Addition Of Polyacrylamide Research Articles

Advanced treatment of biologically treated coking wastewater by membrane distillation coupled with pre-coagulation

In this study, a laboratory-scale membrane distillation (MD) system was developed for advanced treatment of biologically treated coking wastewater (BTCW), while the effect of pre-coagulation was also investigated. Results showed that membrane distillation could effectively reject the salts (>99.1%) and organic pollutants in BTCW (>96.2%) and no membrane wetting was observed. The remaining organics in distillate was largely determined by the amount of volatile substances in the feed. Pre-coagulation with poly-aluminum chloride (PACl) was found to be effective for significantly reducing the contaminant level in BTCW. This in turn significantly reduces the propensity of membrane fouling. Use of polyacrylamide (PAM) as a coagulant aid could further decrease the contaminant level in BTCW, but it may lead to even severer membrane fouling. Scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS) and fluorescence spectra analyses revealed that the interaction between PACl and remaining organics could prevent the formation of calcium carbonate on the membrane surface, whereas the addition of PAM facilitated the accumulation of aggregates on membrane surface, leading to serious membrane fouling. This study shows that membrane distillation coupled with pre-coagulation could serve as a potential alternative for advanced treatment of biologically treated coking wastewater.

An investigation on cutting quality by adding polymer in abrasive water jet

ABSTRACTAn experimental investigation is presented to improve the cutting quality in abrasive water jet (AWJ) cutting of marble by an addition of polyacrylamide (PAM). Considering experimental data, the kerf widths have a remarkable change when the PAM concentration approaches to 400 ppm. The deviation between top and bottom kerf width reaches the minimal value when PAM concentration is equal to about 600 ppm. In addition, the surface topography analyses illustrate that an addition of PAM can broaden the cutting wear zone and make the cutting quality better. Furthermore, the effects of PAM on the surface roughness are assessed by a profilometer. It is eventually found that the surface roughness decreases initially and then increases greatly with the increase of the depth of cut. Additionally, the minimum surface roughness occurs when the PAM concentration is 600 ppm, which agrees well with the experimental result of kerf width. An increasing stand-off distance or traverse speed produces a higher surface roughness.

The regrowth ability of alum–humic flocs: effect of polyacrylamide

The effect of polyacrylamide (PAM) dosage and mixing time on the formation, breakage, and regrowth of alum flocs was explored by Mastersizer 2000. The result showed that the coagulation efficiency and regrowth ability of broken flocs were determined by the mixing time, PAM dosage, and pH value. When PAM was dosed simultaneously with alum, the broken flocs could not regrow, independent of PAM dosage, while the regrowth ability of broken flocs increased as the dosing time of PAM delayed. Broken flocs could fully regrow when PAM was dosed 5 min after the addition of alum. Both flocs’ size and regrowth ability enhanced with the increase in PAM dosage when PAM was dosed 5 min or more later than alum. Although the size of alum-HA flocs could be slightly improved by PAM, the addition of PAM significantly improved both the growth ability of flocs and the regrowth ability of broken flocs at pH 7 and 8. This might be caused by the variation of chemical bonds with pH for PAM and alum precipitate. Scanning electron microscopic images proved that when PAM was dosed simultaneously with alum, PAM would be covered by alum-HA precipitate nanoparticles; but more PAM could be seen on the surface of flocs when PAM was dosed 6 min after the addition of alum. The variation of chemical bonds on the surface of precipitate primary nanoparticles may induce the irreversibility of broken flocs. The hydrogen bonding between PAM and alum-HA flocs may be the main flocculation mechanism for the high growth of flocs and regrowth of broken flocs.

Effects of Anionic Polyacrylamide on Carbonation for the Crystallization of Precipitated Calcium Carbonate

The effects of different types of anionic polyacrylamide (PAM) on crystallization behavior of precipitated calcium carbonate (PCC) prepared via carbonation using calcium hydroxide and carbon dioxide gas. The percentage of aragonite phase increased higher reaction temperature. The use of anionic PAM resulted in the formation of larger PCC aggregates than in the case of PCC crystallized without anionic PAM. This outcome resulted from a contraction of the PAM coils due to the electrostatic screening and counterion condensation effects. The carbonate ions were combined with aggregated calcium ions. Furthermore, the carbonation reaction time could also be reduced by the addition of anionic PAM.

Using polyaluminum chloride and polyacrylamide to control membrane fouling in a cross-flow anaerobic membrane bioreactor

The objective of this study is to determine the feasibility of using flocculants to control membrane fouling in anaerobic membrane bioreactors (AnMBRs), which has not been previously reported. The effects of two typical polymeric flocculants, polyaluminum chloride (PAC) and polyacrylamide (PAM), on the properties (filterability, soluble microbial products (SMP), zeta potential and floc size) of anaerobic sludge were studied by batch experiment. The addition of either PAC or PAM can improve the filterability of the mixed sludge liquor but with different mechanisms and dosages. PAC mainly decreases the SMP, while PAM enlarges the floc size. The recommended PAC dosage is 500mg/L because a higher dosage would cause significant inhibition to anaerobic digestion. The effects of three flocculant addition methods on membrane fouling were tested in two lab-scale anaerobic membrane bioreactors. PAC at a dosage of 500mg/L was shown to be more effective than PAM in the control of membrane fouling through the reduction of TMP and the rate of TMP increase by facilitating the decrease in SMP and the improvement of sludge filterability. The addition of PAC at the beginning of the operation was the best way to control membrane fouling as the running period could be effectively extended.

Enhanced Al-H2O-based fuels combustion characteristics with polyacrylamide at low pressures

The combustion behavior of nano-aluminum-water (n-Al-H2O) mixture with addition of polyacrylamide (PAM) was investigated in argon at 0.1∼1.5 MPa using a constant-pressure strand burner. The burning rates of n-Al-H2O mixture were measured. The results show that PAM addition can not only help improve the burning rate of n-Al-H2O mixture, but also decrease the pressure index of burning rate. The mixture of n-Al powder and H2O cannot be ignited in argon at 0.1 MPa, but the mixture of n-Al powder and H2O with the 3 wt % PAM can be ignited, and the mixture can support the self-sustaining combustion. The burning rate is 7.64 mm/s. Moreover, the burning rate increases with increasing the pressure. In addition, the combustion process and flame image characteristics were obtained by a high-speed photography technique, and the element composition and surface morphology of the condensed combustion products were evaluated using a scanning electron microscopy combined with energy dispersive X-ray system.

Effect of a Polymer Additive on Heat Transfer and Pressure Drop Behaviors of Upward Air–Water Flow in an Inclined Smooth Circular Tube

This article presents an experimental study of the effect of polyacrylamide (PAM) on heat transfer and frictional pressure drop behaviors of upward air–water two-phase flow in an inclined smooth circular tube with an upward inclination angle of 8 degrees from the horizontal direction. The test tube has an inside diameter of 40 mm and an outside diameter of 48 mm. A PAM water solution with a concentration of 300 ppm was used in the experiments. The liquid phase superficial velocities are 0.52, 1.02, and 1.46 m/s and the gas-phase superficial velocities are from 1.79 to 6.54 m/s. Heat transfer tests were performed by cooling the air–water flow inside the test tube through its wall using the cooling water with a heat transfer length of 3 m, and two-phase pressure drops were measured over a length of 3.1 m. Results show that the air–water two-phase frictional pressure drops can be reduced from 26.2% to 42.7%, while the two-phase heat transfer coefficients can be reduced from 39.7% to 80.8% with addition of PAM. Furthermore, new proposed physical mechanisms of the two-phase frictional pressure drop and heat transfer reductions are used to explain the experimental results.

Transformation of the structural organization of clay sediments and soils under the impact of polyelectrolytes

The effects of polyacrylic acid (PAAc) and polyacrylamide (PAA) adsorption by quartz sand, montmorillonite, kaolinite, gray forest soil, and chernozem on the texture of the sorbents were studied. It was shown that the polymolecular adsorption was typical of the applied polyelectrolytes. The addition of PAA in a concentration of 0.05% to the solution resulted in consolidation of the sediments with a decrease in their volume. In the case of montmorillonite, a loose gel precipitate formed; its volume decreased by about 6% during the experiment. The adsorption of polyelectrolytes slightly affected the average radii, total surface area, and volume of the pore space (within 4–20%). The transformation of the surface of minerals and soils under the action of polyelectrolytes resulted in a significant change in the differential pore volume. The number of pores of about 0.0014 μm in size hardly changed at all. However, wider pores (0.011–0.45 μm) appeared. The adsorption of PAAc resulted in the appearance of wide pores (1.6–22.0 μm), and the adsorption of PAA resulted in the appearance of two narrow classes of micropores. A much more even distribution of differential porosity in the range of 3.6–4.5 μm was revealed. Thus, the transformation of the surface of adsorbents by polyelectrolytes led to changes in the pore-size distribution.

Cationic polyacrylamide as coagulant aid with titanium tetrachloride for low molecule organic matter removal

This is the first attempt to use cationic polyacrylamide (PAM) as coagulant aid with titanium tetrachloride (TiCl4) to improve the coagulation performance and floc properties. Coagulation–flocculation treatment was applied to simulated water (with fulvic acid (FA) as model organic matter) for both coagulation behavior investigation and floc characterization. The effect of PAM on floc reformation properties after cyclic breakage/regrowth was also investigated. Ultrafiltration experiments were performed to investigate the influence of PAM aided TiCl4 coagulation on the membrane fouling. The results showed that organic removal was enhanced by PAM addition at low TiCl4 doses. Floc growth rate and floc size were significantly affected by dosing sequence. TiCl4–PAM significantly improved the floc strength factors (Sf) and recovery factors (Rf). The dosing sequence of TiCl4 and PAM significantly influenced the floc structure. Characterization of the flocculated sludge indicated that TiO2 with anatase structure and high photocatalytic activity could be obtained from the TiCl4–PAM flocculated sludge.

Interaction of adsorbed polymers with supported cationic bilayers

The interaction forces between bilayers of the cationic surfactant di(tallow ethyl ester)dimethyl ammonium chloride (DEEDMAC) were measured using a Surface Forces Apparatus (SFA) with and without an adsorbing polymer, polyacrylamide (PAM). In the absence of PAM, the forces measured between the bilayer surfaces were purely repulsive on approach and separation and is charge regulated. Addition of PAM induced structural changes to the bilayer interfaces, and resulted in the formation of bilayer-like patches of DEEDMAC decorated PAM (hydrated) on the mica surface. The interaction potential between these surfaces showed a modified DLVO interaction with an additional monotonic steric hydration repulsion on approach with an exponential force decay length of Dsteric ∼ 1 nm consistent with the measurements of hydration forces. On separating the surfaces, interdigitated polymers bridge between the two surfaces, resulting in a weak adhesion (adhesion energy, W0 ∼ 0.1 mJ m−2). Our results provide a picture of the complex molecular structure and interactions between uncharged adsorbing water soluble polymers and supported charged bilayers, and highlight the effects of adsorbing polymers on the structure of bilayers. Implications for the stability of vesicles in dispersions have been also discussed.

Influence of inactivation agents on phosphorus release from sediment

The effects of inactivation agents, including common polymeric aluminium (Al) chloride (CPAC) and Ecological Type PAC (UNIC), on phosphorus (P) released from sediment are unclear. To determine these effects, we performed seven experiments using various inactivation agent additions. The experimental schemes used were as follows: (1) CPAC, 15 mg Al L−1; (2) CPAC (15 mg Al L−1) + polyacrylamide (PAM) (0.5 mg L−1); (3) UNIC, 5 mg Al L−1; (4) UNIC, 15 mg Al L−1; (5) UNIC, 60 mg Al L−1; (6) control set without any inactivation agent addition; and (7) alkali shock load (the pH value of overlying water in the scheme 7 was adjusted to 11 by addition of sodium hydroxide to simulate alkali shock load at 13 days after CPAC addition). The experiments were conducted in glass columns, each containing 0.3 L sediment from Lake Dianchi and 3 L of overlying water. The results showed that P release rate decreased as the amount of inactivation agent added increased. P release rate was calculated according to each inactivation agent and the amount of inactivation agent added. Release rate found was in the decreasing order: (6) > (3) > (4) > (1) > (5) > (2). The corresponding rate was calculated to be 7.11, 6.16, 4.55, 1.76, 1.46 and 1.00 mg P m−2 day−1, respectively. Dissolved total P (DTP) was the main form of total P (TP) in the overlying water. After the addition of PAM, the DTP:TP ratio decreased while the dissolved inorganic P (DIP):DTP ratio increased. With increasing the amount of inactivation agents added, both DTP:TP and DIP:TP ratios decreased. Experimental group 3 had similar DTP:TP and DIP:TP ratios to experimental group 6. These results are significant in terms of the large-scale application of inactivation agents for reducing levels of bioreactive P. Alkali shock load (experimental group 7) caused failure in the inactivation of P by CPAC.

Investigation of the stability of an alumina suspension in the presence of ionic polyacrylamide

The influence of solution pH on the adsorption mechanism of polyacrylamide (PAM) on the alumina surface and stability of its suspension in the presence of polymer were investigated. The structure of polymer adsorption layer was determined from the spectrophotometric, viscosity, surface charge and zeta potential measurements which enable determination of adsorbed amount of polymer, thickness of the polymer adsorption layer, surface charge density and zeta potential of Al2O3 particles in the absence and presence of PAM. The measurements of stability of alumina suspension without and with adsorbed polyacrylamide were also carried out using two methods: spectrophotometry and turbidimetry. The obtained results indicate that solution pH influences the structure of PAM adsorption layer (decrease of adsorbed amounts of polymer and increase of its adsorption layer thickness with the increasing pH). These conformational changes of polyacrylamide molecules with the rising pH have an impact on stability of the alumina suspension. The most pronounced effect of polymer on the stabilization properties of investigated systems is observed for PAM addition at pH 6 resulting in a great destabilization of the alumina particles by bridging flocculation.

Effectiveness of Fly Ash and Polyacrylamide as a Sand-Fixing Agent for Wind Erosion Control

Searching for an effective and economical sand stabilization measure has an important significance in wind erosion control. Wind tunnel experiments were conducted to evaluate the sand-fixing effect of fly ash (FA) at three different application rates (10, 20, and 30 % (w/w) soil). The additional effect of polyacrylamide (PAM) was also studied under two different application rates (0.05 and 0.1 % (w/w) soil) on the basis of the optimum FA usage. The results indicated that the utilization of FA increased the threshold wind speed of the treated soil significantly, which was further increased by the addition of PAM. The soil treated with 20 % FA could most effectively withstand the pure wind with a wind speed of 8 m s−1 for 10 min, while only the slightest wind erosion occurred after exposure to the sand-carrying wind with a wind speed of 8 m s−1 for 10 min. However, moderate wind erosion occurred after exposure to both the pure wind and the sand-carrying wind with a wind speed of 14 m s−1 for 10 min, respectively, and there was a decline in the wind erosion rate with the increase of FA application rate. The soil treated with 20 % FA and 0.05 or 0.1 % PAM could effectively withstand the pure wind with a wind speed of 14 m s−1 for 30 min, while only the slightest wind erosion occurred after exposure to the sand-carrying wind with a wind speed of 14 m s−1 for 30 min. The combination of a 20 % FA and 0.05 % PAM application rate is recommended to give effective and economical wind erosion protection.

Treatment of Pulp and Paper Mill Wastewater with Various Molecular Weight of PolyDADMAC Induced Flocculation with Polyacrylamide in the Hybrid System

Flocculation studies between dual polymers on pulp and paper mill wastewater are reported in this paper. The effects of different molecular weights of polyDADMAC and different dosages of Polyacrylamide (PAM) were studied. The molecular weights of polyDADMAC used were 8.8×104, 10.5×104 and 15.7×104 g/mol. The flocculation performance was analyzed in jar tests with PolyDADMAC and Polyacrylamide dosages ranging from 0.4-2.0 mg/L﹣1 and 0.4-8.0 mg/L﹣1 respectively. A higher molecular weight and a 6.0 mg/L﹣1 dosagepolyDADMAC gave the highest level of flocculation based on turbidity and TSS removal. In addition, increasing the molecular weight of PolyDADMAC increased ζ potential values approaching zero. This indicated that polyDADMAC acts as a destabilizer. Based on TSS, the addition of PAM will improve the size of microflocs created by polyDADMAC. It demonstrates that PAM acts as a bridger between microflocs.

Application of Biodegradable Polymers on Hydroseeding

Erosion soil loss is an important problem to be solved. Polyacrylamide (PAM), a biodegradable polymer, has been used in irrigating ditch to reduce soil loss for a long time. It can also be used as an aggregate agent to keep the balance of soil water. The performance of PAM as a soil aggregate agent of silty clay loams was conducted by the wet-sieving method in this study. The effects of PAM on the germination and growth of Bermuda and Bahia were observed. The experiments were conducted in a controlled box with constant temperature and humility. An out-door experiment was also conducted to understand the germination rate of seeds and the development of roots of grasses in ambient condition. Experimental results showed that the addition of PAM would delay the germinations of seeds. However it could enhance the growth of the Bermuda and Bahia grasses.

Effect of trace amounts of polyacrylamide (PAM) on long-term performance of activated sludge

This study aims at evaluating the impacts of PAM addition on activated sludge performance. Four lab-scale sequencing batch reactors (SBRs), each with a working volume of 3 L, were investigated with different PAM concentrations. Experiments were conducted with varying organic loading rate and the sludge volume index (SVI), particle size, zeta potential, specific oxygen uptake rate (SOUR), mixed liquor suspended solids (MLSS), COD and ammonium removal efficiency were monitored over a 105-day period. The results showed that all of the PAM addition not only improved the removal efficiencies of COD and ammonium, but also exhibited some advantages on sludge performance. It was found that the sludge performance of settling property, flocculation and microbial activity increased with increasing concentration of PAM. However, high level of PAM (1 mg/L) led to the formation of large amounts of loose-structure flocs, which eliminated dissolved oxygen transfer and caused the sludge disintegration, resulting in bad settleability and lower microbial activity. In this way, when the dosage of PAM was 0.1 mg/L, the sludge had the best settling property and activity.

Hydraulic Characteristics of Depositional Seals as Affected by Exchangeable Cations, Clay Mineralogy, and Polyacrylamide

Depositional seals, formed when turbid waters infiltrate into soils, lead to a reduction in the hydraulic conductivity (HC) of soils and increased runoff. In this study, the effect of anionic polyacrylamide (PAM) on the HC and flocculation of depositional seals made of three clay minerals (montmorillonite, illite, and kaolinite), saturated with either Na or Ca, was investigated. A silt loam soil was packed in columns and leached with 5 g L−1 suspensions of the reference clays. Deposition of the clay particles on the soil surface formed seals. In the PAM treatment, dry granules of linear PAM were spread on the soil surface before the suspension application. Calcium seals were more permeable than Na seals in all the clay types, up to 26 times greater for montmorillonite. The HC of the seals for the clay minerals was in the order kaolinite (2.8–3.5 mm h−1) > illite (0.6–3.0 mm h−1) > montmorillonite (0.09–1.0 mm h−1). The addition of PAM generally enhanced clay flocculation, with the magnitude of the enhancement depending on the type of the exchangeable cation. The Na‐saturated seals in the three clay types had significantly higher initial HC with the PAM treatment. This increase, however, was transient except in Na‐illite. The impact of PAM on the degree of clay flocculation and floc density partially explained the effects of PAM on the HC of the depositional seals. An increase in clay flocculation or a decrease in floc density caused by PAM resulted in an increase in depositional seal HC.

Effect of Matrix Elasticity on the Continuous Foaming of Food Models

The aim is to understand the effect of matrix elasticity on continuous foaming using food models based on glucose syrup. This was modified by adding polyacrylamide (PAA) with 2% whey protein isolate (WPI) or Tween 80 as foaming agents. Foaming was conducted in a stirred column. Rotation speed N and gas-to-liquid flow ratio (G/L) were varied. Overrun, average bubble size d (32), texture and stability were measured using densimetry, image analysis, and rheometry, respectively. Experimental results showed that 0.01% PAA did not modify the viscosity of 2% WPI models, but conferred low elastic behavior. PAA (0.05%) doubled matrix viscosity and drastically increased elasticity. The increase of elasticity became slower for further PAA addition. Foaming experiments demonstrated that theoretical overrun could not be achieved for inelastic WPI models in two cases: for high viscosity and low N, as dispersion effectiveness was reduced; for high G/L and N because of enhanced coalescence. Matrix elasticity was shown to increase overrun at constant viscosity for high G/L by enhancing interface stabilization. However, in elastic models, gas dispersion was more difficult and d (32) was higher than in inelastic fluids of similar viscosity. Finally, when the limiting step was dispersion, foaming was shown to be negatively affected by matrix elasticity.

Electrochemical Degradation of Pulp and Paper Mill Wastewater. Part 2. Characterization and Analysis of Sludge

In this paper, we report the characteristics and the management of the sludge generated by the batch electrochemical (EC) treatment of the black liquor (BL) of a small paper mill based on agricultural waste as raw material. The study shows that the sludges obtained from the EC treatment of the BL at its natural pH without any additive and with 625 mg dm-3 sodium chloride (NaCl) or 10 mg dm-3 polyacrylamide (PAA) during the EC process had very good settling characteristics. PAA addition hastens the EC process, and the sludge settling rate improves considerably. The settling velocity of the sludge obtained from the EC treatment without any additive could be satisfactorily correlated with the model of Richardson and Zaki. The results of the gravity filtration of the treated BL showed that the addition of NaCl (625 mg dm-3) improved the filtration characteristics and reduced the values of the specific cake resistance (α). The values of the specific cake resistance (α) and the resistance of the filter medium (...

Controlling Tailwater Sediment and Phosphorus Concentrations with Polyacrylamide in the Imperial Valley, California

External loading of phosphorus (P) from agricultural surface discharge (tailwater) is the main cause of excessive algae growth and the eutrophication of the Salton Sea, California. Continuous polyacrylamide (PAM) applications to agricultural irrigation water inflows were evaluated as a means of reducing sediment and P in tailwater. Zero (control) and 1 mg L(-1) PAM (PAM1) treatments were compared at 17 Imperial Valley field sites. Five and 10 mg L(-1) PAM treatments (PAM5, PAM10) were conducted at one site. The particulate phosphorus (Pp) fraction was determined as the difference between total phosphorus (Pt) and the soluble phosphorus (Ps) fraction. We observed 73, 82, and 98% turbidity reduction with PAM1, PAM5, and PAM10 treatments. Although eight field sites had control tailwater sediment concentrations above the New River total maximum daily loads (TMDL), all but one were made compliant during their paired PAM1 treatments. While PAM1 and PAM10 reduced tail water Pp by 31 and 78%, none of the treatments tested reduced Ps. This may have been caused by high irrigation water Na concentrations which would reduce Ca adsorption and Ca-phosphate bridging on the PAM. The PAM1 treatments resulted in <0.5 mg L(-1) drain water polyacrylamide concentrations 1.6 km downstream of PAM addition, while PAM5 and PAM10 treatments produced > 2 mg L(-1) drain water polyacrylamide concentrations. We concluded that, although PAM practically eliminates Imperial Valley tailwater sediment loads, it does not effectively reduce tailwater Ps, the P fraction most responsible for the eutrophication of the Salton Sea.