Supernatant Turbidity Research Articles

The effect of flocculant anionicity on the resistance of quartz flocs to mechanical treatment

Five polyacrylamide (PAM)-based flocculants of similar molecular weights but different degrees of anionicity were selected to investigate the effect of physicochemical properties of the tested polymers on resistance of quartz flocs to mechanical treatment. The flocculated quartz suspension was prepared at two different flocculant dosages and each sample was subjected to either ultrasonication or screening to break the flocs. The tests were performed as a function of ultrasonication duration and screen size while settling rate of flocs, turbidity of supernatant and adsorption density of flocculants were measured as indices of strength of flocs. Adsorption studies showed that adsorption density of flocculants on fine quartz surface remained unaffected by ultrasonication and screening tests, indicating that the observed changes in floc sizes was not a result of desorption. It was found that ultrasonication not only breaks the flocs but also affects the polymer chain, while screening as a strength measurement technique only breaks the flocs. In relation to dewatering applications that rely on floc strength to allow water to flow freely, such as pressure filtration, it was found that at the same adsorption density of the flocculants, PAMs with flexible chains produced the most resistant flocs. These results are attributed to the ability of these flocculants to conform to the shape and size of the flocs.

Experimental study on environmental chemical effect and purification treatment of waste slurry in horizontal directional drilling

The waste slurry generated during Horizontal Directional Drilling (HDD) has detrimental effects on water sources, soil, and organisms. Existing studies lack quantitative analysis and assessment of the environmental hazards of waste slurry. The treatment of waste slurry is usually done by physical curing or chemical curing agents. The treatment effect of these treatments is unsatisfactory or not environmentally friendly enough. Research on the application of Microbially Induced Calcite Precipitation (MICP) in waste slurry purification can help provide innovative solutions. This study began by acquiring the basic properties, mineral composition, and particle size distribution of the waste slurry through experiments. The effects of different concentrations of waste slurry on soil chemical properties were compared, including the measurement of total dissolved solids (TDS), turbidity, and heavy metal ion concentrations of waste slurry supernatant. Additionally, the environmental impact of the waste slurry was assessed from an electrochemical, turbidity, and ionic composition perspectively. A combination formulation containing 2.8 wt% urease, 5 wt% urea, and 3.5 wt% calcium chloride was used to purify the waste slurry. The supernatant of the MICP treated waste slurry undergoes electrochemical testing to evaluate the effectiveness of MICP technology for slurry treatment. The findings indicate that both chemical additives and stratum contaminants significantly contribute to slurry pollution. When the waste slurry constitutes more than 40 wt% of the soil mass fraction, the electrical conductivity (EC) of the soil surpasses the threshold of 1000 μs/cm, and the pH level rises to approximately 9.5, rendering it unsuitable for plant growth. Moreover, the TDS, turbidity, and heavy metal ion concentrations in the waste slurry supernatant exceed the permissible environmental discharge limits. Notably, the concentration of arsenic (As) exceeds the national standard by 18 times, cadmium (Cd) by 20 times, and selenium (Se) by 208 times, posing a high risk of environmental pollution. However, the comparison of ion concentrations in the supernatant before and after MICP treatment reveals that MICP demonstrates effective cementation and co-precipitation of heavy metal ions. MICP purified 66.6 % of arsenic (As), all cadmium (Cd), 75 % of phosphorus (P), and 76 % of selenium (Se) from the waste slurry supernatant. The results of this research contribute to the quantitative evaluation of the environmental hazards of waste slurry. It also helps to promote the application of MICP in waste slurry purification.

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.

Changes in organic fractions, cations, and stabilization from feces to fecal sludge: implications for dewatering performance and management solutions

Abstract Reliable dewatering performance remains a key challenge in fecal sludge management, and the controlling factors or mechanisms are not well understood. There remain limited studies on constituents in feces and fecal sludge and how they affect the dewaterability of fecal sludge. This study aimed at evaluating a range of constituents in feces, and to gain empirical knowledge toward a mechanistic understanding of how they influence dewaterability. In this study, cellulose reduced capillary suction time, decreased supernatant turbidity, and increased cake solids. While hemicellulose decreased supernatant turbidity, lignin increased supernatant turbidity, capillary suction time, and cake solids. Extracellular polymeric substances (EPS) increased both capillary suction time and supernatant turbidity and decreased cake solids, whereas lipids increased turbidity. Cations had no significant effect on dewatering properties. Overall, fecal sludge stored in containments had better dewatering performance than ‘fresh’ fecal sludge, which was attributed to stabilization. Field fecal sludge had a higher relative abundance of Pseudomonas, which is associated with better aggregation, and fewer small particles (<10 μm) that clog filters to reduce dewatering performance. Further understanding of stabilization and developing an agreed-upon metrics of stabilization are essential for predicting fecal sludge dewatering performance, and developing smaller footprint dewatering treatment technologies.

Removal of Turbidity from Raw water by Novel Coagulant Based on PVC Pipe Waste and Sodium Alginate

In the current study, waste polyvinyl chloride pipes were used as a primary material in the reactions, which are widely used for water supply and drainage systems where the waste pipes were prepared by cleaning them from suspended materials and grinding them into small particles, then reacting natural polymers from a plant; Alginic acid. We have obtained modified polymer (PVC/Alginate) or AL-PVC which have been grinded to obtain a powder. Four methods were used to characterize the properties of natural and prepared polymers: Fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM) X-ray diffraction (XRD), and thermogravimetry (TGA-TG). The effectiveness of AL-PVC polymer as a coagulant flocculant in the treatment of surface water has been studied. Tests were carried out in the laboratory on two kinds of water (50 NTU and 100 NTU). The first one is the synthesis of water mixed with high and low concentrations of bentonite, simulating thus turbid water. The second one is raw water from the treatment station of the Shatt Al-Arab River. The performance of the coagulation-flocculation process has been assessed by measuring the supernatant turbidity for different pH, doses, and flocculation times of the AL-PVC polymer. The obtained results show that AL-PVC polymer effectiveness was strongly dependent on pH and the doses of AL-PVC polymer, the initial turbidity, and the water quality. The physical and chemical methods used in the present study of water treatments are mainly due to their simplicity, ease of use, low cost as well as excellent removal efficiency.

Aerobic granulation in an oxidation ditch using the residual sludge after extracting slime-extracellular polymer substances

Sludge granulation in continuous flow reactors (CFRs) is still of great challenge with the hardly obtained hydraulic selection pressure. A novel method was investigated for cultivating granular sludge in an oxidation ditch by recycling the residual sludge after extracting slime-extracellular polymer substances (slime-EPS). Compared to the raw sludge, bioactivities of the residual sludge slightly decreased based on endogenous, autotrophic, and heterotrophic respiration rates (SOURe, SOURA, and SOURH). When the slime-EPS extracted sludge was returned to the main reactor, the SOURe reduced and maintained stable later. For the first and second recycling, SOURA increased from 0.80 to 1.69 mgO2/gSS/h, and 0.16 to 1.21 mgO2/gSS/h, respectively, while SOURH exhibited initial decrease, subsequent increase and later stable trends. Moreover, total nitrogen in effluent decreased from 8.09 to 7.22 mg/L, and the protein-to-polysaccharide concentration ratio increased from 0.49 to 1.55. In addition, the mixed sludge of raw and residual sludge exhibited higher coaggregation capacity with decreased supernatant turbidity, triggering the granulation process. After 94-day operations, granules larger than 200 μm accounted for 32 % in the oxidation ditch, where neither hydraulic selection pressures nor feast-famine phases were provided. Therefore, returning the slime-EPS extracted sludge to the CFRs is a promising approach for aerobic granulation.

Conditioning fecal sludge of public toilets with coupled zero-valent iron and persulfate: Efficiency and mechanism

This study investigated the efficiency of fecal sludge conditioning using peroxydisulfate (PDS) activated by zero-valent iron (ZVI). For fecal sludge obtained from public toilets in a densely-populated rural area in China, the ZVI/PDS coupling greatly improved its dewaterability as well as the supernatant quality in terms of organic matter and nutrient contents. The capillary suction time (CST) and supernatant turbidity of fecal sludge can be reduced up to 97% and 73% respectively in 10 min by the combination of 0.15 g/g TS ZVI and 0.2 g/g TS PDS. Protein removal, especially for tightly and loosely bound extracellular-polymeric-substance (EPS), is more linearly correlated to CST reduction than polysaccharide removal. Fecal sludge dewatering was improved by the hybrid functions of radical oxidation and iron coagulation. The ZVI/PDS treatment produced larger and looser flocs, probably because 1) surface ionic and hydrophilic groups of fecal sludge were reduced, 2) surface charge was neutralized, and 3) secondary structures of EPS proteins were altered by the radicals. The excellent fecal sludge dewatering was related to strengthened particle hydrophobicity and reduced sludge viscosity and compressibility. The results highlight that the ZVI/PDS combination is potentially an effective conditioning approach for fecal sludge from public toilets.

Research on floc structure and physical properties based on pipeline flocculation

The flocculation effect of tailings has an important influence on the turbidity of thickener overflow and the solid-liquid separation effect of tailings slurry. However, pipeline flocculation has not been applied to the tailings dewatering in the thickening process of mines. Moreover, previous studies are limited by the size of the experimental device, and the variation of floc structure with settling height during the free settling process in the thickener was insufficient. Therefore, based on a plot thickener with sufficient height (113 cm) and the pipeline flocculation device, the evolution of the structure and physical properties of flocs with settling height can be clearly explored. And the effects of flocculant dosage, tailings slurry concentration, flocculant slurry concentration, and fluid shear gradient on floc structure, physical properties, and supernatant turbidity in pipeline flocculation were studied. The evolution of floc size and physical properties with settling height in thickener with or without shear was also analyzed. The results show that when the flocculant dosage is 90 g·t−1–105 g·t−1, the concentration of tailings slurry is 20 wt% ~ 25 wt%, the concentration of flocculant solution is 0.005 wt% ~ 0.01 wt%, and the fluid shear gradient is 29.2 s−1–48.7 s−1, the tailings particles are fully mixed with the flocculant solution. Which effectively reduces the turbidity of the overflow. The flocs were broken during the settling process. Accordingly, the floc size and settling velocity decreased with the decrease in settling height, and the density and strength of flocs increased with the decrease in settling height. The reasonable control of the shearing speed of the rake can improve the settling velocity of flocs, which is beneficial to the solid-liquid separation of thickening. Through the research of this study, a method of thickening and dewatering mine tailings slurry through pipeline flocculation was proposed. The variation law of floc structure in the process of free settling in thickener was explored, which provided a reference for the rapid solid-liquid separation of tailings slurry in the thickener.

Ultrafine quartz flocculation: Part II. Main variables

Flocculation is a complex process, usually dependant on various conditions to perform adequately. Nevertheless, the relevance and interaction of the process variables are not easily found in literature. In this study, nine variables of ultrafine quartz flocculation systems, defined in Part 1 of this study, were analysed. The effects of each variable and their interactions in the system were investigated based on flocculation and sedimentation tests. The results were statistically evaluated using the supernatant turbidity as experimental response. The evaluations resulting from the statistical approach indicated that suspension pH (5.49%) was the most significant variable, followed by flocculant concentration (4.07%) with the second greatest effect on the turbidity of the supernatant. Solid concentration, agitation intensity, and surfactant conditioning time (4.05%, 3.51% and 3.51%, respectively), also have significant effects on ultrafine quartz flocculation. The flocculant concentration and the surfactant conditioning time were the variables with the most significant interactions with the main variables. The Camp Number values showed a negative exponential relationship with the turbidity results, proving to be an important tool to evaluate flocculation. Backscattered electron scanning microscopy images of flocs formed in the presence of 30 g/t PAM showed compact flocs in the size range between 150 and 365 µm, with noticeable sphericity.

Particle size as a driver of dewatering performance and its relationship to stabilization in fecal sludge

Poor and unpredictable dewatering performance of fecal sludge is a major barrier to sanitation provision in urban areas not served by sewers. Fecal sludge comprises everything that accumulates in onsite containments, and its characteristics are distinct from wastewater sludges and from feces. There is little fundamental understanding of what causes poor dewatering in fecal sludge. For the first time, we demonstrate that particle size distribution is a driver of dewatering performance in fecal sludge, and is associated with level of stabilization. Higher concentrations of small particles (<10 μm) and smaller median aggregate size (D50) corresponded to poor dewatering performance (measured by capillary suction time (CST) and supernatant turbidity) in field samples from Kenya and Uganda and in controlled laboratory anaerobic storage experiments. More stabilized fecal sludge (higher C/N, lower VSS/TSS) had better dewatering performance, corresponding to lower concentrations of small particles. Samples with the largest aggregates (D50 > 90 μm) had higher abundance of Gammaproteobacteria Pseudomonas, and samples with the smallest aggregates (D50 ≤ 50 μm) were characterized by higher abundance of Bacteroidetes Vadin HA17 and Rikenellaceae. Contrary to common perceptions, stabilization, particle size distribution, and dewatering performance were not dependent on time intervals between emptying of onsite containments or on time in controlled anaerobic storage experiments. Our results suggest that the stabilization process in onsite containments, and hence the dewaterability of sludge arriving at treatment facilities, is not dependent on time in containment but is more likely associated with specific microbial populations and the in-situ environmental conditions which promote or discourage their growth.

The effects of ultrasonic wave on heterogeneous coagulation and flotation separation of pentlandite-serpentine

It is well known that in the flotation of copper-nickel sulfide ore, pentlandite and serpentine are easy to form hetero-aggregation, which makes it difficult to separate them. Therefore, dispersion operation is indispensable, including chemical and physical dispersion. Chemical dispersion is usually achieved by adding dispersing reagents, which is widely used in mineral flotation, while the study of ultrasonic dispersion in copper-nickel sulfide ores in physical dispersion is less reported. Thus ultrasonic dispersion technology was introduced to weaken the hetero-aggregation and to improve the floatability of pentlandite. Through the implementation of a series of conditional tests of influence factors including ultrasonic site, ultrasonic probe type, ultrasonic time, and ultrasonic power, the optimum ultrasonic dispersion system was demined, and the results showed that the ultrasonic power was the key factor affecting the dispersion of pentlandite-serpentine. Then the dispersion mechanism of ultrasonic was revealed by means of supernatant turbidity measurements, particle-size distribution (PSD) analyses, scanning electron microscopy (SEM), and atomic force microscope (AFM) in succession. Coupled with supernatant turbidity measurements, PSD analyses and SEM images of flotation concentrates all confirmed that the ultra-fine serpentine particles coating on the coarse pentlandite particles were effectively dispersed. AFM analyses depicted the morphological changes of surface roughness treated by different ultrasonic power, and confirmed that the ultrasonic power of 200 W could increase the surface roughness and floatability of pentlandite but decrease that of serpentine. Thus, the difference in floatability between the two minerals were enlarged so as to achieve efficient separation of the two minerals. The results of this research are helpful to understand clearly the mechanism of ultrasonic dispersion of pentlandite-serpentine, which provides an alternative dispersion technology and exhibits great potential for further study and application.

Characteristics of Coal Slurry Aggregate Induced by Inorganic Salts

The impact of coagulant type and dosage on the clarity, zeta potential, floc size, and floc structure of a coal slurry suspension was investigated. The results showed that the critical coagulation concentrations of trivalent ions are 0.81 mM and 0.018 mM for coal–coal and coal–kaolinite, respectively, which are lower than those of divalent ions. The initial settling was more affected by AlCl3 and FeCl3 than MgCl2 and CaCl2, while the supernatant turbidity was significantly decreased at a lower dosage (0.06 mM) for trivalent ions, consistent with the classical Derjaguin–Landau–Verwey–Overbeek theory, zeta potential results, and adsorption behaviors of quartz crystal microbalance with dissipation. The floc size and settling rate induced by AlCl3 and FeCl3 were greater than those of divalent ions at lower concentrations and tended to have an irregular and porous structure, enhancing the coagulation effect. The findings highlight the differences in the physical characteristics of floc size and structure in optimizing the coagulation process produced by electrical neutralization and sweep-floc coagulation of amorphous metal hydroxide precipitates.

Performance improvement and mechanism of composite PAC/PDMDAAC coagulant via enhanced coagulation coupled with rapid sand filtration in the treatment of micro-polluted surface water

The coagulation and filtration are widely used for surface water due to cost effectiveness therefore the need to study its’ improvements for safe drinking water that meet national standards. The performance of enhanced coagulation of composite coagulants (ECC) using poly aluminium chloride/poly di-methyl di-allyl ammonium chloride (PAC/PDMDAAC) coupled with rapid sand filtration (RSF) was studied. This was performed using jar testing, optimized, and operated at same dosage and supernatant turbidity (SDST) mode; also, the interception points for PAC and composites at baseline turbidity between 1.0 and 1.50 NTU with fixed RSF operating conditions while water parameters like turbidity, CODMn, NH3N, and zeta potentials were used as indicators for improved removal rates. Furthermore, the floc size and morphology analysis at optimum dosage combined with zeta potentials were used to explained the mechanism of ECC-RSF. The results showed that most composites out-performed PAC only, before and at the interception points; however, beyond this point, the superior performance disappears with the increasing PAC dosage above 3.0 mg/L. At the optimum dosage, composite PAC/PDMDAAC at 1.60 dL/g, 10:1 showed the best overall removal rate at SDST mode of 99.36%, 64.50%, and 66.18%, respectively for turbidity, NH3N, and CODMn. The dominant mechanism of composite coagulation is charge neutralization within the dosage range used and strengthened by adsorption-bridging due to the presence of PDMDAAC while the major mechanism during filtration is adsorption. It was concluded that depending on the raw water quality, the coagulation mode of SDST at baseline turbidity near 1.0 NTU can maximized the water quality removal for composite PAC/PDMDAAC. New operational insights about maximizing the performance of composite PAC/PDMDAAC coagulants have been put forward.

Comparison of pre-treatments mediated by endoglucanase and TEMPO oxidation for eco-friendly low-cost energy production of cellulose nanofibrils.

Specific kinds of enzymes have been used as an eco-friendly pre-treatment for mechanical extraction of cellulose nanofibrils (CNFs) from vegetal pulps. Another well-established pre-treatment is the 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-mediated oxidation, which has gained considerable attention. Pre-treatments assist in fiber swelling, facilitating mechanical fibrillation, and reducing energy consumption; however, some of these methods are extremely expensive. This work aimed to evaluate the influence of enzymatic pre-treatment with endoglucanase on the energy consumption during mechanical fibrillation of cellulose pulps. Bleached pulps from Eucalyptus sp. and Pinus sp. were pre-treated with endoglucanase enzyme compared to TEMPO-meditated oxidation. Average diameters of CNFs pre-treated with enzymes were close to that found for TEMPO-oxidized nanofibrils (TOCNFs). Results showed that enzymatic pre-treatment did not significantly modify the pulp chemical and morphological characteristics with efficient stabilization of the CNFs suspension at higher supernatant turbidity. Energy consumption of pulps treated with endoglucanase enzymes was lower than that shown by pulps treated with TEMPO, reaching up to 58% of energy savings. The enzyme studied in the pulp treatment showed high efficiency in reducing energy consumption during mechanical fibrillation and production of films with high mechanical quality, being an eco-friendly option for pulp treatment.

Enhanced Settling and Dewatering of Oil Sands Mature Fine Tailings with Titanomagnetite Nanoparticles Grafted with Polyacrylamide and Lauryl Sulfate

In this study, a three-in-one nanoflocculent that consists of nanoparticles of titanomagnetite (NTM) grafted with multiple segments of hydrophobically modified chains of polyacrylamide (PAM) with sodium laurel sulfate (SLS) was developed for enhanced settling and dewatering of oil sands mature fine tailings (MFT). The existence of NTM allowed more than one segment to graft/functionalize (i.e., hydrophobic and hydrophilic) on the same surface. This three-in-one nanoflocculent not only provides better exposure for the functionalized species, but it also increases the nanoflocculant specific gravity and dispersibility for better interactions. The NTM was initially synthesized by the coprecipitation method and subsequently grafted with PAM and SLS at room conditions. The flocculation and dewatering performance of the as-synthesized nanoflocculants was evaluated using the initial settling rate (ISR), supernatant turbidity, sludge volume index, capillary suction time (CST), and specific resistance to filtration (SRF). Flocculation of the MFT suspension using the novel optimized nanoflocculants at 3000 ppm had 15 times faster ISR, and the supernatant turbidity, CST, and SRF had stronger outcomes than the traditionally used 20,000 ppm commercial anionic PAM. This study demonstrates the potential of designing nanoflocculants to effectively enhance settling and dewatering of oil sands tailings, while reducing the required amount of coagulants.

Monovalent Antigen-Induced Aggregation (MAA) Biosensors Using Immunomagnetic Beads in Both Sample Separation and Signal Generation for Label-Free Detection of Enrofloxacin.

Exploring new functions of nanomaterials can help facilitate the development of biosensors for the detection of antibiotics. Herein, a new detection modality based on monovalent antigen-induced aggregation (MAA) of immunomagnetic beads (IMBs) was proposed for rapid and label-free detection of enrofloxacin (ENR), which endowed IMBs with the abilities of both sample separation and signal generation. In the presence of ENR, the initially well-dispersed IMBs were aggregated and the degree of aggregation was in a concentration-dependent manner. After exploring the mechanism underlying IMB aggregation and investigating the key parameters affecting it, a label-free biosensing platform was developed for rapid and sensitive detection of ENR. Based on the significant differences in the magnetic separation speed and size between the aggregated and well-dispersed IMBs, two methods were proposed for quantitatively determining ENR, i.e., measuring the turbidity of the IMB supernatant after magnetic separation for a given time and visualizing and calculating the grayscale value of the aggregated IMBs trapped on the surface of a nitrocellulose membrane. A three-dimensional (3D)-printed syringe was designed and fabricated for automatic filtration of IMBs. This immunosensor allowed for sensitive detection of ENR in less than 15 min without any labels. It exhibited a satisfactory limit of detection of 0.79 ng mL-1 and showed the feasibility for ENR detection of spiked chicken meat with recovery rates ranging from 74.8 to 98.3%. The MAA immunosensor can act as a promising tool to detect trace levels of ENR and has the potential to be applied to complex food samples.

Experimental Study on the Effect of C-PAM and A-PAM on Dewatering Performance of Waste Mud

:In order to improve the treatment capacity of waste mud, C-PAM and A-PAM were used to treat waste mud in this paper. The effects of C-PAM and A-PAM on the flocculation effect of waste mud were discussed. The key mechanisms of C-PAM and A-PAM on the flocculation of waste mud were deeply analyzed by analyzing the variation characteristics of particle size distribution, water content of filter cake, Zeta potential of supernatant and turbidity of supernatant during the treatment process. The results showed that the flocculation effect was the best when the dosages of C-PAM and A-PAM were 140 mL (2%) and 30 mL (2%), respectively. The adsorption bridging of C-PAM and A-PAM plays a leading role in the treatment of waste mud, but the electric neutralization is not obvious. This research can reduce the amount of waste mud and has practical significance.

Comparisons of coagulation efficiency of conventional aluminium sulfate and enhanced composite aluminium sulfate/polydimethyldiallylammonium chloride coagulants coupled with rapid sand filtration

Conventional aluminium sulfate (AS) coagulant's inability to effectively meet stringent water quality requirements have created the need to explore enhanced composite coagulants. The coagulation efficiency of AS and composite AS and polydimethyldiallylammonium chloride (AS/PDMDAAC) coagulants were investigated using jar test and then, coupled with rapid sand filtration (RSF). The various composite AS/PDMDAAC at different intrinsic viscosity of PDMDAAC and mass ratio of PDMDAAC to AS in coagulant solutions were optimized and operated at same supernatant turbidity (SST) or same dosage mode (SD). The results showed about 7–10% reduction in dosage for all composite AS/PDMDAAC and also improved water qualities compared to AS only. The patterns of water quality improvements at lower (0.65 dL/g), medium (1.60 dL/g), and higher (2.60 dL/g) intrinsic viscosity of cationic polymer PDMDAAC among different mass ratio of PDMDAAC to AS in the composite mixtures were 5:1 > 20:1 > 10:1; 10:1 ≥ 5:1 > 20:1; 20:1 > 10:1 > 5:1 respectively. The percentage removal efficiencies for AS and optimal composite coagulant at intrinsic viscosity (1.60 dL/g) and mass ratio (10:1) operated at SST or SD after filtration for CODMn, NH3N and turbidity were (71.20, 72.72, 73.33%); (69.15, 69.23, 73.08%) and (93.89, 95.07, 97.26%) respectively. It was concluded that enhanced composite AS/PDMDAAC coagulants operated at SST mode showed significant water quality improvement than conventional AS having 7% and 31.8% for COD and NH3N removal while operational mode at SD produced more significant water quality improvements than conventional AS with 9.49%, 45.45%, and 39.55% for COD, NH3N, and turbidity removal before filtration respectively. More importantly, all composite AS/PDMDAAC met stringent water quality requirements before and after filtration. This research provided new insight about application of economical and effective alternative composite AS/PDMDAAC coagulant useful in the treatment of water for large population.

Flocculation and dewatering of oil sands tailings with a novel functionalized polyolefin flocculant

• Use of novel partially-hydrophobic graft polymer flocculant for mineral tailings treatment. • Grafts of PMA with different molecular weights and densities were attached to EPDM backbones. • Use of a central composite experimental design to assess the effect of polymer architecture on flocculation and dewatering performance. • The performance of the graft copolymers was quantified by initial settling rate (ISR), capillary suction time (CST), supernatant turbidity, and sediment solids content. This work investigates the impact of the molecular weight and grafting density of partially hydrolyzed poly(methyl acrylate) grafted onto ethylene-propylene-diene copolymer backbones (EPDM -g- HPMA) on the flocculation and dewatering of oil sands mature fine tailings through a central composite experimental design by measuring initial settling rate, capillary suction time, supernatant turbidity, and sediment solids content. Flocculants with high molecular weight grafts and low grafting densities reduced the initial settling rates, decreased supernatant turbidities, and increased the solids content of the flocculated sediments. The capillary suction time, however, depended mostly on the charge density and on the hydrophobicity of the grafted copolymer. The effect of the EPDM backbone molecular weight was also investigated. Shorter backbones resulted in flocculants that dispersed more easily in water and settled the sediments faster. In addition, they decreased the supernatant turbidity and increased the solids content in the sediments. EPDM -g- HPMA flocculants with graft molecular weight of 179 kDa and grafting density of 13% are outstanding filtration aids, helping generate sediments with 43% solids content and outperforming a reference commercial polyacrylamide flocculant.

Application of Response Surface Methodology For Modeling and Optimization of A Bio Coagulation Process (Sewage Wastewater Treatment Plant).

Cactus has shown great capabilities as a bio coagulant/flocculent in the treatment of wastewater and as a factor for sustainable development of the environment, due to its abundance and non-toxicity for human health. This has encouraged the present study based on the design of experiments to optimize the two operating factors: the bio coagulant dosage and initial pH. The effect of these considered factors on turbidity and chemical oxygen demand (COD) reduction performances was investigated to treat sewage wastewater from plants by the coagulation/flocculation process using the response surface methodology (RSM) based on a central composite faced design (CCFD). The effect of the pH on the supernatant turbidity removal and the COD reduction was very significant whereas that of the coagulant dosage was insignificant on the COD removal efficiency. Experimental results revealed that the maximum reduction of turbidity and COD could be reached at a coagulant dosage of 28 mg/l and a pH of 12. At these optimal conditions, the removal efficiency of turbidity and COD was 98.33% and 96.55% respectively. By the end of the treatment, final values of 0.84 NTU and 20.8 mg/l were obtained for turbidity and COD, respectively. A notable decrease of orthophosphate (O- PO4-2), nitrite (N-NO3-), ammonium (N-NH4+) and suspended matter (SM) was observed. The study also showed that the quadratic regression model could be used as a theoretical basis for the process based on a high coefficient of determination R2 value > 0.96, obtained from the analysis of variances (ANOVA).