Integration Of Industrial Water Management Into The Engineering Classroom
As environmental regulations increase and get stricter, green engineering novel solutions become more appealing to industry. Green engineering approaches look into obtaining new designs/methods that are environmentally benign and also economically profitable. This paper presents a pollution prevention class module that focus on water/wastewater management. Its primary objective is to provide the engineering students with a series of tools to design optimal industrial water networks. Introduction Water is a key element for the normal functioning of the chemical and petrochemical industry. Steam stripping, liquid-liquid extraction and washing operations are among the many processes present in refineries and chemical plants where water is intensively utilized. Several procedures have been proposed to design economical wastewater treatment. With a few exceptions, these procedures rely on the application of certain rules of thumb. The current installations usually merge several waste streams and use appropriate technologies in series to clean this stream before disposal. These are therefore, end-of-pipe non-distributed wastewater cleanup solutions. Several papers discuss these options. Belhateche (1995) offers a complete discussion of these technologies. Starting in the eighties and increasingly in the nineties, water re-use started to become popular as means of reducing the total amount of water intake. This, in turn, not only saves upstream treatment of raw water but also reduces wastewater treatment costs. In addition, the concept of distributing the treatment among the various polluted streams and even decentralizing it is gaining acceptance. Industry and the EPA in the US are also seriously considering and discussing the advantages and disadvantages of zero-liquid discharge solutions as the ultimate goal of green water utilization in process plants. † To whom correspondence show be addressed. ‡ University of Oklahoma. Norman, OK. Email: bagajewicz@ou.edu P ge 580.1 Until a few years ago, the problem of water treatment was considered as a set of sequential treatment operations of a single wastewater stream consisting of the wastewater from all unit operations (desalters, strippers, etc). At the same time, without the concept of wastewater reuse, these processes are fed by freshwater only. Such a system is depicted for three water user processes (Pi) and three treatment units (Ti) in Figure 1a. One way of obtaining improved designs is the reuse of wastewater from one process to feed another without sending it to treatment first. This reduces the cost because the overall water intake is smaller (figure 1b). The next step is to introduce a series/parallel designs of the wastewater treatment unit without merging all the wastewater streams (figure 1c). Finally, treatment can be decentralized in such a way that some pollutants are removed from wastewater of selected processes allowing the reuse of these waters (figure 1d). P1 P2 P3 Fresh Water T1 T2 T3 Wastewater Treatment