Can anyone suggest some cost effective water treatment methods for heavy metals removal other than biosorption and photoremediation?
Adsorption or membrane process is possible however it depends on the concentration of heavy metal that you have in the water you are treating
Dear Megha, more detailed cost comparison would need a determination regarding species of heavy metal ions, concentration range, type of water source and options for concentrate disposal.
Sorry, your Q is very unspecific! Not all and every metal can be removed in the same way. Name your metals and their speciation in your water (i.e. soluble, or in oxide, complexed, or ...) and then we might get closer to the right answer.
Yes, There are beacoup de physicochemical processes, like precipitation, adsorption, ion exchange, reverse osmosis, .....etc.
bioleaching is one of the effective process. However as mentioned by others, cost effectiveness is a case to case basis. Heavy metal removal is a big challenge. Adsorption is a good technology provided we have some low cost adsorbent
Maghda, I don't believe photoremediation will help with heavy metal removal, as you suggest. Metals may be used to improve photocatalysts such as TiO2, but the photoremediation treatment itself is typically used for degrading organic micropollutants, and/or for disinfection.
As Boris stated before, I do believe that you need to provide more information to get an accurate answer. What are the physico-chemical characteristics of your water? What metal are you talking about? In what species, concentration? For instance, if your metal concentration is low and the cost of the soil is cheap in your area, even phytoremediation could be a good cost-effective option. But it would be impossible to use if the concentrations are higher than the plants can tolerate, or if other circumstances (like pH, salinity, other pollutants, etc) make it difficult for the plants to survive
All methods are effective but The best method varies considering distinct circumstances.
If it is low concentration, then you can chose precipitation, adsorption, ion exchange, reverse osmosis, .....etc. if you can concentrate the water, ED to remove it
Iron exchange method is a good method for removal of metal ions and also anions present in water and also cost effective. It is cheaper than Reverse osmosis
Yes, it is possible to remove the heavy metals from waste water effectively after a clean pre-treatment of the waste water and then by applying inflow biocarbon adsorption process. Here, the entire treatment option is a low cost method and the removal efficiency is good. There are other methods like membrane techs, showing good removal efficiency but, its costly.
I once did a research on this and made use of commercial activated carbon. (CAC). It is efficient and cost effective as well. However, I was able to locally make them using date palm seeds which was less costly and even as effective as the CAC. I will suggest its Activated Carbon in general.
Also, the effective method depends on the type of heavy metal. CAC helped remove CrVI) effectively and it was cost effective.
There are lots of method of treatment but by using any non pathogenic bacteria or fungus and do bioadsorption of heavy metals is eco-friendly and cost effective and durable one. And further we can use the same microbial biomass for more adsorption of heavy metals from water.
Adsorption is very good for dilute solutions. In high concentrations and large quantities, chemical coagulation or precipitation will be better.
I have some papers on adsorption in my RG. You can have a look at them.
At low concentration, surface adsorption using low cost nanomaterial surface will be cheapest but chemical precipitation/co-precitation should be effective when metal concentration will be high.
Low Cost: Adsorption. Ionexchange
Most effective: membrane distillation to concentrate the stream, then electricdialysis to remove the metal ion
I think R.O whit nanoTechnology... for example: Nano tubes for this research.
Maybe... In pailot examination... more effective than other methods... but in local scale you should mixing other methods with nanothecnology .... combained these methods are cost effectiveness... even though you can remove units which not cost effective... Best RegarDs :)
Dear Megha... Please see Cm of Uday Ghosh.... this comment similar to my idea...
Sorption is the best technique (required specific sorbent) by low cost adsorbent material or modified low cost adsorbent material by hydrothermal treatment.
e.g see this article: http://rd.springer.com/article/10.1007/s11356-012-1029-3
If are heavy metals in low concentration the best (as cost vs yield) is the removal with the following sequence:
Step 1
Reaction with Na2S (in little excess)
Step 2
React the previous solution with FeSO4 (this will bond the excess sulfides)
Step 3
Bring to the required pH (usually 8,5) with caustic soda or lime.
Some ppms of anionic polyelectrolyte at the end will help for the best sludge floculation and separation
It is evident from the literature survey search that ion-exchange, adsorption and membrane filtration are the most frequently studied for the treatment of heavy metal wastewater. Try: http://www.scopus.com.scopeesprx.elsevier.com/record/display.url?eid=2-s2.0-78650520448&origin=resultslist&sort=plf-f&src=s&st1=Removal+of+heavy+metal+ions+from+wastewaters%3a+A+review&sid=A7B041C2A3A8BC322092041E2F99BF6A.euC1gMODexYlPkQec4u1Q%3a20&sot=b&sdt=b&sl=69&s=TITLE-ABS-KEY%28Removal+of+heavy+metal+ions+from+wastewaters%3a+A+review%29&relpos=5&relpos=5&searchTerm=TITLE-ABS-KEY%28Removal+of+heavy+metal+ions+from+wastewaters%3A+A+review%29
Ion Exchange method is widely used for removal of heavy metals and is cost effective.
I think that rusted nano iron powder will be a cost effective material for removing trace heavy metal ions from the contaminated water.
Ion exchange is good technique for separation and selective but it requires desorbing eluents to extract it.
Adsorption using low cost adsorbent like industrial wastes, agricultural wastes etc.
in my opinion biological method is the most cost effective and you need no special scientific know how for the same except the condition in which a particular species of plant or bacteria survive. Secondly you can use the concept of constructed wet land and for that you need to take help of an environmental engineer.
@Jatin: The discussion from the beginning revealed already a lot of useful info. One shall continue and not repeat the discussion. In this light I would propose (also to Eva) to try finding cost effective organic material that can be used instead of activated carbon when one seeks solution among ad- or absorbents. Please bear in mind that the pH vs. redox potential is crucial also for absorbents, not only for coagulation and redox chemical reactions.
you can try with adsorption with various natural adsorbents with optimizing pH,adsorbent dosage and duration.
in my opinion Membrane Distillation + ElectroDeposition is the most cost effective method . membrane distillation will concentrate the fluent and ED will recovery the heavy metal.
First u have find what type of heavy metals are there in waste water then u have to decide the process selection. Any have it would be effective when we are going for biological treatment
Oxidising agents can be of help here. Try Chlorine, Permanganate of Ferrate
Above Chaoyang Feng suggested the method of Membrane Distillation + Electrodeposition, which is a novel technology might be interesting for your system. However, the long time running still has trouble because the efficiency will decrease dramatically if the membranes are wetted during the operation. If anyone can offer some cases of long running employing Membrane Distillation it should be helpful for evaluating this method for your system.
Ion Exchange is cost effective method for removal of Heavy metals. Latest technique is reverse osmosis which removes heavy metals ans also bacteria.
The use of immobilised cells of the microorganism is most cost effective and economic metod of removal . Because first of alll according to literature review the method is superb and easily handle with the researchers and also the beads i.e. Immobilised cells can be used again n again for the removal of heavy metals from contaminated sites.
Precipitation at ph 9 followed by nanofiltration(if required outlet is very strict
I agree with the part of nanofiltration or reverse osmosis polishing, if a water of high purity is the target. However, precipitation at water pH = ~9 effective only for some heavy metals (e.g., Cu, Cr, Zn, Ni) and not in all cases! The most powerful and economically viable method is probably coagulation with iron or aluminium-based coagulants with a coagulant dosage an pH, which depend on the water composition and the metal(s) to be removed.
Heavy metal ions if present at high concentration level can be separated by precipitation from the water at pH ~ 10. At this stage supernatent will still have traces of metal ions. If it be seen that metal ion concentration in water above their permissible level, it can be treated effectively by the hydrous Fe(III) oxide at pH > 5.0.
Nowadays adsorption by agricultural waste and by-product has gained more attention and research interest for the removal of heavy metals from waste water due to its surface area, adsorption capacity and plenty abundant in nature.
Use of BioChar is a cost effective and a sustainable method
http://www.biochar-international.org/biochar
Use of bio-adsorbents like doped/impregnated/loaded/modified chitosan chitin, biomass derived sorbents for removal of metal,depending of chemistry of metal.
in my opinion, there are several materials for heavy metal removal such as natural zeolites in macro/micro or nano scale size. they are very cheap materials but with low exchange capacity. So you can use other treatment methods such as chemical precipitation for high heavy metal loads decreasing. Then after you can use zeolites to removal trace concentrations of residue heavy metals.
Other techniques with high removal efficiency are: Reverse osmosis, Nano filtration, etc.
The water purification process in most municipalities has six steps. They are coagulation/flocculation, sedimentation, filtration, stabilization, fluoridation, and chlorination. Aluminum sulfate, or filter alum, is added to the water coming into the purification facility during coagulation/flocculation. Adding hydrated lime is the next step that occurs during sedimentation.most of impurites settle in sediments.
I agree with the fact that it mainly depends on which metals and what is the concentration . adsorption techniques using natural and cheap activated carbon (i.e (olive stone proved good results.You may use microwave preparation for better results and sustainable energy use. Zeolite is a good adsorpent as well or even modified bentonite which is natural low cost material
Lots of great methods posted!
Ion exchange with sodium titanates could be used for waste water treatment. This includes TiO2 based nanotubes synthesized by the hydrothermal method in NaOH.
There is some research out there from the 1980s or so about sodium titanates. More recently they talk about the TiO2 nanotube ion exchange and titanate nanotube ion exchange.
Good luck!
Megha,
The most cost effective method is the spectroscopic technique other then scattering techniques still better option.
There is some research about preparation of the electrospun nanofibers or nanofiberous membranes and their applications to the adsorption of heavy metals from an aqueous solution.
Polymer nanofibers, an important class of nano-materials, have attracted increasing attention in the last 10 years because of their high surface-to-mass (or volume) ratio and special characteristics attractive for advanced applications.
Mehdi,
no doubt you are approaching towards the goal but the characterization must be done through some experimentation and i.e. either scattering or spectroscopic.
Membrane distiallation (MD) reject theoretically 100% metallic contaminants.
You can see my article list and let me know if you are interested, I can send you my articles in detail.
Good Luck!
Thank you Lijo
Can you please send me your article on membrane distiallation
In my opinion, the most useful from an economic point of view should be the ion-exchange methods. I mean, both, methods that are already considered as the classic - a method of using natural zeolites, and methods with the use of the new exchangers based on nanocarriers such as titanium compounds (i.a. TiO2 or titanates).
It should be taken into account that the decisive factor profitability of many methods for removing heavy metals - including ion-exchange methods - is the concentration of these metals in the wastewater. At high concentrations of metals in wastewater, ion-exchange methods must be preceded by lower-cost methods of pre-treatment (preferably the precipitation methods), or else cease to be economic.
I think most economical is simply growing plant species which are tolerable to that condition. As plant extract heavy metals and other nutrient present in water and excess material get dump in vacuoles , roots , stem and other plant organ.
Dear Gulshan!
I believe you have in mind also that the plants have to be harvested and stored (dumped) in a special place where the heavy metals will mean no further threat for the environment. Simply burning the wood of the plants will again release the metals in the environment (fly ashes). Burning in special furnaces, washing the exhaust gases and collecting the ashes may be an option ...
Megha,
Most cost effective method to detect heavy metals is the AAS.
Mr Boris
I m agree about your answer sir. After extracting metals by plants, they can be burn in special furnaces. Even Apart from that after burning that plant materiel we can prepare micro nutrient fertilizer by that ash..
Mario
I see that you almost completely copied my earlier opinion.
Do I have to understand it in such a way, that you agree "word for word" with my opinion?
Heavy metals can be removed economically by sedimentation- flotation-filtration processes.
Dear Virendra ... I thought that we were talking about trace concentrations of heavy metals ...
Dear Mario (and Andrzej)! Do I see copy/paste? What about research ethics?
Heavy metals can not be removed economically by sedimentation- flotation-filtration processes. As we know this is just for large amount of heavy metals ion. For trace amount, new method should be used.
If heavy metal is in traces the sedimentation-flotation and filtration method is widely used in India. This is most cast effective.
Dear Virendra! Can you give me an example for the concentration ratios where your proposed technology works? ... i.e. the inflow and outflow concentrations for selected heavy metals? THX! Boris
There is a lot of information about removal of heavy metals using agricultural as well as food waste. They are most cost effective since they are waste that no body wants and one would be doing the environment a favour by reusing vast amount of waste that we produce. Tea and coffee waste can be used, powder and wheat straw, sunflower straw, blackgram bran, use of humulus lupulus (hop), rice bran, lathyrus sativus, rice husk, rice straw, barley straw, coir pith, olive stones, barley straw etc. that can be used for heavy metal removal from water.
..i'll recommend phyto-remediation as a cost effective option for removal of trace concentrations of metals from water.
Numerous approaches have been studied for the development of low-cost adsorbents. Babel and Kurniawan [2003] reviewed the technical feasibility of various low-cost adsorbents for heavy metals removal and concluded that the use of low-cost adsorbents may contribute to the sustainability of the surrounding environment and offer promising benefits for commercial purpose in the future. Many researches showed effective adsorption of heavy metals using agricultural
products and by-products such as walnut expeller meal, peanut skins, wool, tea leaves, coffee powder, sugar beet pulp, hazelnut shell activated carbon, pecan shell-based granular activated carbons modified rice husk, rice husk activated carbon and maize husk.
Membrane filtration has received considerable attention for the treatment of inorganics, since it is capable of removing not only suspended solid and organic compounds, but also inorganic contaminants such as heavy metals. Depending on
the size of the particle that can be retained, various types of membrane filtration such as ultrafiltration, nanofiltration and reverse osmosis can be employed for heavy metal removal.
Reference:
S. Babel, T. A. Kurniawan, “Low-cost adsorbents for heavy metal uptake from contaminated water: a review”, J. Hazard. Mat. , vol. 97, 2003, pp. 219-243.
One of the new emerging cost effective treatment methods for heavy metals is electro coagulation. A lot of papers have been published in the last ten years dealing with this issue
I agree with preceded opinions about electrocoagulation, but I would specify to iron electrocoagulation (EC) and derivative techniques based on iron coprecipation. A cheaper method is an application of zero-valent iron (ZVI) that can have dual role, i.e. adsorb heavy metals and supplement treated water with iron ions that in contact with oxidation agent will precipitate to ferrihydrite enabling adsorption of dissolved heavy. Therefore, in my opinion, I think the iron-based techniques are cost effective, but of course it depends on the raw water quality that can influence EC and ZVI.
In our aquatic research facility we have been using finely chipped used automobile tire rubber - it is the consistency of fine activated charcoal. These ships have a very high content of sulphydryl groups due to the vulcanization process and bind metals with high affinifty and high capacity.
First of all, I fully agree with the suggestions given by Abdel Sabour and Aly. Heavy metal removal is not a ticklish issue in view of vastness of literature available . Bioremediation, phytoremediation and vegetable waste biomass can easily adsorb any kind heavy metal . There are heavy metal tolerant weeds or fire wood species, which can be grown in the area and the land can be reclamated inexpensively. In removal of heavy metals, phytochelators play a very big role in plants
I think that for heavy metals removal, you can use to test the chemical precipitation at the proper pH value.
electrochemical methods will definitely help you. Refer to some basic books and references.
Heavy metal removal is a burning topic and across the globe many workers are working on the projects but the most efficient one I feel is the Biochemical removal.
Dear Colleague,
Removal method of metals from waters depends on concentrations and kind of metals. Generally The heavy metal contents of wastewaters can
be effectively removed to acceptable levels byprecipitating the metal in an insoluble form.Heavy metals are typically precipitated from
wastewater as:
hydroxides
sulfides or sometime sulfates
carbonates
see:http://cpe.njit.edu/dlnotes/CHE685/Cls06-2.pdf
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