عنوان مقاله
حذف یون های فلزات سنگین از فاضلاب: مقاله مروری
فهرست مطالب
چکیده
مقدمه
فنون تصفیه پسماند فلزات سنگین
ملاحظاتی در خصوص روش های تصفیه فلزات سنگین
نتیجه گیری
بخشی از مقاله
رسوب هیدروکسید
رایج ترین روش رسوب شیمیایی، رسوب هیدروکسید است زیرا روش رسوب دهی آسان بوده، دارای هزینه کم بوده و کنترل اسیدیته در آن راحت است. انحلال پذیری هیدروکسید های مختلف فلزی در دامنه اسیدی 8 تا 11 به حداقل می رسد. هیدروکسید های فلزی را می توان توسط فلکوله شدن و رسوب گذاری حذف کرد. طیف وسیعی از هیدروکسید ها برای رسوب فلزات سنگین از فاضلاب بر اساس هزینه پایین و سهولت استفاده مورد استفاده قرار گرفته اند. معمولا در مقیاس صنعتی، آهک نیز مورد بهره برداری قرار می گیرد. (جدول1).
کلمات کلیدی:
Removal of heavy metal ions from wastewaters: A review Fenglian Fu a,*, Qi Wang b a Faculty of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China b Faculty of Applied Mathematics, Guangdong University of Technology, Guangzhou 510006, PR China article info Article history: Received 4 March 2010 Received in revised form 16 October 2010 Accepted 9 November 2010 Available online 8 December 2010 Keywords: Heavy metal wastewater Treatment technology Review abstract 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, coagulationeflocculation, flotation and electrochemical methods. About 185 published studies (1988e2010) 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. 2010 Elsevier Ltd. All rights reserved. 1. Introduction Heavy metals are elements having atomic weights between 63.5 and 200.6, and a specific gravity greater than 5.0 (Srivastava and Majumder, 2008). With the rapid development of industries such as metal plating facilities, mining operations, fertilizer industries, tanneries, batteries, paper industries and pesticides, etc., heavy metals wastewaters are directly or indirectly discharged into the environment increasingly, especially in developing countries. Unlike organic contaminants, heavy metals are not biodegradable and tend to accumulate in living organisms and many heavy metal ions are known to be toxic or carcinogenic. Toxic heavy metals of particular concern in treatment of industrial wastewaters include zinc, copper, nickel, mercury, cadmium, lead and chromium. Zinc is a trace element that is essential for human health. It is important for the physiological functions of living tissue and regulates many biochemical processes. However, too much zinc can cause eminent health problems, such as stomach cramps, skin irritations, vomiting, nausea and anemia (Oyaro et al., 2007). Copper does essential work in animal metabolism. But the excessive ingestion of copper brings about serious toxicological concerns, such as vomiting, cramps, convulsions, or even death (Paulino et al., 2006). Nickel exceeding its critical level might bring about serious lung and kidney problems aside from gastrointestinal distress, pulmonary fibrosis and skin dermatitis (Borba et al., 2006). And it is known that nickel is human carcinogen. Mercury is a neurotoxin that can cause damage to the central nervous system. High concentrations of mercury cause impairment of pulmonary and kidney function, chest pain and dyspnoea (Namasivayam and Kadirvelu, 1999). The classic example of mercury poisoning is Minamata Bay. Cadmium has been classified by U.S. Environmental Protection Agency as a probable human carcinogen. Cadmium exposes human health to severe risks. Chronic exposure of cadmium results in kidney dysfunction and high levels of exposure will result in death.
