Turbidity Removal Rate Research Articles

Coagulation-Flocculation Process of Nutrient-Rich Suspended Solids from Aquaculture Effluent Using Bioflocculant

Due to the growth and development of the aquaculture industry, appropriate wastewater treatment is needed to reduce uncontrolled pollution and environmental impacts. Therefore, this research uses green technology method, which is the coagulation-flocculation process to treat aquaculture wastewater. Natural flocculants have been the focus of research of many research due to the negative impact from using chemical flocculant. In this study, the potentiality of local plants of moringa leaves and seed (Moringa oleifera), banana pith (Musa), neem leave (Azadirachta indica) and Pandan leave (Pandanus amaryllifolius) as bioflocculant were studied. This study also focuses on nutrient recovery. The potential of sludge obtained through the coagulation-flocculation process as fertilizer was investigated in comparison with commercial fertilizer. Through this study, it is shown that Moringa oleifera seed recorded the highest rate of suspended solid removal from synthetic kaolin water at 36.7% and highest turbidity removal rate at 34.8%. Previous studies have shown that aquaculture sludge contains 1.27 % of nitrate, 0.32 % of phosphorus and 0.65 % of potassium. The characteristics of sludge produced through the process of coagulation-flocculation resembles organic fertilizer. This shows that treated aquaculture sludge has potential to be used as an organic fertilizer. With this, it can promote the use of sustainable green technology for effective aquaculture wastewater treatment.

Comparison of peracetic acid and sodium hypochlorite enhanced Fe(Ⅱ) coagulation on algae-laden water treatment

In this study, Fe(Ⅱ)/peracetic acid (PAA) and Fe(Ⅱ)/sodium hypochlorite (NaClO) systems were applied as the combined preoxidation and coagulation process to enhance algae removal. A high removal rate of algae and turbidity could be achieved, with most algal cells keeping intact when adding reasonable concentrations of PAA and NaClO to enhance Fe(Ⅱ) coagulation. The variations of chlorophyll a, malondialdehyde, and intracellular reactive oxygen species suggested that moderate oxidation with only destroying surface-adsorbed organic matter rather than cell integrity was realized. The generated organic radicals, Fe(Ⅳ), and hydroxy radical played the major roles in the Fe(Ⅱ)/PAA system for the moderate oxidation of algal cells, but direct oxidation by NaClO rather than producing reactive species in the Fe(Ⅱ)/NaClO process contributed to the preoxidation. Concurrently, the in-situ formed Fe(Ⅲ) greatly promoted the agglomerating and settling of algae. The analysis of cell integrity, biochemical compositions, and fluorescence excitation-emission matrices spectra demonstrated that excess NaClO but not PAA would seriously damage the algal cells. This might be because that NaClO would directly oxidize the cell wall/membrane, while PAA mainly permeates into the cell to inactivate algae. These results suggest that Fe(Ⅱ)/PAA is an efficient strategy for algae-laden water treatment without serious algae lysis.

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.

Efficient treatment of the starch wastewater by enhanced flocculation–coagulation of environmentally benign materials

The high concentration, complexity and refractory of organic pollutants in actual starch wastewater are becoming major obstacles to realizing efficient water purification. Herein, bentonite was selected from four kinds of clay minerals (i.e. kaolin, zeolite, attapulgite and bentonite) as coagulant aids, and chitosan-modified bentonite combined with polyglutamic acid was used for enhanced coagulation treatment for starch wastewater. Among them, bentonite can adsorb soluble pollutants in starch wastewater, chitosan modification can enhance the coagulation effect, and the flocculant of polyglutamic acid is conducive to the removal of particulate matter through bridging effects. The combination of the three can effectively and deeply remove pollutants in starch wastewater. Under the optimal conditions, the removal rates of chemical oxygen demand, total nitrogen, total phosphorus and turbidity can reach 86.2 %, 80.3 %, 52.3 % and 98.2 %, respectively, which are far higher than that of the vast majority of coagulants currently reported. Density functional theory calculation was carried out to reveal the mechanisms for the enhanced coagulation-flocculation system and explained the adsorption and coagulation mechanism, respectively. The electrostatic potential around aluminum in bentonite of 14.248 kcal.mol−1 is more conducive to the adsorption of negatively charged organic pollutants, and that bentonite has lower adsorption energy (-1.43 eV) than chitosan and polyglutamic acid.

Evaluating the Applicability of High-Speed Air Flotation Technology for Water Supply: A Case Study in Tianjin Binhai New Area

The development and application of advanced water purification technology is crucial to guarantee a sufficient supply of clean water. However, conventional water purification technology consumes large amounts of coagulants, with the formation of intractable sludge. Herein, the applicability of high-speed air flotation technology for the purification of actual water sources was evaluated in Tianjin Binhai New Area. During a three-year survey, the raw water exhibited periodic pollution characteristics with algae cells as the main removal targets in all seasons. The raw water had both low temperatures and low turbidity in winter, another obstacle for water treatment. Based on the scientific analysis of the water’s quality, the water purification process was comprehensively optimized via regulating the dosage of agents and operating parameters and using high-speed air flotation equipment. The results showed that a dissolved air pressure of 0.40 MPa, reflux ratio of 8%, and SUEZ-1# dissolved air release head combined with pre-chlorination with PACl plus FeCl3 (PACl/FeCl3 ratio = 2:1) were suitable for attaining a good purification performance. High turbidity removal rates (80.9–86.2%) and algae cell removal rates (92.5–98.1%) were obtained even in the high algae period of summer and low turbidity period in the winter, proving the superior stability and applicability of the high-speed air flotation system.

A Case Study of Swine Wastewater Treatment via Electrochemical Oxidation by Ti4O7 Anode.

With the rapid development of breeding industry, the efficient treatment of dramatically increasing swine wastewater is gradually becoming urgent. In particular, the development of application technologies suitable for the relatively small piggeries is critical due to the time cost and space requirements of conventional biological methods. In this study, Electrochemical oxidation (EO) was selected to systematically explore the treatment performance of three different swine wastewaters by Ti4O7 anode. It was observed that the colors changed from dark brown to light yellow after 60 min treatment at 50 mA/cm2, and the removal rates of turbidity and suspended solids ranged from 89.36% to 93.65% and 81.31% to 92.55%, respectively. The chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and total phosphorus (TP) of all the three swine wastewaters were simultaneously removed to a very low concentration in 120 min, especially for sample III, 61 ± 9 mg/L of COD, 6.6 ± 0.4 mg/L of NH3-N and 5.7 ± 1.1 mg/L of TP, which met the Discharge Standard of Pollutants for Livestock and Poultry Breeding (GB 18596-2001). Moreover, 70.93%-85.37% mineralization rates were also achieved in 120 min, confirming that EO treatment by Ti4O7 could efficiently remove the organic matters in wastewater. Excitation-emission matrix (EEM) and UV-vis spectrum characterization results further proved that aromatic compounds and macromolecules in wastewater were rapidly removed, which played important roles in the mineralization processes. The findings here provided an efficient and environment-friendly technology for swine wastewater treatment.

Synthesis of antibacterial polyaluminium silicate sulfate /sepiolitenano composite coagulant for oilfield sewage treatment

The utilization of a large amount of anionic polyacrylamide (APAM) and sodium alkyl benzene sulfonate can induce the emulsified oil to acquire a stable emulsified colloid system in polymer flooding oily wastewater. However, for the traditional inorganic coagulants, such as polyaluminum, polyiron, etc., a relatively large number of bacteria will breed after oily sewage is treated for a specific period of time. Along these lines, in work, a new type of antibacterial polymeric aluminum silicate sulfate/sepiolite coagulant (PASS-H) was synthesized by using grafting hydrophobic antibacterial monomers in combination with coagulants composed of sepiolite as the base material for improving oily sewage purification. The structure and the surface morphology of the copolymer were systematically characterized, indicating that PASS-H was successfully synthesized. In addition, the coagulation performance of the polyaluminum silicate sulfate (PASS), modified sepiolite, and PASS-H during the treatment of polymer-containing oily wastewater was compared. In the coagulation experiments, PASS-H exhibited excellent turbidity, oil removal, and antibacterial properties. At 60 mg/L, the turbidity, oil removal rate, Zeta potentialand maximum floc size were 98%, 95%, 1.59 mv, and 26 μm, respectively. The mechanism of coagulation was thoroughly investigated based on the order of dosing, the tested water pH, Zeta potential, floc size, and the impact of the floc morphology on the coagulation. The coagulation behavior of the separate addition of the modified sepiolite and PASS was weaker than that induced by the one-time addition of PASS-H. Moreover, the enhanced charge neutralization, bridging adsorption, sweeping, and adsorption played a synergistic role in reducing the total amount of PASS-H and improving the coagulation ability. The introduction of antimicrobial monomers in PASS-H can also effectively inhibit the regeneration of sulfate-reducing bacteria (SRB) in the water. Finally, the residual turbidity and oil removal rate of the different coagulants were statistically analyzed. The extracted results have practical significance for both cost reduction and efficiency increase in large-scale applications.

Preparation of amphiphilic cationic polyacrylamide (CPAM) with cationic microblock structure to enhance printing and dyeing sludge dewatering and condition performance.

Flocculation is an important pretreatment technology for sludge dewatering, and the flocculant's performance is the key factor to determine the flocculation effect. Cationic polyacrylamide (CPAM) is commonly used in dewatering and conditioning of printing and dyeing sludge (PD sludge), and the research of high-efficiency flocculant is a hot spot in the field of PD sludge dewatering. Hydrophobic butylacrylate (BA) and (2-(Methacryloyloxy)ethyl) trimethylammonium chloride (DMC) were introduced into the copolymer, and amphiphilic (hydrophilic/lipophilic) CPAM, namely TP-ADB, with microblock structure was synthesized by ultrasonic initiated template copolymerization in this study. The functional group composition of TP-ADB was determined by FTIR and 1H NMR. Thermogravimetric analysis (TGA) showed that TP-ADB had good thermal stability. The amphiphilic rheological properties of the copolymer were measured according to the apparent viscosity. In addition, 1H NMR and TGA results confirmed the existence of microblock structure in the copolymer chain. The polymerization mechanism was discussed by association coefficient (KM) measurement. The results showed that the template copolymerization initiated by ultrasonic followed the law of free radical copolymerization. The pre-adsorption of DMC with sodium polyacrylate template (NaPAA) before the reaction confirmed that the template polymerization accorded with ZIP I mechanism. The cationic microblock structure and hydrophobic association of TP-ADB promoted the dewatering performance of PD sludge (FCMC = 72.9%, turbidity removal rate = 98.9%, SRF = 4.2 × 1012m·kg-1). Hydrophobic association enhanced the bridging, sweeping, and net catching effect, and promoted the growth of floc size and fractal dimension. Cationic microblock structure can produce compact floc with higher mechanical strength by enhancing electrical neutralization and electrical patching. As a skeleton, the compressibility of filter cake was reduced and the permeability was enhanced, and the PD sludge dewatering effect was significantly improved.

Preparation of Fe3O4@C with water treatment residuals and its potential in the magnetic coagulation process

The resource utilization of water treatment residuals is a hot topic in current research. In this work, a kind of carbon-doped magnetic nanoparticle (Fe 3 O 4 @C) was prepared using backwashing iron mud from the groundwater treatment plant as raw material. The Fe 3 O 4 @C was used for the magnetic coagulation (MC) process to evaluate the superiority of the MC process via comparing it with the traditional coagulation (TC) process. Meanwhile, the Fe 3 O 4 was also used for reference in the MC process to assess the potential and feasibility of the Fe 3 O 4 @C. The synthesized Fe 3 O 4 @C was characterized by SEM, TEM , XRD , VSM , and XPS . Then, coagulation performances and flocs properties were evaluated in both TC and MC processes. In addition, the various roles of magnetic particles in the MC process were discussed. The results showed that the participation of Fe 3 O 4 @C increased the turbidity removal rate from 90.3% to 96.8%, the ultra-violet absorbance at 254 nm (UV 254 ) removal rate from 81.4% to 86.5%, the dissolved organic carbon (DOC) removal rate from 60.4% to 66.9%, and the residual Al content dropped from 2.54 mg/L to 2.07 mg/L. Especially, it is found the Fe 3 O 4 @C had the potential to remove more small molecular weight organic matter during the coagulation process. The flocs were loose and easily broken due to the formation of the Al species-nanoparticle cluster. Fe 3 O 4 @C involved MC process can achieve the same water treatment efficiency as Fe 3 O 4 involved MC process, or even better. Especially, the magnetic seed of Fe 3 O 4 @C based on waste utilization can not only reduce the cost, but also has a good adsorption on small molecular organics. This provides a new reference way for the utilization of iron mud and the development of magnetic seed in the MC process. • Carbon-doped magnetic nanoparticles (Fe 3 O 4 @C) were prepared as magnetic seeds. • Fe 3 O 4 @C could improve the removal of small molecular organics by adsorption. • Recycle utilization of iron sludge was realized.

Effect of hydrodynamic condition on algae control based on montmorillonite modified lime-ceramic sand-lake sediments

Abstract Montmorillonite modified lime-ceramic sand-lake sediment (LC-sediments) was synthesized and its algae removal efficiency was investigated in this study. Montmorillonite not only improved the morphology and surface area of original LC-sediments, but also promoted the algal removal rate due to its inherent properties such as accumulating an electric charge, acting as a flocculant, and displaying a local bridging effect. Based on parameter optimization including the ratio of raw materials, agent dosage, initial algae density, pH and a determination of overlying water, the effect of hydrodynamic conditions on the algal removal process was researched. Under the optimal condition, the removal rates of turbidity, algae density and chlorophyll a could reach 86, 88 and 68%, respectively. As verified with a response surface model, it was shown that low disturbance (stirring) of the algae could promote algal removal by montmorillonite modified LC-sediment. Furthermore, a water column was utilized to approximatively simulate the flocculation and algae control in shallow lakes. This study solved the problem of reducing the dosage of lake sediment and improving the removal efficiency of algae without causing secondary pollution to the environment. It was expected to provide a certain theoretical basis for clay flocculation-based algae control in a real environment.

Flotation and separation of microplastics from the eye-glass polishing wastewater using sec-octyl alcohol and diesel oil

The eye-glass polishing wastewater (EGPW) is an increasingly noteworthy problem because of its high chemical oxygen demand (COD), high turbidity and abundant microplastics (MPs), which threatens the aquatic environment as well as human life. In this study, we analyzed the separation performance of MPs from EGPW using sec-octyl alcohol and diesel oil as frother and collector, respectively. The experimental results demonstrated that the removal rate of MPs, COD and turbidity could reach to 93.9 %, 80.4 %, 83.8 %, respectively. The measurement of induction time, Fourier-transform infrared and X-ray photoelectron spectroscopy were measured to explain flotation mechanism of MPs. Sec-octyl alcohol has little effect on the functional groups of MPs and it mainly reduces the surface tension of gas-liquid interface and improves the stability of bubble. Diesel oil increases the C-C/C-H content of MPs, illustrating that it could absorb on the surface of MPs and improve the hydrophobicity of MPs. The induction time decreases with the increasing dosage of both sec-octyl alcohol and diesel oil, thus improving the separation rate of MPs from the EGPW. These results indicate that bubble flotation exhibits great potential to effectively remove MPs and purify the EGPW, anticipating to facilitate the municipal wastewater management.

Treatment of Chromium Removal Wastewater from Tanning by a New Coupling Technology

In this study, the coupling process of flocculation and membrane separation was used to treat tannery chromium removal wastewater, and the experimental results of the different process operating conditions were investigated to optimize the entire process design. First, the wastewater was pretreated by flocculation ultrafiltration (UF), and the produced water could directly enter nanofiltration (NF) for concentration treatment. The removal rates of turbidity, chroma, and chemical oxygen demand (COD) of the pretreated wastewater were 96.5%, 53.7%, and 45.8%, respectively. Then, NF multistage treatment was used to control the freshwater recovery rate to 90%, where the salt content of the primary freshwater was 200–500 mg·L−1, and the salt content of the secondary freshwater was 800–1000 mg·L−1, which all met the reuse standards of the factory. The total dissolved solids (TDS) and COD of the concentrated wastewater were 44,000–46,000 mg·L−1 and 10,000–13,000 mg·L−1, respectively. Finally, electrodialysis (ED) was used to desalinate the wastewater, and the desalination rate after primary ED desalination was 52.2%. Subsequently, by increasing the temperature of the wastewater in the desalination chamber to 31 °C, the wastewater was subjected to two-stage ED to remove the sulfate in the wastewater for the second time, and the total desalination rate reached 61.9%. The results showed that this new coupling process could realize the efficient reuse of chromium removal from tannery wastewater.

Leachate post treatment, using Ag-TiO2 nanoparticles immobilized on rotating vanes

The current study investigated the capability of Ag-TiO2 nanoparticles in photocatalytic landfill leachate post-treatment. Silver doped Titanium dioxide nanoparticles were coated on rotating vanes and used in an immobilized photoreactor for the first time. The system's efficiency in COD, color, turbidity, and TOC removal, was monitored, and the effect of different parameters including pH, coating surface area, and concentration of immobilized nanoparticles was investigated. Based on the results, the maximum COD, color, turbidity, and TOC removal rates were 62%, 66%, 53%, and 55%, respectively, after 4 h of irradiation under optimal conditions. Experimental data on COD removal were also compared with the first and second-order kinetic models and it was concluded that the degradation process is more compatible with the second-order model. Finally, vanes' durability was tested, and according to the results, each set of vanes was capable of being used for at least six consecutive cycles with a negligible decrease in the treatment efficiency. In comparison with pure TiO2, the synthesized Ag-TiO2 nanoparticles showed higher removal rates in equivalent time intervals, and the whole system proved to be a promising post-treatment approach.

Improving the Performance of the Reverse Osmosis Process with Fiber Filter and Ultrafiltration: Promoting Municipal Sewage Reclamation and Reuse for Industrial Processes

Wastewater reuse presents a promising solution to the growing need for the sustainable use of available water resources. The reclamation of municipal sewage through reverse osmosis can be applied for diverse uses to alleviate chronic water scarcity. In this study, a pilot plant was fabricated to measure the efficiency and the costs that are associated with pretreatment by the fiber filtration and ultrafiltration of secondary effluent from a water resource recovery facility in Taiwan. The results of this dual-membrane process meet the quantity and quality standards for industrial reuse. The pretreatment produced feedwater with a silt density index (SDI15) lower than 4.1, and with average turbidity removal rates of 42.7% (fiber filtration) and 99.2% (ultrafiltration). Following reverse osmosis, a 97.9% rejection of the electrolyte conductivity was achieved in the reclaimed water. The fouling of the membranes was controlled through the application of intensive backwash, chemically enhanced backflushing, and cleaning in place. The proposed system improves the feasibility, reliability, and economy of the dual-membrane process as a tertiary treatment for safe water reuse, and it thereby demonstrates that this technology has reached maturity for the full-scale implementation of sustainable water reuse.

Phytic acid and graphene oxide functionalized sponge with special-wettability and electronegativity for oil-in-water emulsion separation in single-step

Developing an emulsion separation material with one-step in-situ purifying capability and improved security in applications, especially for subsequent scale-up, is valuable but remains a challenge. Herein, the amphiphilic sponge (PA@RGO@MS) was prepared via impregnation and in-situ growth of the negatively charged hydrophilic phytic acid (PA) and the hydrophobic reduced graphene oxide (RGO) on the surface of the melamine sponge (MS) and applied in emulsion purification. The mechanics, wettability, absorption performance of the PA@RGO@MS were analyzed to identify its potential for stable demulsification. Results show that the PA@RGO@MS could purify emulsions (turbidity removal rate = 99.7%; TOC removal rate = 94.14%) in-situ in one step by simple shock absorption, profited from the hydrophilic and demulsification capability of PA, oil absorption of RGO, and wide reaction and storage space of MS. Targeting the emulsion with distinct properties (density, viscosity, and concentration) of the oil phase, the PA@RGO@MS could efficiently enable the purification. Meanwhile, the powerful flame-retardant granted from PA ensures the safe shipment and storage of sponges. The favorable cyclability (turbidity removal rate > 98.5% and TOC removal rate > 89.5% after 10 cycles) and diversified operating modes enhance the practical value of the PA@RGO@MS.

Evaluation of the self-assembled functional PPFS-P-AM composite for treating oilfield sewage

Oilfield sewage has a complex composition with large amounts of emulsified oils, polymers and surfactants. Efficient coagulants are required to purify such sewage to meet emissions standards. In this study, oxidized FeSO4·7H2O and NaHCO3were condensed by basic titration and polyferric sulfate phosphate (PPFS) was prepared by the addition of NaH2PO4·2H2O to improve its charge and stability. In addition, by adding modified palygorskite and cationic amylum, a functional polyferric sulfate phosphate, palygorskite and cationic amylum copolymer (PPFS-P-AM) composite coagulant was synthesized through self-assembly, and then used to treat oilfield sewage. The characteristic functional groups and crystal forms of the coagulant were characterized by FTIR and XRD. The zeta potential and radius of gyration (Rh) indicate that the introduction of palygorskite and cationic amylum enhance the charge neutralization and bridging adsorption abilities, respectively. The optimal dosage of cationic amylum is 5% in 80 mg·L−1 PPFS-P-AM, which provides turbidity and oil removal rates of 98% and 94%, respectively. Observation by SEM shows that the micro-morphology of PPFS-P-AM flocs has adendritic distribution with a reticular macromolecular structure that provides good sweeping performance during the sedimentation process. Finally, an analysis of its properties and performance reveals the mechanism by which PPFS-P-AM coagulates oilfield sewage. PPFS-P-AM provides better coagulation than the other studied coagulants via the synergistic effects of reinforced charge neutralization, bridging adsorption and sweeping.

Preparation and performance evaluation of hybrid polymer flocculants (PAC‐PAM), and comparison experiments with other flocculants

AbstractUsing the initiator system of potassium persulfate, a new PAC‐PAM organic–inorganic hybrid flocculant was synthesized. This flocculant is used in sewage disposal. When the dosage was 10 mg/L and initial turbidity was 160 NTU, the turbidity removal rate of the heterogeneous flocculant reached the highest point of 95.04%, the water treatment effect of the hybrid flocculant is higher than that of other flocculants. The optimal experimental conditions in this experiment were as follows: the ratio of AM monomer to PAC was 8:2, the mass fraction of the added initiator was 0.2 wt%, the reaction temperature was 50°C, the reaction time was 4 h, and the pH of the effluent was neutral or weakly basic. Under the same dosage and different initial turbidity, the turbidity removal effect of hybrid flocculant is better than compound flocculant and PAM or PAC. The results show that the hybrid flocculant is a new material, which is different from the compound flocculant. Moreover, the hybrid flocculant is almost non‐corrosive to the equipment and has the prospect of industrial application.

Purification of bathing wastewater by double suspended layer fluidized bed reactor.

An external radial magnetic field and built-in stainless steel balls formed a magnetic suspended layer (MSL), as observed in this study. Under the condition of crossflow inflow, the flocculating agent and coagulant aids form a flocculated particles suspension layer (FPSL). Thus a double suspended fluidized bed reactor was constructed to treat bathing wastewater. A particle image velocimetry device was used to detect flow patterns and analyze the flocculation conditions. The results showed that under the condition of crossflow inflow, at the same time, the flooding water was 0.023-2.101 m3/h, and the dosage of poly aluminum chloride (PAC) and polyacrylic amide (PAM) was 90 mg/L and 1.5 mg/L, respectively, and removal rates of turbidity, chemical oxygen demand (CODCr) and linear alkylbenzene sulphonates (LAS) reached more than 99, 90, and 80%. Filtration, grid flocculation and particle interception were functions of the MSL. Meanwhile, the crossflow input created additional vortexes, increasing the likelihood of flocculation particle collision, improving the flocculation conditions and cleaning the MSL. The reactor aids in the development of the initial flocculated particles suspension layer, flocculation strengthening, chemical dosage reduction, effluent qualities improvement, and effluent stability maintenance.

Pilot test study on the performance of multiphase flow pump DAF equipment and reservoir water pollution removal by the DAF process

The eutrophication of reservoir water leads to the proliferation of algae, the DAF process can overcome the lack of algae removal capacity in conventional treatment processes, and its pollution removal efficiency is affected by the equipment performance. Among DAF equipment, multiphase flow pumps have attracted attention because of their simple configuration and low failure rate. This paper studied the equipment performance and pollution removal efficiency of a multiphase flow pump for DAF. The results showed that the dissolution efficiency of the equipment was approximately 55% and the average particle size of bubbles was less than 26 μm. When the pressure was greater than 0.36 MPa, the bubble stability time exceeded 4 min. The optimal working conditions were achieved at a dissolved gas pressure of 0.4 MPa. The maximum removal rates of turbidity, chlorophyll a, TOC, UV254 and CODMn by the DAF process were 56.49%, 50.23%, 23.73%, 28.75% and 23.98%, respectively. The trend in pollution removal efficiency was consistent with that of equipment performance parameters. The surface of the microbubbles was hydrophobic and could more easily adsorb high-molecular-weight organic substances with strong hydrophobicity and algae with strongly hydrophobic colloidal layers inside. In addition, regarding the THMFP, the experimental results showed that the removal rates of the precursors CHCl3, CHBrCl2 and CHBr2Cl after DAF were 28.93%, 23.26% and 21.53%, respectively. Surface hydrophobicity is one of the main mechanisms by which microbubbles adhere to pollutants.

Study on preparation of cationic flocculants by grafting binary monomer on cellulose substrate by γ-ray co-irradiation

Carboxymethyl cellulose (CMC) and wood flour cellulose (WFC) graft copolymers were prepared from acrylamide/dimethyl diallyl ammonium chloride (AM/DMDAAC) by γ-ray co-irradiation graft copolymerization method. CMC could obtain an excellent grafting effect at the absorbed dose of 6 kGy and CMC/AM/DMDAAC ratio of 0.2 g:2 g:1 ml, and the grafting rate, grafting efficiency, cationic degree and grafting efficiency of DMDAAC monomer were 790%, 46.01%, 20.17% and 64.56% respectively. Relatively, when the ratio of AM and DMDAAC was 3 g:1 ml and the absorbed dose was 8 kGy, the grafting effect of WFC was the optimum, and the more WFC added, the better graft copolymerization effect. The flocculation effect of the products and cationic polyacrylamide on kaolin wastewater was investigated, and the maximum turbidity removal rate of CMC graft copolymer on kaolin wastewater reached 86.0%, showing an excellent flocculation effect. The flocculation effect under different conditions was WFC graft copolymer＞CMC graft copolymer＞Cationic Polyacrylamide.