Charcoal slow sand bed filtration system for containing microbes from bioprocess lab waste water

[abhivmairal]

Dear All,
We have received recommendation from our safety vendor to install charcoal slow sand bed filtration system. The purpose of this system will be only to contain or to trap the pathogenic microbes from the bioprocess lab wastewater. Currently our bioprocess lab waste water (almost 90%) is being steam autoclaved and been sent to our ETP facility through underground drain pipes. The filter shall be placed close to bioprocess lab since our ETP facility is located around 500 m from our bioprocess lab and the autoclave may not be always 100% efficient and may pass microbes to ETP. Also there is a possibility of leakage of pathogenic waste water to atmosphere thriugh the underground pipes.
We are not completely convinced about the recommendations and have the following two main doubts:
1) In the recommendation, alternate layers of charcoal and sand have been suggested for the filter. Both charcoal and sand have sizes in mm whereas pathogenic microbes have sizes in microns. How can the filter contain the smaller size pathogenic microbes?
2) In several literature, charcoal has been told as the breeding base material for bacteria. Our lab waste water flow is intermittent. This may cause bacteria to breed on the charcoal layer which could cause more bacteria in the treated water than in feed waste water to the filter. Also, many of the papers in literature don't recommend charcoal layer in slow sand bed filters.
3) The slow sand bed filters are mostly used to purify the lake/river water to drinking water where the turbidity and wastewater feed characteristics are more or less same. Our bioprocess lab wastewater has high turbidity (around 40-60 NTU) and characteristics also vary based on the different experiments performed at different times.
Based on the above points we think that this system will not be adequate to contain/trap the microbes from bioprocess lab wastewater. Please let us know your replies and any suggestions for alternate scheme for containment of microbes.
Regards
Abhijeet

 

[ashtree]

Without all the deatils on your wastewater and the bacteria involved it is impossible to know for sure if this will work but in principle it might. It will depend on whether or not the microbes and pathogens you talk about will live and grow in the filter environment and what is the nature , size and frequency of the waste stream that runs through the filter.

For some microbes it would work well, but for others not well at all.

Assuming that the microbes and environment are correct the biofilter will trap many of the bacteria you are refferring but will take a while to acclimatise. Progressively the bacteria will grow what might be called a slime layer on the media granules and around the bacteria colonies which will capture particles and bacteria eventually trapping many or most of the bugs in the system. From time to time these floc particles will breakn off and some of these may leave the filter in the effluent. Occassionally you will have to clean the filter to prevent it becoming clogged.

If this is working well most of the bacteria will be trapped in the media and potentially, these bacteria will work to reduce and absorb certain substances in the waste stream.

I think it would be very optimistic to think that it will trap 100% of all pathogens all the time. You would need to research a bit on the microbes involved.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[abhivmairal]

Dear Sir,

Thanks for your reply!
Our bioprocess lab is mainly working on development of enzymes, bacteria and yeasts for 2G ethanol, biogas generation etc, processes. Although, at present the microbes are not pathogenic, we may end up developing unknown pathogenic microbes while doing genetic engineering in future.

Also, our water use and hence waste water generation is intermittent. It varies from 100 liters/day to 2.5 m3/day on a particular day of week when the fermenter is drained with no activity on weekends. The composition also varies based on the lab use. The bioslime layer is known to be feed specific and needs to be continuously fed with feed wastewater. Hence we doubt whether the solution of charcoal slow sand bed filter will work for us or not.

Waiting for your reply!

Regards
Abhijeet

 

[bimr]

It appears that the safety director has given you a recommendation that is nonsense.

Charcoal will not deactivate or disinfect wastewater with pathogens.

If you have any concern about pathogens, you should be thinking disinfection. Disinfection can be done with heat or chemically with chlorine or ozone.

 

[abhivmairal]

Dear Mr.Bimr,

Thanks for your reply. The recommendation is from a well known multinational company and we totally agree that it doesn't make sense. Even we think that disinfection with heat/chemicals is the best way

 

[bimr]

Ask the person to provide a reference where he has done this before.