Cationic lignin polymers as flocculants for municipal wastewater

In this research, two lignin-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC) polymers were generated and assessed for their efficiency in treating municipally produced wastewater. The removals of chemical oxygen demand (COD) and turbidity were 47.5% and 71.2%, respectively, for the singular flocculation system at the dosage of 40–70 mg/L. For the dual coagulation/flocculation system, the polymer with a higher charge density (AM2) achieved higher COD and turbidity removals than the polymer with a lower charge density (AM1). To achieve the same organic removal from the wastewater, the alum use could be reduced from 150 mg/L in the single alum use to 35 mg/L in the dual system when used along with 65 mg/L of AM2. In both systems, lignin-METAC polymers exhibited better performance than the flocculant used at a local wastewater treatment plant. Lignin-METAC polymers could be used as bio-based flocculants for the replacement of petroleum-based flocculants and inorganic coagulants.     

Removal of boron from ceramic industry wastewater by adsorption-flocculation mechanism using palm oil mill boiler (POMB) bottom ash and polymer

Boron is extensively used in the ceramic industry for enhancing mechanical strength of the tiles. The discharge of boron containing wastewater to the environment causes severe pollution problems. Boron is also dangerous for human consumption and causes organisms' reproductive impediments if the safe intake level is exceeded. Current methods to remove boron include ion-exchange, membrane filtration, precipitation-coagulation, biological and chemical treatment. These methods are costly to remove boron from the wastewater and hence infeasible for industrial wastewater treatment. In the present research, adsorption-flocculation mechanism is proposed for boron removal from ceramic wastewater by using Palm Oil Mill Boiler (POMB) bottom ash and long chain polymer or flocculant. Ceramic wastewater is turbid and milky in color which contains 15 mg/L of boron and 2000 mg/L of suspended solids. The optimum operating conditions for boron adsorption on POMB bottom ash and flocculation using polymer were investigated in the present research. Adsorption isotherm of boron on bottom ash was also investigated to evaluate the adsorption capacity. Adsorption isotherm modeling was conducted based on Langmuir and Freundlich isotherms. The results show that coarse POMB bottom ash with particle size larger than 2 mm is a suitable adsorbent where boron is removed up to 80% under the optimum conditions (pH = 8.0, dosage = 40 g bottom ash/300 ml wastewater, residence time = 1 h). The results also show that KP 1200 B cationic polymer is effective in flocculating the suspended solids while AP 120 C anionic polymer is effective in flocculating the bottom ash. The combined cationic and anionic polymers are able to clarify the ceramic wastewater under the optimum conditions (dosage of KP 1200 B cationic polymer = 100 mg/L, dosage of AP 120 C anionic polymer = 50 mg/L, mixing speed = 200 rpm). Under the optimum operating conditions, the boron and suspended solids concentration of the treated wastewater were reduced to 3 mg/L and 5 mg/L respectively, satisfying the discharge requirement by Malaysia Department of Environment (DOE). The modeling study shows that the adsorption isotherm of boron onto POMB bottom ash conformed to the Freundlich Isotherm. The proposed method is suitable for boron removal in ceramic wastewater especially in regions where POMB bottom ash is abundant.     

Determination of charge density and adsorption behaviour of DMAEA-Q-based cationic polymers by fluorimetric analysis

In wastewater and sludge treatment, cationic polymers are applied at large scale. A correct determination of the charge density and adsorption efficiency is of high importance for an economic and ecologically sound operation. Although several analytical techniques exist for charge density and polymer concentration determination, they often suffer from laborious sample pretreatment, complex instrumentation or interference from background components present in sludge. In this work, an alternative method has been studied to determine the charge density of an important series of cationic polymers used in water and sludge treatment, viz. copolymers containing quaternised dimethylaminoethylacrylate (DMAEA-Q). The method is based on the basic hydrolysis of the cationic moiety, resulting in choline chloride, which is measured by a fluorimetric technique based on the enzymatic conversion of choline. It was demonstrated that the new technique ensures a highly reliable determination of the charge density of these polymers, based on a comparison with the traditional charge titration technique and the data supplied by the manufacturer. Moreover, the specificity of the enzymatic conversion method also allows the determination of non-adsorbed polymer in conditioned sludge samples, without interference from other components. As a consequence, it enables the determination of the optimal polymer dose in practical conditioning and dewatering operations.     

Optimization of the coagulation-flocculation process for pulp mill wastewater treatment using a combination of uniform design and response surface methodology

Pulp mill wastewater was treated using the coagulation-flocculation process with aluminum chloride as the coagulant and a modified natural polymer, starch-g-PAM-g-PDMC [polyacrylamide and poly (2-methacryloyloxyethyl) trimethyl ammonium chloride], as the flocculant. A novel approach with a combination of response surface methodology (RSM) and uniform design (UD) was employed to evaluate the effects and interactions of three main influential factors, coagulant dosage, flocculant dosage and pH, on the treatment efficiency in terms of the supernatant turbidity and lignin removals as well as the water recovery. The optimal conditions obtained from the compromise of the three desirable responses, supernatant turbidity removal, lignin removal and water recovery efficiency, were as follows: coagulant dosage of 871 mg/L, flocculant dosage of 22.3 mg/L and pH 8.35. Confirmation experiments demonstrated that such a combination of the UD and RSM is a powerful and useful approach for optimizing the coagulation-flocculation process for the pulp mill wastewater treatment.     

有机高分子污泥脱水絮凝剂研究

对近年来广泛研究和使用的有机高分子污泥脱水絮凝剂进行了综述,有机高分子污泥脱水絮凝剂按合成方法分为聚合型和天然改性型;聚合型根据电荷类型分为了阳离子型、阴离子型、非离子型和两性型;天然改性型又可分为碳水化合物类和壳聚糖类。同时对污泥脱水絮凝剂的絮凝机理进行归纳阐述。对这六类污泥脱水絮凝剂的优缺点和应用现状进行了论述,并对高分子污泥脱水絮凝剂的发展前景进行了展望。     

DMDAAC复配改性PFSS处理高砷、镉废水的研究

以中高浓度As、Cd废水为处理对象,探讨了二甲基二烯丙基氯化铵(DMDAAC)复配改性聚合硅酸硫酸铁(PFSS)的絮凝性能。PFSS与DMDAAC复配形成稳定的均相复合溶液,当温度为100℃、DMDAAC投加量为200 mL/L、复配时间为5 min时制备的液态复合絮凝剂的絮凝效果最佳。复合絮凝剂在投加量为12.5 mL/L、pH值为8的条件下,能够有效去除废水中的Cd、As,出水中的Cd、As含量满足试验设计要求(Cd≤0.05 mg/L、As≤0.5 mg/L)和《铅、锌工业污染物排放标准》(GB 25466—2010)的要求。FT-IR和SEM检测结果表明,复合絮凝剂是相互融合的复合体系,PFSS改变了DMDAAC所处的化学环境,使其中一些官能团的特征吸收峰发生位移。     

An evaluation procedure for flocculation of coal preparation plant tailings

In solid-liquid separation of coal preparation plant tailings by flocculation, in addition to the type and amount of flocculants, the composition of waste materials including clay minerals must be determined in order to devise an effective and economic sedimentation system. In this study, the characterization of organic and inorganic impurities was made with the help of mineralogical data and instrumental analysis techniques. The effects of polymer type (medium and low anionic, cationic and nonionic), polymer dosage and suspension pH on flocculation mechanism of tailings particles (-0.18 mm) in the Tun?bilek Coal Preparation Plant tailings of Tun?bilek (Turkey) were investigated. Medium anionic polymer accelerated the settling rate of particles. An optimum settling rate (300 mm/min) was reached at a dosage rate of 34.19 g/ton-solids (2.0 mg/l), 51.28 g/ton-solids (3.0 mg/l), 102.56 g/ton-solids (6.0 mg/l) and 119.66 g/ton-solids (7.0mg/l) for medium anionic, low charged anionic, nonionic and cationic polymers, respectively. The lowest turbidity values at low polymer dosages were obtained by the cationic polymer at around 25.64 g/ton-solids (1.5 mg/l) polymer dosages; however, the low anionic and nonionic polymers produced lower turbidity values at higher dosages (>25.64 g/ton-solids). At optimum dosages of the polymer, the settling rate decreased at low and high pHs indicating that the natural pH (pH 8.3) of the suspension is the most appropriate pH for the settling rate. On the other hand, the water clarity values at natural pHs were high for all of the polymers.     

微生物絮凝剂在给水处理中的应用及其动力学研究

从活性污泥中筛选得到一株微生物絮凝剂产生菌,该菌能够利用玉米淀粉废水作为培养基生产微生物絮凝剂M-127.将M-127应用于自来水原水的絮凝试验,结果表明:M-127对原水的絮凝效果优于目前常用的给水絮凝剂,当M-127投加量为6 mg/L,以200 r/min搅拌1min,60 r/min搅拌3 min,静置20 min后,浊度去除率达到93.89%.同时,还研究了M-127在此最佳条件下的浊度去除动力学,并得到了动力学经验方程.     

差减法测定高氯废水的COD值

用国标法测定高氯废水的COD时易产生较大误差,且误差随着Cl~-浓度的增加而增大,为此采用差减法分别测定了含高COD和低COD浓度的高氯废水的COD值,结果表明,含高COD和低COD浓度的高氯废水,分别在Cl~-<12 500 mg/L和<8 000 mg/L时,测定误差在5%以内,满足国标允许范围,而超出此值时则易产生较大误差.     

Accelerated start-up and enhanced granulation in upflow anaerobic sludge blanket reactors

In the present study, the effects of a cationic polymer on reactor start-up and granule development were evaluated. A control reactor R1 was operated without adding polymer, while the other five reactors designated R2, R3, R4, R5 and R6 were operated with different polymer concentrations of 20, 40, 80, 160 and 320 mg/L, respectively. Experimental results demonstrated that adding the polymer at a concentration of 80 mg/L markedly accelerated the start-up time. The time required to reach stable treatment at an organic loading rate (OLR) of 4 g COD/L.d was reduced by approximately 50% in R4 as compared with the control reactor. The same reactor with 80 mg/L polymer was able to achieve an OLR of 12 g COD/L.d after 59 days of operation, while R1, R2, R3, R5 and R6 achieved the same loading rate at much longer period of 104, 80, 69, 63 and 69 days, respectively. Comparing with the control reactor, the start-up time of R4 was shortened markedly by about 43% at this OLR, while other reactors also recorded varying degree of shortening. Monitoring on granule development showed that the granule formation was accelerated by 30% from the use of the appropriate dosage of polymer. Subsequent granules characterization indicated that the granules developed in R4 with 80 mg/L polymer exhibited the best settleability, strength and methanogenic activity at all OLRs. The organic loading capacities of reactors were also increased by the polymer addition. The maximum organic loading of the control reactor was 24 g COD/L.d, while the polymer-assisted reactor added with 80 mg/L polymer attained a markedly increased organic loading of 40 g COD/L.d. The laboratory results obtained demonstrated that adding the cationic polymer could result in shortening of start-up time and enhancement of granulation, which in turn lead to improvement in organics removal efficiency and loading capacity of the UASB system.     

Enhanced granulation by natural ionic polymer additives in UASB reactor treating low-strength wastewater

Effect of natural ionic polymer additives on granulation in lab-scale UASB reactors treating low-strength synthetic wastewater (COD 750-850 mg/L) was examined. The organic loading rate was 1.477+/-0.118 kgCOD/m3/day. Under identical conditions four similar reactors were operated in parallel with the following additives: control with no additive, anionic part of Reetha (Sapindus trifoliata) extract, cationic part of Reetha extract, and Chitosan. By the end of the study period, Chitosan as an additive produced largest granules with mean size of 0.15 mm closely followed by the cationic fraction of the Reetha extract with mean size of 0.144 mm, and anionic fractions of the Reetha extract with 0.139 mm. Control reactor with no additives had the smallest size granules with mean size of 0.128 mm. The fraction of granules in the sludge bed of size >0.1 mm showed similar trend. The largest granule size observed in the reactors with additives was 4-5mm as compared to 2 mm in the control reactor. Cationic polymers were more effective additives for enhancing sludge granulation. Exo-cellular protein, lipid, sugar and total polymer increased with granulation in the reactors. A COD removal efficiency of 95-98% was achieved in all the reactors.     

改性沸石制备及除磷性能研究

采用硫酸、高分子絮凝剂聚二甲基二烯丙基氯化铵（PDMDAAC）和阳离子型聚季铵盐对沸石进行改性,考察了改性沸石投量、pH值、吸附时间对处理效果的影响。结果表明：改性沸石用量为6g/L、pH值为7、吸附时间100min、反应温度为20℃,废水中磷的去除率可达98%以上。     

Agglomeration of struvite crystals

Struvite crystallisation is widely studied as a way to remove phosphorus from wastewater effluents and simultaneously generates a valuable product for the fertiliser industry. However, to date, some crystallisation processes experimented at either pilot/or full scale face problems linked to the formation of fines. This paper presents results on the investigation of struvite agglomerative properties and the possible application of coagulants and/or flocculants to remove fines. Coagulants investigated were hydrolysing metals salts (Al(3+) and Fe(3+)), calcium compounds and a cationic polymer, polydiallyldimethylammoniumchloride (polyDADMAC). The effects of a natural flocculant (alginate) have also been tested. Results demonstrated that destabilisation of struvite particles by chemical addition was feasible and identified polyDADMAC as a good option for the agglomeration of struvite particles. However, optimisation of its dosage under typical pH conditions for struvite formation showed floc formation to be very pH sensitive.     

Experimental study on chitosan composite flocculant for treating papermaking wastewater

k]In this study, the coagulating effect of a novel composite flocculant on treating papermaking wastewater was studied and discussed. Results indicated that it achieved the best coagulating effect when this composite flocculant consisting of 60 mg/l of polymerized ferrous sulfate, 2 mg/l of polyacrylamide and 0.4 mg/l of chitosan, and pH value of wastewater was adjusted to 7.5. It also observed that the removal rate of COD and SS with this novel composite flocculant reached 72.5% and 98.5% respectively. Compared with the conventional flocculant such as polyacrylamide/polyaluminium chloride, the percentage of removing COD and SS using this composite flocculant were increased by 15.2% and 6.4% respectively, moreover, its input cost was cut down by 18.4%. So this composite flocculant has significantly environmental and economic benefits.     

Application of ferrous hydrogen peroxide for treatment of DSD-acid manufacturing process wastewater

A pretreatment method for the biological treatment of wastewater from 4,4'-diaminostilbene-2,2'-disulfonic acid (DSD-acid) manufacturing processes, a refractory dye intermediate wastewater, based on combined ferrous hydrogen peroxide oxidation and coagulation-flocculation, was developed. When the wastewater was treated with ferrous hydrogen peroxide oxidation ([Fe2+] = 2.7 mmol/L, [H2O2] = 0.21 mol/L) after a flocculation using an organic flocculant TS-1 at a dosage of 3 g/L, the overall COD and color removals were 64 and 62%, respectively. BOD5/COD value of the effluent was 0.3. Ferrous hydrogen peroxide oxidation treatment can reduce the solubility of organic molecules with sulfonic group and increase the efficiency of coagulation treatment. The COD and color removals were both more than 90% when FeCl3 was used as the coagulation (dosages of two-step coagulation were 0.031 and 0.012 mol/L respectively) after a ferrous hydrogen peroxide oxidation pretreatment at a H2O2 dosage of 0.06 mol/L.     

Benzoate and salicylate degradation by Halomonas campisalis, an alkaliphilic and moderately halophilic microorganism

Alkaliphiles and halophiles have considerable potential to treat organic pollutants in industrial wastewaters having high pH and salinity. As model aromatic compounds, benzoate and salicylate at concentrations up to 380 mg/L were degraded as carbon and energy sources by Halomonas campisalis, an alkaliphile and moderate halophile. Aerobic batch experiments were performed at 50 and 100g/L NaCl and pH 9. Detected metabolites, catechol and cis, cis-muconate, indicated that H. campisalis used the ortho degradation pathway for both substrates. For benzoate concentrations up to 1600 mg/L, the intermediate 2-hydroxymuconic semialdehyde (2HMSA), characteristic of the meta pathway, was not detected. Improved understanding and characterization of these degradation processes in high pH, high salt systems may lead to improved application of haloalkaliphiles for industrial wastewater treatment.     

臭氧/生物活性炭工艺深度处理焦化废水中试

以经常规生化工艺处理后的焦化废水为研究对象,通过中试考察了臭氧/生物活性炭工艺深度处理焦化废水的效果和可行性。通过测定生化呼吸曲线及相对耗氧速率来判定焦化废水可生化性的提高程度及活性炭生物膜的成熟情况。结果表明,该工艺用于焦化废水的深度处理是完全可行的。在臭氧投加量为15 mg/L的条件下,可显著提高焦化废水的可生化性,臭氧氧化对COD的平均去除率为10.13%。采用自然挂膜方法培养生物膜,生物膜的成熟时间为25 d左右。在生物活性炭稳定运行后,其对COD和氨氮的平均去除率分别可达28.75%和43.80%,出水COD和氨氮的平均值分别为87.50和7.6 mg/L,均达到了《污水综合排放标准》(GB 8978—1996)中的一级标准。     

PAC与PAM复合絮凝剂处理泡菜废水

采用絮凝法对泡菜废水进行了试验,分别考察了絮凝剂的种类、助凝剂的种类、PAM分子量、投加方式、pH值、温度、搅拌转速等条件对泡菜废水絮凝处理效果的影响,为泡菜废水的后期生化处理提供了帮助的同时也可为泡菜厂实际絮凝处理提供一定的参考。在含大量NaCl的泡菜废水中,利用PAM网捕、架桥功能完善了PAC单独作用下絮体细小松散的缺陷,改善了絮凝和沉降性能。研究结果表明:PAC用量150mg/L,PAM用量25mg/L,pH6,温度30℃,250r/min快搅2min,90r/min慢搅2 min,静置30 min后泡菜废水COD、浊度去除率分别达到了37.7%、96.7%。     

复合混凝剂的制备及其对印染废水的处理效果

采用聚二甲基二烯丙基氯化铵、阳离子型聚季铵盐和粉煤灰自制新型混凝剂,并考察了药剂投量、pH值、吸附时间对处理效果的影响。结果表明：复合混凝剂投加量为12g／L、吸附时间为55min、pH值=9、反应温度为20℃时,印染废水的脱色率可达97．9％以上。     

Comparative study of humic acids flocculation with chitosan hydrochloride and chitosan glutamate

Flocculation of dissolved humic acids (HA) and their complexes with metal ions and organic pollutants is a crucial step in drinking water preparation due to significant undesirable effects of humic compounds on water quality. Constant demand for cheap, effective and environmentally friendly flocculants brings about the interest to natural cationic polymers which can be used to neutralize negative charge of humic colloids through polyelectrolyte complexes (PEC) formation. In this work, the interaction of HA with two types of soluble chitosan salts (hydrochloride and glutamate) at different pH and polymer ratios was studied with a focus on electrical charge of PEC formed and effectiveness of color removal in the flocculation process. For both chitosan forms flocculation window was found at pH close to the PEC isoelectric point (pI) in a wide concentration range; however, lower flocculant dose was required when chitosan glutamate was used.