Homogeneous synthesis and characterization of polyacrylamide‐grafted cationic cellulose flocculants

In this work, cationic cellulose (CC) with different degrees of substitution (DS) was successfully synthesized by the reaction between cellulose and 3‐chloro‐2‐hydroxypropyl‐trimethylammonium chloride (CHPTAC) in a 7 wt % NaOH and 12 wt % urea aqueous solution. The structure of the CC was characterized by using elemental analysis, ¹H‐NMR, and FTIR. The DS values of CC ranged between 0.18 and 0.50, which could be obtained by adjusting the reaction temperature, reaction time, and molar ratio of CHPTAC to anhydroglucose unit of cellulose. The cationic cellulose–graft–polyacrylamide flocculant (CC‐g‐PAM) based on CC and polyacrylamide (PAM) was also synthesized in a homogeneous aqueous solution. The flocculation characteristics of CC and CC‐g‐PAM were evaluated in a kaolin suspension. The results showed that CC‐g‐PAM was an effective flocculant for the kaolin suspension under acidic or neutral conditions, and the flocculation efficiency was over 90%, while the CC showed better flocculation performance under alkaline conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43106.     

Synthesis of lignosulfonate-acrylamide-dimethyldiallylammonium chloride copolymer and its flocculation performance

In this work, lignosulfonate-acrylamide-dimethyldiallylammonium chloride (LAD) terpolymer was designed and synthesized by microwave-assisted graft polymerization. The optimal synthetic process was obtained as follows: the monomer ratio was 1:4:4, the amount of initiator was 0.9% (w/w), the monomer solid content was 21 wt %, and the reaction time was 14 min with the microwave power of 280 W. Furthermore, the flocculation performance of LAD was verified by removing acid black-172 dye wastewater. At the LAD dosage of 350 mg L⁻¹, the maximum color removal ratio reached 99.8% in 100 mg L⁻¹ of dye wastewater. The dynamics of dye removal reached higher than 90% after 20 s. The flocculant can maintain color removal ratio more than 98% in a wide flocculant dosage and environmental pH. The flocculation mechanism was mainly electrical neutralization and bridging effect. In general, it is a promising candidate in wastewater treatment in terms of cost, synthetic method, and effectiveness. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48560.     

Effect of coagulation on palm oil mill effluent and subsequent treatment of coagulated sludge by anaerobic digestion

A new effluent treatment scheme is proposed for treating palm oil mill effluent based on coagulation and anaerobic digestion of coagulated sludge. The effectiveness of anionic (N9901) and cationic (N9907) polyelectrolytes manufactured by NALCO (Malaysia) was evaluated both as coagulant and coagulant aid. The results showed that the anionic and cationic polyelectrolytes were best suited as a coagulant aid, and the cationic polyelectrolyte showed better performance than the anionic polyelectrolyte. For an influent chemical oxygen demand (COD) concentration of 59 700 mg L^?1 at an alum dosage of 1700 mg L^?1, the residual COD, suspended solid removal, sludge volume and pH were found to be 39 665 mg L^?1, 87%, 260 mL L^?1 and 6.3, respectively. For the above influent COD and alum dosage with the addition of 2 mg L^?1 of cationic polyelectrolyte as coagulant aid, the results were 30 870 mg L^?1, 90%, 240 mL L^?1 and 6.2, respectively. The sludge resulting from the coagulation process using alum as coagulant and cationic polyelectrolyte as coagulant aid was tested for its digestibility in an anaerobic digester. The quantity of biogas generated per gram of volatile solids (VS) destroyed at a loading rate of 26.7 ± 0.5 and 35.2 ± 0.4 g VS L^?1 d^?1 was found to be 0.68 and 0.72 L g^?1 VS destroyed. The anaerobic biomass when subjected to varying alum dosage in the coagulated palm oil sludge did not exhibit inhibition as the digester performance was in conformity with the regular treatment process Copyright © 2006 Society of Chemical Industry     

Preparation of quaternized carboxymethyl chitosan and its capacity to flocculate COD from printing wastewater

A bioflocculant, quaternized carboxymethyl chitosan (QCMC), was developed by the quaternization of N,O‐carboxymethyl chitosan (N,O‐CMC) and characterized by FTIR, ¹H‐NMR, GPC, and potentiometry. The efficiency of the removal of chemical oxygen demand (COD) in printing wastewater by this flocculant was further reported. Results indicated that the capacity of QCMC to remove the COD from tested wastewater was the best one among the investigated flocculants. The pH had great influence on this capacity and the suitable pH for QCMC to treat the tested wastewater was about 5.0. The utilization of aid‐flocculant, especially bentonite, could improve this capacity obviously, and the increase of mass ratio of bentonite to QCMC resulted in the increase of the capacities of complex flocculant to remove the COD from the tested wastewater. When the mass ratio of bentonite to QCMC was 40, pH of wastewater was 5.0 and amount of complex flocculant in the wastewater was from 2500 to 3142 mg L^?1, the removal ratio of COD was more than 80%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Removal of suspended solids and residual oil from palm oil mill effluent

Palm oil mill effluent (POME) was pretreated to remove suspended solids and residual oil. The processes used were flocculation, solvent extraction, adsorption and membrane separation. Flocculation was used to remove suspended solids, and solvent extraction and adsorption processes were used to remove residual oil. Membrane separation was subsequently applied to remove any residual suspended solids and oil remaining after the pretreatments. The solvent extraction and adsorption processes were operated on a batch basis whereas membrane separation was performed in continuous mode. The treatment efficiency of the processes was measured as percentage removal of suspended solids and oil respectively. The optimum values of the process parameters obtained in the flocculation process were an alum dosage of 4000 mg dm^?3, mixing speed of 150 rpm for 1 h and sedimentation time of 270 min, resulting in 93% suspended solids removal. In the solvent extraction process, a 95% reduction in residual oil was obtained using n‐hexane as a solvent with 20 min of mixing at 200 rpm. The ratio of solvent to POME was 6:10 and carried out at pH 9. In the batch adsorption process, an 88% reduction in residual oil was obtained at a mixing speed of 100 rpm for 1 h, pH 9 and an adsorbent dosage of 300 g dm^?3. In membrane separation processes, GH and CE(GH) membranes gave 63% and 49% reductions in suspended solids and residual oil respectively at pH 9 and pressure of 1000 kPa. Copyright © 2003 Society of Chemical Industry     

Harvesting of Scenedesmus sp. after phycoremediation of meat processing wastewater; optimization of flocculation and chemical analysis of biomass

Meat production is associated with the generation of huge quantities of meat processing wastewater (MPWW) which has high concentrations of nutrients. The utilization of Scenedesmus sp. in the phycoremediation process to treat MPWW has attracted growing interest, but there is inadequate information on the management of biomass of this micro‐organism. This study aims to optimize the harvesting of Scenedesmus sp. biomass generated during phycoremediation through flocculation with alum and its potential biomass by‐product. The removal rates of the chemical oxygen demand, ammonia, total nitrogen, total phosphorus and orthophosphate were 99.16% (R² = 0.95), 97.19% (R² = 0.91), 93.91% (R² = 0.96), 97.25% (R² = 0.85) and 99.38% (R² = 0.9517), respectively. From the result, the best coagulant for recovery efficiency (97.54%) was recorded at pH 8.6 with 116.85 mg L^?1 alum. Three major chemical compounds – tetradecanoic, oleic and dodecanoic acids – were recorded in the extraction of Scenedesmus sp. biomass (as determined by gas chromatography‐mass spectrometry analysis; these have the potential for use in the cosmetic and medical industries. The main functional groups in the harvested biomass were OH, CH, C‐O‐C and CH?CH. It can be concluded that the flocculation method was the most efficient compared to filtration process for recovering Scenedesmus sp. biomass owing to the absence of toxic by‐products. © 2020 Society of Chemical Industry (SCI)     

Adsorption and desorption behaviour of Pb(II) on a natural kaolin: equilibrium,kinetic and thermodynamic studies

BACKGROUND: Pb(II) is common in both waste‐waters and gas emissions. In developing countries, public health problems have been reported concerning Pb(II) pollution, so that stringent measures are required to deal with it. MAJOR RESULTS: The adsorption and desorption behaviour of Pb(II) has been investigated on a natural Chinese kaolin. Several factors, including initial concentration, pH, equilibration time, dosage and temperature correlated positively with Pb(II) adsorption. The Pb(II) adsorption capacity of natural kaolin was 165.117 mg g^?1. A kinetic study shows that Pb(II) adsorption on purified kaolin equilibrates within 35 min. The enthalpy changes of Pb(II) adsorption on purified kaolin were 63.683, 20.488 and 21.371 kJ mol^?1 with entropy changes 262.250, 112.210 and 105.120 J mol^?1 K^?1 for solutions containing 50, 100 and 200 mg L^?1 Pb(II) respectively, indicating an endothermic and spontaneous adsorption process. The desorption of Pb(II) from kaolin was difficult with more than 85% Pb(II) removal. Based on X‐ray diffraction (XRD) analysis, the Pb(II) adsorption on natural and purified kaolin was attributed mainly to the magnesite component and complexation with the mineral surface. CONCLUSIONS: Natural kaolin exhibits a satisfactory performance for adsorption of Pb(II) from aqueous solution. The optimum conditions for adsorption were: ionic strength = 0.01 mol L^?1; pH ≥ 7.2; dosage = 10 g L^?1; temperature = 25 °C; duration ≥ 16 h (C_i = 80 mg L^?1); and the optimum conditions for desorption were ionic strength = 0.1 mol L^?1 and pH ≤ 5.0. Copyright © 2009 Society of Chemical Industry     

Acacia mearnsii de Wild Tannin-Based Flocculant in Surface Water Treatment

Abstract

Drinking water and wastewater treatment usually requires a coagulation/flocculation stage. Some disadvantages are presented by usual agents, above all linked to environmental, economical, and health aspects. Effectiveness of a new wood-derived flocculant agent has been studied, it consists of Acacia mearnsii modified tannin extract. Results have been very satisfactory; low flocculant dosage (up to 10 mg· L^{? 1}) may remove almost all suspended matter in surface water. Flocculant works better in acid pH (4–5), but an accurate dose minimizes the influence of this factor. Temperature does not affect effectiveness, but high initial turbidity may raise process efficiency. Duration of coagulation and flocculation stages seems to affect both positively to turbidity removal and in a non-interaction way. Dosage is much more important than both coagulation or flocculation stages. Treated water does not present either organic matter significantly increasing or a high residual tannin concentration. Microorganisms as total coliforms, fecal coliforms, and fecal streptococcus have been reduced up to 80%, 90%, and 99%, respectively.     

Pigment removal in anaerobically digested effluent through polyelectrolyte flocculation and liquid–liquid extraction

BACKGROUND: Use of flocculation in wastewater treatment involves interactions of polymer with suspended solids and some dissolved organic compounds that can have a significant impact on aggregation process. RESULTS: It was found that a strong interaction between cationic compounds and dissolved pigments in anaerobically digested (AD) wastewater occurred. The interactions were investigated by light adsorption of the pigments using a commercial flocculant added in the solutions and through a liquid–liquid extraction method using a model cationic surfactant (CTAB) dissolved in organic solvents. The absorbance of pigments decreased significantly with added cationic flocculant as the pigments and flocculants formed insoluble complexes that were removed by centrifugation. CONCLUSION: The absorbance results indicate that the pigments can form complexes even at high concentrations (e.g. 2000 mg L^?1) of the flocculants. In addition, the extraction results demonstrated that pigments in the aqueous phase were transferred into the CTAB organic phase due to a strong interaction between the pigments and CTAB. These results suggest that the pigments present in AD effluent could be a negative factor for the flocculation process, probably resulting in the need for a high dosage of flocculants. Copyright © 2012 Society of Chemical Industry     

Modification of β‐cyclodextrin for rapidly decolorizing the dye‐containing wastewaters by flocculation

To strengthen the role of polymer bridging during the flocculation process and thus raise the speed of decolorizing the dye‐containing wastewaters, β‐cyclodextrin–acrylamide–[2‐(Acryloyloxy)ethyl] trimethyl ammonium chloride copolymer (poly[AM(β‐CD)‐AETAC]) with relatively high intrinsic viscosity (84.3 mL g^?1) and cationicity (24.5%) was prepared by solution polymerization. The successful preparation of copolymer was demonstrated by FT‐IR and ¹H‐NMR characterizations. Its excellent decolorization performances as a new flocculant were evaluated with the C.I. reactive orange 5 (RO 5) and C.I. reactive blue 19 (RB 19) solutions using a jar test method. Both the nature of anionic dyes and the pH of dye solutions influence the decolorization effectiveness. For both the RB 19 and RO 5 solutions (0.10 g L^?1), it can be rapidly decolorized in a wide range of pH (2–7) and flocculant concentration (0.12–0.26 g L^?1). For the given dye/flocculant solution system, both charge neutralization and polymer bridging contribute to the decolorization mechanism. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39940.     

一株新型絮凝剂产生菌的筛选及其特性研究

从淤泥中分离到了一株絮凝剂新型产生菌AY11,初步鉴定为德克斯氏菌属。该菌能以廉价的蔗糖为碳源、尿素为氮源,发酵1d生产高效絮凝剂,该絮凝剂对高岭土悬浊液的絮凝率可达96.08%(投加量为2%)。在pH值6～12,温度20～80℃范围内该絮凝剂均可获得较佳的絮凝效果。AY11所产絮凝剂对城市生活污水、日用化工厂废水、染料废水等多种废水均有很好的净化、脱色效果。     

The synthesis of modified alginate flocculants and their properties for removing heavy metal ions of wastewater

A new flocculant was synthesized through the modification of sodium alginate with thiosemicarbazide. In the preparation, amino thiourea groups which had excellent adsorption properties for heavy metal ions were introduced to the flocculant. The structure of the flocculant was confirmed by elemental analysis, Fourier transform infrared, UV spectrophotometry, nuclear magnetic resonance, and thermal analysis. The flocculation behaviors of the flocculant for three heavy metal ions were investigated. The results showed that the removal rates of the flocculant for Pb²⁺, Cd²⁺, and Cu²⁺ reached up to 97.8%, 86.3%, and 80.0%, respectively, and the flocculation capacities were as high as 489, 215, and 160 mg/g, respectively. The excellent adsorption was ascribed to the double effects of electronic interaction and chelation between the flocculant and heavy metal ions. The flocculant had particular flocculation selectivity for Pb²⁺ in the mixed heavy metal ion solutions containing Cd²⁺or Cu²⁺, respectively. The flocculation process corresponded to Langmuir isotherm model, the flocculation kinetics agree with pseudo second order. The flocculant had potential applications for treatment of wastewater. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46577.     

Reductive decolourization and total organic carbon reduction of the diazo dye CI Acid Black 24 by zero‐valent iron powder

In this study, wastewater contaminated by colour and total organic carbon from the diazo dye CI Acid Black 24 was successfully removed by reductive decolourization with zero‐valent iron powder. The effects on decolourization of experimental variables such as iron dosage, initial dye concentration, pH and dissolved oxygen level were evaluated. The best removal efficiencies for decolourization of 99.7% and total organic carbon of 57.4% were obtained with an initial dye concentration of 25.0 mg L^?1 and iron dosage of 200.0 g L^?1. Moreover, the decolourization rates followed pseudo‐first‐order kinetic equations with respect to dye concentration. The colour removal efficiency was simultaneously dependent on iron dosage and various initial dye concentrations, although the colour and total organic carbon removal efficiencies linearly increased with increased iron dosage, reaching a maximum at 100.0 g L^?1. A contour plot was developed to illustrate the 3D relation of removal efficiencies with initial dye concentration and iron dosage. For wastewater with a concentration range from 25 to 100 mg L^?1 CI Acid Black 24 the suggested ideal operation conditions are 100.0 g L^?1 iron dosage, pH 2‐4, normal oxygen concentration of 5‐7 mg L^?1 and reaction time of 30‐60 min. Copyright © 2006 Society of Chemical Industry     

短芽孢杆菌RL-2的絮凝性能研究

从重庆城南污水处理厂活性污泥中筛选出一株高效胞外絮凝剂产生菌RL-2,初步鉴定为短芽孢杆菌(Bacillusbrevis)。该菌株可产生多糖类絮凝剂。RL-2絮凝高岭土悬浊液的影响因素研究结果表明:CaCl2是微生物絮凝剂RL-2的良好助凝剂,当Ca2+存在时,絮凝剂的投加量为5～20mL/L,pH值在3～9范围内,该微生物絮凝剂可有效絮凝高岭土悬浊液,其絮凝率高达98.4%;同时,RL-2对多种固体悬浊液有明显的净化效果。     

AAO工艺+絮凝沉淀处理高COD废水

为解决某植物榨汁饮料厂的废水COD高、有异味等问题,研究了厌氧—缺氧—好氧(AAO)工艺和絮凝沉淀混合工艺对废水的处理效果。探索了初始浓度、曝气量、絮凝剂的种类和投加量等对废水处理效果的影响机制。实验结果表明,初始浓度为4000 mg/L的废水,经AAO工艺后COD去除率可达77%。继续投加合适的絮凝剂后废水COD去除率可达90%。处理后的废水澄清无异味,可进行后续处理排放。     

蒙脱石絮凝剂在河道排污水中的应用研究

使用酸改性无机矿物蒙脱石絮凝剂(MTSF)对进入主干河流的河道排污废水进行预处理,并且与传统絮凝剂聚合氯化铝(PAC)进行对比,研究了不同投加量下絮凝剂对排污水的絮凝除污效果和沉降性能的影响.结果表明,MTSF对排污废水中浊度、SS、TP、COD以及NH4+-N的去除率分别为75.4％、52.0％、97.5％、71.4...     

Biological treatment of high salinity produced water by microbial consortia in a batch stirred tank reactor: Modelling and kinetics study

This study was performed to evaluate the potential of acclimated halophilic microorganisms, commercial microorganisms, and microorganisms from polluted soil to degrade crude oil in high salinity oily wastewater (synthetic produced water) at different salt concentrations ranging from zero to 250,000?mg?L^?1 of total dissolved solids (TDS). The highest degradation of crude oil (>60%) was found for acclimated halophilic microorganisms at TDS of 35,000?mg?L^?1. An increase in the TDS concentrations above 145,000?mg?L^?1 leads to a significant decrease in the growth of microorganisms. The results showed that efficiency of the commercial microorganisms was less than the acclimated halophilic microorganisms. The oil biodegradation followed substrate inhibition kinetics and the specific growth rate were fitted to the Haldane model. The biokinetic constants for the saline oily water at TDS of 35,000?mg?L^?1, i.e., Y, K_s, µ_max, and 1/K_i, were 0.21?mg?MLSS/mg crude oil, 0.27?mg?L^?1, 0.019?h^?1, and 0.002?mg?L^?1, respectively.     

Poly(vinyl alcohol)/quaternized lignin composite absorbent: Synthesis,characterization and application for nitrate adsorption

A new poly(vinyl alcohol) (PVA)/quaternized lignin composite absorbent (PVA/QL) was synthesized from modified lignin and PVA, crosslinked by glutaraldehyde. As‐prepared absorbent was characterized by IR, DSC, SEM BET, and DMA. Effects of shaking time, absorbent dose, initial pH, and temperature on NO₃^? removal from aqueous solution by the absorbent were comprehensively investigated. The results show that the PVA/QL absorbent comprises quaternary ammonium groups in the form of ether bond. The composite absorbent exhibits remarkable network structure with large numbers of connected holes. The mechanical strength of the absorbent is enhanced by combining of PVA with modified lignin and crosslinkage of glutaraldehyde. The effect of pH on adsorption of NO₃^? is apparent and appropriate pH is 2.0. The adsorption process is endothermic, and determined to be consistent with the Langmuir isotherm. Furthermore, it is found that the quaternary ammonium structure and network structure in the surface of PVA/QL are the key factors to remove nitrate. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Flocculation characteristics of kaolin

The effect of metal cations on the flocculation behaviour of kaolin was investigated.The effects of pH, concentration of cations (Mg²⁺ and Al³⁺), and the presence of these cations in causticised cassava starch on the settling rate and percent reduction in sediment density were studied. Results show that the presence of high concentrations of divalent (Mg²⁺) and trivalent (Al³⁺) ions, and the presence of these cations in causticised cassava starch significantly contributed to the existence of low settling rates at high supernatant clarity often observed in some clay slurry treatment systems by flocculation and sedimentation method. It was also established that for efficient flocculation, the systems must be within the alkaline pH range (pH>10). The study further revealed that in some flocculation systems, fast settling corresponds to high sediment volume whereas in others, the opposite applies. It is therefore concluded that this phenomenon should be taken into consideration for proper design and operation of such treatment facilities.     

聚合氯化铝-壳聚糖复合絮凝剂对活性蓝19的脱色研究

文章研究了制备温度(T)、碱度(B)对聚合氯化铝性能的影响和壳聚糖含量(C值)对聚合氯化铝-壳聚糖复合絮凝剂的影响,以活性蓝19模拟染料废水,考察了絮凝剂投加量、pH、T、B对絮凝脱色效果的影响。结果发现,通过Al-Ferron法分析优选聚合氯化铝制备条件为B=2.0、T=50℃;PAC投加量为400 mg/L,pH在中性时,聚合氯化铝絮凝性能最好;聚合氯化铝-壳聚糖复合絮凝剂主要依靠其附加的架桥作用使脱色效果比PAC强;XRD和TEM的表征更好地印证了絮凝机理。