The management of the Organic Fraction of MSW (MSWOF) represents an important issue as a consequence of the relevant impact that this material can have on the environment quality. Infact, if disposed without an adequate and efficient pre-treatment, the natural biological degradation process can lead to the production of an high rate of GHG like CO2 and CH4. Furthermore, the beginning of non controlled processes of anaerobic degradation, can also lead to other problems related to septic conditions and to the production of other substances that can affect seriously the surround area. The latest strategies in waste management (WFD 2008/98/CE) impose to achieve an high amount of recovered materials from waste. As a consequence, the differentiate collection of the OF represents an important way for collecting an high quality organic substrate exploitable for the production of an high quality compost (i.e. organic fertilizer). The remaining fraction of waste, collected in a non differentiated way, need dedicated treatments that are often performed inside MBT plants, in which the stream of the Non Differentiated Waste (NDW) is firstly sorted mechanically, for the production of two main waste streams. An Oversize stream (rich of dry components) and an Undersize stream (rich of MSWOF). Generally, the Underisze stream is aerobically stabilized before final disposal, whereas the Oversize can be furtherly refined for further aims of recovery. In Italy as in other EU countries, there are many MBT plants operating since the ‘90, when both the waste composition and management strategies (i.e. differentiate collection) were quite different. During the years, the increase in differentiate collection and of waste quantity, have produced significant impacts on the operating conditions of the MBT plants, that can lead to a reduction of the efficiency both of the mechanical and biological sections (Di Maria and Marionni, 2011). In this work an analysis of the performances of an existing MBT plant, operating since ’94, have been analysed. The treatment efficiency both of the mechanical sorting adn of the biological treatment section, have been investigated. In particular the treatment efficiency of the biological section has been evaluated also on the basis of the biogas production potential of the waste streams entering and exiting this section. The experimental apparatus exploited for simulating the anaerobic digestion process, works with very high solids contents (i.e. >35%), for reproducing a bulky similar conditions inside landfill. Table 1 shows the mean composition of the waste streams entering (NDW) and exiting (Undersize and Oversize) the MBT plant mechanical sorting section. A large fraction of the undersize stream is represented by rapidly biodegradable material, that is aerobically stabilized in the biologica section of the plant. The main physical property of the undersize entering and exiting the aerobic stabilization section shows (Tab. 2) a significant reduction of the humidity content. The bio-gasification tests (Fig. 1) shows that the aerobic stabilization treatment is able to reduce the biogas yield of the undersize exiting the MBT plant of about 100-150 Nl/kg VS.
Experimental evaluation of the residual biogas potential for MSW organic fraction after composting treatment
DI MARIA, Francesco;
2011
Abstract
The management of the Organic Fraction of MSW (MSWOF) represents an important issue as a consequence of the relevant impact that this material can have on the environment quality. Infact, if disposed without an adequate and efficient pre-treatment, the natural biological degradation process can lead to the production of an high rate of GHG like CO2 and CH4. Furthermore, the beginning of non controlled processes of anaerobic degradation, can also lead to other problems related to septic conditions and to the production of other substances that can affect seriously the surround area. The latest strategies in waste management (WFD 2008/98/CE) impose to achieve an high amount of recovered materials from waste. As a consequence, the differentiate collection of the OF represents an important way for collecting an high quality organic substrate exploitable for the production of an high quality compost (i.e. organic fertilizer). The remaining fraction of waste, collected in a non differentiated way, need dedicated treatments that are often performed inside MBT plants, in which the stream of the Non Differentiated Waste (NDW) is firstly sorted mechanically, for the production of two main waste streams. An Oversize stream (rich of dry components) and an Undersize stream (rich of MSWOF). Generally, the Underisze stream is aerobically stabilized before final disposal, whereas the Oversize can be furtherly refined for further aims of recovery. In Italy as in other EU countries, there are many MBT plants operating since the ‘90, when both the waste composition and management strategies (i.e. differentiate collection) were quite different. During the years, the increase in differentiate collection and of waste quantity, have produced significant impacts on the operating conditions of the MBT plants, that can lead to a reduction of the efficiency both of the mechanical and biological sections (Di Maria and Marionni, 2011). In this work an analysis of the performances of an existing MBT plant, operating since ’94, have been analysed. The treatment efficiency both of the mechanical sorting adn of the biological treatment section, have been investigated. In particular the treatment efficiency of the biological section has been evaluated also on the basis of the biogas production potential of the waste streams entering and exiting this section. The experimental apparatus exploited for simulating the anaerobic digestion process, works with very high solids contents (i.e. >35%), for reproducing a bulky similar conditions inside landfill. Table 1 shows the mean composition of the waste streams entering (NDW) and exiting (Undersize and Oversize) the MBT plant mechanical sorting section. A large fraction of the undersize stream is represented by rapidly biodegradable material, that is aerobically stabilized in the biologica section of the plant. The main physical property of the undersize entering and exiting the aerobic stabilization section shows (Tab. 2) a significant reduction of the humidity content. The bio-gasification tests (Fig. 1) shows that the aerobic stabilization treatment is able to reduce the biogas yield of the undersize exiting the MBT plant of about 100-150 Nl/kg VS.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
