Page 137 - Materials Chemistry, Second Edition

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Sustainable Industrial Design and Waste Management
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individual environmental performance. After that they wanted to enlarge
the scope of their activities and to cooperate with different companies to
look for resource recovery opportunities.
The eco-industrial networking project described in this study was car-
ried out by NIA and the University of Kaiserslautern (Germany). The project
started as a sponsored “workshop on industry and environment” held at the
Indian Institute of Management in Ahmedabad in 1999. The first step was to
understand the main types and quantities of wastes generated by the firms
in the estate. A survey of 500 companies was carried out. As a result of the
survey, the most important waste materials were:

• Chemical gypsum
• Biodegradable waste
• Mild steel scrap
• Waste acids in particular sulfuric and hydrochloric acids
• Chemical iron sludge

Chemical gypsum is generated by 19 chemical industries as a result of neu-
tralization of their acidic wastewater with lime. This gypsum can be used by
cement manufacturing companies provided that it meets certain specifica-
tions. An analysis for the process of recovering the gypsum as a raw material
confirmed that it is economically viable.
Biodegradable waste is produced from a total amount of 10,000 kg of
solid material and 90,000 liters of liquid wastes per year. This type of waste
could be used to generate biogas as an energy resource for the industrial
estate or for a housing development located nearby. An economic analysis
showed that this energy recovery process is extremely favorable.
Sulfuric acid and mild steel scrap can be used as raw materials to make
ferrous sulfate, a chemical used in primary wastewater treatment at the CETP.
Several of the partnerships described above are now being put in place
with the support of NIA. Other possible partnerships that have been identi-
fied in the industrial estate are:

• Using sulfuric acid in the manufacture of phosphate for fertilizer.
• Using iron sludge to prepare synthetic red iron oxide.
• An alternative application for chemical gypsum in the production of
plaster board.
• Reduction in raw material and energy use in the ceramic sector.

In conclusion, the use of a resource recovery project in the Naroda industrial
estate has enhanced the interest of the firms in environmental management
activities and has encouraged the industries in the estate to focus not only
on their individual environmental aspects but also on the effect resulting
from the large number of companies concentrated within the estate.