Biology Reference
In-Depth Information
column and equipped with an aerobic fi lter run at psychrophilic conditions
(24-25°C) and with hydraulic retention time (HRT) of 22-38 d, a zeolite
column for fi nal treatment of effl uents, a gas fl ow meter and a methane
analyzer. Biogas and methane production amounted to 49.8-144.2 l/
day and 39.8-115.4 l/d, respectively. The highest biogas and methane
production was reported at the highest feeding allowance, while the
biogas methane content at 2% feeding allowance was higher than 80%.
A remarkable reduction of volatile solids (92-97%), suspended solids
(96-99%) and total ammonia nitrogen content (59-70%) in the anaerobic
digester was reported; while the zeolite ion-exchange column improved
water quality of effl uent produced by the digester, as the chemical oxygen
demand (COD) was reduced up to 45%. The produced biogas can be used
directly in a burner to produce thermal energy or, following depuration,
can be employed as fuel in a cogeneration plant to produce thermal and
electrical or mechanical energy.
Marine Underwater Depuration System (MUDS)
An underwater device, able to favour the sea auto-cleaning capacities, is
described herein. This system, called MUDS, consists of a percolating
fi lter and is placed at sea over effl uent water from fi sh farms outfl ow of a
submarine pipeline. Due to the density difference, the water effl uent fl ows
through the percolating fi lter: this favours the mixing and a prompt recycling
of organic matter, activating a marine trophic web. Rich microbenthic
communities develop on the MUDS, both interstitially, inside the fi lter,
and on the structure. The community mainly consists of ciliates, nematods,
harpacticoid copepods and polychaetes, all of which being organisms that
increase the depuration effi ciency by consumption of organic matter. This
structure acts also as a deterrent for the illegal trawling activity in the area,
and attracts large numbers of several fi nfi sh species, thus working as a fi sh
aggregating device (FAD) (Cattaneo-Vietti et al., 2003).
Foam Fractionation, Micro-algae Production and Oyster Filtration
Wastewater retention ponds in commercial farms at Atlantic coasts of
France are effi cient in removing up to 1 metric ton of particulate material
(dry weight)/ha/d (faeces and unconsumed feed), but are ineffi cient
in reducing dissolved wastes, both organic (urea, amino acids, protein)
and inorganic (total ammonia nitrogen, phosphates). Forthcoming
outdoor technologies to treat these forms of waste were examined by
trials at different sites: treatment by foam fractionation in extensive
systems (Italian fi sh pond culture), treatment by micro-algae production
( Skeletonema costatum ) and oyster fi ltration ( Crassostrea gigas ) in intensive
systems (sea bass farm, Dicentrarchus labrax ). It can be concluded that foam
fractionation coupled with aeration and water circulation was a good
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