Impact of <i>Moringa oleifera</i>Cake Residue Application on Waste Water Treatment: A Case Study

Most of water treatments require higher expenditure. Chemical coagulant requires higher cost and has some drawback after treatment such as pH changes. Moringa oleifera cake residue (MOCR) is one of the alternatives to replace chemical coagulant. A jar test apparatus was used to monitor water treatment. Water quality of Gebeng River (GR) and waste water (WW) was examined before and after treatment. Different parameters using (MOCR) was investigated. Preliminary laboratory results showed the great potential of the (MOCR) to be used in water treatment. MOCR shows an excellent reduction in turbidity (97 % was removed). The bacteria were reduced from 1.7 × 105 to 8 × 103 CFU/ml. Dissolved oxygen (DO) was improved that elevated from 1.06 ± 0.04 to 5.09 ± 0.03 mg/L. However, chemical oxygen demand (COD) and biological oxygen demand (BOD) were increased from 520.5 ± 0.71 to 865.0 ± 2.12 mg/L and from 120.5 ± 2.12 to 270.5 ± 2.12 mg/L respectively. Nevertheless, there is no significant alteration of pH, conductivity, salinity and total dissolved solid (TDS) after treatment. The iron (Fe) was fully removed while copper (Cu) and cadmium (Cd) were successfully removed up to 98%. The reduction of lead (Pb) also achieved 82.17%. Also, (MOCR) can be stored for long time up to 6 months without affecting the biological properties of MO.

Zeolite and fungi’s flocculability of simulated wastewater containing heavy metal ions or phosphorus

This paper focuses on the flocculability of simulated wastewater containing heavy metal ions (Fe3+, Cd2+) or phosphorus by zeolite, microbial flocculants (MBF) produced by Aspergillus niger and the composite flocculant composed of zeolite and MBF. The main results are presented as follows: zeolite was a good flocculant when the contamination of the three simulated wastewaters was low, but the treated water is of turbidness and the particles in it are hard to precipitate. The MBF have a good flocculability toward Fe3+ wastewater, as well as particulate matter. Significant changes in flocculability occurred after adding the composite flocculant in different simulated wastewa-ters, the best or least effect respective for Fe3+ and Cd2+ wastewater. The research we have done shows that the method by which the composite flocculant is used to treat the wastewater containing heavy metal ions or phosphorus provides important reference value for practical application.

Current Seasonal Variations in Physicochemical and Heavy Metals Parameters of Sewage Treatment Plant Effluent and Suitability for Irrigation

The study aims to investigate the current extent of physicochemical parameters and heavy metal contamination in the effluent of the Jaganpur sewage treatment plant (STP), Dayalbagh, Agra India. Majority of the nearby farmers have access to use of STP effluent in irrigation purposes for growing major edible crops. The problems of using STP effluent for irrigation purpose, continuous water quality analysis required. To check the quality of irrigation water, substantial physicochemical parameters accordance to Indian Standards (IS-Reaffirmed 2002/2003) analysed to calculate Sodium absorption ratio (SAR) and Residual sodium carbonate (RSC). To estimate the heavy metal pollution index (HPI) and metal quality index (MQI), toxic Heavy metals such as As, Cr, Mn, Fe, Ni, Cu, Zn, Pd, Cd, Co, and B also determined in the STP effluent with an AAS and results verified with ICP-OES against certified standards. The high value of SAR (range 13 to 20) and RSC (range -10 to 11) in STP effluent exceeded the permissible limit for irrigation purpose. On the other hand, HPI and MQI values (1692.4 and 58.1, respectively) show that high metal contamination mainly due to industrial and domestic wastewater does not treat appropriately in the sewage treatment plant. Thus it is suggested that further studies are carried out on the STP effluents to improve the water quality through proper treatment. Treated wastewater used for irrigation purposes needs to analyse the contamination like heavy metals and pinpoint the pollution sources.

Protein-derived nitrogen and sulfur co-doped carbon for efficient adsorptive removal of heavy metals

A nitrogen and sulfur co-doped carbon has been synthesized employing egg white as a sustainable protein-rich precursor.According to CHNS elemental analysis,N,S and O heteroatoms accounted for mass fractions of 3.66%,2.28%and 19.29%respectively,and the types of surface functionalities were further characterized by FT-IR and XPS measurements.Although the carbon possessed a smaller surface area(815 m2·g-1)compared to a commercial activated carbon(1100 m2·g-1),its adsorption capacity towards Co2+reached 320.3 mg·g-1,which was over 8 times higher compared to the limited 34.0 mg·g-1 over the activate carbon.Furthermore,the carbon was found to be an efficient adsorbent towards a series of metal ions including VO2+,Cr3+,Ni2+,Cu2+and Cd2+.Combined with its environmental merits,the protein derived carbon may be a promising candidate for heavy metal pollution control.

Urban Wastewater Characteristic and its Management in Urban Areas—A Case Study of Mysore City, Karnataka, India

The rapid growth of the population, the technological and industrial boom has brought enormous prob-lems and degradation of the environment. There is a gradual decline in availability of fresh water to be used for irrigation in India. As a consequence, the use of urban waste water (UWW) for irrigating agricultural lands is on the rise particularly in peri-urban areas of developing countries. Effective collection and treatment of urban wastewater is a critical problem in a developing country like India. A case study was undertaken to assess the characteristic of the urban waste water and its management in Mysore city and its long-term effect on irrigation. The untreated and treated urban waste water was collected during 2008 and analyzed in the laboratory. The suitability of the UWW for irrigation purposes is then evaluated according to the existing water quality standards and the results were compared with Food and Agriculture organization (FAO) irrigation water quality standards. It is evident from the results, that the current situation is not promising especially regarding the Electrical Conductivity, Total Dissolved Solids, Biochemical Oxygen Demand, Chemical Oxygen Demand, Suspended Solids and heavy metal concentrations and also pH of the treated UWW is exceeding the FAO standards. Among the heavy metals, the concentration of Iron and chromium are exceeding the FAO standards.

Optimization and Thermodynamic Studies of Lead (II) and Cadmium (II) Ions Removal from Water Using Musa acuminate Pseudo-Stem Biochar

We recently found out that water from the Ugandan stretch of the Kagera transboundary river (East Africa) is contaminated with lead (Pb2+) and cadmium (Cd2+) ions at levels that are above permissible limits in drinking water. Because lignocellulosic biomass-based adsorbents have been explored for the remediation of metal ions from water, this study investigated the potential of Musa acuminata pseudo-stem (MAPS) biochar for the remediation of Pb2+ and Cd2+ ions from water. Batch adsorption experiments were performed to optimize the adsorption conditions while the isotherms were analyzed using Freundlich and Langmuir models. Results showed that the maximum adsorption capacity at equilibrium was 769.23 mg/g and 588.23 mg/g for Pb2+ and Cd2+ ions, respectively. Langmuir isotherm model provided the best fit for the data, and it was favorable since all r2 values (Cd2+ = 0.9726 and Pb2+ = 0.9592) were close to unity. Gibb’s free energy change was found to be negative for both metals, implying the feasibility of the adsorption process. Correspondingly, the enthalpy change was positive for both metal ions which revealed that the adsorption process was endothermic and it occurred randomly at the solid-liquid interface. These results suggested that biochar from MAPs could be utilized for the removal of Pb2+ and Cd2+ from polluted water in the Kagera transboundary river to make it suitable for domestic use. Further studies should consider chemical modification of the biochar as well as characterization to examine the chemical nature of the biochar.

Impact and Health Risk Assessment of Groundwater in the Vicinity of Dumpsites in Keffi Metropolis, Nigeria

This study investigated the hydrogeochemical characteristics of groundwater impacted by waste dumps through computation of different hydrogeological/chemical indices and related health risk assessment of major heavy metals (HVM) in relation to different population groups in Keffi Metropolis. Samples from ten (10) groundwater sources were collected for analysis. Results revealed that the concentration of major cations from the samples was in the order: Ca2+ > Na+ + K+ > Mg2+, while major anionic constituents were in the order: HCO3- > CO32- > SO42- > Cl- > F- respectively. Water quality index (WQI) computed indicated that the groundwater of the study area is not suitable for domestic purposes particularly drinking as some of the parameters exceed the WHO guidelines. Generally, the HVM hazard quotients (HQ) of non-carcinogenic (NC) and carcinogenic toxicity (TC) for both population groups were lower (HQ < 1) indicating that the groundwater within the study areas did not pose current significant risk. Non-carcinogenic risk uncertainty analysis by Monte Carlo simulations (MCS) further indicated that risk levels of HVM in GW were lower (HQ < 1). Despite the findings in this study, it is important that regular monitoring of GW quality is done in order to ensure that water is potable and prevent human health risks.

静电纺壳聚糖基纳米纤维的制备及其在水处理中应用研究进展

为提高壳聚糖的可纺性,改善壳聚糖基纳米纤维的物理形态和力学性能,对国内外利用静电纺丝技术制备壳聚糖基纳米纤维的相关研究进行了综述。介绍了壳聚糖静电纺丝液的配制要求以及不同纺丝参数对纤维形态的影响;在此基础上,详细综述了壳聚糖化学改性纳米纤维和壳聚糖共混改性纳米纤维的研究进展;最后,对应用壳聚糖基纳米纤维处理废水中重金属离子、染料和其它污染物的研究现状进行总结。研究发现:不同纺丝参数最终均是通过影响射流拉伸的难易程度来改变纤维形态,且通过化学改性和共混改性的方法不仅可提高壳聚糖的可纺性,还可增强壳聚糖基纳米纤维的耐酸性、热稳定性、抗菌性和吸附性;同时指出探寻新的溶剂、共混剂和功能材料以及与选择性分离技术结合来增强对水中污染物的吸附能力是壳聚糖基纳米纤维的未来发展趋势。

电吸附处理重金属离子的研究进展

从电吸附技术的基本原理入手,总结了电吸附处理Cu2+、Pb2+、Cr6+、Cd2+等重金属离子的研究进展,对电吸附处理重金属的未来进行了展望,指出了电吸附处理重金属离子研究目前存在的一些缺陷,并提出了电吸附处理重金属离子走向工业化需要解决的问题。

危险废物处置中心重金属废水处理研究

危险废物处置中心的废水中含有很多重金属离子,主要成分包括铬、铅、汞、砷等,如果不对这些重金属离子进行及时处理,这些污染物就会对环境产生不利的影响。本文针对某危险废物处置中心重金属废水的特点,采用“调节池+絮凝沉淀+A/O工艺+MBR+NF+RO”工艺开展了对重金属废水的处理试验研究,并验证其处理效果。实践证明这种处理技术在重金属废水处理中有良好的应用前景。

MoS_(2)及其改性膜去除水中重金属及核素研究进展

近年来,由于工业、核电及其相关产业的快速发展,水中重金属及核素污染不能忽视,水体安全保障成为全球关注的重要问题。二硫化钼(MoS_(2))纳米材料在杀菌、储氢和水净化等领域备受关注,膜技术由于操作简单、效率高等优点成为去除水中重金属及核素的选择之一。本文综述了近5年来MoS_(2)基纳米材料及膜材料在去除水中重金属及核素的研究进展,重点介绍了MoS_(2)合成与改性的主要方法、MoS_(2)去除重金属及核素过程中的主要影响因素及作用机理、MoS_(2)改性膜制备及膜技术去除水中重金属及核素的前沿研究等,旨在高效去除重金属和核素。

改性海泡石对污泥热解过程中重金属的控制

污泥热解过程中会不可避免地产生多种重金属,危害人类的健康。通过在水平固定床反应器内开展城市污泥与改性海泡石共热解实验,探究海泡石的盐酸浸渍浓度(2~6mol/L)、海泡石的热活化温度(750~950℃)以及污泥与海泡石共热解温度(400~600℃)对污泥热解炭中重金属元素Cd、Zn、Pb、Cr的富集特征、形态变化及生态风险的影响。研究发现,在400~600℃的温度范围内改性海泡石的添加有效地提高了Cd、Zn、Pb的固留率,但对Cr几乎没有富集作用,其中950℃热活化海泡石(950-SEP)对Cd有良好的富集效果,而4mol/L盐酸浸渍海泡石(4H-SEP)对Zn和Pb展现出了更好的富集性能。此外,通过分析重金属赋存形态发现,提高共热解温度和添加改性海泡石,共热解炭中的重金属元素整体向更稳定的形态转化。根据热解炭中重金属的生态风险评估,原始污泥经热解后其生态风险大大降低,在600℃前,改性海泡石可进一步降低重金属的生态风险。

固体废弃物路基填筑材料的重金属污染特性研究进展

路域固体废弃物用作路基填筑是绿色低碳公路建设的一种重要手段,然而多数固体废弃物均不同程度地含有重金属污染物,在降雨入渗、地下水浸泡等复杂环境作用下,重金属会被释放,若处理不当将对周边土壤和地下水造成污染。该文综述了固废材料在路基工程中的综合利用、固废中重金属的浸出行为、迁移研究以及固废重金属的防控处理4个方面的研究现状。发现固体废弃物在路基工程中有广泛应用,但对固废路基的重金属污染特性的研究鲜有报道,重金属在路基中的长期浸出行为和迁移机制尚不明确。为了对固废路基的污染性能进行评估和调控,需要进一步研究污染物在路基结构中的迁移规律。通过对固废中污染物的防控处理技术进行总结对比,发现地聚合物在处置固废中有害重金属方面具有广阔的应用前景。

酸性矿山废水中多种有价金属的高效分离

酸性矿山废水(AMD)中多种有价金属的高效分离回收,是重金属减排和资源化利用的关键。文章通过中和沉淀实验和静态吸附实验探究回收有价金属的最佳沉淀和吸附pH,成功开发了中和沉淀—离子交换—中和沉淀组合工艺,并应用于大宝山AMD的处理。结果表明,AMD在pH为3.00和9.80中和沉淀时,分别沉获64%的Fe_(2)O_(3)富铁渣和51%的Mn O富锰渣。采用离子交换树脂分别在pH 3.95和6.10条件下对AMD中的Cu和Zn进行吸附,得到质量浓度为Cu^(2+)11~26 g/L,Zn^(2+)10~20 g/L的两种解吸液。通过该组合工艺,AMD中的各金属Fe、Cu、Zn和Mn的回收率分别为:96%、81%、70%和60%,实现了有价金属的高效分离回收。若采用此工艺回收大宝山2000 m^(3)/d的AMD中的铜、锌、锰硫酸盐,每年的利润为119万元,经济效益非常显著。此处理工艺为酸性矿山废水的高效资源化利用提供了新路径。

金属有机框架材料对水体中重金属离子去除性能及机理的研究进展

工业化进程的加快导致全球环境污染日趋严峻,尤其是铬、砷、铅、汞、镉、锌、铜及镍等重金属污染极为显著。重金属在水体中多以离子态存在,难以生物降解,将对生态环境和人类健康构成巨大威胁,因此寻求经济、高效的重金属去除方法刻不容缓。水体中重金属去除的方法主要包括离子交换、混凝沉淀、氧化还原、吸附、膜过滤及电渗析等,其中吸附法具有成本低廉、操作简单和适应性强等诸多优点,被认为是去除水体中重金属的优选方法之一。金属有机框架材料(MOFs),因其比表面积大、孔隙率高、活性位点丰富、可调节性强及热/化学稳定性高等特性,被广泛应用于去除水体中的重金属。重点综述了MOFs及其复合材料对铬、砷、铅、汞、镉、锌、铜及镍重金属离子的去除性能,分析了MOFs初始浓度、重金属离子浓度、接触时间、pH值、温度及干扰离子等因素对重金属去除效果的影响。同时,明确了MOFs去除重金属离子的机理。其主要作用机理为吸附、沉淀及氧化还原,其中吸附分为物理吸附和化学吸附,物理吸附主要包括静电引力、扩散作用和范德华力,化学吸附主要包括开放金属位点/配位作用、酸碱作用及氢键作用,而沉淀或者氧化还原伴随在吸附过程中。此外,对今后MOFs材料在重金属污染防治领域的研究方向及潜在应用进行了展望,以期为MOFs材料在环境污染修复领域的研究和应用提供理论基础。

实验室危化品废液“减量化”处理与处置技术研究

传统的实验室废液处理方法,能够将废液中的有害物质转化为无害物质或沉淀下来,但并不能减少废液的产生量。因此,研究提出实验室危化品废液“减量化”处理与处置技术,通过一体化整体工艺思路和设备的设置,对实验室废液进行降危减量处理。数据显示,实验室废液降危减量一体化设备对废液中COD和悬浮物的去除率可达82%和58%,有效降低废液中的有机物含量,减少对环境的污染。实验室废液经过一体化设备处理后,重金属去除效果良好。从经济角度分析,实验室废液降危减量一体化处理的成本可降低85%,可以减轻企业的负担,提高经济效益。

富咪唑型多孔左旋聚乳酸纳米纤维膜制备及其双重净水性能

为开发具有油水分离和吸附重金属离子双重功能的新型膜材料,利用静电纺丝技术制备左旋聚乳酸(PLLA)纳米纤维膜,再依次采用溶剂诱导结晶和1-(3-氨基丙基)咪唑(API)修饰改性得到富咪唑型多孔PLLA纳米纤维膜,并对其微观形貌、化学基团构成、力学性能和润湿性能进行测试与表征,研究了该纳米纤维膜的油水分离性能和对铜离子的吸附性能。结果表明:当丙酮与水体积比为10∶1、丙酮/水混合溶液用量为0.4 mL/(mg纤维)、处理时间为150 s时,溶剂诱导结晶处理所得PLLA纳米纤维膜中多孔纤维的形貌最佳;API修饰改性并未对多孔纤维的形貌和直径产生过多影响,改性后PLLA纳米纤维膜表面出现的咪唑和酰胺基团能够有效改善其润湿性能,使静态水接触角下降了15.6°;与未改性PLLA纳米纤维膜相比,所制得富咪唑型多孔PLLA纳米纤维膜的脆性有所增加,但其断裂强度仍能达到未改性的PLLA纳米纤维膜断裂强度的96.6%,整体力学性能保持良好;利用该纳米纤维膜可实现有效油水分离,分离通量为1044.9 L/(m^(2)·h),分离效率可达99.1%,且其对铜离子吸附性能良好,在pH值为6的铜离子溶液中接触24 h后,对铜离子吸附量可达41.46 mg/g。

固体废物中的重金属对土壤及地下水的污染分析

随着社会经济的发展,工业生产规模的扩大,在工业生产过程中会产生大量固体废物,对生态环境造成严重污染。固体废物中含有大量重金属物质,此类物质会严重污染土壤及地下水资源,影响人们的身体健康。目前,我国土壤及地下水受到固体废物中重金属的严重污染,对社会发展、生态环境和人民生产生活构成了威胁。因此,我们应采取相关措施加以解决。本文简要阐述了固体废物中重金属的来源及影响,并重点研究了解决措施,以供参考。

铜冶炼污酸废水泄漏重金属Zn、As对地下水的影响

铜冶炼过程产生的污酸废水中重金属Zn、As浓度较高,发生泄漏会下渗到区域地下水环境,对地下水环境产生不利影响。选择一维对流扩散模型对铜冶炼污酸废水事故状态下入渗地下水环境情境进行预测,污染物随地下水往下游迁移,特征污染物As、Zn的污染前锋迁移500 m的距离分别需要609、751 d;迁移2 300 m的距离分别需要6 292、7 086 d,该预测结论可为同类企业地下水的防治提供借鉴依据。

城镇污水处理厂污泥与不同秸秆制备陶粒过程控制探究

采用城镇污水处理厂污泥作为原料并添加适当的黏土,分别与甘蔗渣粉、稻草秆粉和玉米秸秆粉3种秸秆在800℃和900℃下焙烧,制备不同比例的陶粒,并对陶粒的吸水率和重金属镉吸附效率进行研究。结果表明:稻草污泥陶粒吸水性最好,随着污泥比例增多,吸水率呈下降趋势,在800℃焙烧的陶粒比900℃略好;制备的陶粒取样量在0.5 g时能够把设定目标重金属镉的量吸附较为完全,且稻草污泥陶粒吸附效率相对稳定,焙烧温度及污泥比例对重金属镉吸附效率影响不大。