Risk-based design of air stripping towers with fuzzy set theory

Frequently, environmental engineers are faced with uncertainty in making design decisions, because the true value of many process parameters is unknown. As an alternative to the probabilistic approach, fuzzy logic can be used for developing a risk-based design methodology. When fuzzy logic methods are compared to probabilistic methods, they yield similar results for the same design conditions. However, fuzzy logic requires fewer assumptions about the uncertainties and less computing power than probabilistic methods. In this case study, the design of air stripping towers was modeled, taking into account uncertainties in mass transfer and in the Henry's constant. For the design of air stripping towers, it was found that in addition to cost, the risk of failure is an important design consideration. When a wide range of designs is examined, it is clear that a significant overdesign is both cost-effective and more reliable.