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1.
The integrated steel industry is considered as one of the important industrial sectors, and its outputs are inputs for other sectors including construction, engineering, medical and scientific equipment, and defence. Massive production, consumption, and export of steel signify a country's economic index. This review outlines the World's steel production quantities, the processes involved, and wastewater generation from the industry and its treatment. Wastewater generated from steel plants is highly complex and requires intensive treatment before discharge into natural water bodies. Technologies adopted for treating wastewater generated from steel industries are deliberated, focusing on coking wastewater treatment. Microbial mediated processes provide an effective means of degrading the contaminants, but the toxicity of certain compounds during higher pollutant load inhibits its further treatment. However, these processes can be integrated with either electrochemical technologies or advanced oxidation processes (AOPs), which can reduce the toxicity level. Hence, when a highly concentrated and complex mixture of contaminants is considered, an integrated approach is a resourceful option in terms of cost-effectiveness and treatment efficiency.  相似文献   

2.
Agricultural subsurface drainage waters containing nutrients (nitrate/phosphate) and pesticides are discharged into neighboring streams and lakes, frequently producing adverse environmental impacts on local, regional, and national scales. On‐site drainage water filter treatment systems can potentially prevent the release of agricultural contaminants into adjacent waterways. Zero valent iron (ZVI) and sulfur‐modified iron (SMI) are two types of promising filter materials that could be used within these treatment systems. Therefore, water treatment capabilities of three ZVI and three SMI filter materials were evaluated in the laboratory. Laboratory evaluation included saturated falling‐head hydraulic conductivity tests, contaminant removal batch tests, and saturated solute transport column experiments. The three ZVI and the three SMI filter materials, on average, all had a sufficient hydraulic conductivity greater than 1 × 10–3 cm/s. Batch test results showed a phosphate decrease of at least 94% for all tests conducted with the ZVI and SMI. Furthermore, the three SMI filter materials removed at least 86% of the batch test nitrate originally present, while batch tests for one of the ZVI filter materials exhibited an 88% decrease in the pesticide, atrazine. Saturated solute transport column experiments were carried on the best ZVI filter material, or the best SMI filter material, or both together, in order to better evaluate drainage water treatment effectiveness and efficiency. Results from these column tests additionally document the drainage water treatment ability of both ZVI and SMI to remove the phosphate, the ability of SMI to remove nitrate, and the ability of a select ZVI material to remove atrazine. Consequently, these findings support further investigation of ZVI and SMI subsurface drainage water treatment capabilities, particularly in regard to small‐ and large‐scale field tests.  相似文献   

3.
Magnetic hydroxyapatite (HAP), which combined superparamagnetic Fe3O4 nanoparticles and HAP, composite materials were prepared by ultrasound method in this paper. It has also been found that these materials have the ability to adsorb phenol in wastewater. The magnetic materials were investigated by scanning electron microscope, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy, thermal gravimetric analysis, vibrating sample magnetometer, and N2 adsorption in order to elucidate the morphology, structure, and other properties. When the prepared magnetic materials were calcined at 200°C, the prepared Fe3O4 was oxidized to Fe2O3, possessing loose‐shaped holes with a high specific area of 325.2 m2/g, a magnetization intensity of 12.5 emu/g, and the N2 adsorption isotherm belongs to porous adsorption type I. Moreover, the magnetic HAP can adsorb 90% phenol in wastewater. This means that it is an excellent recyclable phenol sorbent for sewage treatment. Experiments confirmed that the Freundlich adsorption isotherms model applies to lower phenol concentrations (0–50 mg/L), while for high phenol concentrations (50–500 mg/L) the Langmuir adsorption isotherms model fits. The magnetic sorbents have the capacity to regenerate after reaching adsorption saturation using ethanol as eluant and external magnetic field as separation unit. The efficiency of adsorption was reduced only by 10% over a six time use period.  相似文献   

4.
A simple modification of the conventional air-stripping process introduced as cascade air stripping is proposed for efficient and economical removal of semivolatile and low volatility contaminants from ground water. The technical feasibility and economic viability of this process are evaluated using field test results and cost model simulations. The field tests enabled the process model to be verified at various water flow rates ranging from 150 gpm to 400 gpm. The field study also demonstrated the feasibility of the proposed system at a near full-scale level. Cost models were used to compare the proposed process to conventional air stripping and granular-activated carbon adsorption in removing a range of contaminants. This analysis showed that the treatment cost (ø/1000 gal) of cascade air stripping is about 15 percent lower than conventional air stripping and about 40 percent lower than granular-activated carbon adsorption.  相似文献   

5.
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6.
Ground water contamination profiles from five wood treatment facilities across the country have been compared. The distributions of organic priority pollutants at the five sites are similar, with the most common contaminants being polynuclear aromatic hydrocarbons and phenolic compounds. These contaminants are the predominant constituents of creosote, which is a common wood preservative. Inorganic contaminants have also been detected at these sites, but their distributions are not uniform across all sites. The distributions of the organic priority pollutants at the five sites appear to differ from those at other hazardous waste sites. Suggested recommendations for choosing monitoring parameters for wood treatment facilities are presented.  相似文献   

7.
Water treatment with metallic iron (Fe0) is still based on the premise that Fe0 is a reducing agent. An alternative concept stipulates that contaminants are removed by adsorption, co‐precipitation, and size‐exclusion in a reactive filtration process. This article underlines the universal validity of the alternative concept. It is shown that admixing non‐expansive material to Fe0 as a pre‐requisite for sustainable Fe0‐based filtration systems. Fe0‐based filters are demonstrated an affordable, appropriate, and efficient decentralized water treatment technology.  相似文献   

8.
Textile industry is one of the fastest growing industries and significantly contributes to the economic growth in Malaysia. However, this industry also has high water consumption and subsequently produces high discharge rate of wastewater with high load of contaminants. The release of dyes into the environment during textile fiber dyeing and finishing processes is a main source of water pollution. Individual wastewater treatment through physical, biological, or chemical method is often very costly and results in large amount of sludge. Thus, there is a need to look for alternative treatment processes that covers from pre to post wastewater treatment stage. This paper reviews the current scenario with respect to textile industry effluent in Malaysia and technologies available for the treatment of the effluent. Prospects, challenges, and recommendations for future direction as well as on‐going research works dedicated to the treatment of textile wastewater are also reviewed in detail.  相似文献   

9.
Recently, increased industrial and agriculture activities have resulted in toxic metal ions, which has increased public concern about the quality of surface and groundwater. Various types of physical, biological, and chemical approaches have been developed to remove surface and groundwater metal ions contaminants. Among these practices, zero‐valent iron (ZVI) is the most studied reactive material for environmental clean‐up over the last two decade and so. Although ZVI can remove the contaminants even more efficiently than any other reactive materials. However, low reactivity due to its intrinsic passive layer, narrow working pH, and the loss of hydraulic conductivity due to the precipitation of metal hydroxides and metal carbonates limits its wide‐scale application. The aim of this work is to document properties, synthesis, and reaction mechanism of ZVI for the treatment of metal ions from the surface and groundwater in recent 10 years (2008–2018). So far, different modified techniques such as conjugation with support, bimetal alloying, weak magnetic field, and ZVI/oxidant coupling system have been developed to facilitate the use of ZVI in various environmental remediation scenarios. However, some challenges still remain to be addressed. Therefore, development and research in this field are needed to overcome or mitigate these limitations.  相似文献   

10.
Rhizofiltration is a subset technique of phytoremediation which refers to the approach of using plant biomass for removing contaminants, primarily toxic metals, from polluted water. The effective implementation of this in situ remediation technology requires experimental as well as conceptual insight of plant–water interactions that control the extraction of targeted metal from polluted water resources. Therefore, pot and simulation experiments are used in this study to investigate the rhizofiltration of a lead containing wastewater using plants of Carex pendula, a common wetland plant found in Europe. The metal contaminant extraction along with plant growth and water uptake rates from a wastewater having varying Pb concentration is studied experimentally for 2 wk. The temporal distribution of the metal concentration in the wastewater and the accumulated metal in different compartments of C. pendula at the end are analyzed using atomic absorption spectrometry. Parameters of the metal uptake kinetics are deduced experimentally for predicting the metal removal by root biomass. Further, mass balance equations coupled with the characterized metal uptake kinetics are used for simulating the metal partitioning from the wastewater to its accumulation in the plant biomass. The simulated metal content in wastewater and plant biomass is compared with the observed data showing a good agreement with the later. Results show that C. pendula accumulates considerable amounts of lead, particularly in root biomass, and can be considered for the cleanup of lead contaminated wastewaters in combination with proper biomass disposal alternatives. Also, the findings can be used for performing further non‐hydroponics experiment to mimic the real wetland conditions more closely.  相似文献   

11.
In these studies, the efficiency of various decontamination protocols was tested on small pieces of materials commonly used in ground water sampling devices. Three materials, which ranged in ability to sorb organic solutes, were tested: stainless steel (SS), rigid polyvinyl chloride (PVC), and polytetrafluoroethylene (PTFE). The test pieces were exposed to two aqueous test solutions: One contained three volatile organic compounds (VOCs) and one nitroaromatic compound, and the other contained four pesticides. Also, three types of polymeric tubing were exposed to pesticide solutions. Generally, the contact times were 10 minutes and 24 hours for sorption and desorption.
The contaminants were removed from the nonpermeable SS and the less-sorptive rigid PVC test pieces simply by washing with a hot detergent solution and rinsing with hot water. Additional treatment was required for the PTFE test pieces exposed to the VOCs and for the low-density polyethylene (LDPE) tubing exposed to the pesticide test solution. Solvent rinsing did not improve removal of the three VOCs from the PTFE and only marginally improved removal of the residual pesticides from the LDPE. However, a hot water and detergent wash and rinse followed by oven drying at approximately 105°C was effective for removing the VOCs from the PTFE and substantially reduced pesticide contamination from the LDPE.  相似文献   

12.
ABSTRACT

Magnetic fields of planets, stars and galaxies are generated by self-excitation in moving electrically conducting fluids. Once produced, magnetic fields can play an active role in cosmic structure formation by destabilising rotational flows that would be otherwise hydrodynamically stable. For a long time, both hydromagnetic dynamo action as well as magnetically triggered flow instabilities had been the subject of purely theoretical research. Meanwhile, however, the dynamo effect has been observed in large-scale liquid sodium experiments in Riga, Karlsruhe and Cadarache. In this paper, we summarise the results of liquid metal experiments devoted to the dynamo effect and various magnetic instabilities such as the helical and the azimuthal magnetorotational instability and the Tayler instability. We discuss in detail our plans for a precession-driven dynamo experiment and a large-scale Tayler–Couette experiment using liquid sodium, and on the prospects to observe magnetically triggered instabilities of flows with positive shear.  相似文献   

13.
With a high population density, immense commercial and industrial activities, Hong Kong produces over two million tonnes of municipal wastewater each day. Until recently, about 50% of the municipal wastewater enters water courses, rivers, and coastal waters without treatment. Untreated organics, heavy metals and refractory synthetic materials accumulate in certain areas, and have led to breakdown of aquatic and marine ecological systems, closure of beaches, red tides and bioaccumulation in seafood. In 1974, a team of consultants was commissioned to study the water pollution problems encountered in Hong Kong. After two decades in the effort to improve the water environment, a flexible framework for environmental planning and management over the following ten years has been designed. This programme comprises (1) establishment of water control zones and pollution control legislation, (2) upgrading of services and facilities for management of municipal sewage and chemical wastes, and (3) construction of the "Strategic Sewage Disposal Scheme". In line with this programme, a priority has been set on implementing a "polluter pays policy" which requires the industries to share the costs of sewage treatment and encourages them to install on-site wastewater pretreatment facilities to reduce wastewater generation and to ensure sustainable development.  相似文献   

14.
In military out of area missions of the Bundeswehr, it can be necessary to produce drinking water even from highly polluted surface waters containing a variety of organic, inorganic, and microbiological contaminants. Thus, mobile drinking water purification systems must be able to remove such contaminants as far as possible to meet the requirements of the German and European drinking water regulation/directive. Presently, two novel drinking water purification units applying membrane filtration undergo intensive long‐term trials carried out by the Bundeswehr. If these trials positively proof the functionality of these units and their ability to remove all possible contaminants they shall substitute so far available devices which use large amounts of chemicals and charcoal filtration for water purification.In the course of a research project, the functionality of the new devices and their efficacy to remove high amounts of algae, microbes, and organic and inorganic pollutants are additionally tested in “worst‐case” field studies. In September 2000, the first mobile drinking water purification unit was tested at the Teltowkanal in Berlin, Germany.This canal was chosen because it carries high burdens of municipal sewage effluents. The results from the fatigue test confirmed the ability of the water purification unit to reduce the concentrations of all contaminants meeting the maximum tolerance levels set by the German/European drinking water regulation.The pre‐filtration device was very effective in removing algae and solid particles to protect the membranes from clogging and to enable an almost maintenance‐free operation. Residues of pharmaceuticals and some other organic contaminants have almost totally been removed from the surface water where they were detected at individual concentrations up to the μg/L‐level.  相似文献   

15.
In light of water quality monitoring paradigms shifting to a more holistic approach, it is essential that environmental microbiologists embrace new methodological developments in clinical virology to create rapid, laboratory‐free methods for the identification of wastewater pollution. It is widely accepted that routine monitoring of fecal indicator bacteria (FIB) does not adequately reflect human health risks associated with fecal pollution, especially risks posed by viruses. Enteric viruses are typically more resistant to wastewater treatment and persist longer in the environment than FIB. Furthermore, enteric viruses often have extremely low infectious doses. Currently, the incorporation of sanitary surveys, short‐term monitoring of reference pathogens, exploratory quantitative microbial risk assessments, and predictive ecological models is being championed as the preferred approach to water management. In addition to improved virus concentration methods, simple, point‐of‐use tests for enteric viruses and/or improved viral indicators are needed to complement this emerging paradigm and ensure microbial safety worldwide.
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16.
Olive mill wastewaters (OMWs), which are known to have deep impacts on the receiving water bodies due to their high‐strength contents of organic materials and color, must be treated before discharge. For this reason; a number of research studies have been available in current literature related to the treatment of OMWs. However, no widely accepted treatment alternatives have been proposed yet. The common results of these studies suggest that OMWs must be pretreated prior to final purification processes. This study focuses on the comparison of alternative pre‐treatment processes in the aspect of chemical oxygen demand (COD) removal and costs of operation. Centrifuging, lime precipitation, acid cracking, and electrocoagulation processes were performed to compare removal efficiencies and operational costs. The COD removal efficiencies for centrifuging, lime precipitation, acid cracking, and electrocoagulation processes were determined to be 30.1, 24.1, 20.0, 53.7%, respectively, with operational costs being $0.30, $0.37, $1.42, and $11.60 per cubic meter of wastewater treated, respectively. The centrifuging process was concluded to be the most appropriate one according to the COD removal efficiency and cost of operation.  相似文献   

17.
Sustainable access to safe drinking water and basic sanitation is an important part of the millennium development goals (MDGs). For most African countries, an extensive effort is needed for the last three remaining years for the achievement of the MDGs, especially in Sub‐Saharan Africa. Current practices for water and wastewater treatment in Africa are insufficient to ensure safe water and basic sanitation. To address this challenge, joint efforts are needed, including transforming to green economy, innovating technologies, improving operation and maintenance, harvesting energy, improving governance and management, promoting public participation, and establishing water quality standards.  相似文献   

18.
Surface waves in seismic data are often dominant in a land or shallow‐water environment. Separating them from primaries is of great importance either for removing them as noise for reservoir imaging and characterization or for extracting them as signal for near‐surface characterization. However, their complex properties make the surface‐wave separation significantly challenging in seismic processing. To address the challenges, we propose a method of three‐dimensional surface‐wave estimation and separation using an iterative closed‐loop approach. The closed loop contains a relatively simple forward model of surface waves and adaptive subtraction of the forward‐modelled surface waves from the observed surface waves, making it possible to evaluate the residual between them. In this approach, the surface‐wave model is parameterized by the frequency‐dependent slowness and source properties for each surface‐wave mode. The optimal parameters are estimated in such a way that the residual is minimized and, consequently, this approach solves the inverse problem. Through real data examples, we demonstrate that the proposed method successfully estimates the surface waves and separates them out from the seismic data. In addition, it is demonstrated that our method can also be applied to undersampled, irregularly sampled, and blended seismic data.  相似文献   

19.
Ozonation is a treatment step which was first applied in the 1960s in pool water treatment for disinfection as well as for oxidation of pool water contaminants. Contact time between ozone and pool water was identified to be of significance with an increased elimination efficiency regarding chloramines, trihalogenmethane formation potential and the permanganate index for longer reaction times. Oxidation via OH radicals might be the dominating pathway. In this study ozonation was compared with the ozone based advanced oxidation processes ozone/UV and ozone/hydrogen peroxide regarding the elimination efficiency of both disinfection by‐products (DBPs) and DBP precursors. It was observed that AOPs in comparison to ozonation showed an increased elimination efficiency regarding total organic carbon (TOC), the organically bound halogens adsorbable on activated carbon (AOX) and AOX formation potential. A contact time of 3 minutes between pool water and oxidant turned out to be practically sufficient. Just for the trihalomethane (THM) formation potential ozonation showed a slight advantage compared to the AOPs because ozonation is a highly selective oxidant and OH radical reactions are known to produce small reactive molecules which are easier transformed to THMs. Combination of membrane filtration and AOPs resulted in an elimination of 10 to 90 % of the DBPs and their precursors. The ozone/hydrogen peroxide process is suggested for pool water treatment because of the higher elimination rates compared to ozonation and of economic reasons compared to the ozone/UV process.  相似文献   

20.
Heat is a powerful tracer to quantify fluid exchange between surface water and groundwater. Temperature time series can be used to estimate pore water fluid flux, and techniques can be employed to extend these estimates to produce detailed plan‐view flux maps. Key advantages of heat tracing include cost‐effective sensors and ease of data collection and interpretation, without the need for expensive and time‐consuming laboratory analyses or induced tracers. While the collection of temperature data in saturated sediments is relatively straightforward, several factors influence the reliability of flux estimates that are based on time series analysis (diurnal signals) of recorded temperatures. Sensor resolution and deployment are particularly important in obtaining robust flux estimates in upwelling conditions. Also, processing temperature time series data involves a sequence of complex steps, including filtering temperature signals, selection of appropriate thermal parameters, and selection of the optimal analytical solution for modeling. This review provides a synthesis of heat tracing using diurnal temperature oscillations, including details on optimal sensor selection and deployment, data processing, model parameterization, and an overview of computing tools available. Recent advances in diurnal temperature methods also provide the opportunity to determine local saturated thermal diffusivity, which can improve the accuracy of fluid flux modeling and sensor spacing, which is related to streambed scour and deposition. These parameters can also be used to determine the reliability of flux estimates from the use of heat as a tracer.  相似文献   

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