Water Reuse: A Successful Almost Zero Discharge Case

This paper presents a procedure to optimize a real problem of freshwater and wastewater reuse allocation. The case study is an industrial polypropylene unit and the solution achieved is an almost zero discharge case. The problem was decomposed into subsystems according the type of approach used to water minimization: process changes, regeneration reuse and regeneration recycling. For the regeneration approach, an innovative photochemical process capable to remove all the organic compounds contained in the wastewater in order to make it suitable to be reused in the process was used. For process changes approach, since the major water used in factory is for the cooling process system, a hybrid system composed by air cooler and wet cooling tower is been proposed to replace the wet cooling tower. The air cooler system is used first and the final temperature approach is achieved by the wet cooling tower. Thus, the main scope of the present work is to show that is possible to reach the "almost zero discharge" for an industrial case by using innovative wastewater treatment technologies together with optimization of water/air cooling systems. The results obtained prove that the water minimization techniques used can effectively reduce overall fresh water demand and the overall effluent generated, resulting in lower costs of fresh water and effluent treatment costs.