The researchers studied how adding powdered activated carbon (PAC) to a wastewater treatment system affects water quality and the formation of harmful compounds called trihalomethanes (THMs). They found that adding PAC improved the removal of organic matter and reduced the formation of THMs in the treated water. PAC also helped prevent the build-up of organic material on the system's membranes. However, adding PAC led to the formation of more toxic types of THMs. Using higher levels of chlorine and longer contact times increased THM formation but decreased the proportion of the more harmful THMs.