磷酸镁水泥固化/稳定化重金属性能及作用机理研究进展

磷酸镁水泥(MPC)作为一种新型无机胶凝材料,是由过烧氧化镁和磷酸盐通过酸碱中和反应制备得来,具有早期强度高、结构紧密和体积形变小等优点,在固化/稳定化重金属方面受到广泛关注,但存在放热量大、凝结速度快等缺点.本文归纳了国内外学者对磷酸镁水泥固化/稳定化重金属和重金属污染土的研究,重点讨论重金属离子对磷酸镁水泥抗压强度...     

受污染底泥固化/稳定化处理及营养物质释放特征研究

以广州市车陂涌受污染底泥为研究对象,通过掺杂不同比例的粉煤灰、水泥、石灰和膨润土,对底泥进行固化/稳定化处理试验,探讨底泥经处理后的产物中碳素和营养盐的释放特征。结果表明：实验条件下底泥固化/稳定化处理基本不会减少碳的释放,但会改变其释放形态,未经处理的底泥释放的TOC被迅速矿化,而底泥固化/稳定化处理产物释放的TOC稳定存在。在试验期内,底泥固化/稳定化处理对产物的硝态氮释放无明显影响;固化/稳定化处理能有效促进氮磷的稳定,固化体氨氮和磷酸盐的释放量明显降低,分别比未经处理的底泥减少了67.4%和76.4%以上。不同来源的粉煤灰由于成分不同,在底泥固化/稳定化处理中的作用存在差异,掺杂珠江电厂的粉煤灰Z对氨氮和磷酸盐的稳定化效果优于恒运电厂的粉煤灰H。固化/稳定化技术为疏浚底泥提供了一种安全的处理方法,为粉煤灰提供了一种有效的资源化途径。     

水泥固化六价铬污染土力学性能及微观结构研究

通过一系列无侧限抗压强度和电阻率试验,研究养护龄期、水泥掺量和六价铬离子含量对固化污染土无侧限抗压强度和电阻率的影响以及无侧限抗压强度和电阻率之间的关系。研究发现:水泥固化铬污染土的无侧限抗压强度和电阻率随着养护龄期的增加而增大,但增长速率有所不同。铬离子含量越高,水泥固化铬污染土的无侧限抗压强度越低,电阻率越低;水泥掺量越多,水泥固化铬污染土的无侧限抗压强度越大,养护龄期越长,后期增长较大;当养护龄期较短时,固化土的电阻率随水泥掺量的增大略有提高。10%水泥掺量下的无侧限抗压强度(p_u)和电阻率(ρ)近似呈线性关系:p_u=0.740ρ+1.853,R~2=0.917。淋滤实验结果表明:随着固化剂掺量和养护龄期的增加,重金属浸出率降低,固化效果较好。核磁共振试验结果发现:水泥掺量越高,其水化产物越多,水化产物嵌入孔隙,孔径范围越小。微观空隙分析表明:水泥掺量越高,试样整体的平整度和密实性越好,强度越高。     

硫酸铝废渣和石灰外掺低标号水泥水化、硬化性能研究

采用扫描电镜、X射-线物相分析,对改性砂浆样水化机理进行了分析,在此基础上,对外掺硫酸铝废渣水泥胶砂进行了多项物理性能测试.实验结果表明:硫酸铝废渣在低标号水泥中掺量大于14%出现急凝.最佳掺量为6%—10%时,硫酸铝渣水泥胶砂龄期强度均增加,早期强度增大最为明显.铝渣水泥胶砂龄期水化状况良好,水化产物(AFt,AFm,CH)较基准胶砂数量多且发育良好.铝渣低标号水泥胶砂综合实验表明,其耐久、耐候性能优良.     

TiO2/粉煤灰的制备及光催化性能研究

以钛酸丁酯为原料,以粉煤灰微珠为载体,采用溶胶-凝胶法制备了TiO2/粉煤灰光催化剂.负载于粉煤灰表面的TiO2平均粒径约为7nm,晶型为锐钛矿型,该催化剂在太阳光下降解初始浓度为10mg·l-1的甲基橙,经6h,甲基橙的降解率可达98.9%,将其应用于实际样品的测定,经3h降解率可达96.1%,显示出优越的光催化降解性能.     

石粉、市政污泥及粉煤灰保温材料的试验研究

通过研究利用石粉、市政污泥和粉煤灰烧结保温材料的方法,通过对不同烧结温度、不同配比原料制成的烧结材料性能进行了研究.实验结果表明,烧结温度为1050℃时,粉煤灰、市政污泥和石粉烧结保温材料的最佳配比为1:1:8,烧结保温材料强度为17.9 MPa,孔洞率为39％,导热系数为1.20 W/(m2·K),表观密度为1200...     

稳定塘处理污水的机理研究及应用研究进展

稳定塘污水处理系统具有基建投资和运转费用低、维护和维修简单、便于操作、能有效去除污水中的有机物、无需污泥处理等优点,近年来越来越受到人们的重视,其净化过程与自然水体的自净过程相似。本文总结了稳定塘中有机物、氮和磷的去除机理,有机物的去除一般包括沉淀和絮凝、厌氧微生物的作用、好氧微生物的作用、浮游生物的作用和水生植物的作用,氮在稳定塘内的去除,主要是通过生物同化吸收转化为自身有机氮、氨氮的吹脱作用、形成生物沉淀以及硝化/反硝化等几种途径,磷元素去除涉及有机磷在微生物作用下分解氧化,菌藻及其他生物吸收无机磷合成新细胞,以及可溶性磷与不可溶性磷之间的转化等多种机制的共同作用。针对传统稳定塘中存在的缺陷,人们不断地对稳定塘进行改良,出现了许多新型塘,其中包括高效藻类塘、水生植物塘和养殖塘、高效复合厌氧塘、超深厌氧塘、生物滤塘等塘型。为了提高污水的处理效率,研究人员还开发了许多组合塘的工艺,与传统生物法组合的UNITANK工艺+生物稳定塘、水解酸化+稳定塘工艺和折流式曝气生物滤池+稳定塘工艺等,各类塘型组合的多级串联塘系统、生态综合塘系统、高级综合塘系统(AIPS)等。目前稳定塘处污水理系统还依然存在占地面积大、水力停留时间较长、效率低下、散发臭味、处理效果受气候条件影响大等缺陷。今后应该在稳定塘系统的研究中,以菌、藻的活动为主体,以主要营养元素C、N、P的迁移为线索,建立系统内各种生物、化学反应之间的联系,通过减小塘深、机械搅拌、跌水坡等方法改善供氧条件,对天然塘型进行精确修整、分隔组合,使之更加符合高效反应器的构造,从而提高稳定塘设计的合理性。加入人造载体提高塘内微生物浓度,从而大大提高有机负荷,有效减少占地面积,组合沉淀池、间歇砂滤、砾石滤墙、微滤、气浮、土地处理、人工湿地系统、加入化学药剂等处理工艺或方法,以去除出水中的藻类,改善环境卫生条件,满足不同出水水质的要求,从而为国内稳定塘技术的进一步改进提供科学依据。     

三氯苯生产废渣中的有机氯化合物氯苯、多氯联苯及多氯联苯醚的分析

采用柱层析、气相色谱及色-质联用的分析方法,对氯苯生产中的蒸馏残渣进行了研究。样品溶液预先经氧化铝柱分离,然后对各组份进行鉴定和分析。初步结果表明,残渣中除含有二、三、四、五、六氯代苯类及多种六六六异构体外,尚包括对环境及人体健康有较大危害作用的三、四、五、六、七氯联苯及五、六、七、八氯代联苯醚类。     

硫酸盐废水生物处理产生的硫化物处理含Pb2+、Zn2+的钢丝酸洗废水

在一套小型搅拌反应器中,研究了碱沉淀(KOH,处理a)、碱沉淀及硫酸盐废水厌氧处理产生的硫化物出水混合(KOH+出水混合,处理b)、碱沉淀及N2吹脱硫酸盐废水厌氧处理产生的硫化物(KOH+N2吹脱,处理c),以及碱沉淀、硫酸盐废水厌氧处理产生的硫化物出水混合和N2吹脱硫化物联合(KOH+出水混合+N2吹脱,处理d)等4组处理方式对含Zn2+、Pb2+的钢丝绳酸洗废水处理效果的影响.废水pH值为0.7,Zn2+和Pb2+含量分别为450和3274 mg.L-1.结果表明,KOH+出水混合+N2吹脱的处理方式对废水有较好的处理效果,Zn2+和Pb2+的去除为氢氧化物、硫化物沉淀的共同作用结果,处理后,废水中Zn2+和Pb2+的去除率均达99.6%以上,满足污水综合排放标准(GB 8978—1996).     

A/SMBBR处理生活污水效能研究及生物膜菌群结构分析

采用SDC-03作为生物载体,考察特异性移动床生物膜法对生活污水中有机污染物的去除效果,并运用Illumina Hiseq高通量测序技术对微生物进行分析.实验结果表明,COD、氨氮和总氮的平均出水浓度分别为25.65 mg·L~(-1)、5.14 mg·L~(-1)、14.55 mg·L~(-1),平均去除率分别为91.05%、92.39%、83.44%.该工艺能适应较低温度,最佳HRT和DO浓度分别为10—12 h、3—4 mg·L~(-1)之间.采用Chao1指数、Shannon指数、Simpson指数及PD whole tree值等指数对微生物种群多样性进行分析.对反应器的微生物从门和属两个科目进行分析,得出门水平丰度前10的微生种和属的物种组成.门水平前十的物种分别为变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、芽单胞菌门(Gemmatimonadetes)、Saccharibacteria、厚壁菌门(Firmicutes)、绿弯菌门(Chloroflexi)、放线菌门(Actinobacteria)、硝化螺旋菌门(Nitrospira)、酸杆菌门(Acidobacteria)、Thermomicrobia.变形菌门和拟杆菌门大量存在于在好氧池中,芽单胞菌门和厚壁菌门有助于反硝化反应的进行;在属水平中得知未知的菌属占大部分.     

Leaching characteristics of heavy metals during cement stabilization of fly ash from municipal solid waste incinerators

The leaching characteristics of heavy metals in products of cement stabilization of fly ash from a municipal solid waste incinerator were investigated in this paper. The stabilization of heavy metals such as Cd, Pb, Cu, and Zn in fly ash from such incinerators was examined through the national standard method in China based on the following factors: additive quantity of cement and Na₂S, curing time, and pH of leaching liquor. The results showed that as more additives were used, less heavy metals were leached except for Pb, which is sensitive to pH of the leachate, and the worse effect was observed for Cd. The mass ratio of cement to fly ash = 10% is the most appropriate parameter according to the national standard method. When the hydration of cement was basically finished, stabilization of heavy metals did not vary after curing for 1 d. The mixtures of cement and fly ash had excellent adaptability to environmental pH. The pH of leachate was maintained at 7 when pH of leaching liquor varied from 3 to 11.     

制革污泥固化稳定化处理

为有效控制制革污泥中的重金属铬污染并安全填埋,采用石灰、粉煤灰和煤渣作为固化剂对制革污泥进行固化/稳定化处理,考察固化剂对制革污泥中重金属毒性的影响,并探讨了固化/稳定化的最佳工艺条件.结果表明,当石灰、粉煤灰和煤渣的掺量分别为0.12 kg.kg-1、0.02 kg.kg-1和0.08 kg.kg-1,养护天数为6 d时,制革污泥固化块抗压强度达到884 kPa,含水率由固化前的79.60%降低至30.20%,满足《危险废物填埋污染控制标准》（GB 18598—2001）的要求.固化块浸出液中Cu、Pb、Zn、Ni浓度同固化前相比,分别降低了92.1%、96.7%、92.8%、88.9%,Cr、Cd、Mn均未检出.固化块浸出液的铬浓度随着石灰添加量的增加而降低,随粉煤灰添加量的增加则为先降低、然后再升高,当石灰与粉煤灰添加量比为6∶1时,协同固化效果显著.     

Hydrothermal treatment of MSWI fly ash for simultaneous dioxins decomposition and heavy metal stabilization

Researches on the hydrothermal treatment of municipal solid waste incineration (MSWI) fly ash were conducted to eliminate dioxins and stabilize heavy metals. In order to enhance decomposing polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs) during hydrothermal process, a strong reductant carbohydrazide (CHZ) is introduced. A hydrothermal reactor was set up by mixing raw MSWI fly ash or the pre-treated fly ash with water and then heated to a pre-set temperature; CHZ was spiked into solution according to specially defined dosage. Experimental results showed that under the temperatures of 518 K and 533 K, the decomposition rates of PCDDs/PCDFs were over 80% and 90%, respectively, by total concentration. However, their toxic equivalent (TEQ) decreased only slightly or even increased due to the rising in concentration of congeners 2, 3, 7, 8-TCDD/TCDF, which might be resulted from the highly chlorinated congeners losing their chlorine atoms and being degraded during the hydrothermal process. Better results of TEQ reduction were also obtained under the higher tested temperature of 533 K and reactor with addition of 0.1%wt CHZ was corresponded to the best results. Good stabilization of heavy metals was also obtained in the same hydrothermal process especially when ferrous sulphate was added as auxiliary agent.     

Coal fly ash and straw immobilize Cu,Cd and Zn from mining wasteland

Soil heavy metal contamination is a major health issue. Chemical immobilization of toxic metals is a promising technique to solve this issue. In this study, soil was sampled from a copper mining-polluted area in eastern China. Coal fly ash and straw were applied to soil samples at 5 % w/w ratio and 2 % w/w ratio, and incubated for 6 weeks. The CaCl₂-extractable Cu, Cd and Zn, phytoavailability and soil microbial activity were measured. The results showed that coal fly ash, straw and the mixture of coal fly ash and straw decreased CaCl₂-extractable metals. Coal fly ash or the mixture of the two amendments are therefore efficient metal stabilizers.     

Retention characteristics of Cu2+, Pb2+, and Zn2+ from aqueous solutions by two types of low lime fly ashes

The technical feasibility of utilization of fly ash as a low-cost adsorbent for the removal of metals from water has been studied. For two types of fly ashes, the retention capacities of copper, lead, and zinc metal ions have been studied. Contact time, initial concentration, and pH have been varied and their effect on retention mechanism has been studied. The dominant mechanisms responsible for retention are found to be precipitation due to the presence of calcium hydroxide, and adsorption due to the presence of silica and alumina oxide surfaces in the fly ash. First-order kinetic plots have revealed that the rate constant increases with increase in the initial concentration and pH. Langmuir adsorption isotherms have been plotted to study the maximum adsorption capacities for metal ions considered under different conditions. X-ray diffraction studies revealed the formation of new peaks corresponding to respective metal ions precipitates under alkaline conditions.     

石灰泥炭对镉铅锌污染土壤上小白菜生长和元素吸收的影响

采用盆栽方法研究了在镉、铅、锌污染土壤上,石灰和泥炭对小白菜生长状况及对污染元素(Ｃｄ,Ｐｂ,Ｚｎ)和养分元素(Ｎ,Ｐ,Ｋ,Ｃｕ,Ｍｎ,Ｆｅ)吸收的影响。结果表明,石灰消除了重金属的毒害症状．显著促进小白菜的生长、显著抑制小白菜对镉、铅、锌的吸收。石灰对氮、钾、铜、锰的吸收也有显著抑制作用。泥炭对小白菜生长的改善效果及对铜、铅、锌吸收的抑制效果较石灰差。提高酸性土壤ｐＨ值是减少作物对重金属吸收的有效方法。     

Characteristics of the stabilized/solidified municipal solid wastes incineration fly ash and the leaching behavior of Cr and Pb

Fly ash is a hazardous byproduct of municipal solid wastes incineration (MSWI). An alkali activated blast furnace slag-based cementitious material was used to stabilize/solidify the fly ash at experimental level. The characteristics of the stabilized/solidified fly ash, including metal leachability, mineralogical characteristics and the distributions of metals in matrices, were tested by toxic characteristic leaching procedure (TCLP), X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) respectively. Continuous acid extraction was utilized to extract metal ions and characterize their leaching behavior. The stabilization/solidification procedure for MSWI fly ash demonstrates a strong fixing capacity for the metals by the formation of C-S-H phase, hydrated calcium aluminosilicate and ettringite. The stabilized/solidified fly ash shows a dense and homogeneous microstructure. Cr is mainly solidified in hydrated calcium aluminosilicate, C-S-H and ettringite phase through physical encapsulation, precipitation, adsorption or substitution mechanisms, and Pb is mainly solidified in C-S-H phase and absorbed in the Si-O structure.     

Combined treatment of chemical,pharmaceutical and cosmetic industrial effluents by waste stabilization ponds

Influent and final effluent was collected from the CMM Ltd., Bethora, Ponda, Goa and were analysed for pH, DO, BOD, enzyme activity and chlorophyll content of the waste stabilization pond for over a period of two years of which the data for one year (pre monsoon, monsoon and post monsoon periods) is given. The study revealed that the DO was maximum during the pre-monsoon months and least during the monsoon. Maximum removal of BOD and phosphate was observed during the pre-monsoon periods. Enzymatic activity was at its peak during the monsoons than during the other months. Chlorophyll content was maximum during the pre-monsoon months due to increased growth of phytoplankton as the conditions were favourable for their growth. Also depending on the concentration of different chlorophyll pigments, one can come to know the different groups of algae inhabiting the stabilization ponds.     

利用废弃物煅烧水泥时重金属Pb、Cd的逸放污染

利用废弃物作为代替原料煅烧水泥已广泛应用于水泥生产,但其带来的环境污染问题不容忽视。以利用废弃物生产水泥的厂家为研究对象,采用原子吸收分光光度法检测所采集样品中重金属Pb、Cd的含量,对水泥生产过程中重金属Pb、Cd的逸放及其对周围土壤的污染进行研究。研究结果表明:利用废弃物煅烧水泥的过程中,重金属Pb、Cd的逸放率很高,其中立窑的Pb、Cd逸放率高达84%～90%,湿法回转窑的Pb、Cd逸放率达到63%～74%;在水泥厂上下风向500m、1000m和2000m处采集土壤样品,工厂周围的土壤均已受到不同程度的重金属污染,位于工厂下风向的土壤受到的污染更为严重,距离工厂500m处土壤中重金属Pb、Cd的含量均超过了国家标准的最大限量;对几家工厂员工的头发进行随机取样,头发样品中Pb含量均超过正常限量。