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Finding a Filtration Scheme that Filters Properly and Efficiently

Q: 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?

A: 1) One usually only feeds from the bottom if the slurry tends to settle. Otherwise, we feed from the top corner. We rarely use center feeding.
2) One should wash from the top left cross-wise and out the bottom right.
3) Always blow down from the top to the bottom so liquid drains out.
4) Countercurrent, because one wants the wash to go through the cake (i.e., from the top left to the bottom right or from the top right to the bottom left depending      on how the press is ported).
5) We never dilute the feed since thicker slurries are generally easier to filter.
6) Altering feed solids isn't a good idea based on (5) above. Variable feed rates are generally accomplished anyway as the cake builds up. Hence, one starts at a fairly high flowrate to fill the press, which then drops off fairly rapidly as the cake builds up. This is why pump selection is critical.

Here are more of the latest questions on: Liquid Filtration

How do I decrease percentage of solids entering the heat exchanger?
I have been assigned to manufacture an evaporator for liquid phase of digestate originating from biogas plant. My inputs are that liquid digestate contains around 7.7% of dispersed solids and the biggest particle is maximum 500 micron in diameter (size of perforation on a screw press sieve that performs primary solid-liquid separation). My goal is to try and decrease percentage of solids entering the heat exchanger as much as possible or economically viable so to diminish heat transfer surface fouling problems. Which filtration options do you find most adequate for aforementioned task?

Before mechanical screw press separation I have from 12% to 18% of solids and after mechanical screw press separator I get from minimum 4 to maximum 7.7% of solids in liquid phase. Solid phase after separation has 27%-33% of solids and I would like to evaporate enough water from the liquid phase so to achieve similar percentage of solids (27%-33%) in the liquid phase as well. I want to do it through evaporation. Since my goal is to obtain an end product (solid and liquid phase mixed after evaporation) with around 30% of solids, and I can not do that directly through evaporator (due to fouling of inner heat exchange surfaces of evaporator), I decided to raise percentage of solids entering the evaporator only to around 14% which proved to be maximum practical limit. Because I want to evaporate as much water as possible and I'm limited with 14% solids (we have enough thermal energy though) it is very important to maximally lower percentage of solids prior entering the evaporator. This way when I reach maximum of 14% of solids in the evaporator I will have great portion of water already evaporated and only small amount will remain. The lower percentage of solids entering the evaporator the smaller portion of water remains when 14% of solids is reached after evaporation. This is OK for me since this evaporation product being concentrated to 14% of solids will be mixed with the mechanically separated solid phase (27%-33% solids) afterward. Weight ratio between solid phase (30% solids) and liquid phase (14% solids) will be tipped heavily towards solid phase so adding this 14% liquid phase should get me only slight decrease of percentage of solids in solid phase (from 30 to around 29%). Therefore I need as effective filtering of solids as possible prior to entering the evaporator.

Just to point out that we did try to raise percentage of solids in the evaporator but it could have only been done in scraped surface evaporators which are costly to produce and costly to operate so I can not use them.

What can I do to lower these maximum 7.7% of solids to lets say 0.1% (if I do that, then my math of lowering 30% of solids in the end product to 29% is OK)?

Is there a way to scale down batch filtration through bag and cartridge filters?
Is there a way to scale down batch filtration through bag and cartridge filters? We experience variable filtration time of suspensions of different batches of active charcoal and would like to evaluate the performance of the filter media on a lab scale (0.5 - 5 L). In the plant we pressure filter active charcoal suspensions from a batch reactor (stirred tank) through a three-stage filter system: a 5 um bag filter, a 1 um cartridge filter, and a 0.2 um (absolute) cartridge filter. The setup uses 10 in cartridges.

What is the best filter for Calcium Nitrate?
We are using a liquid 75% Calcium Nitrate solution.After filling stainless steel tanks, there is a cloudiness. When we allow to settle, there is a small amount of white residue visible at the bottom of the tank. What would be the best filter to work with the Calcium Nitrate.

How do we increase suspension material removal?
We have a wastewater process involving 3 micron bag filtration then tied to activated carbon drums in a series to remove suspension materials and active pollutants from agricultural pesticide tank washing. We are looking to increase suspension material removal and remove more active emulsifying concentrate pollutants from the filtration stream. Any ideas?

What is the proper filter to remove suspended coal tar?
Can you suggest a filter to remove suspended coal tar particles from the ammonia liquor in the pressure line?

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