Gee Chandler, i don't know.  Biochemists on this list please help answer 
Chandler's question!
h

On 5/10/2014 4:30 PM, Chandler Davis wrote:
> Thanks Herb.  Is Jim right in crediting Legionella with some of the
> power of the sand filter to remove noxious bacteria?  Does it then
> actually damage the efficacy of the filter to allow antibiotics
> into it?
>
> Chandler
>
>
>
> On Sat, 10 May 2014, herb fox wrote:
>
>> On 1st reading Jim's post appeared to be asserting that Legionella is 
>> not to be feared: "Hurray for Legionella. So badly demonized."
>> Just to set the record straight:
>>
>> Legionella bacteria have been found to make up a significant portion 
>> of the bacterial population in slow sand filters. Some species of 
>> Legionella are human pathogens (Calvo-Bado et al, 2003a). As such, i
>> t is recommended that the sand filter not be kept inside the 
>> greenhouse where high temperatures can lead to proliferation of 
>> Legionella (Calvo-Bado et al., 2003a). As well, levels of Legionella 
>> should be
>>  monitored to prevent harm to workers
>>
>> Calvo-Bado L.A., Pettitt T.R., Parsons N., Petch G.M., Morgan J.A.W., 
>> Whipps J.M. 2003b. Spatial and temporal analysis of the microbial 
>> community in slow sand Filters used for treating horticultural irri
>> gation water. Applied Environmental Microbiology 69:2116?2125.
>>
>> Certainly the fears associated with Legionaires Disease have been and 
>> will be used to stimulate "the sales of antibiotics for water systems 
>> in the industrialized countries."  What else would one expect
>> from an economic system for which the primary motivation has been 
>> reduced to maximizing profit.  That in the system in which we are 
>> presently compelled to live there are daily insults from big pharma
>> does not remove the fact that there are real, dangerous diseases, or 
>> even worse that the wanton proliferation of antibiotics enables the 
>> evolution to new, antibiotic resistant forms.  However, to deny or
>> lessen concern with the harmfulness of the responsible bacteria is 
>> not an appropriate response.
>>
>> There can be no widespread Science for the People as long as the 
>> profit motive is the underlying basis for the invention, production 
>> and distribution of pharmacologicals.
>>
>> Expressions of passionate hatred of science being used against the 
>> people especially those not well armed to understand its threats does 
>> not lead to remediation as successfully as it leads to a
>> fundamental distrust of science.  The offer of, if possible, 
>> scientific remediation along with a popular explanation of why the 
>> positive science is superior and why the fundamental problem is actually
>> science for profit has a better chance of gaining wide spread public 
>> support for Science for the People as a movement, and ultimately a 
>> change of consciousness that makes possible a humane,
>> post-capitalistic society.
>>
>> herb
>>
>> On 5/10/2014 11:15 AM, Jim West wrote:
>>
>> Thanks John,
>>
>> I too appreciate biosand filters, with their bacteria colonies 
>> building gels that filter out other microbes.
>>
>> Legionella bacteria makes up a "significant proportion" of the 
>> bacteria in slow-sand filters. Hurray for Legionella. So badly 
>> demonized, increasing the sales of antibiotics for water systems in 
>> the indus
>> trialized countries.
>> Ref:
>> http://www.ces.uoguelph.ca/water/PATHOGEN/SlowSand.pdf
>>
>> Jim West
>> http://harpub.tk
>>
>> ==========
>> Thanks Herb. The biosand filter is an excellent low cost and 
>> appropriate technology. see http://www.howard.edu/kenya for work some 
>> of our howard engineers without borders students did in a rural communit
>> y in wesern kenya. the team went back last year and installed another 
>> eleven filters. when we went back, we visited an orphan house where 
>> the team had installed a biosand filter the previous trip. the or
>> phan house "mom" told us she hadn't had a single case of water borne 
>> stomach ailments in her 20 orphans since we put in the biosand filter 
>> and trained her to operate and maintain it.
>>
>> john
>>
>> On Thu, May 8, 2014 at 8:28 PM, herb fox <[log in to unmask]> 
>> wrote:
>> I read the post and ancillary material before Sam posted it and 
>> rejected it for other reasons than those raised in the posts.
>>
>> I found the whole approach paternalistic and disrespectful of those 
>> it intended to help.  Advanced technology requiring 1st world 
>> production techniques is not the way of Science for the People.  SftP 
>> sho
>> uld be of, by, and for the People.  As much as possible it should be 
>> based on the traditions of the people, be producible by them and use 
>> indigenous materials.  The issue of potable water is central to i
>> mproving and extending the lives of people throughout the world, in 
>> Haiti also for example.  There a colleague, Bob Giles, with a long 
>> experience in Haiti and adequate command of the language worked with
>>  some young Haitians and USA university students to resurrect a 
>> device that could be made entirely with indigenous materials, require 
>> existing native skills, and be understood by those who would be using
>>  it.
>> The bio-sand filter is a slow filtration system that uses a casing 
>> made from cement and filled with three different layers of sand. The 
>> system purifies water in four basic steps: mechanical trapping (sus
>> pended solids and pathogens are physically trapped), predation 
>> (pathogens are consumed by other microorganisms), adsorption 
>> (pathogens become attached to other suspended solids in water and the 
>> sand grai
>> ns) and natural death (pathogens finish their life cycle or die 
>> because of oxygen and/or food starvation).
>>
>> ?Another key aspect of the bio-sand filter is the bio-layer,? she 
>> notes. ?This layer removes up to 70 percent of pathogens through 
>> mechanical trapping and predation.?
>> During Giles?s visit to Haiti last summer, he and his HDSC staff 
>> hired workers to build the filters and conducted a teachers? science 
>> training program for select graduates of College St. Jean in Les Cayes.
>> ?The young adults in the training program were taught how to test 
>> water and develop technical reports detailing water quality before 
>> and after filtration,? he says. ?They will be responsible for 
>> installing fiv
>> e filtration systems within the community.
>> Those of you who have read Cliff Conner's book know, as one reviewer 
>> put it the triumphs of science rest on a "massive foundation created 
>> by humble laborers," he writes. "If science is understood in the 
>> fundamental sense of knowledge of nature, it should not be surprising 
>> to find that it originated with the people closest to nature: 
>> hunter-gatherers, peasant farmers, sailors, miners, blacksmiths, folk h
>> ealers and others."
>>
>> Let those who believe in Science for the People and have been 
>> privileged to become knowledgeable in a science do their utmost to 
>> respect the people they would help by making them integral to the 
>> process of defining problems and participating from the beginning in 
>> obtaining solutions that rely as much as possible on their 
>> traditions, materials, and processes of doing and thinking.  PhDs 
>> might be amazed a
>> t how much can be learned from the people they want to help.
>>
>> herb
>>
>>
>>
>>