1,721,124 research outputs found
The valorisation of residual waste bales by urban mining
No full textIn the last decade, the approach to waste management has undergone severe changes. The urgent need to face the sustainable demand for energy and materials while limiting the burdens associated to traditional waste handling practices have figured out the concept of waste as a resource. New strategies boosting the extensive recovery and diverting waste from disposal activities have been promoted and framed in the wider context of the urban mining, promoting the full exploitation of waste as resource for either new materials or energy production. Such approach has been recently proposed to handle over 5 million tons of pretreated municipal solid waste produced and stored in the form of bales in Campania Region, in southern Italy, between 2000 and 2009. However, since the feasibility of this approach is related to the waste composition as well as to the selection process, an experimental study was performed at an industrial mechanical treatment plant to assess the potential for valorisation of this
waste. Results showed that the overall sustainability of the urban mining strategies for the management of Campania waste bales is tightly linked to the flexibility of the selection process scheme to be adopted, which should make the waste recovery fit the market demand of either material or energy
Anaerobic digestion of mechanically sorted organic waste: The influence of storage time on the energetic potential
No full textThe separate collection is the privileged practice to manage municipal solid waste (MSW) in order to meet the more and more ambitious recovery targets enforced by legislation. Nevertheless, considerable amounts of unsorted MSW are still produced at European level and mechanical biological treatments (MBTs) are widely spread to pursue their valorization. Most MBT plants rely on aerobic biostabilization methods, whose product cannot be qualified as compost and raises the issue of its fate. Anaerobic digestion is an interesting option to treat mechanically selected organic waste, but its feasibility may be limited by the prolonged storage time of this kind of waste. This study evaluated the variation of the energetic potential of the organic fraction mechanically sorted from MSW deposited for different periods. Results showed that such potential decreased by 46% after only 3 days storage and further reduction was observed with increasing the deposit time. Experimental outcomes allowed the identification of an inverse relation between methane production and deposit time and addressed the proposal of a simplified approach to estimate the maximum storage period to take the greatest advantage from the anaerobic treatment of mechanically sorted organic waste
Combined anaerobic/aerobic treatment of OFMSW: Performance evaluation using mass balances
No full textIn the last years the treatment of the organic fraction of municipal solid waste has been carried out using combined anaerobic/aerobic processes, where anaerobic digestion is followed by the aerobic stabilization of the digestate. Such a treatment provides a positive net energy balance associated with the methane energy recovery as well as the production of a soil conditioner. However the high complexity of the treatment requires an accurate management of all the treatment units. To this end, mass balances represent a useful tool, allowing both the control and maximization of process yields as well as the minimization of the treatment costs. This work aims at evaluating the performances of a combined anaerobic/aerobic source-sorted OFMSW plant by means of mass balances, elaborated with reference to both conventional and non-conventional operational parameters.Results pointed out the key role of organic waste pretreatment as well as the effectiveness of both anaerobic and aerobic processes in providing an adequate biostabilization level of the treated waste
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