Investigation of high-turbidity tap water problem in Najaf governorate/middle of Iraq

Abstract Turbidity is a fundamental measure for assessing the quality of water supplied by water treatment plants (WTPs) employing a conventional treatment process. If it is present in amounts exceeding the permitted limit, disinfectants are less effective in killing microorganisms and the water becomes unsafe to drink. This article is a part of a comprehensive study that aims to investigate the high-turbidity problem of tap water in two cities of Najaf governorate and offer suitable measures to solve this problem. The purpose of this study was to determine how WTPs impact the turbidity of tap water. The work covered two main WTPs located in Najaf governorate: Unified Najaf and The Old Kufa. It included the collection of water samples from three locations in each plant: the influent of flash mix unit (raw water samples), the effluent of clariflocculation unit (settled water samples), and the effluent of filtration unit (filtered water samples). The samples were analyzed for turbidity using a turbidity meter. The efficacy of each plant's treatment units was revealed by monitoring the turbidity of the water inside each facility. For the Unified Najaf WTP, out of 99 TRE readings, there were 3, 92, and 60 positive values for TREc, TREf, and TREp, respectively. The maximum values of TREc, TREf, and TREp were 22.3, 86.5, and 61.5%, respectively. The performance of Old Kufa WTP was worse than that of Unified Najaf WT. Out of 99 TRE values, the number of positive values was 6, 76, and 31 for TREc, TREf, and TREp, respectively. They also showed that only 26 out of 99 and 9 out of 99 effluent turbidity readings in Unified Najaf and Old Kufa WTPs, respectively, satisfy Iraqi standards for tap water turbidity. The bad performance of the WTPs was the main reason behind the high-turbidity tap water in Najaf governorate. This study identified the causes of that performance and proposed solutions.