Slow filtering

One question about filtration. I am using the hochstrom to filter ethanol crude with the 20u filters. After about 1/2 a gallon it really slows down. Should I be swapping filter papers that often or am I doing something wrong? Biomass was run through a 45u bubble bag before the hochstrom.

The quick fix is to, as you said, change your filter papers more frequently. The long term fix is to get more surface area to allow you to filter a bigger volume before having to change filter papers. What size of diameter filter are you using?


The hochstrom is a stainless steel 6" filter:

The short term fix may be to stage your filtration, so that you start with larger than 20u filters and once all your liquid has been filtered at a larger size, re-run your filtration at 20u (assuming that 20u is your final filtration stage). Without more info on the liquid you’re trying to filter I can’t speak exactly to what your stages should be.

I don’t know what your vacuum setup looks like but in my experience, deeper vacuum/more CFM never hurts, and more surface area as @SoStupendous said. Bel-Art makes an 18" benchtop Buchner that isn’t bad if you make some modifications to it (See here: Winterizing smarter, not harder) otherwise Sambo Creeck makes some enormous winterizing trolleys that use up to 32" diameter filter papers, they sell the largest Buchner’s I’ve seen