Citation: Altowayti, W.A.H.; Shahir, S.; Othman, N.; Eisa, T.A.E.; Yafooz, W.M.S.; Al-Dhaqm, A.; Soon, C.Y.; Yahya, I.B.; Che Rahim, N.A.N.b.; Abaker, M.; et al. The Role of Conventional Methods and Artificial Intelligence in the Wastewater Treatment: A Comprehensive Review. Processes 2022, 10, 1832. https://doi.org/10.3390/pr10091832 Academic Editor: Andrea Petrella Received: 9 August 2022 Accepted: 7 September 2022 Published: 12 September 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). processes Review The Role of Conventional Methods and Artificial Intelligence in the Wastewater Treatment: A Comprehensive Review Wahid Ali Hamood Altowayti 1, * , Shafinaz Shahir 1, *, Norzila Othman 2 , Taiseer Abdalla Elfadil Eisa 3 , Wael M. S. Yafooz 4 , Arafat Al-Dhaqm 5 , Chan Yong Soon 2 , Izzati Binti Yahya 2 , Nur Anis Natasha binti Che Rahim 2 , Mohammed Abaker 6 and Abdulalem Ali 5 1 Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, Johor, Johor Bahru 81310, Malaysia 2 Micro-Pollutant Research Centre (MPRC), Department of Civil Engineering, Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia, Johor, Parit Raja 86400, Malaysia 3 Department of Information Systems-Girls Section, King Khalid University, Mahayil 62529, Saudi Arabia 4 Computer Science Department, Taibah University, Medina 42353, Saudi Arabia 5 Faculty of Engineering, School of Computing, Universiti Teknologi Malaysia (UTM), Johor, Johor Bahru 81310, Malaysia 6 Department Computer Science of Community College, King Khalid University, Muhayel Aseer 61913, Saudi Arabia * Correspondence: ahawahid2@live.utm.my (W.A.H.A.); shafinazshahir@utm.my (S.S.) Abstract: Water pollution is a severe health concern. Several studies have recently demonstrated the efficacy of various approaches for treating wastewater from anthropogenic activities. Wastewater treatment is an artificial procedure that removes contaminants and impurities from wastewater or sewage before discharging the effluent back into the environment. It can also be recycled by being further treated or polished to provide safe quality water for use, such as potable water. Municipal and industrial wastewater treatment systems are designed to create effluent discharged to the surrounding environments and must comply with various authorities’ environmental discharge quality rules. An effective, low-cost, environmentally friendly, and long-term wastewater treatment system is critical to protecting our unique and finite water supplies. Moreover, this paper discusses water pollution classification and the three traditional treatment methods of precipitation/encapsulation, adsorption, and membrane technologies, such as electrodialysis, nanofiltration, reverse osmosis, and other artificial intelligence technology. The treatment performances in terms of application and variables have been fully addressed. The ultimate purpose of wastewater treatment is to protect the environment that is compatible with public health and socioeconomic considerations. Realization of the nature of wastewater is the guiding concept for designing a practical and advanced treatment technology to assure the treated wastewater’s productivity, safety, and quality. Keywords: water pollution; precipitation; adsorption; membrane; artificial intelligence 1. Introduction There are generally three types of wastewater or sewage: domestic, industrial, and storm sewage [1]. Domestic wastewater, also called sanitary sewage, is wastewater either from blackwater (wastewater from toilets that contain feces, urine, or toilet paper) or greywater (water from sinks, baths, washing machines, and others) [2]. Pollution and exorbitant use seriously compromise the availability of fresh and clean water around the earth and may cause a critical impact in the future. It is mandatory to protect and produce healthy water of sufficient quality at an economical cost while conserving the ecosystems. Every country will release liquid and air emissions and solid wastes. Wastewater is essentially the water supply that comes from the people in the city after it has been used in various applications [3]. Processes 2022, 10, 1832. https://doi.org/10.3390/pr10091832 https://www.mdpi.com/journal/processes