Inżynieria Ekologiczna Nr 2

TECHNOLOGIE ODOLEJANIA GRUNTÓW, ODPADÓW, ŒCIEKÓW
the soil or water column. Bacteria can be injected directly into ‘hot spots’ of contamination
within the soil, sprayed onto the surface of a slick within a contaminated water body or
in some cases the oil or petrol etc. can be abstracted in aqueous phase and treated in a
purpose built bio-reactor commissioned on-site.
Benefits or Direct Application verses ‘Pump and Treat’ Techniques
There are several trains of thought with respect to the most effective application technique
for bio-remediation technology. To a large extent the most efficient technique is
highly site and pollutant specific.
In the past, the bio-remediation of shore lines and soil adversely affected by major oil
spill has been achieved through the stimulation of the indigenous population of microorganisms.
Products have been developed which biologically invigorate the inherent bacterial
population at a particular site to such an extent that that the oil or pollutant is more
rapidly broken down. In this case the only addition required is a ‘Nutrient’ which can be
both cheap and effective in certain instances.
At the next level of bio-remedial sophistication, it is possible to apply large volumes
of the precise bacteria known to be able to survive in the environment in question and to
effectively degrade the pollutant causing the problem. There is knowledge on the bio-degradation
capabilities of each species of bacteria which has been isolated from polluted
sites. Moreover, many species can be cheaply cultured on an industrial scale. As such, it is
usually preferable to physically add a cocktail of bacteria by spraying onto the soil or water
surface of by direct injection.
With the current level of sophistication in industrial bio-technology, bacteria can by
cultured to in excess of 10´12 individual bacteria per millilitre of product. With this degree
of bio-enhancement, bacteria can be added to a site in such high numbers that there is
no real requirement for a natural population to be present. Again a biological activator
product is add along with the bacteria to stimulate biological activity and to promote longevity
of the population.
Direct applications of bacteria and activator in this way require a more detailed knowledge
of the site conditions and the type of pollution which will be encountered. When
applying a bacterial culture directly to a contaminated site, whether it be on the surface of
a water body or deep in the soil under a building, of example, the application will usually
take the form of a cocktail of between six and ten different species. Using a mixture allows
for each species to be highly specific in its usefulness and it its tolerance of environmental
conditions while the complete application can solve a complex pollution problem under a
variety of environmental conditions.
Where it feasible to commission a bio-reactor on-site, the treatment process can be
massively accelerated since the level of control over the environment in which the bacteria
are expected to thrive is increased. A bio-reactor usually takes the form of a glass-fibre
reinforced plastic tank some 3 metres in diameter and standing 3 metres high. The units
therefore have a capacity of 6.000 litres. Polluted water can be passed through at a rate of
up to 1.000 litres per hour. Units of this size can be easily transported to any location. As
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