Environmental Engineering Reference
In-Depth Information
industrial area, such as electric and thermal energy, technical gas (i.e., steam overheated) and
industrial water, with advantageous conditions for the industries, and also sustains the
territory industrialization by giving services and utilities similar to the most industrialized
areas of the country. Furthermore, it treats the waste of the industrial activities of the
industrial area, and also waste coming from activities of regional and extra-regional territories
with specific authorization codes (EWC European Waste Catalogue).
The firm in this case study is a partner of the manager company and purchases from it
steam, water and electric energy. Before the final discharge, it sends the wastes to the
treatment plant [16][17].
The industrial process of nonwovens production is divided into the following phases:
•
bottle washing and flake production: from plastic bottles PET material is selected and
sent to a washing centre and then to the mill to be reduced into little pieces; at the
end bottles are centrifugated to set apart the water, and sent to a washing section. The
obtained product is called flake.
•
polyester drying-up and extrusion by forming threads set in a random way on a
sucked carpet: flakes are heated until they become crystals, then they are dried and
extrapolated. After extrusion, the melted polymer gives rise to a film;
•
mechanical binding process (needlepunch technology);
•
glass thread inclusion between the two films and further mechanical binding;
•
thermo-fixture and longitudinal cut, and consequent selvedge production;
•
thermal consolidation and product incorporation in resins.
To summarize, the analysis of life cycle defines the functional unit as 1 m
2
of fixed and
reinforced nonwoven, and considers one year's time for the system and the process.
In the following inventory analysis, data are collected, measure units are converted, and
data refer to their functional unit, as shown in Figure 12.
The diagram in Figure 12 summarizes resources, energy consumption, all emissions (to
air, water and ground) and production of waste.
Thanks to software, it has been possible to assess the impacts on the environment (i.e.,
CO
2
eq, CH
4
, SO
X
e PM10, COD, BOD and solids).
Industrial waste referred to in the considered firm are divided into two categories:
•
waste products: these are not dumped, but used again in the production cycle or sold
for other purposes (polymer badge, nonmelted selvedges, melted selvedges, felts, roll
line starts);
•
wastes of various origin (residues of the washing system, iron waste, wood waste,
paper, some oils, etc.)
For an economic-environmental assessment, it is necessary to incorporate the system
analysis with a cost/benefit analysis by emphasising emissions and energy savings.
If the analysis is extended to the whole area where the firm is located, the processes of all
the productive activities have to be analysed in order to find the the best area for fuel co-
production.
