混凝沉淀技术及其在纺织印染废水处理中的应用前景

本文对纺织印染污水处理中采用的几种混凝剂进行小结与评价，并开展一些技术讨论，从而确定了混凝沉淀技术在纺织工业污水处理中的应用前景。     

Significance of iron compounds in chemical and electro‐oxidation treatment of sugar industry wastewater: Batch reaction

Industrialization plays a major role in a nation's growth. However, with an increase in industrial activities, pollution levels are also increasing. Among all industries, the sugar‐processing industry is one that requires large amounts of water to process the sugar, and, consequently, it discharges large amounts of water as effluent. Highly polluted wastewater brings changes to the physicochemical characteristics of the surrounding environment. Iron compounds have had a significant impact when they are used in wastewater treatment in various applications, including when they are used to minimize the pollution levels in sugar industry wastewater (SIWW). To minimize the pollutant levels from SIWW, iron compounds have been key for uses in treatments involving chemical and electro‐oxidation. Two different methodologies of electrocoagulation and chemical coagulation have been used to treat SIWW. In electrocoagulation, an iron plate is used as an electrode material under specific operating conditions. Ferrous sulfate and ferric chloride have been used as chemical coagulants at various pH and mass loading levels. The use of iron metals shows an 82% reduction in chemical oxygen demand (COD) and an 84% reduction in color at the optimum condition of pH 6, an electrode distance of 20 millimeters, and a current density of 156 square centimeters. As a chemical coagulant, iron salt (ferrous sulfate) provides a reduction of 77% COD and a 91% reduction of color at pH 6 and a 40‐millimole mass loading. Electrochemical treatment using iron was found to be suitable to treat SIWW. The sludge generated after treatment can be burned or composted with the possible recovery of some of the treatment costs.     

Ipomoea dasysperma seed gum: an effective natural coagulant for the decolorization of textile dye solutions

An investigation of dye decolorization from synthetic dye solutions using the non-ionic, water-soluble, high molecular weight seed gums Ipomoea dasysperma and guar gum as coagulants was undertaken. The use of galactomannans derived from plants in this system presents a sustainable method of textile effluent treatment. These natural coagulants extracted from plants proved to be workable alternatives to conventional coagulants like polyaluminum chloride, as they are biodegradable, safe to human health, are cost effective when compared to imported chemicals and have a wider effective dosage range for flocculation of various colloidal suspensions. Coagulant dose and coagulation pH are important factors influencing the mechanism of coagulation. Also the type and chemical structure of the dye plays an important role in the coagulation process. The seed gums alone were found to be effective for decolorization of direct dye and in combination with PAC their coagulation efficiency was well extended even for reactive and acid dyes.     

A review of textile industry: Wet processing,environmental impacts,and effluent treatment methods

The word “textile” means to weave and was taken from the Latin word “texere.” Nowadays, textiles not only fulfill humankind's basic necessity for clothing, they also allow individuals to make fashion statements. As one of the oldest industries, the textile industry occupies a unique place in India. It is responsible for 14% of the total industrial manufacture in India. However, the textile industry is also considered to be one of the biggest threats to the environment. Pretreatment, dyeing, printing, and finishing operations are among the various stages of the industrial textile manufacturing process. These fabrication operations not only utilize huge quantities of power and water, they also generate considerable amounts of waste. The textile industry utilizes a number of dyes, chemicals, and other materials to impart the required qualities to the fabrics. These operations produce a significant amount of effluents. The quality of effluents is such that they cannot be put to other uses, and they can create environmental problems if they are disposed of without appropriate treatment. This review discusses different textile processing stages, pollution problems associated with these stages, and their eco‐friendly alternatives. Textile wet processing is described in detail, as it is the key process in the industry and it also generates the greatest amount of pollutants in textile processing. The environmental impact of textile effluents is discussed, as textile effluents not only impose negative effects on the quality of water and soil, they also imperil plant and animal health. In this paper, various methods for treating textile effluents are described. Discussion of physical, chemical, biological, and advanced treatment technologies of effluent treatment are included in this paper.     

Treatment of Agro‐Based Industry Wastewater by the Electro‐Oxidation Method: Comparative Results From Iron and Aluminum Metal Plate

Among the various technologies available to treat wastewater from sugar production, electro‐oxidation, or electrocoagulation, is considered one of the best. Moreover, it is a cost‐effective method. Although it is considered an advanced form of chemical coagulation, it does not require the addition of chemical coagulants, as the coagulant is generated through the dissolution of the sacrificial anodes that are connected to the electric current in the treatment chamber. This article examines how an electro‐oxidation system can be established and explores the variables that affect the process.     

四川省企业环境经济效益的分析评价

目前对于企业环境经济效益的分析评价,缺乏科学易行的方法。本文根据污染物排放量与经济效益间的关系,提出了单位等标污染负荷利税法,即每排放单位等标污染物所产生的年利税值。据此对四川省6个行业44家企业的环境经济效益进行了统计分析,并对其应用Excel模糊聚类进行了分级评价。结果表明:不同企业间单位等标污染负荷利税值存在多个数量级差异。造纸、纺织企业环境经济效益最差,体现了行业性弊病。制药、建材、机械电子行业企业环境经济效益整体较好,但仍有部分"粗放型"企业环境经济效益差。部分机械电子、化工企业依赖技术革新,环境经济效益优良。与定性分析评价方法相比,单位等标污染负荷利税法更能发现"高产值、高污染"下的误区,该法结合应用Excel模糊聚类分析,可简易、客观分析评价不同企业、行业甚至不同经济规模单元间的环境经济效益。     

Response surface optimization of acid red 119 dye from simulated wastewater using Al based waterworks sludge and polyaluminium chloride as coagulant

In this research, the performance of Polyaluminium Chloride (PAC) and Polyaluminium Chloride sludge (PACS) as coagulants for acid red 119 (AR119) dye removal from aqueous solutions were compared. The sample of PACS was collected from "Baba Sheikh Ali" water treatment plant (Isfahan, Iran) where PAC is used as a coagulant in the coagulation/flocculation process. A response surface methodology was applied to evaluate the simple and combined effects of the operating variables including initial pH, coagulant dosage and initial dye concentration and to optimize the operating conditions of the treatment process. Results reveal that the optimal conditions for dye removal were initial pH 3.42, coagulant dosage of 4.55 g dried PACS/L and initial dye concentration of 140 mg/L for PACS, while the optimal initial pH, coagulant dosage and initial dye concentration for PAC were 3.8, 57 mg/L and 140 mg/L, respectively. Under these optimal values of process parameters, the dye removal efficiency of 94.1% and 95.25% was observed for PACS and PAC, respectively. Although lower amount of PAC in comparison with PACS was needed for specific dye removal, the reuse of PACS as a low-cost material can offer some advantages such as high efficiency for AR119 dye removal and economic savings on overall water and wastewater treatment plant operation costs.     

Regeneration of industrial district wastewater using a combination of Fenton process and ion exchange—A case study

Regeneration studies of wastewater effluent from an organized industrial district (OID) for possible reuse in textile industry as process water was investigated. Advanced treatment methods including Fenton process, polyaluminium chloride (PAC) coagulation and ion exchange were applied on OID effluent. In Fenton process removal efficiencies for suspended solids (SS), chemical oxygen demand (COD), SAC₄₃₆ (spectral absorption coefficient), SAC₅₂₅ and SAC₆₂₀ were determined 61%, 36%, 35%, 49% and 67%, respectively. After Fenton process, wastewater samples were coagulated with PAC. Optimum removal efficiencies for SS, COD, Fe ion, SAC₄₃₆, SAC₅₂₅ and SAC₆₂₀ were determined 83%, 18%, 93%, 32%, 36% and 58%, respectively. Ion exchange experiments were conducted on chemically coagulated wastewater samples to improve the quality of wastewater. Optimum dosage of resins was determined. The experiments revealed that 1:1 resin ratio (20 mL H-type resin:20 mL OH-type resin) gave the best removal rates for the parameters considered in this study. Study results indicated that quality of the wastewater was suitable for the process water characteristics of textile industry and unit wastewater treatment cost was determined as 2.54 €/m³.     

Removal of heavy metal ions from wastewaters: a review

Heavy metal pollution has become one of the most serious environmental problems today. The treatment of heavy metals is of special concern due to their recalcitrance and persistence in the environment. In recent years, various methods for heavy metal removal from wastewater have been extensively studied. This paper reviews the current methods that have been used to treat heavy metal wastewater and evaluates these techniques. These technologies include chemical precipitation, ion-exchange, adsorption, membrane filtration, coagulation-flocculation, flotation and electrochemical methods. About 185 published studies (1988-2010) are reviewed in this paper. It is evident from the literature survey articles that ion-exchange, adsorption and membrane filtration are the most frequently studied for the treatment of heavy metal wastewater.     

Wastewater management in small- and medium-size enterprises: case studies

Wastewater management in small and medium-sized enterprises representing the chemical and food industries was investigated. The results showed that wastewater discharged from an ink-production factory was highly contaminated with organic pollutants. Anaerobic biological treatment followed by chemical coagulation using ferric chloride aided with lime proved to be very effective and produced an effluent that complied with national regulatory standard for wastewater discharge into public sewage network. Also, management of wastewater from a confectionery factory representing the food sector was carried out. Aerobic biological treatment using plastic-packed trickling filter proved to be an effective treatment method. However, application of in-plant control measures alleviated the requirement for the construction of a wastewater treatment plant. The applied pollution prevention and cleaner production measures involved good housekeeping, recovery of spent chocolate, modification of floor cleaning and installation of suction devices for the removal of sugar and starch powders. All improvement measures were documented by cost/benefit analysis.     

炼厂脱盐脱钙废水处理工艺

原油中的钙盐主要存在于石油胶质和沥青质中。在原油加工过程中,有机钙盐因分解形成钙沉淀物而影响正常生产。对于原油中钙的脱除,目前应用最广泛的是螯合沉淀脱钙技术。炼厂脱盐脱钙废水中的钙、磷、石油胶质会对污水处理场造成不良影响,因而必须对脱盐脱钙废水进行预处理。预处理工艺包括物理和物理化学手段、生物处理工艺、化学氧化处理技术。技术可行性分析表明,可采用AOP高级氧化技术与生物处理相结合的工艺对脱盐脱钙废水进行预处理。     

Environmental training and cleaner production in Indian industry—A micro-level study

An attempt has been made to analyze various types of organizational training imparted in Indian Industries while implementing cleaner production. The study was carried out in two industrialized states of India, namely Maharashtra and Gujarat. with participation of eight firms from each state. The various sources of training for the Indian industries have also been studied. A case study each from the two states, viz. Maharashtra and Gujarat have been presented in this paper. It is found that more than half of the industrial units have given importance to various kinds of training during the implementation of cleaner production. When it comes to training in environmental management system (EMS), nearly half of the firms have gone in for it. Among the sources of training, the most useful training was the training imparted by in-house staff and on-the-job training. Lastly, suppliers of cleaner technologies seem to have also played an active role in training as revealed by few of the participating units     

美国废水治理发展与展望

文章介绍了美国废水治理过程中环保法规和主要水处理技术的发展,阐述工业废水治理的发展及其前景。     

Benchmarking compliance performance: A new chemical industry report

Environmental Information Services, Inc. (EIS) publishes detailed reports and offers custom research related to the full spectrum of environmental issues facing corporations. In this new article, EIS reports on the compliance performance of the largest companies in the chemical industry focusing on five key environmental concerns: toxic waste management, air pollution, water pollution, spills, and Superfund. It is important to note that the following article does not contain normalized data and graphs which would adjust findings to various size features (e.g., domestic revenues per company). This as well as detailed environmental policy and programs data on each company can be obtained from EIS. In future issues of EQM, EIS compliance reports will be presented for other major industries to help companies of all sizes benchmark their environmental performance and improvement efforts.     

Development of a novel fungal consortium for the treatment of molasses distillery wastewater

In India, cane molasses–based distilleries are major production centers of ethanol. These industries release a dark brown colored effluent known as spent wash, which even after anaerobic treatment retains the color. The commonly used practices of treatment fail to remove the color and COD. A novel fungal consortium was developed for the treatment of this recalcitrant wastewater. The consortium was run on a bioreactor with undiluted distillery effluent for 40 days. In the first 14 days, 61.5% color and 65.4% COD removal was achieved. Further, the fungi were able to use wheat straw as carbon source as evidenced by scanning electron microscopy (SEM) while treating the distillery wastewater. It is expected that such a treatment step will lead to development of a treatment technology for distillery wastewater without the need for diluting it.     

青岛市挥发性有机物排放清单及重点行业排放特征研究

根据收集的青岛市九大类排放源的活动水平数据,本研究采用排放因子法结合调研实测等工作建立了青岛市VOCs源排放清单,结果表明,工业企业VOCs排放占总排放的比例达到43.17%。其中,工艺过程源类中排放占比较高的行业依次为橡胶和塑料制品业、非金属矿物制品业、原油加工及石油制品制造业、化学原料和化学制品制造业、黑色金属冶炼和压延加工业等;溶剂使用源类中排放占比较高的行业为金属制品业、皮革皮毛羽毛制品和制鞋业、印刷业、铁路船舶航空等设备制造业、汽车制造业等。通过对重点行业重点企业进行入场调研采样分析,本研究发现不同行业中VOCs组成特征有差异,多数行业VOCs物种排放以卤代烃、芳香烃、烷烃等为主,纺织印染业、制鞋业等部分行业以含氧有机物排放为主。通过调研和实测对部分行业的VOCs排放因子水平做了本地化深入研究,调研统计青岛市约49%的企业安装了VOCs治理设施;在企业所安装的VOCs治理设施中吸附法占比最大,占比为26%。     

Color removal from dye-containing wastewater by magnesium chloride

Color removal by MgCl(2) when treating synthetic waste containing pure dyes was studied. The color removal efficiency of MgCl(2)/Ca(OH)(2) was compared with that of Al(2)(SO(4))(3), polyaluminum chloride (PAC) and FeSO(4)/Ca(OH)(2). The mechanism of color removal by MgCl(2) was also investigated. The experimental results show that the color removal efficiency of MgCl(2) is related to the type of dye and depends on the pH of the waste and the dosage of the coagulants used. Treatment of waste containing reactive dye or dispersed dye with MgCl(2) yielded an optimum color removal ratio when the pH of the solution was equal to or above 12.0. For both the reactive and dispersed dye waste, MgCl(2)/Ca(OH)(2) was shown to be superior to MgCl(2)/NaOH, Al(2)(SO(4))(3), PAC and FeSO(4)/Ca(OH)(2) for color removal. A magnesium hydroxide precipitate formed at pH values greater than 12.0, which provided a large adsorptive surface area and a positive electrostatic surface charge, enabling it to remove the dyes through charge neutralization and an adsorptive coagulating mechanism. So, the MgCl(2)/Ca(OH)(2) system is a viable alternative to some of the more conventional forms of chemical treatment, especially for treating actual textile waste with high natural pH.     

The Concepts of Energy,Environment, and Cost for Process Design

Abstract

The process industries (specifically, energy and chemicals) are characterized by a variety of reactors and reactions to bring about successful process operations. The design of energy-related and chemical processes and their evolution is a complex process that determines the competitiveness of these industries, as well as their environmental impact. Thus, we have developed an Enviro-Energy Concept designed to facilitate sustainable industrial development. The Complete Onion Model represents a complete methodology for chemical process design and illustrates all of the requirements to achieve the best possible design within the accepted environmental standards. Currently, NOx emissions from industrial processes continue to receive maximum attention, therefore the issue problem of NOx emissions from industrial sources such as power stations and nitric acid plants is considered. The Selective Catalytic Reduction (SCR) is one of the most promising and effective commercial technologies. It is considered the Best Available Control Technology (BACT) for NOx reduction. The solution of NOx Emissions problem is either through modifying the chemical process design and/or installing an end-of-pipe technology. The degree of integration between the process design and the installed technology plays a critical role in the capital cost evaluation. Therefore, integrating process units and then optimizing the design has a vital effect on the total cost. Both the environmental regulations and the cost evaluation are the boundary constraints of the optimum solution.     

Heavy equipment maintenance wastes and environmental management in the mining industry

Maintenance wastes, if not managed properly, represent significant environmental issues for mining operations. Petroleum hydrocarbon liquid wastes were studied at an Australian site and a review of the literature and technology vendors was carried out to identify oil/water separation technologies. Treatment technologies and practices for managing oily wastewater, used across the broader mining industry in the Asia-Pacific region, were also identified. Key findings from the study were: (1) primary treatment is required to remove grease oil contamination and to protect secondary oily wastewater treatment systems from being overloaded; (2) selection of an effective secondary treatment system is dependent on influent oil droplet size and concentration, suspended solids concentration, flow rates (and their variability), environmental conditions, maintenance schedules and effectiveness, treatment targets and costs; and (3) oily wastewater treatment systems, based on mechanical separation, are favoured over those that are chemically based, as they simplify operational requirements. Source reduction, through housekeeping, equipment and reagent modifications, and segregation and/or consolidation of hydrocarbon waste streams, minimizes treatment costs, safety and environmental impact.     

厌氧消化在纺织印染废水处理中的地位

纺织工业废水具有高浓度、高色度、高碱度、低BOD/COD比值的水质特性。近几年来对该污水采用了厌氧消化工艺,获得了良好的处理效果。本文对该污水处理系统工程中的厌氧消化技术进行小结和评价,从而确定了厌氧消化技术在纺织工业行业污水处理的地位。