生物沥浸细菌的培养及其对污泥脱水性能的影响

以高碑店污水处理厂的浓缩污泥作为生物沥浸对象进行脱水预处理,研究了生物沥浸细菌的培养及其对污泥脱水性能的影响。将回流污泥上清液分别接种到SM液体培养基和9K液体培养基,通过分离培养、富集获得以氧化硫硫杆菌和氧化亚铁硫杆菌为主的生物酸化细菌,不断转接使培养基pH值降到2以下所需时间由最初的8~10 d缩短到3~4 d,然后共同接种到浓缩污泥中,经强化培养获得生物沥浸的接种物。不同营养物质投加量的沥浸试验发现,当其他条件保持一致时,S投加量为2 g/L的试验组降低体系pH值、提高体系ORP的能力要强于投加量为1 g/L的试验组;在S投加量一定的情况下,Fe SO4·7H2O投加量2 g/L时生物沥浸效果较好。生物沥浸后污泥的脱水性能得到显著改善,经板框脱水可使泥饼含水率降到65%以下。     

花生壳生物炭对Pb~(2+)和Cu~(2+)的吸附及影响因素分析

以花生壳生物炭为吸附材料,通过批量试验探究了pH值、生物炭投加量、初始重金属离子浓度、吸附时间对生物炭吸附Pb~(2+)和Cu~(2+)的影响,并利用Langmuir和Freundlich等温吸附模型、准一级和准二级吸附动力学模型分别进行等温吸附和吸附动力学分析。结果表明,花生壳生物炭吸附Pb~(2+)和Cu~(2+)的适宜pH值分别为4. 5～5. 5和5～6。在Pb~(2+)和Cu~(2+)的初始浓度分别为100和75 mg/L,花生壳生物炭投加量分别为2和6. 25 g/L,吸附时间分别为480和900 min条件下,Pb~(2+)和Cu~(2+)达到吸附平衡时的吸附量分别为49. 32和11. 35 mg/g,且吸附过程符合Langmuir等温吸附模型和准二级吸附动力学模型。同时发现,花生壳生物炭能更快更好地吸附Pb~(2+)。     

西宁盆地坡缕石粘土对Cd^2＋吸附性能研究

试验研究了西宁盆地坡缕石粘土对Cd^2＋的吸附性能,考察了改性方法、搅拌时间、粘土投加量、吸附温度、溶液初始浓度等因素对吸附效果的影响。结果表明,采用Na2CO3改性时,Na2CO3与粘土最佳配比为3∶100;吸附的适宜条件为：搅拌时间50min、粘土投加量1.5g/100mL Cd^2＋溶液、吸附温度20℃;在试验的浓度范围内,Cd^2＋在粘土上的吸附规律符合Langmuir等温模型。西宁盆地坡缕石粘土对Cd^2＋具有较好的吸附性能,粘土投加量为每100mL Cd^2＋溶液2.5g时,处理后溶液中Cd^2＋含量下降到0.1mg/L以下,符合GB8796-1996第一类污染物最高排放标准。     

改性钢渣的制备及其吸附除磷性能

研究了改性钢渣吸附除磷影响因素、等温吸附线特征和吸附动力学,并对生物处理后的出水进行吸附除磷研究。结果表明:在初始磷浓度10mg/L,投加量10g/L、pH为7时,改性钢渣吸附后总磷浓度为0.687mg/L,去除率达93%;改性钢渣对磷的吸附符合Langmuir模型,理论饱和吸附量是1.977mg/g,吸附动力学符合准二级动力学模型(R20.99);实际生活污水的吸附除磷中,投加量为50g/L,反应2h后出水总磷浓度达到《城镇污水处理厂污染物排放标准》(GB18918—2002)一级B标的排放要求。     

耐酸性酵母菌筛选及强化污泥生物沥浸预处理研究

针对水溶性有机物对硫杆菌的毒害作用导致生物沥浸效率降低的问题,开展了耐酸性酵母菌生理生化特性研究,并验证了其强化污泥生物沥浸预处理的可行性。结果表明,菌株BJ-1属于红酵母菌属,其适宜的温度和pH范围分别为28～30℃和3.0～7.0,说明酵母菌BJ-1为中温耐酸性菌。当酵母菌BJ-1初始接入浓度为1×10⁶个/mL时,能够较好地加速生物沥浸进程,并使沥浸污泥的脱水性能提升5～6倍,经过其处理后污泥的沉降率提高3.1倍,毛细吸水时间缩短51%,污泥比阻降至1.0×10¹²m/kg以下。脱水效果最佳时间是沥浸2 d。     

生物沥浸法对常规脱水污泥再深度脱水的效果

为了考察生物沥浸法对常规脱水污泥(指在浓缩污泥中加PAM等高分子絮凝剂并经带式或离心脱水后获得的含水率在80%左右的脱水污泥)进一步深度脱水的效果,将常规脱水污泥用中水稀释成含水率为97%左右的液态污泥后,采用批式运行模式进行生产性生物沥浸法调理(每批次处理污泥为60 m3),然后在不加任何化学絮凝剂的情况下直接用隔膜厢式压滤机进行压滤脱水。结果表明,以浓缩池含水率为97%的浓缩污泥作为对照,在上批次沥浸污泥(接种物)与待处理的液态污泥体积比为1∶1时,生物沥浸过程可在24 h内完成,污泥比阻由沥浸初期的3.56×1012m/kg降低至0.43×1012m/kg。生物沥浸后的污泥通过150 m2的隔膜厢式压滤机,在1.2~1.5 MPa压力下压滤1.5 h,泥饼含水率可稳定地降低到60%以下,外观呈土黄色块状,无臭味。经检测,泥饼有机质和高位热值在生物沥浸处理前后没有降低,且压滤液清澈,无色无味,COD为120~170 mg/L,总氮为40~60 mg/L,总磷在0.5 mg/L以下。可见,常规脱水污泥经稀释后进行生物沥浸法深度脱水处理是完全可行的。     

磁性壳聚糖交联沸石的制备及对Cu2+的吸附性能

随着工业化的快速发展,Cu²⁺污染日益严重。为了减轻Cu²⁺污染,通过沸石和磁性纳米Fe3O4的联合作用,制备出一种新型多层吸附材料,即磁性壳聚糖交联沸石(FS-CS)以改善壳聚糖的吸附作用,从而达到去除Cu²⁺的目的。通过扫描电镜能谱仪(SEM-EDS)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)对FS-CS的结构和性能进行表征,并考察FS-CS投加量、吸附时间、pH对吸附Cu²⁺的影响。结合吸附动力学、吸附热力学等多种方法,探讨其吸附机理。结果表明：FS-CS吸附Cu²⁺的最佳初始pH为5,最佳吸附时间为4 h,最大吸附容量可达32.705 mg/g,且FS-CS具备良好的分离和可再生能力;FS-CS对Cu²⁺的吸附过程符合准二级动力学模型,吸附等温线符合Freundlich吸附模型。     

生物絮凝剂Pullulan絮凝Pb2+的性能研究

进行了生物絮凝剂Pullulan絮凝水中Pb^2＋的试验，探讨了Pullulan与电解质AlCl3的复合比、絮凝溶液pH值以及初始Pb^2＋浓度对絮凝效果的影响。结果表明：在Pullulan与AlCl3用量比为4：1．1、溶液pH值为6．5～7．0、Pb^2＋初始浓度为10、25、60、100mg／L时，分别投加8、25、40、80mg／L的Pullulan，对Pb^2＋的去除率可达最高，分别为73．86％、76．30％、77．07％、81、19％。6次重复性试验表明Pullulan的絮凝效果具有较高的稳定性。     

活性污泥中提取的藻酸作为铜吸附剂的研究

采用实验室培养的活性污泥提取藻酸并制备藻酸钙吸附剂,用于去除污水中的Cu2+,考察了其吸附和解吸性能及影响因素,并采用城市污水处理厂的剩余污泥进行验证.结果表明:pH值和藻酸钙投量对其吸附Cu2+有明显影响,当pH值为4、Cu2+初始浓度为100 mg/L、藻酸钙投量为0.7 g/L时,对Cu2+的平衡吸附量为41.96 mg/g;藻酸钙对Cu2+的吸附过程符合Langmuir模型;以盐酸为解吸剂,藻酸钙的解吸率可达到90%.实际剩余污泥可制备(203±11)mg/g的藻酸钙,对Cu2+的吸附量可达51.44 mg/g,而解吸率可达到94%.采用剩余污泥制备藻酸钙吸附剂,操作简单、成本低、对Cu2+的吸附高效、易于再生,具有工业应用前景.     

厌氧污泥胞外聚合物(EPS)对水中U(Ⅵ)的吸附试验研究

通过试验,探讨了以厌氧污泥胞外聚合物(EPS)为吸附材料,在溶液中的pH、EPS投加量、初始铀质量浓度及透析温度等因素影响下,该EPS对水中U(Ⅵ)的吸附效果与作用机制。试验结果表明:EPS吸附铀的最佳pH值为6,最高吸附量为0.891 mg/g EPS;当铀的初始质量浓度为20 mg/L,EPS投加量为56.1 g/L时,可以达到最佳去除率98.3%。     

改性沸石对废水中锰的吸附研究

采用吸附法去除水体中重金属锰,以NaOH对天然沸石改性,对含Mn的水体进行处理,通过单因素实验系统考察了改性沸石用量、吸附时间、初始浓度、温度对吸附效果的影响,研究结果表明在25℃,吸附剂用量为1.0 g,吸附时间120 min,对初始浓度为1.0 mg/L时,锰的去除率可达到99.3%,最大吸附容量达到9.93 mg/g。     

合成碳羟基磷灰石对废水中锰离子的吸附研究

利用废弃的蛋壳制备碳羟基磷灰石(CHAP),研究了其对废水中Mn2+的吸附作用,并探讨了CHAP用量、Mn2+浓度、温度、pH对吸附效果的影响.试验结果表明:在pH值为6、温度为30℃、搅拌时间为1 h、CHAP用量为3 g/L、Mn2+初始浓度为70 mg/L的条件下,CHAP对Mn2+的去除率可达到97.9%,吸附容量为22.84 mg/g;CHAP对Mn2+的吸附过程符合Langmuir和Fre-undlich吸附等温式,吸附反应是自发放热过程;H0准二级动力学模型能较好地描述CHAP对Mn2+的动力学吸附行为.     

Bioleaching of heavy metals from contaminated sediment by indigenous sulfur-oxidizing bacteria in an air-lift bioreactor: effects of sulfur concentration

The effects of sulfur concentration on the bioleaching of heavy metals from the sediment by indigenous sulfur-oxidizing bacteria were investigated in an air-lift reactor. Increasing the sulfur concentration from 0.5 to 5 g/l enhanced the rates of pH reduction, sulfate production and metal solubilization. A Michaelis-Menten type equation was used to explain the relationships between sulfur concentration, sulfate production and metal solubilization in the bioleaching process. After 8 days of bioleaching, 97-99% of Cu, 96-98% of Zn, 62-68% of Mn, 73-87% of Ni and 31-50% of Pb were solubilized from the sediment, respectively. The efficiency of metal solubilization was found to be related to the speciation of metal in the sediment. From economical consideration, the recommended sulfur dosage for the bioleaching of metals from the sediment is 3g/l.     

The use of the aquatic moss Fontinalis antipyretica L. ex Hedw. as a bioindicator for heavy metals: 3. Cd2+ accumulation capacities and biochemical stress response of two Fontinalis species

We studied heavy metal stress responses of two Fontinalis species, F. antipyretica and F. dalecarlica, collected from two habitats in Germany and Canada. The capacities of the two species for extracellular adsorption (biosorption) and intracellular uptake (bioaccumulation) of Cadmium (Cd2+) were investigated in the laboratory. Time-dependent Cd2+ adsorption by cell wall and intracellular uptake differed significantly between the two species. These differences were related to the number of Cd2+ binding sites, resulting from differences in leaflet surface and cell wall composition. Glutathione (GSH) levels in response to Cd2+ exposure were monitored over a 10-day period. GSH synthesis differed significantly between the two species. Both Fontinalis species appear to be suitable for heavy metal biomonitoring in aquatic habitats.     

Removal of copper,nickel, cobalt and manganese from aqueous solution by kaolinite

The removal of some heavy metals such as Mn(II), Co(II), Ni(II), and Cu(II) from aqueous solution is studied using a raw kaolinite. The sorption of these metals on kaolinite conformed to linear form of Langmuir adsorption equation. Langmuir C(m) constants for each metal were found as 0.446 mg/g (Mn), 0.919 mg/g (Co), 1.669 mg/g (Ni), 10787 mg/g (Cu) at 25 degrees C, respectively. Also, kinetic and thermodynamic parameters such as enthalpy (deltaH), free energy (deltaG) and entropy (deltaS) were calculated and these values show that adsorption of heavy metal on kaolinite was an endothermic process and the process of adsorption was favoured at high temperatures.     

电凝聚法去除废水中重金属离子Cr6+、Cu2+的研究

考察了初始pH值、电解时间、电流强度、NaCl投量、离子共存及曝气量等因素对电凝聚法处理含Cr6+、Cu2+废水的影响。结果表明,随初始pH值的升高,对Cr6+的去除率呈先上升后下降的趋势,并在pH值=6时达到最高,而对Cu2+的去除率逐渐上升,并在pH值=5时达到最高后趋于稳定;对Cr6+、Cu2+的去除率均随反应时间及电流强度的增大而增大,并在时间为20min、电流强度为4 A时达到了比较稳定的去除效果;NaCl投量对Cr6+、Cu2+的去除率基本没有影响,其作用是适当地提高废水的电导率,降低能耗;对混合溶液中Cr6+、Cu2+的去除效果比单一溶液时好,金属离子共存对电凝聚处理重金属废水起促进作用;适当的曝气会提高重金属的去除率。     

Comparisons of low-cost adsorbents for treating wastewaters laden with heavy metals

In this article, the removal performance and cost-effectiveness of various low-cost adsorbents derived from agricultural waste, industrial by-product or natural material are evaluated and compared to those of activated carbon for the removal of heavy metals (Cd(II), Cr(III), Cr(VI), Cu(II), Ni(II) and Zn(II)) from metals-contaminated wastewater. To highlight their technical applicability, selected information on pH, dose required, initial metal concentration, adsorption capacity and the price of the adsorbents is presented. It is evident from the survey of 102 published studies (1984-2005) that low cost adsorbents derived from agricultural waste have demonstrated outstanding capabilities for the removal of heavy metal (Cr(VI): 170 mg/g of hazelnut shell activated carbon, Ni(II): 158 mg/g of orange peel, Cu(II): 154.9 mg/g of soybean hull treated with NaOH and citric acid, Cd(II): 52.08 mg/g of jackfruit), compared to activated carbon (Cd(II): 146 mg/g, Cr(VI): 145 mg/g, Cr(III): 30 mg/g, Zn(II): 20 mg/g). Therefore, low-cost adsorbents can be viable alternatives to activated carbon for the treatment of metals-contaminated wastewater. It is important to note that the adsorption capacities presented in this paper vary, depending on the characteristics of the individual adsorbent, the extent of surface modification and the initial concentration of the adsorbate. In general, technical applicability and cost-effectiveness are the key factors that play major roles in the selection of the most suitable adsorbent to treat inorganic effluent.     

Characterization of barley straw biochar produced in various temperatures and its effect on lead and cadmium removal from aqueous solutions

Conversion of agricultural wastes into a carbon rich material (i.e. biochar) using pyrolysis process could be an appropriate approach for their management. This study was carried out to convert barley straw to biochar in different temperatures (300, 400 and 500°C) and to investigate the potential of the produced biochar as a sorbent of heavy metals (Pb and Cd). Considering the pretest results of Pb and Cd sorption, the biochar produced at 500°C (BS500) was selected to find effect of pH, the sorbent dose, the initial concentration of Pb and Cd and the contact time on metal removal efficiency. The results showed that the optimum conditions of adsorption were pH = 6, the sorbent dose 1 g/L and the contact time of 45 min. The adsorption kinetics and isotherms had the best fit to the pseudo‐second order and Langmuir models, respectively.