Proceedings

Many large-scale production processes brewing, antibiotic fermentation and extraction processes, dairy and food processing
generate biological sludges and biosolids. These result either as a direct by product of the production processes or as part
of the wastewater treatment processes associated with these activities in the form of primary and secondary sludges. These
sludges are distinct from the more commonly perceived solids management issues arising from the treatment of municipal
wastewater. Indeed with industrial sludge each situation is arguably unique with no two production processes or production
facilities generating the same type of sludge or biosolids. Also location and company/country politics may generate and drive
sludge management solutions down a specific route. This paper will discuss an emerging technology, AFC (advanced
fluidised composting) as an alternative to more traditional sludge management technologies and other "accepted
technologies" that are on the marketplace for management of pharmaceutical industry organic residues and sludge's. 

The pharmaceutical industry in general generates three distinct categories of biosolids organic/inorganic sludge's.
1. As a direct direct result of the production activities: Potentially containing antibiotic fermentation/extraction
residues including spent mycelium other cell debris, high strength organic wastes, tars and by-products
arising from fine chemical synthesis.
2. Primary sludge's from the first stage of wastewater treatment, primary settlement if carried out:
Potentially these can contain inorganic particulates sand, silt, grit, insoluble fine chemical intermediates,
active pharmaceutical intermediates (API's), insoluble catalysts potentially containing heavy metals, activated
carbon and ion exchange resins.

3. Secondary sludges from wastewater treatment either activated sludge, fixed film or anaerobic sludges:
Containing activated sludge biomass, xenobiotic compounds (API's) not removed by the wastewater
treatment process. Unconverted/un-hydrolysed mycelium/biomass not removed in the primary
treatment process.

With the cessation of sea dumping of sewage sludge at the end of 1998, land recycling has become the favoured option
for disposal of municipal sludges. Whilst this is an established practice with the increasing public awareness of the fate of
wastes, specifically sewage derived sludge for beneficial agricultural recycling. There are a number of concerns
specifically of Salmonella, E. coli and BSE (bovine spongiform encephalophy) entering the food chain even with
stringent management methods in the recycling operations.

Also more recently concerns have been raised regarding the accumulation of toxic heavy metals in soils as a result of land
application of sewage sludge for beneficial re-use. Indeed in some European countries the recycling of sewage sludge to
land is in the process of being totally eliminated. The European Commission appears to be potentially
recommending tighter heavy metal limits in the new directive for land recycling of sludges thus driving sludge disposal
down the destruction route of for instance thermal oxidation (incineration) rather than the beneficial re-use route14. The
options are now becoming increasingly fewer for truly sustainable routes for sewage sludge disposal.

The use of dwindling landfill site space for sludge disposal is clearly not a sustainable option as more pressure is being
bought to bear to reduce high content organic wastes and sludge's being landfilled. As a further barrier to landfill
increasingly punitive landfill taxes are being introduced. There is an active initiative to reduce volumes of waste being
landfilled, not increasing them specifically with high organic content sludge's.
The alternative "total destruction" routes such as thermal oxidation (incineration) in the eyes of the public are not
deemed an acceptable solution to the disposal of sludge because of the perceived fears of atmospheric emissions
specifically particulates and dioxins. Even co-firing dried sludge with coal, municipal refuse or as a support fuel in
brick/cement manufacture are seen as incineration by the "back door". Despite the sensible use of the thermal energy
recovered by the destruction of the organic sludge.....


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