Page 145 - Sustainability in the Process Industry Integration and Optimization

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by 28 percent and the joint cost of freshwater and wastewater
treatment by 27.9 percent. Investment costs for the modifications,
which require a membrane area of 83 m , amount to €117,205. The net
2
present value of the optimal water network is positive at a 15 percent
discount rate, and the payback period is 1.3 years. The price of
freshwater has a significant impact on the optimal water network.
Increasing freshwater prices result in the identification of additional
opportunities for reuse and regeneration reuse. Examples include
water reuse between the rinser for nonreturnable bottles and the
bottle washer, water reuse between the pasteurizer and the bottle
washer, and regeneration reuse between wort boiling and the CIP
system.
Complete implementation of the proposed design could allow
the brewery to reduce its current freshwater demand by about
25 percent and to reduce its costs for freshwater and for wastewater
treatment by about 27 percent. Furthermore, the brewery’s ratio of
water consumed to beer sold would decrease to 4.53 : 1 (from 6.04 : 1),
which is important for cleaner production and sustainable
development within the company.

5.7 Summary

Water is used in most process industries for a wide range of
applications. Today, industrial processes and systems that use water
are subject to increasingly stringent environmental regulations
concerning the discharge of effluents. Moreover, the demand for
fresh water continues to increase.
The pace of these trends has increased the need for improved
water management and wastewater minimization. Adopting water
minimization techniques can effectively reduce overall freshwater
demand in water-using processes and also reduce the amount of
effluent generated. These reductions bring reductions also in costs
incurred to acquire freshwater and treat effluents.
The field has been developing rapidly, and every year brings a
number of new and more efficient approaches. This chapter has
reviewed and demonstrated, through selected case studies, current
methodologies that have been applied to minimize water use and
wastewater in the processing industry.