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Liquid Filtration

Liquid Filtration by Ernest Mayer, DuPont

Ernest Mayer is a senior consultant with DuPont, Wilmington, Del. He has specialized in solid/liquid separation since 1980, with a particular emphasis on environmental applications and filter media characterization. He also has taught many internal courses on solid/liquid separation and written more than 200 papers. He is chairman of the Users Committee of the American Filtration and Separations Society and winner of the society’s 2005 Lifetime Achievement Award.

Is there equipment that filters, washes and dries?
Is there any equipment that is used as reaction (precipitation) plus filtration plus solvent wash plus filtration cum dryer in series? Such equipment can reduce capital cost significantly and also result in almost no solids handling, since in our case dried product has to be dissolved in a solvent.
Category: Liquid Filtration

What is the best filter for handling toxic substances?
In case of closed filtration of solvent with solutes >50 micron, what is the best filter available for batch operation, with respect to fewer solid handling problems, ease of operation and comparatively economical in the pesticide industry with hazardous product? Is the Nustche filter a reasonable choice?
Category: Liquid Filtration

Is there a low-cost filtration method that can remove the majority of solids?
We are treating anaerobically digester slurry from farming operations. A solids separator followed by gravity-fed screens leaves us with an 85 degree F liquid that still has a suspended solids content of 15000 mg/L (1.5%). The particle size is < 50 microns with a steep drop off below 20 micron. So still a high volume of relatively small particles need to be economically removed.
Category: Liquid Filtration

What's The Best Way To Filter Activated Clay?
I have a slurry of used lubricating oil containing activated clay. The intention is to regenerate the used oil. However, the slurry could not pass the stainless filter. I thought about using a cloth filter. What do you suggest?
Category: Liquid Filtration

Extracting Maximum Oil From The Slurry
We have a slurry of 50% solid concentration with solvent, hexane and oil. For closed/gas tight filtration, what you will suggest for 10 to 80 micron particles to get separated and extract maximum oil?
Category: Liquid Filtration

Finding An Appropriate Filter
What is your recommendation for an appropriate filter for the filtration of 90% concentration by weight Ammonium Nitrate solutions as per the following specs: (1.) Temperature = 90 to 110 degrees C (2.) Ph = 4.8- to 5.2 sp Gravity is 1.3 - 1.4 (3.) Liquor contains water, Ammonium Nitrate, mud/insoluble inorganics of size varying from 0.5 microns to a few hundred microns, organic coating agents that float as scum. (4.) We are interested in a continuous filter, minimum turbidity (5.) Other objective is to use Minimum quantity of water for cake washing. (6.) Caution: Process medium is corrosive. Presently our storage tanks/pumps are made of SS316. Filtration capacity requirement is around 8 - 10 m3/hr
Category: Liquid Filtration

Vacuum Belt Filters vs. Ceramic Disc Filters
What are the main differences between vacuum belt filters and ceramic disc filters in terms of capital and operational costs?
Category: Liquid Filtration

Finding a Filtration Scheme that Filters Properly and Efficiently
We are operating an old plate-and-frame filter press to filter polymer from the water/ascetic acid supernatent produced in the process. Local "artist" operators and SOPs based upon legend tend to provide inconsistent and non-scientific-based proposals for lifter press optimization. Could you direct me to a basic plate-and-frame filtration operation scheme designed to use the filter properly and most efficiently? Questions are very basic and include: 1. Feed from the top? Feed from the bottom? 2. Wash from the top? Wash from the bottom? 3. Blow down from top? Up from Bottom? 4. Cycle wash directions? Co-current or counter current washes? 5. Dilute feed at first? For how long? 6. Benefits of altering solids content in feed while loading? Variable feed rates?
Category: Liquid Filtration

Filtering Impurities From Polymer Solutions
We need to remove impurities such as solid particles from polymer solutions. The volume of the polymer solution for each batch is about 2000-3000 ml and the viscosity of the solution is around 1000-2000cP. The particle size we want to filter is 1-2um above. What kind of filter system is good for us?
Category: Liquid Filtration

Recommending appropriate filter for an aqueou slurry
Request for your recommendation for appropriate filter for the filtration of aqueou slurry as per the following specs: 1. temp. = 30 to 60 deg C 2. Ph = 1.4 to 1.6 3. Slurry contains water, lactic acid, Calcium sulfate powder, traces of sulfuric acid. 4. Slurry concentration : 16 to 25 wt % Calcium sulfate 5. Pressure = 1 to 4 bar g. 6. We are interested in a continuous filter , minimum loss of lactic acid with the wet cake of Calcium sulfate (cake is to be rejected ) 7. Other objective is to use Minimum quanity of water for cake washing. 8. Caution : Process medium is corrosive.
Category: Liquid Filtration

Appropriate Bag Filter
I am processing a liquid solution of H2SO4 with some metal particles. I want to filter this solution and filter out everything over 1 Micron in size. Any suggestions? Is there a bag filter that would be appropriate? This process will be run 3-4 times daily and I don't want to change cartridge filters every day.
Category: Liquid Filtration

Filters for gear oils
What types of filters should be used to filter out impurities in 100 gear oils. Particle count is important.
Category: Liquid Filtration

Use of activated carbon filter for removal of oil from urea mother liquor
We are pumping back 65 cubic meters per hour of urea mother liquor (approximately 70% concentration) to the crystallizer vessel after centrifuging urea crystals. Centrifuge oil seal leakage is a frequent problem contaminating return mother liquor with 90 PPM oil in it. Can we apply activated carbon filter to remove oil from urea solution? How can we estimate filter sizing indicating: pressure drop across bed; activated carbon; equipment; steam regeneration required; final purity with respect to oil content; annual cost (maintenance and operation) of such filter; first investment cost; basic literature to size such device (rule of thumb).
Category: Liquid Filtration

Extract light fraction in oil
I'm using a proprietary thermal oil to heat different equipment. We are using around 250,000 L. The close-cup of a new oil is 210ºC and we are around 95ºC. Is there a way to extract the light fraction in this oil to come back to a more decent flash point? Either by filter or a kind of online distiller?
Category: Liquid Filtration

Filters for a waxy stream
What type of filtration would one use to remove fines from a waxy stream?
Category: Liquid Filtration

Filter requirements
We are running experiments about the extraction of hydrocolloids from fruits and we’re using filtration textiles with pore diameter of 0.021 mm in the lab. As we are planning to go on bench scale, the provider of the filter is telling us he can give us a filter with stainless steel mesh of 0.037 mm. He has a lot of experience in the industry and tells me we should have no worries and that this size should work fine. Should I believe this provider and purchase the machine?
Category: Liquid Filtration

Rules of thumb on UF systems
My process uses ultra filtration. There are many variables to watch on the system such as feed pressure, membrane pressure, recycle pressure, permeate flow rate and concentrate (reject) rate. What parameters are most important to watch? Is there a good resource for general rules of thumb on UF systems?
Category: Liquid Filtration

Filtration equipment for solids
During the depolymerization reaction of natural polysaccharides, the viscosity of the product reduces as per the requirement. The insolubles, like fiber, etc. are to be filtered off. We are facing a problem with the filtration using equipment such as a basket centrifuge. The filter cloth chokes immediately. What type of filtration equipment should be used?
Category: Liquid Filtration

Clogged filter press cloths
In our plastics reclaiming plant, we use high density salt water solutions to separate plastic by specific gravity. These solutions have higher viscosities than water. Some "dirt" always comes in with the plastic feedstock and ends up contaminating the fluids. We are concentrating the dirt in a clarifier (with polymer flocculant) and then filtering the clarifier bottoms to recover the fluid. The problem occurs when the recessed plate type filter press cloths tend to "slime" causing high delta P, low flow rates and wet cakes. We have tried adding diatomaceous earth, lime and perlite as "body feed" to improve permeability with limited success. Do you have any suggestions?
Category: Liquid Filtration

Filtering technology
I am a synthetic organic chemist by trade and find myself in a new position of carrying new products for an animal repellent company that incorporates predator animal urines in their products through the EPA registration process. The bacterial and viral protocols we have had developed through Cornell University School of Veterinary Medicine involve our company pasteurizing and filtering the animal urines. We hope to use through 5 and 0.2 um media to remove many bacteria and spores. I currently have limited equipment, other than gravity filtration materials, to attempt to carry this out. I have had difficulty even on the 25 um level with fluted papers. We will be facing the filtration of 5 to 55 gal lots in production and I need to filter a 1 gal lot for EPA testing ASAP. What route would you suggest I go and/or is there a filtering consultant who we could contract to perform the smaller filtration in the meantime? Any direction you can provide would be very much appreciated.
Category: Liquid Filtration

Selecting filtration equipment
What is the procedure for selecting filtration equipment? (i.e. Nutsche filter, filter press and centrifuge.) If possible, please explain with equations and calculations.
Category: Liquid Filtration

Hot oil filters
I want to filtrate hot oil (250°C) from solid matter. What is the best type of filter to use?
Category: Liquid Filtration