Copper wastewater pollutants

Concentrations of Toxic Pollutants Found in Primary Copper Wastewater... 

The pollutants of concern are the same as in wet basic oxygen furnaces, but the concentration of metals (primarily lead and zinc, but also arsenic, cadmium, copper, chromium, and selenium) in wastewater is higher because of the higher percentage of scrap charged. Wastewater treatment operations are similar to those for the wet basic oxygen furnaces, including sedimentation in clarifiers or thickeners and recycle of the water.14... 

Refining operations have two principal wastestreams, waste electrolyte and cathode and anode washwater. Spent electrolyte is normally recycled. A bleed stream is treated to reduce copper and impurity concentration. Varying degrees of treatment are necessary because of the differences in the anode copper. Anode impurities, including nickel, arsenic, and traces of antimony and bismuth, may be present in the effluent if the spent electrolyte bleed stream is discharged. Tables 3.14 and 3.15 present classical and toxic pollutant data for raw wastewater in this subcategory. 

Classical Pollutants in Raw Wastewater from the Primary Copper Subcategory... 

Concentrations of Toxic Pollutants in the Raw Wastewater of the Secondary Copper Subcategory... 

Many toxic pollutants were detected in the process wastewaters from metal molding and casting processes. The toxic pollutants detected most frequently in concentrations at or above 0.1 mg/L were phenolic compounds and heavy metals. The pollutants include 2,4,6-trichlorophenol, 2,4-dimethyl-phenol, phenol, 2-ethylhexyl, cadmium, chromium, copper, lead, nickel, and zinc. Each type of operation in the foundry industry can produce different types of pollutants in the wastewater stream. Also, because each subcategory operation often involves different processes, pollutant concentrations per casting metals may vary. 

Some innovating treatment technologies may be introduced in the treatment of wastewater generated in the aluminum fluoride industry to make its effluent safer. The ion exchange process can be applied to the clarified solution to remove copper and chromium. At a very low concentration, these two pollutants can be removed by xanthate precipitation.24 A combination of lime and ferric sulfate coagulation will effectively reduce arsenic concentration in the wastewater. 

Prominent among the heavy metals found in the wastewater generated in the copper sulfate industry are copper, arsenic, cadmium, nickel, antimony, lead, chromium, and zinc (Table 22.11). They are traced to the copper and acids sources used as raw materials. These pollutants are generally removed by precipitation, clarification, gravity separation, centrifugation, and filtration. Alkaline precipitation at pH values between 7 and 10 can eradicate copper, nickel, cadmium, and zinc in the wastewater, while the quantity of arsenic can be reduced through the same process at a higher pH value. 

In the pesticide industry, metals are used principally as catalysts or as raw materials that are incorporated into the active ingredients, for example, metallo-organic pesticides. Priority pollutant metals commonly incorporated into metallo-organic pesticides include arsenic, cadmium, copper, and mercury. For metals not incorporated into the active ingredients, copper is found or suspected in wastewaters from at least eight pesticides, where it is used as a raw material or catalyst zinc becomes part of the technical grade pesticide in seven processes and mercury is used as a catalyst in one pesticide process. Nonpriority pollutant metals such as manganese and tin are also used in pesticide processes. 

At least three pesticide plants use priority pollutant metals separation systems in the United States [7]. One plant uses hydrogen sulfide precipitation to remove copper from its pesticide wastewater. The operating system consists of an agitated precipitator to which the H2S is added, a soak vessel to which sulfur dioxide is added, a neutralization step using ammonia, and a gravity separation and centrifuging process. Copper is removed from an influent level of 4500 mg/L to 2.2 mg/L. 

Chemical precipitation is applicable to most heavy metals likely to be found in contaminated gronndwater. Examples of metals that have been removed to a concentration of less than 1 ppm inclnde cadminm, chrominm, nickel, zinc, manganese, copper, tin, iron, arsenic, lead, and mercnry. Chemical precipitation is widely nsed to meet National Pollution Discharge Elimination System (NPDES) reqnirements for the treatment of heavy-metal-containing wastewaters. In many cases, metals precipitation may also be nsed as a pretreatment step prior to discharge of the wastewater to a pnblicly owned treatment works (POTW). 

Nano-photosynthesis can produce sugar and starch for food and further synthesis of cellulose can produce paper and wood to avoid clear-cutting forests. Carbon retrieved from the atmosphere and recycled from existing wastes by MNT will be used to make carbon nano-tubes, with superior properties to steel. Carbon will be the most common structural and functional element for a MNT-based civilization [32,33]. A carbon-based MNT material production model is conceptualized as in Fig. 9. If there is a specific need for metal, a nano-factory with trillions of nano-assemblers will synthesize steel, copper, and alloys in order to skip mining and refining [32,33]. Therefore, industrial wastewater, hazardous wastes and air pollution will all vanish. 

Most of the metals such as copper, nickel, chromium, silver, and zinc are harmful when they are discharged without treatment. The most widely used method for the treatment of metal polluted wastewater is precipitation with NaOH and coagulation with FeSCU or A12(S04)3 with subsequent time-consuming sedimentation. Other methods include adsorption, ion exchange, and reverse osmosis. Each method has... 

Pollutant Discharge Elimination System (NPDES), municipal and industrial entities that discharge wastewater (e.g., sewage, pulp, and paper) into national waterways are required to obtain a permit and meet imposed effluent limitations. These limitations, designed to be protective of water uses, human health, and aquatic life, are generally expressed in terms of a numerical limitation for a specific chemical (e.g., 10pgl of copper). However, one shortcoming to chemical-specific requirements is that bioavailability and toxicity of multiple chemical species in complex effluents are not directly evaluated. 

---