Composite Flocculant Research Articles

Study on Demulsification Pre-Treatment of Emulsified Wastewater

In this paper, the flocculation effect of single flocculants and compound flocculants on emulsified wastewater under different conditions was studied. The effect of flocculant type, dose, settling time and composite ratio of flocculant on the treatment of emulsified wastewater were investigated through single-factor condition tests, and then the optimal conditions of flocculants for treating emulsified wastewater were obtained. The results showed that the single inorganic flocculant could break the stable state of the emulsion when the pH was adjusted to 7 and formed tiny flocs, but it took a long time to settle down. The single organic flocculant had no flocculation effect. The inorganic–organic composite flocculants could effectively solve the problem of emulsion breaking and flocculation, and could form large flocs and alum flower formations at the same time, with mud and water effectively separated. The best conditions for the composite flocculants were as follows: under the condition of room temperature and pH 7, the dose of PFC was 2250 mg/L and APAM was 5 mg, the homogeneous stirring time was 10 min, and the settling time was 0.5 h. The removal rate of COD and turbidity reached 84.75% and 99.86%. The study could provide a new treatment idea and method for the pretreatment of stabilized high-turbidity wastewater.

Experimental investigation on sedimentation characteristics of coastal slurry by flocculation

Coastal waste slurry has a negative impact on the environment due to its slow, natural settling characteristics. In this study, the organic, inorganic, and composite flocculants were applied to improve the mud-water separation performance. A series of experiments with sedimentation columns and particle size analysis were conducted to investigate the effects of flocculant type, dosage and combination on slurry settling rates and its associated mechanisms. The experimental results show that different types of flocculants varied in improving the settling efficiency of slurry, while the flocculation effect of inorganic flocculants is relatively poor. The settling efficiency of organic polymer flocculants on slurry is in order of anionic polyacrylamide (APAM) > cationic polyacrylamide (CPAM) > nonionic polyacrylamide (PAM), with their optimal dosage 0.2%, 0.1%, and 0.1%, respectively. Moreover, the combination of APAM and Solid Polymeric Ferric Sulfate (SPFS) can further improve the efficiency of mud-water separation by enhancing electro-neutralization and net sweeping capability. Subsequently, the change in the particle size distribution of the slurry demonstrates that flocculation causes the aggregation of fine particles in slurry to form coarse particles. These findings have implications for improving the sedimentation characteristics of waste slurry to reduce environmental pollution.

Novel polyferric titanium silicate/chitosan composite flocculant for organic polymeric pollutant removal: optimization, performance and mechanism

A novel inorganic-organic composite flocculant polyferric titanium silicate/chitosan (PFTS/CTS) was successfully synthesized in this study. The optimal preparation parameters of flocculant were optimized by orthogonal experiment with organic polymer polyacrylamide (PAM) removal rate as the evaluation index. The results shows that the examined preparation parameters are in the order of aging time > m(Fe + Ti):m(CTS) > n(Fe + Ti):n(Si), and the best experimental formula is that aging time = 2 days, m(Fe + Ti):m(CTS)=5 and n(Fe + Ti):n(Si)=0.5. The obtained PAM (50 mg/L) removal rate is 78.7% under the selected suitable wastewater treatment condition. Compared with the single CTS, PFTS and polyferric silicate (PFS), PFTS/CTS exhibits superior flocculation performance. The reason for the improvement of flocculation performance of PFTS/CTS can be attributed to its good crystallinity, special scaly accumulation structure and high positive charge, as well as the synergistic effect of inorganic flocculant and organic flocculant in the PFTS/CTS flocculant, which is successfully composited through coordination bond between titanium ions of PFTS and hydroxyl or amino groups of CTS. The main mechanism of treating PAM by PFTS/CTS is physical and chemical effect including micro-flocs are formed through chelate, charge neutralization and adsorption in the first process, and then the larger particles are formed by bridging, wrapping and sweeping. In addition, the flocs of treating PAM using PFTS/CTS are dense and large, its formation and the sedimentation are fast. The prepared flocculant exhibits eminent application prospects in the field of PAM wastewater.

Flocculation-enhanced photobiological hydrogen production by microalgae: Flocculant composition, hydrogenase activity and response mechanism

The practical application of microalgal photobiological hydrogen was limited by its low yield and short production time. In this study, the promotion of inorganic flocculants (polymeric aluminum chloride, PAC) and organic flocculants (cationic polyacrylamide, CPAM) to the aggregate formation and photobiological hydrogen production of prokaryotic microalgae (Synechocystis sp.) and eukaryotic microalgae (Chlamydomonas reinhardtii) were investigated. The effectiveness of PAC-CPAM composite flocculants in promoting aggregation was compared to single PAC or CPAM, with flocculation efficiencies exceeding 92.2 % for both microalgal strains. After aggregate formation, hydrogen production in Synechocystis and C. reinhardtii increased by 65.9 % and 80.2 %, respectively, compared with the control (without flocculation). Their hydrogenase activity rose to 1.14 and 28.2 μmol H2/(mg chlorophyll·h), respectively. Aggregation sustained the photosynthetic activity of both Synechocystis and C. reinhardtii, with the photosynthetic system electron transfer rate (ETR) 1.54–1.72 times higher than that of the control. The formation of aggregates enhanced microalgal respiration, accelerating the reduction of oxygen content, and increasing hydrogenase activity. Notably, the increased respiration in Synechocystis and C. reinhardtii aggregates supplied more electrons, enhancing hydrogen production by consuming intracellular organic matter. Aggregate formation upregulated the expression of Synechocystis and C. reinhardtii hydrogenase genes by average 2.1-fold and 2.5-fold, respectively. Simultaneously, the expression of genes related to photosynthetic system Ⅱ, ferredoxin, pyruvate ferredoxin-oxidoreductase, and oxidative phosphorylation were upregulated, with a significant effect observed in C. reinhardtii aggregates. The results of this study advanced the utilization and industrialization of microalgae-based green hydrogen production, contributing to carbon neutrality.

Study on formula and mechanism of chemical admixtures for slurry-like mud treated by physicochemical combined method

To achieve value-added recycling of slurry-like mud (MS) and resolve the shortage issue of construction fill materials, physicochemical combined methods (PCCMs), which integrate flocculation, solidification, and vacuum preloading (optional), have been proposed to enhance the engineering properties of MS. The optimization of chemical admixtures, which consist of solidification and flocculation components, is crucial in ensuring the effectiveness and cost-efficiency of PCCM in practical application. In this study, a number of solidification model tests are performed to optimize the solidification components for PCCM via determining the optimal mixing ratio in each of the two GGBS-based binders. Subsequently, surcharge preloading deposition tests and vacuum preloading model tests, with different types/dosages of flocculant, are conducted to determine the appropriate flocculation components. The results indicate that OPC-GGBS exhibits remarkable effectiveness in strength improvement, and the use of a combination of organic and inorganic flocculant, particularly CaO-PAM, can significantly enhance the efficiency of PCCM. Moreover, increasing the dosage of the composite flocculants enhances the dewatering process, but the benefit becomes less significant when the dosage exceeds a threshold value of 0.16%. Additionally, this study provides a preliminary understanding of the key mechanism involved in synergizing flocculation, solidification and preloading to enhance the performance of MS. These findings contribute to the optimal design and application of PCCM for the treatment of MS.

Chitosan-β-cyclodextrin composite flocculants dual-drive for efficient microalgae harvesting: Structural evidences, dehydration process, E-DLVO model behavior and biomass utilization

Flocculation is one of the promising methods for harvesting microalgae. In this study, a series of grafted cationic chitosan-cyclodextrin composite flocculants (CTS/β-CDs) with different structural properties were prepared from chitosan and cyclodextrin. The results showed that the harvesting efficiency of CTS/β-CD-1 for C. vulgaris reached 99.91%. The chain type of polymeric flocculants with moderate graft chain lengths (L = 10–20) and tighter branched chain density distribution (D = 1.0–1.8) was favorable for C. vulgaris harvesting. The addition of CTS/β-CDs caused the discrete C. vulgaris cells to be flocculated and aggregated, and the reorganization of particles resulted in larger particles after flocculation, improving the dewatering performance of microalgae flocs. CTS/β-CDs had no significant inhibitory effect on the extraction of lipids, proteins and carbohydrates, and did not affect the extraction and quality of fatty acid methyl esters, and the re-cultivation experiments of the harvested water showed that chitosan-based flocculant was able to effectively reduce the cost of microalgae harvesting. Electrostatic interactions and bridging were the main harvesting mechanisms between CTS/β-CD-1 and C vulgaris. E-DLVO modeling suggested that flocculation is mainly a result of electrostatic and acid-base interactions when the distance between particles is small. At higher pH, the harvesting efficiency of CTS/β-CD-1 with C. vulgaris decreased. The study contributes to a better understanding of the structure–activity relationship between the structural characteristics of flocculants and the harvesting performance.

Preparation of a Magnetic Polysilicate Composite Flocculant for Dye Wastewater Treatment

Preparation of a Magnetic Polysilicate Composite Flocculant for Dye Wastewater Treatment

A novel hydrophobic chitosan-polyaluminum chloride composite flocculant for effectively simultaneous removal of microplastic and antibiotics composite pollution

Composite pollution of emerging pollutants such as microplastics (MPs) with small size and antibiotics has brought a great challenge in the fields of water and wastewater treatment. Up to now, the simultaneous removal of MPs and antibiotics by traditional coagulation is still not satisfied. Herein, a novel composite flocculant named hydrophobic chitosan-polyaluminum chloride (Hmcs-PAC) was designed and prepared for efficiently simultaneous removal of polyethylene terephthalate (PET, 10 μm) and tetracycline (TC) from water. Under the optimal preparation conditions (i.e. Basicity = 1 and the weight ratio of Hmcs:Al = 0.5), the Hmcs-PAC exhibited better removal of both PET and TC than PAC and Hmcs under the same dosage, with the maximum removal efficiency of 99.9 % for PET, and 91.5 % for TC, respectively. The PAC was successfully grafted on the Hmcs via Al-N bond, confirmed by FTIR and 27Al NMR. More importantly, the removal of TC in composite PET + TC system was significantly enhanced by above 10 % compared with that in single TC system, which was mainly attributed to the complexes formation of Hmcs-PAC-PET-TC via the PET bridging effect based on 2D Fourier transform infrared correlation spectroscopy (2D-FTIR-COS) and scanning electron microscopy (SEM) analysis. In contrast, the removal of PET in composite system was slightly lower than that in PET single system, possibly due to the competition of TC for the active sites of hydrolysates of Hmcs-PAC. Furthermore, the presence of co-existing ions except CO32− had adverse effect on the coagulation removal, especially for TC. While the increase in temperature, humic acid and anionic surfactant content showed a promotion effect on the removal of PET and TC. Finally, the prepared Hmcs-PAC exhibited a potential removal of composite pollutants from urban sewage. This study can provide a promising flocculant for the effective co-removal of MPs and antibiotics from water and wastewater.

The treatment of micro-polluted waterbodies using composite flocculant

The treatment of micro-polluted waterbodies using composite flocculant

Effect of nano Fe3O4-(CMC-Na)-PFS coagulant on coagulation–ultrafiltration process for treatment of algae -rich water

A novel composite flocculant (PCNF) was prepared using nano Fe3O4 as the condensed core, sodium carboxymethyl cellulose (CMC-Na) as the binder, and polyferric sulfate (PFS). The results indicate that the mass ratio of Fe3O4 to PFS is the key factor determining the flocculation effect of PCNF. When the mass ratio of Fe3O4 to PFS is 1:3, the Zeta potential value is approximately − 1.5 mV, indicating better removal of algae through adsorption electroneutralization. The resulting floc, characterized by negative charge and a loose structure, forms a filter cake layer that is easily backwashed on the surface of the ultrafiltration membrane. This floc also creates strong electrostatic repulsion with the membrane surface. Experimental results demonstrate that the specific flux decreased to 0.69, the total relative pollution was 0.33, and the proportion of irreversible pollution was only 34.65%, all of which were superior to traditional flocculant like PACl. Through microinterface mechanism analysis, it is concluded that the new PCNF flocculant, in combination with algal matter, forms a floc structure critical for mitigating ultrafiltration membrane pollution caused by high algal content in natural surface water.

The treatment of micro-polluted waterbodies using composite flocculant

The treatment of micro-polluted waterbodies using composite flocculant

Coal gasification crude slag based complex flocculants by two-step acid leaching process: synthesis, flocculation and mechanisms.

Coal gasification crude slag (CGCS) is the side-product of the coal gasification process, and its effective utilization has attracted great attention. A novel flocculant of poly-aluminum-ferric-acetate-chloride (PAFAC) was synthesized based on the recovery of CGCS by a two-step acid leaching process, namely HCl-acid leaching and HAc-acid leaching, which was optimized by an acid leaching liquor volume ratio of HCl to HAc of 3 : 2, polymerization pH of 3.5, and reaction temperature and time of 70 °C and 3.0 h, respectively. The performance of PAFAC was further evaluated by kaolin simulated wastewater, domestic sewage, river water, and aquaculture wastewater. The results revealed that PAFAC was feasible for the removal of turbidity, chemical oxygen demand (COD) and total phosphorus (TP). Moreover, PAFAC was characterized by X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence spectrometry (XRF) and scanning electron microscopy (SEM), which proved that PAFAC was a kind of amorphous polyionic composite. Additionally, the acid leaching kinetics and flocculation mechanisms were further investigated. It was found that the acid leaching process was followed by the unreacted shrinkage core model, and the flocculation process was dominated by charge neutralization, adsorption bridging and precipitation net trapping. The work is expected to develop a new method for the safe disposal of CGCS and provide a novel way for the preparation of Fe-Al composite flocculants, especially, offering a potential strategy for the promotion of the additional value of the coal chemical industry.

Influence of composite flocculants on electrokinetic properties and electroosmotic vacuum preloading behavior of sludge

In recent years, dredging projects in rivers and lakes have generated large volumes of sludge that exhibit high water content and low permeability. This dredged sludge needs to be treated quickly to reduce its volume, thus reducing transportation costs and environmental impacts. Flocculation combined with electroosmotic vacuum preloading is a new technology for dewatering sludge. At present, the influence of flocculants on the electrokinetic properties of sludge has not been thoroughly studied, and composite forms of these have not been applied in electroosmotic vacuum precompression. Therefore, inorganic flocculant and organic flocculant were combined to form a composite flocculant, which was used in electroosmosis vacuum preloading to increase the water discharge effect of dredged sludge. Based on analyzing the mechanism of flocculants, two kinds of composite flocculants, PAC-APAM and FeCl3-APAM, were configured, and the optimal ratio of inorganic flocculant and organic flocculant in the composite flocculant was determined with a settling column test. The properties, including pore size distribution, electric conductivity, and electroosmotic permeability coefficient, of the sludge mixed with flocculants PAC, FeCl3, APAM, PAC-APAM, and FeCl3-APAM were analyzed by NMR tests and Miler Soil Box tests. In addition, a model test of electroosmotic vacuum preloading treatment of dredged sludge was conducted, and the influences of different types of flocculants on the surface settlement, water discharge, current, pore water pressure, and shear strength of the sludge were compared and analyzed. The results showed that the composite flocculants suggested in this study were able to increase the electroosmotic permeability coefficient of sludge more significantly than single-type flocculants. In situations where electroosmotic vacuum preloading combined with composite flocculants was used to treat sludge, water discharge, and consolidation settlement were larger, and the shear strength of the treated sludge was higher. Compared with FeCl3-APAM, PAC-APAM showed better performance in electroosmotic vacuum preloading.

Experimental study on electroosmosis-solidification of engineering slurry pretreated by composite flocculant

Experimental study on electroosmosis-solidification of engineering slurry pretreated by composite flocculant

Preparation of composite coagulant for the removal of microplastics in water.

In this work, a composite flocculant (polyferric titanium sulfate-polydimethyldiallylammonium chloride [PFTS-PDMDAAC]) with a rich spatial network structure was prepared for the treatment of simulated wastewater containing polystyrene (PS) micro-nanoparticles. Characterization results showed that the surface of the PFTS-PDMDAAC was a three-dimensional network polymer of chain molecules that exhibited good thermal stability and formed an amorphous polymer containing multiply hydroxyl-bridged titanium and iron. When n(OH- ):n(Fe) = 1:2, n(PO4 3- ):n(Fe) = 0.35, n(Ti):n(Fe) = 1:8, n(DMDAAC):n(Fe) = 5:100, and the polymerization temperature is 60°C, the prepared composite flocculant has the best effect. The effects of dosage, pH, and agitation intensity on the flocculation properties of PFTS-PDMDAAC were also studied. The optimal removal rates of PS-μm and haze by PFTS-PDMDAAC were 85.60% and 90.10%, respectively, at a stirring intensity of 200 rpm, a pH of 9.0, and a PFTS-PDMDAAC dosage of 20 mg/L. The flocs produced by the PFTS-PDMDAAC flocculation were large and compact in structure, and the flocculation mechanism was mainly based on adsorption bridging. Kaolin played a promoting role in the process of PS-μm removal by PFTS-PDMDAAC floc and accelerated the formation of large and dense flocs. This study provided a reference for the coagulation method to remove micro-nanopollutants in the actual water treatment process. PRACTITIONER POINTS: A composite flocculant with rich spatial network structure (PFTS-PDMDAAC) was prepared. PFTS-PDMDAAC can effectively remove micro-nano polystyrene (PS) in wastewater. The floc produced by PFTS-PDMDAAC is large and compact in structure. The flocculation mechanism of PFTS-PDMDAAC is mainly adsorption bridging.

The characteristics and flocculation mechanisms of SMP and B-EPS from a bioflocculant-producing bacterium Pseudomonas sp. XD-3 and the application for sludge dewatering

In this study, a novel bacterium Pseudomonas sp. XD-3 with bioflocculant-producing capability was identified and characterized. Strain XD-3 produced two kinds of flocculating active substances, soluble microbial products (SMP) and bound extracellular polymers substances (B-EPS). The flocculation efficiency of SMP was about 79.3% and that of B-EPS was 79.9%. Charge neutralization, ion bridging and hydrogen bonding played important roles in the flocculation of SMP, while ion bridging and hydrophobic force dominated the flocculation in B-EPS. Spectral analysis revealed that –OH and –COO- in SMP and B-EPS provided abundant binding sites for ion bridging. The presence of CNH3+ in SMP participated in charge neutralization. The hydrophobic groups of C-(C/H) and OC contributed to the hydrophobic force of B-EPS. In addition, both SMP and B-EPS contained proteins secondary structures that were beneficial for bioflocculation, such as α-helix, three-turn helices, β-sheet and aggregated strands. B-EPS exhibited satisfied sludge dewatering effect, with a water content reduction from 93.66% to 83.9% and a specific resistance to filtration (SRF) reduction from 13.48 × 1012 m/kg to 7.74 × 1012 m/kg. The composite flocculant of B-EPS and Al2(SO4)3 further reduced the SRF to 1.54 × 1012 m/kg at pH 4, CaCl2 dosage 23.3 g/kg, B-EPS 0.93 g/kg and Al2(SO4)3 150 g/kg.

Study on the matching rules and control mechanisms between flocculants and slurry settlement characteristics

In order to realise efficient, economic, low carbon and environmentally friendly slurry disposal, floc sedimentation velocity (S f ), supernatant volume (V s ), water content of bottom mud (W b ), supernatant turbidity (N s ) and pH value were determined by slurry sedimentation tests, specific resistance tests, and water quality analysis. Orthogonal tests were performed to analyze the matching rule and control mechanism between flocculants and the slurry settlement characteristics. The results show that polyaluminum chloride (PAC) and polyferric chloride (PFC) had a low dose and a fast sedimentation rate. The sedimentation effect of 20 ionic degree cationic polyacrylamide (CPAM-20) in organic flocculant is the best. Although flocculants can shorten the sedimentation time, excessive flocculants can also weaken the slurry separation effect. The sedimentation efficiency of organic flocculants is higher than that of inorganic flocculants, but it is easy to form foam on the supernatant surface. For the composite flocculants, the sensitivity sequence of S f , V s and W b is PAC>CPAM-20>PFC. PAC plays a controlling role in the sedimentation effect of the slurry.

Efficient magnetic flocculation for microalgae harvesting using a novel composite flocculant of Fe3O4-based starch-grafted-cationic polyacrylamide

As a flocculant for algae harvesting, a novel magnetic starch-grafted-cationic polyacrylamide composite (MAG@ST-g-CPAM) was developed in this study, and the harvesting efficiency of the composite was assessed with comparison to starch, Fe3O4 magnetite nanoparticles, cationic polyacrylamide and starch-grafted-cationic polyacrylamide. The feeding ratios for flocculant synthesis were optimized, and impacting factors were examined. Magnetic particles were recovered for cyclic use, and the effect of MAG@ST-g-CPAM flocculation on water reuse was examined. The results showed that MAG@ST-g-CPAM flocculation successfully achieved harvesting efficiencies of 93.2 % and 97.3 % at doses of 25 mg/L and 30 mg/L, respectively, which were superior to those of other flocculants. The optimized feeding ratio of acrylamide:Fe3O4:starch was 6:4:3. The late exponential algal growth solution with a pH range of 5–6 was most favorable for algae flocculation. A total of 93.7 % of Fe3O4 magnetite nanoparticles was recovered at pH = 3, and flocculation facilitated the reuse of water by effectively eliminating fulvic acids from the culture solution. This study demonstrated that MAG@ST-g-CPAM is a promising flocculant for algae harvesting.

NEW COMPOSITE MATERIALS AND PROCESSES FOR CHEMICAL, PHYSICO-CHEMICAL AND BIOCHEMICAL TECHNOLOGIES OF WATER PURIFICATION

In traditional methods of water purification, the use of chemical reagents leads to the appearance of toxic by-products and wastes that require complex energy-consumption processing technologies. In accordance with the principles of sustainable development and “green” technologies, a significant revision of existing water treatment methods is required. The review highlights the main trends of innovative development of water purification and disinfection technologies. Modifications of water treatment agents (flocculants, sorbents, membranes) by integration of nanoparticles, environmentally compatible materials and “smart” composites into traditional structures are described. The use of composite nanoparticles is promising, particularly the use of particles with the “magnetic core – shell” structure, in which functional elements are attached to the surface, that provide the selective capture of contaminants, including pathogenic microorganisms. The existence of the magnetic core makes it possible to manipulate particles by the applied magnetic field, which is important for their complete extraction from the water upon completion of their functions. The use of new composite flocculants containing inorganic and organic components capable of ensuring highly effective capture of contaminants from the water, significantly reduces the volumes of flocculants and generated sludges and therefore allows to reduce the cost of the sludges processing and the harm of their disposal in the environment. New carbon nanostructures and natural polymers have an important role to play. In the new generation membranes, the disperse nanoparticles may provide antibacterial and photocatalytic properties, resulting in the high efficiency of disinfection and purification. A novel trend is the development of hybrid structures of coagulants and membranes with the properties which are regulated by the external stimulus, which are temperature, pH, light, electric, magnetic and electromagnetic fields. The use of such «smart» structures will increase the purification efficiency, reduce energy consumption and water purification waste volumes, due to the decrease in membranes fouling. The use of biopolymers and composites based on plant raw materials for the water purification is attractive due to their natural decontamination under the influence of the components of the environment, such as air, soil micro-organisms and sunlight, but also due to the absence of the secondary pollution. Among innovative chemical water treatment technologies Advanced Oxidation Processes play an important role, in particular, by involving electromagnetic fields and ultrasonic activation. By these methods, harmful organic impurities and pathogens are destroyed without the intensive use of chemicals or the production of toxic by-products. The integration of biochemical wastewater treatment with a microalgae growing system can become a promising waste-free, cost-effective "green" technology.

Understanding synergistic mechanisms of silicate decorated polyaluminium chloride and organic polymer flocculation for enhancing polymer-flooding wastewater treatment

The efficient removal of oil droplets and particles from volumes of a stable emulsified oil-contaminated polymer-flooding wastewater has been an interesting yet challenging research topic within the oilfield. In this work, a highly efficient composite flocculant (PAC-PSi-PDMDAAC) was prepared by modifying activated silicic acid onto polyaluminium chloride (PAC) through Si-O-Al bond firstly and then combined with polydimethyldiallyl ammonium chloride (PDMDAAC) by physical blending, the preparation conditions and the flocculation parameters that influence of the turbidity removal and oil removal were experimentally investigated. The optimal conditions are shown as follows: pH= 3.04, PAC/PSi = 5:1, PAC/PDMDAAC = 1:0.3. The characterization of composites were analyzed by Fourier infrared (FTIR), Thermogravimetry (Tg) and Static light scattering (SLS). The results revealed that PAC underwent the addition of PSi and PDMDAAC to form high-polymeric species. In addition, the formation of more denser flocs in wastewater treatment was affirmed with scanning electron microscope (SEM) analysis. The flocculation experiments results showed that the maximum turbidity removal rate and oil removal efficiency for polymer-flooding wastewater could reached 98.3% and 91.3% at dosage of 120 mg/L, respectively, and its flocculation efficiency was much better than that of flocculants (PAC, PAC-PSi and PAC-PDMDAAC), which confirmed the synergistic enhancement of performance of PAC by PSi and PDMDAAC. However, the Zeta potential results indicated that the maximum Zeta potential value of PAC-PDMDAAC treatment was not beneficial for oil and particles removal, which indicated the adsorption bridging effect of lager aggregates played a most significant role in the flocculation process. And this newly synthesized PAC-PSi-PDMDAAC would be a promising flocculant for polymer-flooding oily wastewater treatment to reduce oil and particulate matters.