I am evaluating the performance of lab-scale bioreactor in treating phenol containing wastewater. While building a model based on the performance I obtained i.e., phenol removal efficiency versus the variables, I am not sure what is the acceptable range of the R square in the model. Of course, the higher the R square the better the model. However, there is an acceptable R square of model in specific field. So, I would like to know the proper range and minimum R square for the model under the aforementioned biological wastewater treatment approach. Thank you.