In wastewater treatment plants, chelating agents can interfere with metal removal processes, allowing toxic metals to pass through untreated and contaminate the environment.6,7Some studies have suggested that >1 mg/L concentrations can interfere with biological processes.7,8
Full Answer
Can alkaline chemistry be used to treat nickel in wastewater?
Compared with the prior art, the nickel-containing wastewater treatment method has the obvious advantages as follows: (1) in the treatment method, the …
What is nickel and how is it used?
Under normal conditions nickel does not react with water. Solubility of nickel and nickel compounds. Elementary nickel is water insoluble at T=20 o C pressure = 1 bar. However, nickel compounds may be water soluble. Nickel chloride is most water soluble; 553 g/L at 20 o C, to 880 g/L at 99.9 o C. Nickel carbonate has a water solubility of 90 mg ...
What happens when you add nickel to water?
Unfortunately, alkaline chemistry contains chelators and/or complexors and organic additives to allow for the co-deposition of the nickel in the deposit with the zinc. These chelators/complexors make the wastewater extremely difficult to treat through conventional chemical or physical treatment methods.
What happens if you put nickel in plants?
Results showed that the chelator could remove copper, nickel and chromium up to 99% when the concentrations of copper, nickel, and chromium ions were 63.55, 58.69, and 52.00 mg/L, respectively. The...
How do you remove nickel from wastewater?
Nickel ion can be removed from nickel-containing wastewater by several techniques: chemical precipitation, ion floatation, ion exchange, adsorption, membrane filtration, and electrochemical treatments [4,5].
How is heavy metals removed from waste water?
The conventional processes for removing heavy metals from wastewater include many processes such as chemical precipitation, flotation, adsorption, ion exchange, and electrochemical deposition. Chemical precipitation is the most widely used for heavy metal removal from inorganic effluent.
What are the toxic metals present in wastewater?
The most common toxic heavy metals in wastewater include arsenic, lead, mercury, cadmium, chromium, copper, nickel, silver, and zinc. The release of high amounts of heavy metals into water bodies creates serious health and environmental problems and may lead to an upsurge in wastewater treatment cost.Nov 10, 2014
What chemicals are used to treat waste water?
Specialized chemicals such as chlorine, hydrogen peroxide, sodium chlorite, and sodium hypochlorite (bleach) act as agents that disinfect, sanitize, and assist in the purification of wastewater at treatment facilities.
Which method is suitable for treatment of heavy metals in wastewater?
To remove heavy metal ions from wastewater, many conventional techniques such as membrane filtration, reverse osmosis, ion exchange, chemical precipitation, electrodialysis, electrochemical treatment, and adsorption have been employed.
How do you treat heavy metal waste?
Various treatment technologies employed for the removal of heavy metals include chemical precipitation, ion exchange, chemical oxidation, reduction, reverse osmosis, ultrafiltration, electrodialysis and adsorption (Fu & Wang 2011).Nov 3, 2016
What are the effects of heavy metals in water?
Heavy metals can contaminate private wells through groundwater movement and surface water seepage and run-off. People that consume high levels of heavy metals risk acute and chronic toxicity, liver, kidney, and intestinal damage, anemia, and cancer.Feb 17, 2022
What are the harmful effects of metals?
Several acute and chronic toxic effects of heavy metals affect different body organs. Gastrointestinal and kidney dysfunction, nervous system disorders, skin lesions, vascular damage, immune system dysfunction, birth defects, and cancer are examples of the complications of heavy metals toxic effects.Apr 13, 2021
How heavy metals are harmful for the water environment?
The persistent pollutants such as heavy metals can then enter the food chain through marine life such as fish which can then affect predators such as bigger fish, birds and mammals, including humans, which migrate and transport the pollutant to different ecosystems [2].
What chemical is added to treated water and why?
Chlorination is the process of adding chlorine to drinking water to kill parasites, bacteria, and viruses.
How does pH increase in waste water?
Common chemicals used to increase alkalinity and pH include:Calcium oxide or calcium hydroxide (as lime slurry)Sodium hydroxide (caustic soda)Sodium carbonate (soda ash) or sodium bicarbonate.Magnesium hydroxide or magnesium bicarbonate.
What is sodium hydroxide used for in wastewater treatment?
Sodium Hydroxide is a strong alkali which, among other facts, means that it is highly ionized and has a high pH. Thus, in wastewater treatment these products can be used to raise the pH level of the water. It is also helpful in the process of removing heavy metal particles from the water.Dec 9, 2019
What is nickel used for?
It is applied in alloys for treatment of heavy metal polluted surface water, in nickel-cadmium batteries, as a catalyzer and as a pigment. Pure nickel is often applied as a protective coating on steel and copperobjects. Nickel-copper alloys have been applied in coins for a very long time.
Where does nickel accumulate in rats?
Nickel accumulation in rats mainly occurs in lungs, where concentrations exceed those in other organs by 4-40 times. There are approximately 70 species of plants that accumulate extraordinarily high nickel concentrations. This may be up to 10,000 ppm (dry mass).
How much nickel is in seawater?
Seawater contains approximately 0.5-2 ppb of nickel, and rivers contain approximately 0.3 ppb. Phytoplankton contains 1-10 ppm nickel (dry mass), resulting in a 103-104bioconcentration factor compared to seawater. Bentic algae can be found both in freshwater and salt water, and may contain between 0.2 and 84 ppm nickel.
How much nickel is in the human body?
The human body contains approximately 10 mg nickel. Nickel is a dietary requirement for a number of organisms, therefore it might be of significance to humans. The human dietary need is estimated at only 5 μg, which is the result of a 150 μg intake.
Where is nickel found in soil?
Phosphate fertilizers contain traces of nickel. Nickel is often present in agricultural soils situated near fossil fuel industries. Organic matter often adsorbs nickel, causing coal and oil to contain traces of the element.
Where does nickel come from?
The main nickel source is pentlandite. The element accumulates in sediments and is a part of various biological cycles. Nickel may end up in water from both point and non-point sources. Diffuse nickel emissions may stem from power plants, waste incinerators and metal industries.
Is nickel toxic to plants?
Nickel is a dietary requirement for many organisms, but may be toxic in larger doses. Metallic nickel and some other nickel compounds are teratogenic and carcinogenic to mammals. Nickel concentrations in plants are usually 1 μg/g, and concentrations above 50 μg/g are toxic.
How to treat zinc and chrome wastewater?
Zinc and chrome wastewater can be treated through conventional methods, such as precipitation and the use of polymers in a lamella clarifier, followed by a filter press to dewater the sludge. The highly complexed alkaline zinc and nickel, however, does not want to precipitate and the chelated metals tend to stay in solution.
What is the process of removing heavy metals from wastewater?
The processes that generate waste streams containing heavy metals include: Mining operations. Precipitation and ultrafiltration provide two ways to remove heavy metals from wastewater that are superior to conventional ...
What are the problems associated with sewage treatment?
Today’s manufacturers should be aware of the problems and penalties associated with discharging industrial wastewaters into sewage treatment systems. Corrosion and other interference with those systems, expo sing workers to toxic substances and hazardous fumes, expensive sludge disposal costs and the pass-through of toxic pollutants ...
How much solids can be processed in UF?
Tubular UF can process solids concentrations of up to 18% (w/w), but the most efficient operation normally occurs between 3 and 5% solids. The sludge normally is drawn off and passed through conventional thickening and filter press processes or similar processes to produce dewatered solids, typically for landfill disposal.
What is the Clean Water Act?
Compliance with tightening federal regulations for wastewater treatment, handling and disposal—such as the Clean Water Act (CWA), the Resource Conservation and Recovery Act (RCRA) and the Safe Drinking Water Act (SDWA)—requires manufacturers to be focused on the wastewater issue . There are additional regulations on the state and local level ...
What is the theme of World Water Day 2019?
The theme for World Water Day 2019 was “Leaving No One Behind,” the central promise of the UN’s 2030 Agenda for Sustainable Development. Advertisement.
Is nickel a hazardous waste?
Nickel is a hazardous constituent and is not exempted. The addition of wastewaters from the zinc and nickel process will cause the filter press cake to become a listed RCRA hazardous waste with the F006 designation, resulting in significant increases to disposal and regulatory costs.
How to treat zinc and chrome wastewater?
Zinc and chrome wastewater can be treated through conventional methods, such as precipitation and the use of polymers in a lamella clarifier, followed by a filter press to dewater the sludge. The highly complexed alkaline zinc/nickel, however, doesn’t want to precipitate and the chelated metals tend to stay in solution.
What processes are used to remove heavy metals from wastewater?
The processes that generate waste streams containing heavy metals include: Precipitation and ultrafiltration provide two ways to remove heavy metals from wastewater that are superior to conventional solutions.
What is tubular ultrafiltration?
Tubular Ultrafiltration is a very effective method of removing virtually all of the precipitated metal hydroxide/sulfides/carbonates from a treated wastewater stream. The resulting high-quality permeate can be fed directly to reverse osmosis equipment for reuse.
Is nickel a hazardous waste?
Nickel is a hazardous constituent and is not exempted. The addition of wastewaters from the zinc/nickel process will cause your filter press cake to become a “listed” RCRA hazardous waste with the F006 designation, resulting in significant increases to your disposal and regulatory costs. Removing the Solids.
Is phosphate precipitation common?
Phosphate precipitation is another option, although this process is not as common. Finally , there are membrane technologies available that utilize a proprietary additive in conjunction with a chelate breaker for precipitating the chelated metals. The advantages of this process include:
Is carbonate coprecipitation soluble?
Carbonate coprecipitation using sodium or calcium carbonate can also be helpful; for example, for soluble lead reduction , lead carbonate is essentially insoluble (0.00011 g/100 mL at 20°C) and will precipitate out. Phosphate precipitation is another option, although this process is not as common.
Does alkaline chemistry contain chelators?
Unfortunately, alkaline chemistry contains chelators and/or complexors and organic additives to allow for the co-deposition of the nickel in the deposit with the zinc. These chelators/complexors make the wastewater extremely difficult to treat through conventional chemical or physical treatment methods.
What is EIW in electroplating?
Electroplating industry wastewater (EIW) characterized by high chemical oxygen demand (COD) is a big source of water and air contamination with heavy metals. The formation of cyanide complex with heavy metals is responsible for its elevated COD. The concentration of heavy metals in EIW can be removed by the use of different precipitating agents (sulfide and hydroxide). But the major bottleneck in the removal of these metals is the presence of cyanide in EIW resulting in chelation with all the metals that are soluble in water. The present work focused on, the treatment of EIW containing Cr, Ni, Zn and CN and the optimization of dosage concentration which was reliable for the dissociation of cyanide complex for maximal removal efficiency. We used hydroxide, sulfide and carbonate precipitation from different precipitating agents (NaOH, Ca (OH) 2, CaCO 3 Na 2S5H 2O, NaHS and NaHSO 3). Sulfide precipitation was a viable option for the treatment of EIW as compared to hydroxide and carbonate precipitation. Moreover, COD reduction capacity of sulfide precipitation was higher than others. It was also found that Ni and Cr made a complex with cyanide that halted the removal efficiency while there was no evidence for Zn complexation; otherwise fragile complexation was evidenced.
Is DTPA a good chelate for Fe?
... DTPA is a good chelate for Fe in acidic soils because of the relatively high solubility of soil Fe at low pH and the high stability of Fe-DTPA chelate (Norvell and Lindsay, 1972;Morere et al., 2001;Cox and Kamprath, 1972;Hill and Lloyd, 1957). Polyaminepolyacetate chelates are organic compounds which have the ability to keep metals in a soluble form (Zing et al., 2005;Norvell and Lindsay, 1969; Xu and Xu, 2008). ...
How to treat waste rinse water?
To treat waste rinse water, maintain the pH between S and 11. Add the sodium borohydride solution slowly. The amount of borohydride to remove 1 gram ofnickel is theoretically 1.1 grams. However the borohydride reacts with other metals and some organics thus requiring about two times the expected amount. Thesodium borohydride is added as a 12% solution in 43% sodium hydroxide. Additional sodium hydroxide is often needed to maintain the pH between 8-11. Theadvantages are low cost, good efficiency , and good removal from chelating agents. The disadvantages include poor settling, often requiring filtering, and theredissolving of some of the metal after 1 hour.
What is the best solution for plating?
Caustic soda (sodium hydroxide) magnesium hydroxide and lime are effective for treating spent plating solution. However, a large amount of sludge is generated.The sludge should be dewatered. Using lime some of the phosphorus compounds are also precipitated. Flocculating materials are added to increase the size of theprecipitated particles of metal hydroxides and speed settling. Even so settling takes a long time. Metals such as zinc and aluminum are soluble in alkaline solutions,thus will not be removed. The effluent usually contains enough nickel and soluble metal compounds that a polishing step is reused to meet the regulations. Polishing isdone by diethylthiocarbamate, ion exchange, reverse, or osmosis .
How do I love thee let me count the ways?
When Elizabeth Barrett Browning wrote her famous poem "How Do I love Thee" which starts "How do I love thee, let me count the ways" she had never heard ofelectroless nickel. When electroless nickel plating was introduced to the world in about 1947, most of us had never heard of the strict regulations in treatment anddisposal of electroless nickel plating solutions and rinse water. Today we are faced with many choices for the treatment and disposal of these plating solutions andthe rinses necessary for the process. How do you choose the right process or combination of processes for your circumstances? A major input the decision makingprocess is being aware of the choices available. What are the choices today? Let us consider some of them.
What is electrowinning in chemistry?
Electrowinning is a term used to describe plating metal from a solution for recovery purposes . The water containing nickel is introduced to a plating cell with manyanodes and cathodes. DC current and voltage is applied and nickel is deposited on the cathode. The cathodes may be stripped of nickel from time to time, and thenickel reused. Sulfuric acid/peroxide is often used for stripping. The current efficiency is low, therefore the cost of electricity is a factor.
Is reverse osmosis the same as plating?
Reverse osmosis as described under waste rinse water treatment works the same for plating solution. It is likely to be more cost effective when it is used to extendthe life of the plating solution.
Can ferrous sulfide be used in plating?
Ferrous sulfide and diethvthiocarbamate treatments of the spent plating solution can be done, but is usually expensive and produces hazardous sludge in quantity.Removal of nickel and all other heavy metals that may be present is effective leaving little behind. Most of the regulation can be met. Note, however, that as in othertreatments the effluent after removal ofmetals will contain chelating agents that can combine with other metals if the effluent is mixed with other metal containing waste streams. It is best to discharge theeffluent from nickel removal separately from all other waste streams in some cases further treatment (oxidation of the organics) to meet BOD and Sulfide sledges areCOD requirements unacceptable in most land fills.
Can ion exchange be used to treat nickel plating?
Ion exchange alone is not usnally used to treat spent electroless nickel plating solutions. However, Roger Anderson and Wayne Neff have developed a process forextending the life of a plating solution which could be adopted to waste treating as well. Ion exchange is used to remove nickel and sodium. The nickel is reclaimedby removing the sodium from the resin bed using dilute sulfuric acid, then eluting the nickel from the bed to be returned to the plating solution. The sulfate isprecipitated using a two stage calcium treatment then the orthophosphite is precipitated using magnesium oxide. The remaining effluent after filtering is returned to theplating solution.
What is chitosan used for?
Chitosan (CTS), benzaldehyde, CS 2 and NaOH were used as raw materials. The synthesized xanthated chitosan (XCTS) was characterized by Fourier transform infrared spectroscopy (FTIR) and used as aqueous sodium salt solutions. Stock solutions of XCTS were prepared in two stages. First, powdered chitosan (1.0 g) was dissolved in 30 mL of acetic acid (3% solution) at room temperature with constant stirring for 0.5 h. Anhydrous ethanol (20 mL) was added, and the solution was placed in a KH5200DB digital ultrasonic cleaner (Kunshan Hechuang Ultrasonic Instrument Co. Ltd., China) after adjusting the solution pH to 6.0 using HCl (1 mol/L). Then, a certain amount of benzaldehyde that was dissolved in 20 mL of anhydrous ethanol in advance at a C6 H 5CHO:CTS molar ratio of 7:1 was dropwise added into the above solution. The reaction mixture was heated to 70 °C in a water bath, underwent constant ultrasonic oscillation for 4 h using a JB-2 thermostatic magnetic stirrer (Shanghai Ray Magnetic Xinjing Instrument Co. Ltd., China) and produced the intermediate product, Schiff’s base chitosan. It was used for subsequent reactions after washing with 20 mL of anhydrous ethanol. Next, 2 mL of CS2 and 50 mL of NaOH (5% solution) were mixed at 30 °C and stirred for 30 min. The Schiff’s base chitosan was added to the reaction mixtures, and the final product, XCTS, was obtained by stirring all reactants at 60 °C for 4 h. During the reaction process, due to the lower boiling point of CS 2 (46.5 °C), the unreacted CS 2 would be cooled and returned to the reactor via a reflow condenser, so that it fully reacted. The intermediate (Schiff’s base chitosan) and XCTS were precipitated with anhydrous ethanol and anhydrous methanol, respectively, and then dried under vacuum after filtration and washing. The FTIR spectra were determined using an IR Prestige-2 infrared spectrometer (Shimadzu Co., Japan) using the KBr dispersion method from 4000–500 cm −1. A synthetic scheme of XCTS is shown below:
Is EDTA a chelating agent?
EDTA is a widely used chelating agent and is often found in all kinds of wastewater. It is therefore necessary to investigate the influence of EDTA coexisting with Cu 2+. EDTA with copper ions in a 1:1 M ratio was added into water samples containing 25 mg/L copper ions, and the pH of the system was adjusted between 2.0–6.0. Jar tests were conducted at different XCTS doses which varied from 45 to 120 mg/L. The results are shown in Fig. 5.
Does copper cause turbidity?
In practice, some substances that caused turbidity are often found in waste waters containing copper. Therefore, the effect of turbidity on removal of copper was investigated. The water samples used in these tests, which were synthesized using copper chloride, kaolin, and tap water, contained both Cu2+ (25 mg/L) and turbidity (0, 40, 100 and 200 NTU). Flocculation experiments were made by using different dosages of XCTS at pH 6.0. The results are shown in Fig. 8, Fig. 9.
Does XCTS remove turbidity?
Based on the synthesis of a novel, macromolecular heavy metal flocculant, xanthated chitosan (XCTS), the experimental data obtained in this work indicated that XCTS not only removed turbidity as convention al floccul ants but also exhibited very good efficiency for the removal of copper ions from wastewater. Some important factors that affect this process were studied and contributed to a better process knowledge and facilitation of selecting the optimal treatment conditions. The primary conclusions resulting from this work are summarized as follows:
Why Companies Should Care
A Commitment to Wastewater Treatment
- The goal of this agenda is to cut the proportion of untreated wastewater in half and increase safe water reuse by 2030. Guy Ryder, the director-general of the UN International Labor Organization (ILO) and the Chairperson of UN-Water, believes that to achieve this goal, there must be a commitment to improve the management of wastewater from both the business community an…
Understanding Variables
- The concentration and chemical form of the soluble heavy metals in a particular wastewater stream varies, depending on the industry and the mix of operations at a processing site. For example, in the plating industry, specialty chemical suppliers have developed alloy technologies such as zinc, nickel and other alloy coatings to maximize the high corrosion resistance of the m…
Removing Solids
- Typical removal strategies involve precipitating the metals in an insoluble form—such as hydroxides, sulfides, carbonates or some combination—and removing the precipitate with tubular ultrafiltration (UF) (for high-quality filtrate) or conventional clarification. The resultant sludge then is collected, thickened and dewatered for landfill disposal and listed as F006 (but at a much sma…