Science topic

Water Purification Technologies - Science topic

Water Purification Technologies are water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids and gases from contaminated water. Most water is purified for human consumption (drinking water) but water purification may also be designed for a variety of other purposes, including meeting the requirements of medical, pharmacology, chemical and industrial applications. In general the methods used include physical processes such as filtration, sedimentation, and distillation, biological processes such as slow sand filters or activated sludge, chemical processes such as flocculation and chlorination and the use of electromagnetic radiation such as ultraviolet light.
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Do I use direct solar radiation during a day or global solar radiation during a day.
help me please 
thanks advance 
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Solar still efficiency = distillate × hfg/ Total solar intensity × glass area× time
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So how do people convert this in the industry? At what concentration? Will the bed volume influence the conversion. Will Co-flow influence the conversion when compared to backflow? This technology should be well known, just that I am not able to hit the right phrase to google.
If you have a process flow diagram, can you please share it? Or please enlighten me with the procedure for large-scale conversion.
Regards
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You can check table 5 in the paper below for some techniques:
Regards,
K
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Hi, we are trying to figure out if ultra-purified water can be stored. We have a Thermo Smart2Pure 3 uv/uf.
If it is possible to store the ultra-purified water:
1. Will the type I water change its conductivity, resistance and TOCS (total organic carbon) to a type II or type III?
2. And how long can it be stored for?
3. What type of container would be needed?
If it is not possible to store it:
1. What would you do to decrease the need for filter change, given that our lab will only be using this type of water once a week for a year or more?
Thanks to anyone with information on this!
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You can autoclave it and use it under sterile conditions. This will help when storing it for some time.
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I read an article about separation of pollutant in restaurants' wastewater using electrocoagualation, which says, "There are five electrodes connected in a dipolar mode in the electrochemical reactor." I would like to do the same set-up for my thesis.
Also, how it is different from bipolar mode?
Thank you!
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In the case of the bipolar electrodes, each one of the electrodes, excluding the external ones, which are monopolar, present different polarity at each one of the electrode sides depending on the charge of the electrode in front it. The connection of bipolar electrodes is permanently in serial mode.
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I want to calculate the effusion percentage of silver from the composite to water. From ICP-OES I will be able to calculate the concentration of Ag. But How to calculate Ag effusion percentage? Is there any formula ?
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Please look at the following below attached files which may help you in your analysis.
Thanks
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I am collecting samples of farm derived waste water for my PhD project. Many of them are contaminated with cow dung. I need to filter them to 0.45um for a number of procedures, however, after centrifuging they still take a long long time to filter. I get a lot of samples to filter after each sampling trip and thus time is a commodity that I can't waste.
At present I centrifuge them and then run each sample through a 0.45 filter, however I usually have to change the filters a number of times just to filter one sample. I am happy to use more than one sample but surely there is a better mix of sizes that would work instead of wasting all the o.45um filters.
Anyone got any ideas or tips?
Thanks very very very much.
Gregg
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You can use successive white sand filters with different grain sizes starting with larger grain sizes and ending with smallest grain size.
Best wishes
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Ex: Think total hardness is 200ppm. Total treated water requirement is 5000L/day.
Then how calculated the
a) Softener vessel size?
b) Required resin volume?
c) Salt regeneration time?
d) Dosage of salt?
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Ideally, a water softener should be sized so that it does not regenerate any more often that every three days (wastes water and salt), nor go longer than 14 days before regenerating (can cause compacting of resin, and fouling with sediment or iron). 7 days between regenerations is probably best - especially if iron is present. For the majority of homes, our 1 cubic foot unit is more than enough capacity. There are conditions that would create a need for a larger unit: larger family (6 or more) and/or very hard water (over 15 grains). Use the following formula to calculate the proper size: 1. Multiply the number of people in your family times 70 (gallons of water used per day, national average). 2. Multiply the answer by your water hardness in grains per gallon (to convert mg/l or ppm to grains, divide by 17.1). If iron is present, add 5 grains for every ppm (mg/l) of iron (iron MUST be dissolved iron - it appears clear from the tap but leaves reddish-brown stains). 3. This is your "grains per day" number. Divide this number into each of the softener capacities until you find the best size.
You can find additional data on:
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Some researchers at Cornell have developed stacked rapid sand filtration technology for use in the developing world.  As I understand it, it is useful for doing what traditional rapid sand filtration does, but you can use it in small to medium size municipalities in the developing world where the electrical power required for backwashing is not as available and/or reliable.
We are trying to see how well this technology might work to improve water quality from a nearby river in a rural jungle region of Honduras.  It is just an attempt.  It may work terribly.  I just thought I would see if anyone had any helpful opinions or advice about SRSF and/or its use in various contexts.
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It can be a good alternative, but never forgetting the qualitative control of the water resources that will be filtered and their respective uses.
Regards!
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Hello everybody, I have been overwhelmed by the responses I have had to the Process Stress in Wastewater Treatment Survey. This is the last time I will be posting the survey before it closes. So please, if you can spare 10 min to fill in the survey it would be greatly appreciated. Thank you again for your support!
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Through the Advanced Oxidation Processing
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What is the best and most economical water purification method that can be used in Africa to purify the water for drinking purpose for people?
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Membrane methods are the most effective and fouling can be mitigated. The most robust systems are Reverse Osmosis since they are the most used in the world. Water treatment from seawater is best achieved by Reverse Osmosis.
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I have started working on the above mentioned model, I would like if someone can guide me on this, how to pursue this type of modelling as it can be used/setup in rural areas where there are lack of resources or lack of funds which ultimately results in people drinking unhygienic water which is not good for their health and hence can get disease like Diarrhoea which causes 4% of all deaths and 5% of health loss to disability (As Per WHO report).
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You have to use rice husk as a precursor for the preparation of activated carbon as adsorbent material for the treatment of waste water.
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Although the contamination of wells with petroleum waste in Jaffna in Northern Sri Lanka had been reported by many people, their claims are being challenged by many, especially local politicians, citing the lack of research evidence in this issue.
How can we remove Oil From drinking water? 
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filter through beds of Diatamaceous earth and chitosan flakes
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I am looking for separation and recovery of iron based nano particles from water stream. Nano particle size is in the range of 50 nm to 1000 nm with 80% particles below 100 nm. Till now I have used following techniques
1. Settling. It Higher takes more than 6 hours for nano particles settling and hence not feasible
2. Ultrafiltration separation - concentration of nano particles is too high for UF membranes to work
Magnetic separation - Did a pilot for magnetic speration but didn't succeeded. Not able to arrive at right surface area of magnetic material for complete (or more than 99%) removal
If anybody has better idea 
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Dear Yashwant
at first you must draw Magnetization curve at 25 C of your adsorbent. From the characterization results, the saturation magnetization (M) of the magnetic material can be carried out.
-Best
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Nano and Micro size particles of P25 TiO2and ZnO semiconductors have nearly same bandwidth and often used for their comparative studies for water purification application for hazardous heavy metals for health, such as As, Cr, dyes, and even E-Coli bacteria. Could someone kindly throw more light on this subject to clearly  understand and conclude which one of these two photo catalysts is more suitable from the points of views as follows: over all performance, health, safety, system cost, sludge management, environment friendly, material reuse life, etc. Best regards.
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agree with @Zhaohui Wang
regards
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Water purifiers can remove water hardness but are not handy.
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The answer really depends on how much water do you want to treat and to what level. The BRITA water filters (and many others) are handy and remove much of the calcium and magnesium ions ( using a small ion exchange column) but they only treat small volumes at slow speed. There are larger columns but obviously much less handy
Yoram
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Everybody knows about Water Treatment Plants for clean water. But everyone does not know about problems over there. Settling Tanks are a main unit of any Water Treatment Plants, there are must be suspended about 95-98% dirty particles. But in really there are suspended just 40-50% solids. It is a result of incorrect design.
What is the reason?
The reason is next.
At the present time for Settling Tanks (Clarifiers or Sedimentation Basins) Design Engineers are used traditional (conventional) sedimentation theory. But accordance that theory it is not possible to calculate the dimensions of Settling Tanks accurately and to develop construction models.
Why?
Because more than 100 years ago A.Hazen (1904) suggested Newton's gravitational law. It was a fatal mistake because that Newton's law is considering just one external force in the water: gravitation. For decision this problem T. Camp (1946) offered artificial approach: "ideal settling tank" for calculate depth of Settling Tanks theoretically. However, everybody can not believe in ideal things in practice. As a result specialists in the field of World Water Industry cannot calculate correct sizes of Settling Tanks because all Global Water industry handbooks and manuals are giving traditional sedimentation theory yet.
Correct Settling Tanks Design can be done if specialists will consider three external forces acting to the any elementary volume of water: gravitation and forces of hydrodynamical pressure that normal to both sides of elementary volume and directed to the different sides. It is Newton's Second Law. Based on the Newton's Second Law I developed Alternative Sedimentation Theory. As a result everybody: scientists, engineers and even students can calculate correct sizes of Settling Tanks, create construction models and to choose effective of one.
More information on the web:
http://en.wikipedia.org/wiki/Talk%3ASettling (click "show" on the Extended content's line).
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Dear Dr. Ali hadi Ghawi,
Thank you very much for your second recommendation!!!
I am appreciate for that!!!
With best Regards,
Sadyrbek Djighitekov 
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sea water desalination
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i think the only benefit when i use 6 PV , i will use less st.st fittings 
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In many Indian states, the water contaminated with naturally occurring fluoride is a big problem. In recent years, non-thermal plasma technology has been popular to purify the drinking water. Is there possibility to remove the halide anions from the water using plasma technology?  or Can we combine the plasma technology and nano-technology to solve the such problems? 
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Thank you Prof. Bachir Achour for sharing useful links.
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Hi,
I and a colleague are from Biola University (California,USA) are currently working on a water defluoridation research project. We are very much interested in helping the water conditions in West India and possibly working with you in this. We are thinking of incorporating adsorption and electrostatic interactions in our project.
I just want to ask you what the current state of things are (in terms of defluoridation techniques and known processes) in there. And also, I saw a post of yours answering a question regarding this very topic(https://www.researchgate.net/post/Which_is_the_best_techniques_for_removal_of_the_high_fluoride_concentration_level_in_groundwater). You mentioned something about a Domestic Defluoridation unit that you have filed a patent on April 2016? Can you expound more on that?
Thank you so much,
Hannah P.
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Hello every one.
We are working on a project for some industry and we have treated its wastewater with electrocoagulation flotation (ECF) technology successfully. However because of that the final water from wastewater plant will be recycled as a process water, at the end of the wastewater system there is a reverse osmosis. The effluent from the ECF process has oil and grease= 7.5 mg/l and the oil content reduces to 4 mg/l with the aid of active carbon filter but this rate of oil is harmful for the RO. I need a process to remove this amount of oil to 0.1 mg/l (the limit for dissolved oil in water to enter RO) which process do you suggest to me!?
P.S.: 1-DAF (dissolved air flotation)can not be used since its mechanism is the same as electrocoagulation so it will not reduce any further oil.
2-Ultrafiltration is not favored because only ceramic UF should be used (because of the oil) so it will be expensive especially for treating it from 4 mg/l to 0.1 mg/l!
I appreciate your assistance in advance.
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Fluoride is major contaminant in groundwater.
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You need to synthesize selective binders such as calixpyrroles or other pyrrole derivatives for fluoride ion binding and load them on to solid nanomaterials for example magnetic nanoparticles etc. If you search on google you may get many such articles. 
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I am planning to buy an ozone generator for lab use. If I could get the website and pricing that would be very helpful.
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The very basic ones you can find on sites like aliexpress, starting from usd 20.
We have one installed on a simple timer running for 15 minutes at night.
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Some one explain, Bio fouling occurred in seawater reverse osmosis and how to control? why its happening specially below configuration of pre treatment.
Seawater+ DAF + Ultra filtration 
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Yes, interesting article Prof. Bachir,
kind Regards
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A project I'm involved with requires treatment of saline waters at approximately 10 ppt salinity. Pre-treatment will remove Ca and Mg, suppliers recommend 2 stage RO to produce maximum make water, minimum brine. However, its difficult to believe that from 60 m3 per day of above water can be treated to yield more than 60% water under 2,000 ppm TDS. Without getting into commercial discussion, is Dow membrane technology the best?
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I found out that species of Cladophora, a green algae, has a great ability to remove arsenic in water. What are the advantages and disadvantages of using phycoremediators like this instead of other chemical and physical techniques like ion exchange, filtration, reverse osmosis, etc. in terms of ecological and economic impacts?
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Dear Christine,
Phycoremediation is much cost-effective as it does not require procurement of huge equipments. Plants can be easily grown without much effort and can be monitored easily. But it is a slower process.  
With my best regards
Prof. Bachir ACHOUR
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I use a carbon-based electrode as a cathode in a divided reactor (via membrane nafion 117), in present of air the efficiencies of wastewater treatment (synthetic wastewater ; paint + electrolyte) is higher than that of the electro-fenton process (electrolyte+air+Fe(2+)).
is it possible and why?
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Dear Mohamed,
I thank you for the remark. Yes, I mean that the electro-Fenton process will give better results. For the moment, there is no better way than this process. Our colleague Erthan indicated  for Electro-Fenton process (electrolyte + air + Fe (2+)). That remains insufficient. He uses air as the oxidant and that's why the results are not good. It is better to use H2O2.
But the development of these processes in water treatment systems remains limited. The main reason is that investment costs and operating costs are significantly higher than those for conventional water treatment techniques.
In order to promote the large-scale development of OAPs, the following solutions are suggested:
1)      further adapt OAPs (oxidation advanced process) to existing water treatment plants in order to increase their effluent efficiency (with respect to emerging and refractory pollutants) without necessarily leading to the major construction of new infrastructures; (2) developing operational strategies to minimize the quantities of reagents while ensuring a purifying efficacy to achieve rejection or drinking water standards that are evolving towards increasing severity; 3) OAPs can advantageously be coupled to biological processes during the treatment of effluents containing refractory organic compounds. This type of coupling makes it possible to take advantage of the advantages of OAPs (short retention time) and of biodegradation (low operating costs). Used in synergy with biological processes, OAPs can be used to transform non-biodegradable compounds into biodegradable products or as a final treatment for the complete oxidation of organic compounds to carbon dioxide.
With my best regards
Prof. Bachir ACHOUR
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please explain the advanced methods to cure or treat the fouling 
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I am carrying out adsorption studies of thiocyanate so I want to find out the amount of thiocyanate left after adsorption.
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please follow this paper for Determination of thiocyanate using iron(III)
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I am having difficulties to find information about full-scale plants that use chitosan or chitosan derivateves for drinking or wastewater treatment (any type of waste)
Have anyone heard about such plants outside Norway?
Thank you!
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I think most papers till now still in lab.
and no full-scale plants implemented yet .
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According to the material balance carried out this required a volume of 1580 m3/h,  but is this feasible? are my calculations correct?
because I am using 40 ppt to dilute 125 ppt to 40 ppt again? is this feasible?
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No the average is always greater then 40.
also the seawater can reach up to be 33% but more than this I don't know what kind of seawater you have unless you have closed seas.
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A huge problem is reported at water filtration plant as sand filters are clogging/choking every 4-6 hours. Backwashing the filters multiple times per day is harming water treatment efficiency. Can anyone suggest a solution?
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I think you need to check suspended solids and turbidity in your raw water.  If turbidity is more than 5 NTU and you are using direct filtration than coagulant dose must be revisited otherwise you may need to add tubesettler or any form of settling before filtration.  Good luck!
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Hi all, I have a question regarding Filter Fouling.
What is your suggestion for cartridge Filters that are fouled very quickly? More Information:
Filter cartridge pore size: 0.45 micron
Membrane Material: PES Cartridge
Length: 20 inch
Purpose: Clarification of Biopharmaceutical product (about 30-40 lit) Problem: the filter is fouled very quickly
Solutions that I tried before:
washing and backwashing with NaOH 0.4 molar (not successful)
washing and backwashing with NaOCl 3.5% (not successful)
I really appreciate any help you can provide.
Many thanks, Sara
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Dear Paola, Abdorrazzagh and Craig. 
Many thanks for your kind and helpful answers. 
Regards,
Sara
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Our company uses large amounts of anthscale chemicals in the sea water desalination plant of three evaporators with capacity of 10500 cubic meteres  per day each. and to  reduce the chemical consumption we are studying the possibility of using Mediagon technology which impresses electrostatic fields in water to make scale making salts suspended as colloids and not allow them to precipitate on the pipe wall of the water box condenser. Is this technology been used in such applications or not?
your quick answer will be highly appreciated.
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Totally agree with Prof. Aiman
The pilot plant study would be a good point for starting the technology!
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I want details of sustainable technologies used in sea water treatment and how to use them in a wastewater treatment plant of a hotel  
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Reverse Osmosis is the commercially available and quite cost effective technique
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Looking for any recent research or innovations on the water treatment. Work with poor communities in rural Africa and most current treatment systems are very expensive for the community. Would there be any appropriate technology solutions? Recently drilled two boreholes near Lake Turkana with good yield but water is too salty for drinking and farming as well. Also ideas of how to use this water would be welcomed.
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 Can geothermal water serve both as feed and heat transfer for thermal desalination? I know its possible for membrane desalination technologies, but how about in thermal desalination?
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Unless prohibited by laws (of physics, etc.) most things are possible. Cost is the issue. In any heat transfer scenario, whether membrane distillation or various other thermal desalination designs, you would need to understand both the scaling potential and the corrosion potential in the process equipment. These factors will depend on the exact compositions of the geothermal brine (especially sulfur content and redox potential) and the temperature range (and for corrosion the mat's of construction involved).
I'd suggest you do some analysis first, since the impacts of scaling will really increase your potential operating costs. If you simply want to have some "fun" engineering research, study air-gap membrane distillation using newer microporous membranes that you may have access to. You can always publish research that uses new materials because of the potential for a "surprise".
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The bore well (underground) water has total hardness of 400 ppm and total alkalinity of 300 ppm. The requirement is to achieve concentrations of the above parameters as low as possible by some treatment. Water flow is around 2500 cum per hour. 
Following are the questions;
1. What are the various effective, proven &economic methods available for the same. ?
2. Can both these parameters be reduced in a single method.?
3. What is the lowest concentration values that can be achieved by such treatment?
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If you need to reduce both parameters substantially in a single process nanofiltration seems an obvious choice.
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i am making a prototype for RO desalination system and want to know the least pressure for effective freshh water production, and at that pressure what is the flow rate per unit area of the membrane?
and if you can give further articles or papers.
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You must know the feed seawater condition and the feed after chemical pretreatment from SDI, pH, TDS, and the temperature. Then you can choose the appropriate type of membranes. The least pressure, is the pressure just greater than the net driving pressure (which  depends on the feed TDS).   
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The main drawback of the Forward osmosis (FO) desalination system is the lack of efficient draw solution recovery process.
How does the recovery unit take out the draw solution from the potable water?
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Dear Nabil,
In my understanding, the methods used to separate the draw solute from water after FO depend on the properties of the draw solutes. For the commonly used inorganic salts, such as NaCl, RO is used. For the synthetic draw solutes which are the research focus in recent years, the posttreatment approaches are diverse. For example, magnetic nanoparticles which have been used as draw solutes can be separated from water via a external magnetic field. The following links are for your reference
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I measured the EEM spectra (using a fluorescence spectrophotometer) and fluorescence on molecular weight (using HPSEC-FLD) of the DOM from two different source water.
Sample A with high TOC and hydrophilic exhibited high EEM spectra, but showed low fluorescence signals across a continuous range of molecular weight.
While Sample B with low TOC and hydrophobic exhibited low EEM spectra, but showed high fluorescence signals.
Does it mean that low fluorescence signal of Sample A is affected by its hydrophilic properties? Does it indicate that Sample A has different DOM based on its molecular weight?
Thanks in advance for  sharing your opinion
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No.  Sample A has a higher ionic content which has no or little TOC (examples phosphate, sulfate...).  Only organic molecules (which have Carbon) have a TOC.
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With regards to effective removal of bacteria, virus & also for trouble free maintenance.
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Zilmil, while both UF & UV help in water purification, disinfection but the basic difference between the two lies in one being a mechnaical filteration and UV being part of a electrical system where UV light generated by a lamp at required intensity helps in altering the DNA of micro-organisms inactivating them , leaving them unable to perform vital cellular functions.
Pls accept for my apologies for a delayed reply. 
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I prepared the powder from the cactus opuntia pad and extracted using distilled water (1gm to 100ml). I did the Jar test using Cactus extract (0.1 to 5 ml per liter) but it didn't show any coagulation efficiency at both high and low turbid water.
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Dear Yirga,
The following study demonstrates the preparation method for Cactus Opuntia sp. coagulant:
In this study, the potentiality of Cactus opuntia (ficus-indica), as a coagulant for the treatment of simulated industrial water-based paint wastewater in terms of colour, chemical oxygen demand (COD) and turbidity was investigated. The coagulation ability was assessed for 1 L of effluent using the standard jar test apparatus by varying the operational variables like eluent type (water, NaCl and BaCl2), eluent concentration (1–5 N), coagulant dosage (1–6 g), coagulant volume (20–100 mL), initial pH (5–11) and initial effluent concentration (3100, 4224, 5650, 6258 and 7693 mg/L named as sample number 1–5, respectively). The results were maximum when 100 mL of 3 g of C. opuntia, eluted using 3 N NaCl was used as a coagulant to treat a litre of effluent. The favourable pH to run the treatment was confirmed as the actual pH of the sample (7.2–7.8). It was found that the removal efficiency increased as the pollution load swelled. The FTIR study revealed the presence of various functional groups, which are responsible for the coagulation process. The obtained results were compared with conventional coagulant ferric chloride. The results acknowledged that Cactus opuntia (ficus-indica) a natural, eco-friendly coagulant, could be a strong alternative to the conventional coagulant in the treatment of water-based paint wastewater.
Hoping this will be helpful,
Rafik
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From the literature I have read, most researches in water-compatible MIPs have selected methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA), and 2,2′-Azobis(2-methylpropionitrile) (AIBN), as their monomer, cross-linker, and initiator, respectively. However, little or no explanation has been given as to why these chemicals were selected.
There are several other functional monomers, cross-linkers, and free radical forming initiators that can be used to develop MIPs, so I was wondering why these chemicals seem to be the chemicals of choice across a wide range of template imprinting? Is there some sort of advantage that MAA, EGDMA, and AIBN have in this case?
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Dear Cody,
The following text taken from a review article entitled " Molecularly Imprinted Polymers: Present and Future Prospective" illustrates the reasons behind the selection of the monomer, cross-linker, and initiator {methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA), and 2,2′-Azobis(2-methylpropionitrile) (AIBN)} in MIPs preparation:
Initator:
Today, the most common method used to obtain MIPs is the free radical polymerization. Generally, the synthesis procedure is performed under mild reaction conditions (e.g., temperature lower than 80 °C and atmospheric pressure) in bulk or in solution, and it is tolerant for a wide range of functional groups and template structures. The polymerization reaction is normally very rapid; it is started by an azo-initiator, commonly azo N-N’-bis isobutyronitrile (AIBN) and by thermal or photochemical initiation. Data in literature demonstrate that photo-initiated polymerization at low temperature decreases the kinetic energy of the prepolymerization complex increasing its stability and allowing greater binding capacity and specificity than thermal initiated polymerization which requires
temperatures higher than 40 °C. Recently Athikomrattanakul et al. attempted to
prepare MIPs for nitrofurantoin recognition by thermal initiation, but was unsuccessful.
Monomer:
The choice of monomer is very important in order to create highly specific cavities designed for the template molecule. Typical functional monomers (Figure 4) are carboxylic acids (acrylic acid, methacrylic acid, vinylbenzoic acid), sulphonic acids (2-acrylamido-2-methylpropane sulphonic acid), heteroaromatic bases (vinylpyridine, vinylimidazole). In the non-covalent approach they are normally
used in excess compared to the template to favor the formation of template-monomer assemblies. In fact, association between the monomer and the template is governed by an equilibrium, and the functional monomers normally have to be added in excess, relative to the number of moles of the template to favor the formation of the complex, with template:functional monomer ratios typically of 1:4. Consequently, this led to a number of different configurations of the template-functional monomer complex, which produced a heterogeneous binding site distribution in the final MIP, with a range of affinity constants. The extensive use of methacrylic acid (MAA) is due to its capability to
act both as hydrogen bond and proton donor and as hydrogen bond acceptor.
Cross linker:
In imprinted polymers synthesis, the cross-linker also fulfils important functions. The cross-linker is important in controlling the morphology of the polymer matrix, serves to stabilize the imprinted binding sites and imparts mechanical stability to the polymer matrix in order to retain its molecular recognition capability. Different cross-linkers have been used. High cross-link ratios are generally used in order to access permanently porous (macroporous) materials with adequate mechanical stability. Ethylene glycol dimethacrylate (EGDMA) and trimethylolpropane trimethacrylate
(TRIM) are the most commonly employed. Some authors found that cross-linker has a major impact on the physical characteristics of the polymers and much less effect on the specific interactions between the template and functional monomers. TRIM as cross-linker gives polymers with more rigidity, structure order and effective binding sites than EGDMA. In the case of polymerization obtained by precipitation method, it has been seen that optimizing the amount of cross-linker and reducing the concentration of the template, the polymer binding properties are improved and the level of non-specific interactions is decreased. In another study it has been observed that the type of cross-linker strongly influences the final size and yield of MIP nanoparticles. In fact, when divinylbenzene was used as the cross-linker, polydisperse MIP particles were obtained in low yield, whereas, trimethylolpropane trimethacrylate (TRIM) led to uniform nanoparticles in high yield (90%). 
For more on this topic, please see the review article contained in the attached file.
Hoping this will be helpful,
Rafik
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Formaldehyde starting concentration (40000 mg/L), COD starting concentration 60000mg/l).
UV-fenton worked fine but not to the required level (<10mg/l for formaldehyde and <1000 mg/L for COD), is there any other post treatment available such as flocculants, coagulants that may help.
Thanks
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Dear Max,
A recent review article entitled "A review on application of flocculants in
wastewater treatment " describes the use of biopolymers based flocculants to reduce COD and organic substances. The tables contained in the review depict the names of the flocculants and their removal efficiency towards COD and organic substances (see attached file).
I suggest that after the use of flocculation, to conduct biological treatment which should be followed by oxidation processes.
The following link and attached two files contain: (1) a review on the use of flocculants, (2) a publication on the biological treatment and (3)  a publication on the use of selected Advanced Oxidation Processes (AOPs) for the removal of formaldehyde:
Hoping this will be helpful,
Rafik
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I am modeling my protocol after the methodology described in Asaoka et al., 2015, A membrane extraction method for trace level phosphate analysis. I'm wondering if anyone else has tried this method. 
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High sink strength Fe oxide and anion exchange strips are used in soil research used in research  on soil P
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Where can I find free research papers on the above topic please?
Tasks:
1. Review of fouling and scaling mechanisms in desalination
2. Mitigation assessment of the above
3. Carry out a sustainability study which includes environmental aspect, safety and economic aspects.
Requirements:
1. Prediction of fouling behaviour
2. Methods to overcome the key challenges to the processes.
3. Emperical/semi-theoretical calculations
Application of:
Reaction Engineering
Unit Operation
Thermodynamics
Chemical Process Safety
Heat and Mass Transfer
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Hi Nishtha,  Please find attached publication which could be beneficial for your work.
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Understanding the fundamental operation of trickling filters and activated sludge process is essential. 
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Dear Abdul-Kadri,
Biological trickling filters and the activated sludge process have demonstrated 100 years of consistent and reliable operation. Filters require an efficient influent screenings system and normally follow a primary settling stage. They can tolerate 25% over-load conditions and can be expected to produce a well nitrified effluent with suspended solids 30 mg/L and BOD 20 mg/L. They do not remove nutrients. Distribution nozzles require regular cleaning and distribution seals an annual check. The most common problems are ponding on the media surface and possibly nuisance from midges. They require 10x more land than activated sludge but use 10x less power as the oxygen is supplied by natural ventilation. Activated sludge plants typically achieve an effluent with suspended solids 15mg/L and BOD 10 mg/L and can be designed to remove nutrients. They are less tolerant of organic over-loads, toxins and in particular low dissolved oxygen all of which can result in bulking and solids washout. They require more electrical and mechanical maintenance and need trained and knowledgeable operators.
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Some of RO water purification system used stage of minerals filter which is consists of coarse ball particles called "MT-T33-GAC-1020" there's no information about this medium. Any body has information of that kind of medium ?
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Dear Mustafa,
They are used in post In-line filters contain coco nut shell which are design to reduce unwanted odor, taste, and chlorine, improved taste. Choice of polypropylene media used for sediment removal. In-line filters are an ideal choice of final polishing filter in home reverse osmosis drinking water systems, ice maker, and food service application. Martin GAC post In-line filter comply with NSF Standard.
  
Feature
Efficient removal of chlorine and organic chemicals
Improve the taste of water
Installation eliminates the need for additional filter housing
Competitively priced carbon filters
 Ideal for f\residential and commercial applications
 All in-line filters include a pre- and post-filter
Application
Pre and post RO
Refrigerator
 Ice maker
l  Drinking water purify
For more on this, please use the following link:
Hoping this will be helpful,
Rafik
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I am a WASH and urban development specialist living and working in East Africa. I am attempting to scope out “temporary” solutions to sanitation and waste challenges in large unplanned settlements in Dar es Salaam and Nairobi and am looking to receive feedback/critique/advice. I understand these solutions do not sound politically/technologically correct, but with local resource limitations, I seek to identify low-cost, non-motorised and intuitive methods that can be implemented quickly on the ground.
What solutions can be sourced locally, easily and affordably to mitigate the risks of high fluoride levels in tap/well water (e.g. bone char, condensation, boiling)? Mechanised and complex solutions (while noted as more effective) are unrealistic in local contexts due to costs, lack of skills, etc. 
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Bone char is a well known method that has been developed for removing fluoride from drinking water in Tanzania.
My institute was involved in this research 15 years ago. I think the engineering faculty in University of Dar-Es-Salaam are still working on this technology. 
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What maximum concentration of per-sulfate for degradation purpose is allowed or should be used. In my case 5mM is having good efficiency but my supervisor insists on using not more than 2mM. Is there any cut off value for any reason?
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Dear Sauleha,
Generally, persulfate is used in a concentration range of 1000 and 2000 uM (micromolar) and this concentration is very effective in the degradation of micropollutants . Increasing the concentration to more than 2000 uM is not expected to enhance the effectiveness of persulfate.
For more on this topic, please see the publication contained in the following link:
Hoping this will be helpful,
Rafik
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I want to use ZnO nanoparticles in water reatment. But I do not know what concentrations are more appropriate response.
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Dear Hasan, three PDF articles attached. Two are from closed sources...
Wishes, Andrey
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What is the best method to estimate water resistivity knowing the salinity/chlorinity and formation temperature?
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Dear Matteo,
The simplest method is the measurement of the resistivity by reading a resistivity device. In the absence of such a device, you can take the measure
of the resistivity by the "method of the pipe", the results are relatively
imprecise, especially for conductive water and whose implementation
work requires certain precautions.
With my best regards
Prof. Bachir ACHOUR
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I am working on a proyect to apply electrolysis to water with neonicotinoids in order to break these compounds and decontaminate the water. So far I've tried dilute HCl and an ethanol+alcohol+couple drops of acid electrolytes but I keep only getting the water electrolysis and my compound is not changed. Suggestions on what electrolyte I can use? I've thought about salts like NaCl, Na2SO4, etc. but haven't tried these. I'm using two Pt electrodes.
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Thanks Rafik! I was not aware of the method of sonication and appreciate the hint. I'm working specifically with Imidacloprid and have been performing electrolysis on dilute HCl with some Imidacloprid dissolved in it, so nothing as complex as sonication. Will continue to work on this decontamination and take your suggestion into account.
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Due to water scarcity it might be wise to collect urban run-off for various purposes. How one can develop a sound monitoring plan to check out the quality of urban run-off for various purposes? What type of online equipment is necessary? What are the costs? Is there any software to bring out the appropriate location of online monitoring stations? What type of water parameters should be monitored? 
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Howdy, A.R.,
It is not only  a good idea. In my country (Belgium) when folks build new houses or appartments or whatever buidling its obligatory by law to:
1. Insulate a newly built  house or any other type of new buidling , so that energy is not wasted during the winter, spring and autumn seasons;
2. Collect all precipiatation, whether as snow, hail or rain from the rooftops into a subsurface reservoir of about at least 5 cubic meters (5000 liters of water). This so-called gray  water MUST obligatorily be used to flush toilets, wash cars, irrigate gardens, clean stone floors, wash clothes,...
3° Last but not least a citizen building a new house is oblighed by law to rpovide electricity for the house using photo-vlotaic solar cells.
People not following these law imposed investmennts lose the buidling and encironemntal permits to build a house or wahetever buidling.
That's what the law imposes in my country with regard to collceting precipitation run-off from roofs of housing, buildings or whatever has a roof.
Mean precipitation level in my country is about 1200 mm, hence we never have water shortages. MOroever, the population has to recycle everything that is reclable. This has led to an almost closed material cycle for many chemicals and products over the last 20 years. The recycling percentage is over 70%.
So, welcome in Belgium. Called a failed state by the English UKIP party. Can you dig that?
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Does it matter to use different oven (vacuum and normal lab oven) because last time I used the normal oven, the SPEEK polymer was a bit overdried.
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first of all, I think it depends on the degree of sulfonation of your sPEEK and the solvent you used for casting. I'm trying putting it in the 60 C oven for 48 h and then in the vacuum oven heated to 120 C overnight (solvent:NMP, DS around 55%).
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We are working on effects of Moringa oleifera and charcoal filters in water purification.....both drinking and sewage waters and studying the presence of certain groups of bacteria e.g coliforms. We want to broaden the research and include the presence and absence of biofilms in the study but do not know how to go about this....your help will be appreciated...even links to materials that can assist us in this study
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I will strat with a simple hypothesis and methode. You could use a filtered bacterial suspension throught a charcoal filter then put it on a 0.22µm mitrocellulose filter and place the two filters onto a solide agar plate (nitrocellulose in touch with the agar). After incubation, remove the charcoal filter and stain the bacteria using live/dead fluorescent dye  and observe using epifluorescence or CLM.
It's one technics to obtain biofilm on a fiberglass filter which is placed onto a 0.22µm filter before incubation. Here, you will use the charcoal filter instead of the fiberglass. 
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My research work is on Removal of Iron from drinking water using ion exchange resins. For that, initially I am using resins to remove iron from standard iron solution to find out the optimum time for highest % removal but after maintaining the pH to 6-7 and then treating the standard solution with resins and adding hydroxylamine, 1,10-phenanthroline, sodium acetate I want to know what is the maximum time that one can leave the solution for color development before going for spectrometer testing.
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Dear Sir,
But the addition of NaOH and HCl to maintain the pH dilutes the color and so the observed absorbance is generally lower than the actual absorbance of the solution. So, should the absorbance be multiplied with a dilution factor? 
Also, the color developed darkens when left for a day when Base and acids are added to maintain pH. 
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I am studying about Jartest experiment. And I am struggling with some definitions: restabilization, charge neutralization, and sweep floc. What happen when these phenomena occur in coagulation process; and if I do the experiment, how can I determine the result of my experiment is sweep floc, charge neutralization or restabilization?
Please help me if you know about this, thank you!
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Dear Hoang Minh Le,
The coagulation/flocculation (C/F) processes are mainly due to charge neutralisation and sweep flocculation mechanisms. However, the SF mechanism has also its CN property moreover than its well-known weighting characteristic. On this weighting characteristic, the literature has usually focused without taking in consideration the SF’s CN property. This review discusses the implicated mechanisms in destabilisation of colloids and aggregation of flocs. Colloids are very small particles that have extremely large surface area. The consequence of this smallness in size and mass and largeness in surface area is that in colloidal suspensions: gravitational effects are negligible and surface phenomena predominate. Hence, during C/F process, colloids are removed by CN and SF mechanisms which act on the anionic charge of the colloid by its neutralisation prior to its removal by sedimentation/filtration. The sweep flocs can be described as large aggregates of Al(OH)3/Fe(OH)3 that are formed when Al/Fe salt is added to water. Further,sweep flocs are positively charged and the colloids of clay minerals abundantly found in the water are negatively charged. As a result, the colloidal particles are electrostatically attached to the sweep flocs in the neutral pH water as to the hydrolysed metalliccations. Even if researches have greatly elucidated the growth, breaking and the re-growth of flocs, further research is required to understand CN and SF mechanisms and optimise the C/F process at the nano level.
Restabilization  - Enhance the the forces acting to keep the particles apart after they contact each other (i.e., lower repulsion forces).
Dosing  Strategies  (for hydrolyzing metal salts)
Define zones of  effectiveness:
Zone 1:  Low dosage, insufficient coagulant added to produce destabilization.
Zone 2: Dosage sufficient to cause efficient and rapid destabilization
Zone 3: Dosage high enough to cause restabilization  (charge reversal or polymer –foldback)
Zone 4: Dosage high enough to get sweep floc which results in good  destabilization.
Regards,
Prem Baboo
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The unit must be small scale, and lightweight. The raw materials used must be from natural resources
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There are a variety of home water treatment systems available on the market.  You may be able to apply or downsize one of these whole house systems, and add in reverse osmosis system or boiling the treated water for drinking.  Survivalists use a small pump to pull water through a porous ceramic cup and possibly activated charcoal before boiling or adding chlorine for drinking.  Its a good idea as long as the user understands the limits as well as when to avoid polluted waters, how often to do testing, conditions when lake water is more apt to be polluted as after major storm events, industrial, agriculture, mining, urban pollutant possibility, etc.  I am not in computer, but will try to send you a good publication on drinking water from forests and grasslands.
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Project title : Removal of phosphate ion using cassava peel activated carbon and steel slag
Electric Arc Furnace Slag (EAFS)as media filters to remove synthetic phosphate ion.Removal of phosphate will be check using discrete analyzer
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Dear Chew Xian Cheng,
The following is a recent review article published in Enironmental Technology Review (2016) describes the use of slag in many areas including wastewater and water treatment which may be helpful:
Environmental Technology Reviews
Production and applications of electric-arc-furnace slag as solid waste in environmental technologies: a review
Reviews
DOI:10.1080/21622515.2016.1147615
Soraya Hosseinia*, Salman Masoudi Soltanib, Paul S. Fennellb, Thomas S.Y. Choongc & Mohamed Kheireddine Arouaa
Published online: 21 Mar 2016
Abstract
Slag, a by-product of steelmaking industries, has invaluable potentials for various environmental applications. Slag is generally produced in different types of furnaces working under various operating conditions and contains alumina, calcium oxide, silica and so on. Physical and chemical properties of a typical slag dictate the distinct methods of slag solidification including air cooling, steam introduction and injection of additives. Owing to this uniquely-widespread range of properties, slags are being increasingly considered attractive materials in a broad range of applications. They are widely used in transportation industry, construction, and cement manufacturing as well as wastewater and water treatment. This makes slag an important substitute for natural resources, leading to significant minimization in natural resource utilization. This paper walks through a comprehensive essay of steelmaking slag retained in a wide range of furnaces, their modifications and their applications alike.
Hoping this will be helpful,
rafik
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dear all, i am a chemical engineer working in International petrochemical (pvt) limited. We have a sodium sulfate plant and we have 3 evaporators at site. About 1.3 tons of water is being evaporated per hour. And the heated vapors are being wasted in air. I want to recover those vapors some how. For that i am considering 2 Options right now.
1- Mechanical Vapors re-compressor.
2- Thermal Vapors Re-compressor.
The pressure of steam available is about 75 psi. Kindly tell me the Right proposal for the right action in terms of cost and optimization.
Best Regards
Muhammad Fahd
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I think that if you have a steam at 75 psi is more convenient a TVC.
MVC use only electrical power and the steam can not be used.
With 1.3 ton of steam you can produce 8 -10 tons per hour of distillate water.
Giorgio
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Am working on the Ballast Water Management System, where we use a UV sterilization unit.
According to some previous studies a minimum sterilization dose of 16,000 micro Watt seconds per cm2 is required and most of the UV sterilization manufacturers uses a range between 30,000 to 50,000 micro Watt seconds per cm2.   Is this the right assumption?
What is the right UV sterilization dose that can be used for treating the Ballast Water (sea water)?
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please give information about usuage of different sand media in water treatment?
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Dear Chiru Chiranjeevi,
Sand filters are used for water purification. There are three main types;
1-Rapid (gravity) sand filters
2-Upflow sand filters
3-sSlow sand filters
All three methods are used extensively in the water industry throughout the world. The first two require the use of flocculant chemicals to work effectively while slow sand filters can produce very high quality water free from pathogens, taste and odor without the need for chemical aids.
A sand bed filter is a kind of depth filter. Broadly, there are two types of filter for separating particulate solids from fluids:
Surface filters, where particulates are captured on a permeable surface
Depth filters, where particulates are captured within a porous body of material.
In addition, there are passive and active devices for causing solid-liquid separation such as settling tanks, self-cleaning screen filters, hydrocyclones and centrifuges.
There are several kinds of depth filter, some employing fibrous material and others employing granular materials. Sand bed filters are an example of a granular loose media depth filter. They are usually used to separate small amounts (<10 parts per million or <10 g per cubic metre) of fine solids (<100 micrometres) from aqueous solutions. In addition, they are usually used to purify the fluid rather than capture the solids as a valuable material. Therefore they find most of their uses in liquid effluent (wastewater) treatment.
Particulate solids capture mechanisms
Sand bed filters work by providing the particulate solids with many opportunities to be captured on the surface of a sand grain. As fluid flows through the porous sand along a tortuous route, the particulates come close to sand grains. They can be captured by one of several mechanisms:
Direct collision
Van der Waals or London force attraction
Surface charge attraction
Diffusion.
Operating regimes
They can be operated either with upward flowing fluids or downward flowing fluids the latter being much more usual. For downward flowing devices the fluid can flow under pressure or by gravity alone. Pressure sand bed filters tend to be used in industrial applications and often referred to as rapid sand bed filters. Gravity fed units are used in water purification especially drinking water and these filters have found wide use in developing countries (slow sand filters).
Overall, there are several categories of sand bed filter:
rapid (gravity) sand filters
rapid (pressure) sand bed filters
upflow sand filters
slow sand filters.
Rapid pressure sand bed filter design
Smaller sand grains provide more surface area and therefore a higher decontamination of the inlet water, but it also requires more pumping energy to drive the fluid through the bed. A compromise is that most rapid pressure sand bed filters use grains in the range 0.6 to 1.2 mm although for specialist applications other sizes may be specified. Larger feed particles (>100 micrometres) will tend to block the pores of the bed and turn it into a surface filter that blinds rapidly. Larger sand grains can be used to overcome this problem, but if significant amounts of large solids are in the feed they need to be removed upstream of the sand bed filter by a process such as settling.
Operating parameters for rapid pressure sand bed filters
Rapid pressure sand bed filters are typically operated with a feed pressure of 2 to 5 bar(a) (28 to 70 psi(a)). The pressure drop across a clean sand bed is usually very low. It builds as particulate solids are captured on the bed. Particulate solids are not captured uniformly with depth, more are captured higher up with bed with the concentration gradient decaying exponentially.
Uses in water treatment
All of these methods are used extensively in the water industry throughout the world. The first three in the list above require the use of flocculant chemicals to work effectively. Slow sand filters can produce very high quality water free from pathogens, taste and odor without the need for chemical aids.
Multimedia Filtration
Pressure vessels with sand or other loose media are widely used in industrial filtration applications. During the cleaning cycle, called "backwash", the bed is lifted (or "fluidized") to loosen the filter media and release trapped dirt which is removed in the backwash flow.
After the backwash cycle, the bed is allowed to settle before the filter is returned to service (i.e., normal flow). A "filter-to-waste" cycle is used following the settling to assure the filtration media has sufficiently re-stratified and that any loose dirt is removed from the underdrain / collectors.
Multimedia filtration refers to a pressure filter vessel which utilizes three or more different media as opposed to a "sand filter" that typically uses one grade of sand alone as the filtration media. In a single media filter, during the "settling" cycle, the finest or smallest media particles remain on top of the media bed while the larger, and heavier particles, stratify proportional to their mass lower in the filter. This results in very limited use of the media depth since virtually all filterable particles are trapped at the very top of the filter bed or within 1-2 inches of the top where the filter media particles have the least space between them. The filter run times are thus very short before the filter "blinds" or develops so much head pressure that it must be backwashed to avoid seriously impeding or stopping the flow.
Multi media filters typically utilize three layers of media for multimedia filtration: anthracite, sand and garnet. These media are often chosen for use in multi media filters due to the distinct differences in their densities. Anthracite is the lightest filtration media per unit volume, followed by sand, and then garnet.
The idea behind using media with differing masses is that during backwashing the lightest media with the largest particles (anthracite) will naturally stratify at the top of the filter, while the intermediate sized media (sand) will settle in the middle, and the heaviest media with the smallest particles (garnet) will settle to the bottom.
This layering of the filtration bed encourages the very largest contaminants to become trapped in the first layer of the filter, with smaller particulates sifting farther down into the lower layers. Trapping contaminants in this manner allows for more efficient turbidity removal and for longer run times between backwash cycles. A simple sand filter can be expected to eliminate particles down to 25-50 microns in size, as compared to a multi media filter that can remove particles down to 10-25 microns.
Operating at higher pressure differential is liable to drive particles so deeply into the media bed that backwash is not able to remove them all. Over time the build-up of dirt deep in the filter will cause shortened filter runs and high differential pressures. Filter backwash may include air scour to help loosen packed dirt in the media bed. When this step is included, it is preceded in the backwash cycle by a "drain down" period for water to be bled out of the filter vessel.
Flocculants / coagulants may be used upstream of the filter to induce the tiny dirt particles to join together to form particles large enough to be removed by the filter. This process is called "agglomeration" and, with proper chemical dosage, adequate mixing and adequate contact time, it will enable the filter to remove particles below 10 microns in average diameter.
The Benefits of Multimedia Filtration over Conventional Sand Filters
Unlike traditional sand filters, multi-media water filters are composed of three filtration media, ordered in decreasing porosity. Because of their multi-layer design, multi-media water filters are able to trap and retain a far larger number of particles than traditional sand filters before backwashing becomes necessary.
Trapping sediment and particulates throughout the entire depth of the filter bed, allows multi-media water filters to operate for much longer periods of time than conventional sand filters. The process of multimedia filtration produces high quality, filtered water at much faster flow rates than traditional sand filtration.
Rushton, A, Ward, A S and Holdich, R G (1996). Introduction to Solid-Liquid Filtration and Separation Technology. Wiley VCH. ISBN 978-3-527-28613-3
Coulson, J M; Richardson, J F; Backhurst, J R and Harker, J H (1991). Chemical Engineering. Vol.2, 4th Ed. ISBN 0-7506-2942-8.
 Ives, K J (1990). "Deep Bed Filtration." Chap. 11 of Solid-Liquid Separation, 3rd Ed., Svarovsky L (ed). Butterworths. ISBN 0-408-03765-2
The following links contain studies using different sand types for the filtration of water from variety of sources:
Abstract
 Water samples were taken from three different shallow wells in Abeokuta, Ogun state Nigeria (West Africa). These wells are represented by as raw water A, B and C and were filtered using sand as filter media, sand grains of different sizes was used. The raw water was filtered with fine sand (column 1), coarse sand (Column 2) and very coarse sand (column 3), these loadings are homogenous and the fourth column contains there three sand layers. The filtered water was subjected to laboratory analysis which includes the following: pH value, TDS (Total dissolved solids), EC (Electrical conductivity), TS (Total Suspended Solid), Calcium, Magnesium, Potassium, Hardness and Sodium. The obtained laboratory test results were compared with W.H.O standard for highest desirable and maximum permissible. One way ANOVA and bar Chart are the statistical tools employed in analyzing the data. The fine sand homogenous filter gives the best output, and then followed by the coarse sand, and then the mixture of the sand also gives preferable outputs. The homogenous fine sand media flow rate was slower but give the best output. In situation where sand particles is very small, bed depth is very high, minimal or no chemical treatment will be required after filtration.
2-https://www.google.ps/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwiM9qbwpqjMAhXkFZoKHc3iDlYQIAgvMAI&url=http%3A%2F%2Fwebcache.googleusercontent.com%2Fsearch%3Fq%3Dcache%3AV-yq9ZDIv7QJ%3Awww.hach.com%2Fasset-get.download.jsa%253Fid%253D18374278952%2B%26cd%3D3%26hl%3Den%26ct%3Dclnk%26gl%3Dps&usg=AFQjCNHCw7DmGvzRp6JtCVPdpUaWrBWREg&sig2=jMH-ZAtNdrrKL-ZYBv1omQ
Granular Media Filtration for Water Treatment Applications
Terry Engelhardt
Application Development Manager – Drinking Water
Hach Company
Drinking Water Treatment - Filtration
How drinking water filtration works
Filtration systems are used most often in home water treatment to remove sediment or iron, manganese, or sulfur particles. Filtration can also remove some bacteria from water. In mechanical filtration systems, water passes through a medium such as cloth or sand. Particles become trapped on the surface of or within the medium. The pore size, or space between media granules or fibers, determines what size particles a filter can remove.
Filters are rated according to the smallest particle they can trap. The filter opening size to use depends upon the material to be removed by the filter. A smaller size will satisfy removal requirements but will require more frequent cleaning or replacement of the filter. When these filters are used to pre-treat water for other water treatment devices, such as a reverse osmosis unit, follow the manufacturer’s recommendations.
Surface or screen filters remove the particles at or very near the filter surface. They function very much like a screen; particles of a certain size and larger are retained at the surface while smaller ones move through the openings.
Depth filters have a thick filter medium. Particles are retained throughout the thick filter mat. Depth filters have a gradation in the size of the filter media so that the largest particles are held at or near the filter surface, while progressively smaller particles are captured deeper in the filter where the filter media becomes smaller.
Either filter type may be used for a wide range of particles sizes.
Types of drinking water filters
There are many different types of filters used in drinking water filtration units. They differ in design, cost, and effectiveness. Before purchasing a system, verify that the treatment system you are purchasing has been tested and certified by a third party (for example, National Sanitation Foundation)to ensure manufacturer’s claims. Mechanical filtration systems include cartridge sediment filters, media and multimedia filters, and precoat filters. Which filtration method to select depends on the concentration and size of the suspended solids in the water and the rate at which water needs to be treated. Media filters such as sand filters have a greater contaminant removal capacity than other types of filtration devices. However, cartridge filters with fiber or ceramic filter material are made with a smaller and more uniform pore size and can be more reliable in removing small particles.
Hoping this will be helpful,
Rafik
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probiotics have any wastewater treatment is the tanning? research and evaluate its ability to process less
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A post ozonation is a huge consumer of electrical energy, the goal is to optimize the delivered dose and optimize operating costs.
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I think the only method is to make laboratory experiments that simulate the treatment. Apply different doses of ozone and investigate the resulting quality of the water.
To estimate very roughly the dose without the laboratory experiment I would normalise the ozone applied in similar facilities to the treated waters dissolved organic carbon (DOC). 
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If we collect water after a few cycles of cooling and vaporizing, is there any change in the fundamental properties of water? Reasons?
Here, I am not concerned about water purification or treatment, but with the fundamental qualities as in crystal structure, other physical properties etc.
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Dr. Mikhail, thank you for your comments.
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Looking for physical chemical properties (i.e., octonal-water partition coefficient, pKa value, polarity, dipole moment, ionization potential, etc.), of trace organics to use in my research project. Most references I found only have basic parameters such as water solubility, molecular weight and in some instances pKa value.
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You may wish to obtain access to Aspentech HYSYS or Aspen Plus. Both have large libraries of thermodynamic properties of various organic constituents. They also subscribe to numerous other data libraries. You can also model the probable interactions using the Gibbs Free Energy reactor, and model adsorption, stripping and other common removal techniques. Ideally you will have actual operating data to validate any model.
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i want to know, if small portion of antiscalant is used for chemical cleaning of RO membranes, or not. if it can, in what percentage.
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Dear Suresh Vanik,
All reverse osmosis (RO) feed waters are different in ionic composition. As a result, different types of scale may deposit on the membranes if the correct antiscalant is not used. Selecting the right antiscalant and cleaning chemicals will optimise operating efficiency and help to prevent plant failure.
Below a list of some of the most common types of scales that were identified on RO membranes during autopsy procedures and the appropriate chemicals to use.
Always a membrane autopsy is recommended  to ensure deposits are correctly identified. 
Scale Species Information Antiscalant Cleaners
 
Calcium Carbonate is the most common scale found in membranes. Appears as an off white powder. Easily cleaned with a strong acid product.Genesys LFGenesol 37 and 38
 
 Silica - can be present on a membrane as colloids, aluminosilicates on the lead membrane elements, or as scale on the final elements. Both forms are difficult to remove, being dependent on pH and temperature.Genesys SIGenesol 40 or 703, depending on colloidal or silica scale
 
 Calcium sulphate (gypsum) - crystalline structure with very sharp blade-like features, which cut the membrane surface. Common occurrence in areas where there is a natural sulphate content in the underlying geology. This makes it very difficult to clean.Genesys CASGenesol 50, 34 and 703
Difficult to clean - ask us for advice on cleaning protocol design
 
 Calcium phosphate - appears in many forms. Commonly found in RO membrane systems fed with waste water or agricultural leachate, due to the high phosphate loading.Genesys PHOGenesol 37 and 38
 
 Magnesium hydroxide (brucite) - precipitates at high pH, above 9.5, in membrane systems. Can be found in second pass elevated pH brackish water boron rejection plants, where pH levels are increased above 9.5 with sodium hydroxide to aid boron rejection. Relatively rare.Genesys MGGenesol 37 and 38
  
Barium sulphate (barite) - appears as white crystals, which can take on-blade like formations. Very difficult to clean effectively.Genesys BSGenesol 50 and 34
Difficult to clean - ask us for advice on cleaning protocol design
 
 Strontium sulphate (celestine) - appears as crystals or as needles, which can damage the membrane surface. Very difficult to remove.Genesys CASGenesol 50 and 34
Difficult to clean - ask us for advice on cleaning protocol design.
To view the full publication with figures illustrating the scale species, please use the following link:
Hoping this will be helpful,
Rafik
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My research team have an intention to build the water purifier that can separate a water from its dissolved metal ions. The previous research told that the waste water (we will take that water as a sample) contains thousand times more of amount of chromium ions than the drinkable water
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 The traditional NF membrane is a thin-film composite formed from piperazine (PIP) and tri-mesoyl chloride, typically on top of a polysulfone or polyethersulfone support.  Such a membrane yields >97% rejection of MgSO4.
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How can I dry molecular sieves? Size good good for water?
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Suitable methods are calcination at normal pressure or in vacuum (usually in oil-pump vacuum) http://www.sigmaaldrich.com/chemistry/chemicalsynthesis/learning-center/technical-bulletins/al-1430/molecular-sieves.html
Vacuum drying is much faster (~20 min) and need lower temperatures ( 200oC of heating bath is enough for all types)
3A-type is best, 4A is satisfactory for water
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I'm studying the desorption of a dye from an already loaded biomass. Knowing already the initial dye concentration used during the adsorption phase and the adsorbed quantity of the pollutant, I tried to study the desorption of the dye for a possible regeneration.
A succession of identical desorption experiments was made and the final concentrations at equilibrium were recorded for 5 cycles. It's logistically impossible as you know to do the desorption experiment for over hundreds of cycles. So what I'm seeking is a mathematical solution to predict the number of cycles needed for a complete desorption of dye from the biomass.
Thank you.
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I had an idea for you consider.  If you use a fluorescent dye, you could use a fluorometer to test the concentration as the dye concentration declined to very low levels.  You might be able to set up a recirculating flow apparatus, that would recirculate a given amount of liquid such as 1 liter of water for an hour.  Each hour, you take a sample, drain the rest of liter, and add a fresh clean liter of water.  Continue to do the same as long as you care to.  Or turn off, come back next morning and start again.  Plot the time on x axis and concentration on y axis.  At some point you will be able to predict either  zero or very low concentration.  You will probably need semilog paper, so predicting a zero concentration would be impossible.  Of course you know, different pollutants may be absorbed and retained differently, and this could vary with substrate.  You can enter data into statistical package or perhaps even excel to define an equation on the concentration decline with time or rinses.  You probablt will not have a straight line, so log or exponential curve is likely.  If you dont care about the rinsing number (ie, how many rinses are needed), you could just set up a continous flow through system, and monitor dye concentration loss with time.  If you meter the flow rate, you may want to know that also.  The concentrated fluorescent dye would have to get diluted probably millions of times before you can even read it on a fluorometer.  So if you can see the dye at all, your sample will need a lot of dilution to get a reading.  Perhaps the high concentrations can be read on a colorimeter.  There is some information on using fluorescent dye in pesticide mix to help predict when water samples needed to be sent to lab for pesticide analysis.  The report on my researchgate site has a moth on the cover page (spruce budworm).
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I am searching for alternative material for filtration in Bioretention basin to Silica which would be environmentally feasible ? Research paper shows Glass cullet have similar infiltration and water purification as Silica but depends upon particle angularity, contaminent level, organic contents and size. Fly Ash obtained from furnaces also purifies water but decreases water infiltration in ground .I will be doing combination of Silica Cullet, Silica cullet fly ash, and fly ash silica combinations in Constant head permeability test. Can you please suggest any other substance with similar Hydraulic properties to Silica ? Also best combinations of Silica, Glass, Fly ash for experiment because different papers uses different combinations. Whole idea is material should improve water quality and best infiltration. Can any body help ?
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material with high phosphorus sorption are suitable for bioretention filter media. Materials are fly ash, two expanded shales, peat moss, limestone, and soils ,loam and sand. The peat moss is a phosphorus source, while the two soils, limestone, and one expanded shale have only modest sorption capacity.
One expanded shale and the fly ash have significant phosphorus sorption. Fly ash is unsuitable for use in a pure form, as a result of its low permeability, but phosphorus sorption on the sand increases significantly with the incorporation of small amounts of fly ash.Media modified with metal-silica hybrid materials suitable for areas where high filtration and partial recharge of runoff.