance 92.4% of kaolin suspension was achieved at corresponding optimal flocculation conditions. The result indicated that CPAMF was efficient in high turbid water flocculation. Analysis of FTIR, XRD of flocs, and zeta potential (ZP) of supernatant were accomplished for flocculation mechanism investigation. Because of low recovery factor in reflocculation under the effect of shear force on flocs, the bridging effect was found to be dominant in both acidic and alkaline conditions. Sedimentation experiments under the role of permanent magnet indicated that nano-Fe3O4 could effectively improve the settling property of CPAM. Graphical abstract ᅟ.

Sludge conditioning prior to dewatering: Introducing drainage index as a new parameter

Abstract The conditioning stage is a key parameter for enhancing the efficiency of sludge dewatering. However, the choice of the conditioning procedure (type of flocculant, dosage, mixing conditions) remains a current difficulty. A new index (called drainage index) was introduced to optimize conditioning parameters specifically for sludge thickening on draining table and by extension for sludge dewatering in belt filter press. This easy and quick to measure index was tested via lab-scale drainage experiments. Drainage performance was measured in terms of particles capture rate, final sludge dryness and drainage kinetics. The drainage index allowed to select optimal flocculation conditions prior to gravity drainage. Its relevance to select flocculation conditions insuring a good sludge compression was also demonstrated (except for the polymer selection) from tests carried out in lab-scale filtration–compression device.

Changes in Microcystis aeruginosa cell integrity and variation in microcystin-LR and proteins during Tanfloc flocculation and floc storage

The objective of this study was to determine the influence of Tanfloc on Microcystis aeruginosa cell integrity, microcystin-LR (MC-LR), and proteins during flocculation and floc storage. The effects of Tanfloc addition, stirring, and floc storage time were considered to minimize cell damage and the release of MC-LR and proteins. Optimal flocculation conditions (Tanfloc dosage 10.42 mg L−1, rapid agitation for 0.36 min at 568.88 rpm and slow agitation for 14.14 min at 12.1 rpm) were obtained using the response surface methodology. Up to 98.9% of the M. aeruginosa cells were removed intact at low Tanfloc dosage. During floc storage, Tanfloc initially protected the cells. After 8 d, large-scale cell lysis occurred because Tanfloc had substantially decomposed. Nevertheless, Tanfloc also extended the extracellular MC-LR and protein release time to 8 d. This delay ensured adequate time to decontaminate sludge containing the algae, thereby reducing the risk of secondary pollution. In addition, the low cost of Tanfloc facilitates its widespread application in the management of harmful algal blooms.