Newsgroup: it.scienza.ambiente
Titolo: Trattamento a freddo e biologico dei rifiuti urbani

Invece degli inceneritori da un po' di tempo sono industrialmente
maturate nuove soluzioni per risolvere il problema dei rifiuti in
alternativa alla discarica, all'incenerimento o alla faticosa
raccolta differenziata spinta (che peraltro serve agli inceneritori).
 
E' quella del trattamento meccanico a freddo dei rifiuti urbani seguito
da un processo biologico finale sui residui organici.
 
Il risultato e' una selezione di materiali riciclabili PULITI e biogas.
 
Esempio:
 
http://www.arrowecology.com/thirdlayer/muni2.htm
 
 
Ecco la descrizione della loro implementazione:
 
The fundamental advantage of the ArrowBio Process is two-fold. First, the 
MSW (or other waste stream) is processed directly as tipped from the 
collection truck. In the primary stage, organic and inorganic materials 
are separated through a unique, liquid-based, technology, involving 
gravitational settling, screening, and hydro-mechanical shredding of 
organic solids. Whereas ordinary separation schemes suffer from the 
wetness, or excessive dryness, of MSW, the ArrowBio Process frankly uses 
liquids to great effect.
 
The first stage end products are clean recyclables such as glass, metals, 
and plastic. Items such as batteries are removed gently, without 
breakage, thereby avoiding leakage of potentially toxic materials. Yet 
another, intermediary, product is an organic stream now ready for the 
next, biological, stage. The first stage thus performs two functions, 
separation and preparation, without additional machinery or effort.
 
That is, in addition to removing inorganic and other non-biodegradable 
materials, the liquid-based separation simultaneously conditions the 
organic material for rapid biological action. This is accomplished by 
bringing the organic matter into solution or fine suspension (slurry). 
The solution/suspension is very rich, with a chemical oxygen demand (COD) 
in the tens of thousands of milligrams per liter. This supports the high-
rate transformation of the organic wastes to methane (biogas) by 
naturally occurring microbial communities, in two highly controlled 
sequential reactors. Biogas production far exceeds in-house energy needs.
 
Excess biomass, discharged from the second reactor, is thoroughly 
stabilized and usable directly as an organic soil amendment ("compost"), 
or may be upgraded to a value-added product. Excess biologically 
generated water is either removed from the system (COD in the tens of 
milligrams per liter) or sent as makeup liquid to the up-front separation 
stage. Thus, with respect to energy and water, the system is autonomous.
 
Since it is consumed in producing energy for in-house use and/or export, 
emission of methane (potent greenhouse gas) to the atmosphere is entirely 
prevented. 
 
[pazienza, per ora mi manca il tempo per tradurre]
 
-- 
Roberto Deboni
 
[Messaggio Usenet via Tiscali su 
text.giganews.com
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il sottoscritto informa che non conosce o partecipa al sito/forum Web.]

 da un processo biologico finale sui residui organici.
 
è illusorio !
Funziona bene , per es, in Alto Adige, la raccolta differenziata
Raccolgono in 7 diverse categorie il 94 % dei rifiuti,
che vengono riutilizzati
ed eliminano come irriutilizzabile solo il rimanente 6 %
Credere che la tecnica risolva tutto è errato ...vedi Napoli