What will be happened in industrial-scale bioleaching?

What shall be taken into account when starting big-scale bioleaching? Some ideas:

1. A successive set of bioleaching pilots (with increasing size).

2. Transport of gases (O2, CO2).

3. Nutrients (P, N etc.).

4. Temperature.

5. Risk of re-building metal sulfides.

6. Microbial reduction of sulfate (see point 5.)

7. Chemical inhibition of sulfide-oxidizing metabolism.

8. Efficiency of Fe3+ to dissolute nickel.

9. Continuous control of microbial activities.

These are the basic issues. There may be more of them.

Coming back soon...

Bioleaching of Nickel - A Challenging Task

It seems that the retirement doesn't stop any person, dedicated to her/his work, to continue actual questions of her/his profession. My wife has worked as a nurse and still dreams about her work with schoolchildren...and the interests of mine are the questions of environmental and industrial microbiology. Can't help...

Bioleaching of metals from sulfide rocks is a most interesting thing! It happens in natural conditions on an area in Northern Europe where the rock contains sulfides of certain metals. Those bacteria which can perform this bioprocess are unique - they need bot oxygen and carbon dioxide as well as some other nutrients but no organic carbon source for energy at all. They are typically slow-growing microorganisms on the surface of the stone.

How to maintain an industrial-scale bioleaching process in mines where the conditions can be as different as in Northern Finland (cold, moist) and Australia (warm, dry)? This is the main question which I have studied by using scientific literature and results of laboratories (as far as they are public - what they not always are, indeed!), trying to compare different cases.

- More of the basics of bioleaching and cases in coming posts...keep following!

The Role of Microbes in Bio Boom - Part 2.

Bio Boom is here!

This is a great challenge for countries like Finland (a lot of forests)
and Central Europe (a lot of cattle farms).

What is common to both of them?

After the production of ethanol (and some other beneficial compounds 
(like lignosulfonate) from sulphite pulp process, very few biotechnical 
processes were applied to sulphate pulp processes.

Now it seems that ethanol can be an important product also in
forest industry.

And the cattle...?

Methane and hydrogen are important end-products of certain anaerobic
microbial processes. They were burned in previous times (I recall the
waste water treatment plant of Viikki, Helsinki, where no method to
collect these gases were available on 70's).

If we think the "end product of cows" we easily understand its value
in anaerobic gas production. Large farms in Central Europe are ready
 to apply these techniques for the production of burnable gases.

Third, a most important aspect too, may be easily forgotten: aerobic
waste water treatment (activated sludge process) in Finnish pulp &
paper mills. It has improved significantly the quality of such big rivers 
like Vuoksi and Kymijoki where big integrates of P&P industry
are situated.

- To be remembered: Bio Boom consists of many chemical and
technical innovations. These three issues, discussed above, are real
biotechnology. Biotechnology is a term for all processes which are
based on microbes (or their metabolic products like enzymes),
not only chemical reactions of non-living world. This means that
bioleaching of sulfide minerals is a real biotechnical process -
and makes it easier to understand the difficulties to carry it on.

The Role of Microbes in Biotech Boom, part 1.

The role of microbes in the energy production has been relatively small in older times. Burning of microbial biomass has not been a clever alternative because the tiny size of microbial cells (even billions of cells, 1 000 000 000, can be easily be suspended in one milliliter of water - all too slow to cultivate big lots of biomass) and their water content (drying would be too much energy-consuming procedure). Wood, in opposite, has been an excellent alternative, especially when the material has been dried enough to give positive net balance of energy.

The energy-containing metabolites of microbes, not the microbial cells themselves, have been the subject of research and development of energy production. Because the full-oxidized end-products of aerobic, oxygen-respiring micro-organisms, the fermentative microbes (like ethanol-producing yeasts) and anaerobic bacteria (like methane producers) have got a certain role in energy production. One big benefit of these applications are the non-expensive raw materials of metabolic routes like carbohydrates, manures and other stuff which has either been left from other processes or even regarded as a waste.

(- to be continued soon...)

Challenging R&D in forest industry: not only paper and timber products

"The largest forest industry centre in Europe is located in South-Eastern Finland", says the back cover text of this abstract booklet of Summer School 9.-10. September 2008 by Forest Industry Institute. Future forecasts, scenarios, innovations, specified methods - in an optimistic mood on those days. - But how today? Interesting to check the outcome of these ideas. - Looking forward...

Integrated Prevention of Microbial Growth in ecological niches of a paper mill

An average paper mill consists of several sites where waterborne and biofilm microorganisms can survive and grow. Different kind of populations can be found in different environments, e.g. wet mineral and starch slurries, coating pasts, white waters, pulps and brokes as well as all wet surfaces inside the paper production systems. The effective prevention of these sub-populations is depending of the biocide alternatives (storing, fast-acting or even sporicidic compounds) available. Their use should be combined with other measures, however: the prevention of their growth by process technology, production strategies, cleaning of the processes etc. - This combined activity, if clever planned, can the be called "Integrated Prevention of Microbial Growth".

The most beneficial tool for the planning of IPMG is the HACCP procedure which evaluates the potential microbiological hazards in every site and gives hints to choose the Critical Control Points in the total process.

But - what does the stimulation of microbial growth in a paper mill mean?

It shall be kept in mind when biological waste water treatment plant is the last step of the process water route from water source to recipient lake, river or sea. The growth conditions, in oppotie to those of manufacturing processes, should be as beneficial as possible to keep the growth rates of activated sludge or anaerobic treatment just on optimal level.

We have to understand the microbes and their needs when preventing or stimulating their growth activities. The count of microbes is only one variable - their responses to temperature, pH, redox potential and other growth factors, their metabolic features (e.g. sporulation-germination cycles), their tendencies to grow in water or surfaces) and other important factors should be taken into account when planning the programs for microbe prevention (inside the mill) or stimulation (biological waste water treatment).

- More about these issues in next posts...stay on the line.

(Schematic picture:  MENTU, J.V. 2001)

Pioneer of environmental microbiology!

I recall Dr. Howard E. Worne who was a pioneer in environmental microbiology, incl. bioleaching already on 70's. I met him in Finland when he was already over 70 years - very nice person, indeed.