Advances in Chemical Engineering and Science, 2013, 3, 286-293 http://dx.doi.org/10.4236/aces.2013.34036 Published Online October 2013 (http://www.scirp.org/journal/aces) Process Optimization of Effective Partition Constant in Progressive Freeze Concentration of Wastewater Mazura Jusoh * , Anwar Johari, Norzita Ngadi, Zaki Yamani Zakaria Chemical Engineering Department, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, Skudai, Malaysia Email: * mazura@cheme.utm.my Received August 29, 2013; revised September 30, 2013; accepted October 8, 2013 Copyright © 2013 Mazura Jusoh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Response surface methodology (RSM) was employed to optimize the process parameters for effective partition constant (K) in progressive freeze concentration (PFC) of wastewater. The effects of coolant temperature, circulation flowrate, initial solution concentration and circulation time on the effective partition constant were observed. Results show that the data were adequately fitted into a second-order polynomial model. The linear and quadratic of independent variables, coolant temperature, circulation flowrate, initial solution concentration and circulation time as well as their interactions have significant effects on the effective partition constant. It was predicted that the optimum process parameters within the experimental ranges for the best K would be with coolant temperature of −8.8˚C, circulation flowrate of 1051.1 ml/min, initial solution concentration of 6.59 mg/ml and circulation time of 13.9 minutes. Under these conditions, the effective partition constant is predicted to be 0.17. Keywords: Effective Partition Constant; Wastewater Treatment; Progressive Freeze Concentration 1. Introduction Water is often ranked by its quality. However, there are many different quantifications of water quality, and the quality of water often depends upon its use. Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial proper- ties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. Meanwhile, water treatment can be defined as the ma- nipulation of the water from various sources to achieve a water quality that meets specified goals or standards set by the community through its regulatory agencies. Most wastewater is treated in industrial-scale waste- water treatment plants which may include physical, chemical and biological treatment processes. There are numerous processes that can be used to clean up waste waters depending on the type and amount of contamina- tion. Evaporation is a process commonly used to treat and concentrate wastewater, where the vapour from a boiling liquid solution is removed and a more concen- trated solution remains [1]. However one of the major drawbacks of evaporation in wastewater treatment is when the wastewater contains volatile organic com- pounds (VOCs), therefore evaporation is absolutely not an operation that should be appointed in treating it. An- other dewatering method is reverse osmosis which can produce almost pure water and use the least amount of energy because it involves no phase change [2]. The membrane however can by far be clogged by the content of the wastewater resulting in high osmotic pressure dif- ference across the membrane interface [3], which affects the cost highly when the membrane has to be changed [4]. Hazardous industrial waste disposed by incineration and other high temperature waste treatment systems, are described as the thermal treatment process. In order to avoid the usage of huge power to destroy the hazardous compound, freeze concentration was introduced to lessen energy requirement. Freeze concentration is the process where the water component in a solution is frozen and crystallized as ice so that a more concentrated solution will be left behind in a smaller volume. Advantages of freeze wastewater treatment are 1) less energy is needed to incinerate the resulted concentrated wastewater 2) wastewater including toxic compounds [5] or heavy met- als [6] can be treated which is difficult to treat biologi- cally, and 3) a smaller facility is required compared to biological wastewater treatment [7]. There are two * Corresponding author. Copyright © 2013 SciRes. ACES