© Mehran University of Engineering and Technology 2023 1 Mehran University Research Journal of Engineering and Technology https://doi.org/10.22581/muet1982.2301.01 2023, 42(1) 1-8 Turbidity removal through the application of powdered azadirachta indica (neem) seeds Qandeel Khan a , Uzma Imran a,* , Jeffrey L. Ullman b , Waheed Ali Khokhar a a U.S.-Pakistan Center for Advanced Studies in Water, Mehran University of Engineering and Technology, Jamshoro 76062, Sindh Pakistan b Department of Civil and Environmental Engineering, University of Utah, Salt Lake City, UT 84112 United States * Corresponding author: Uzma Imran, Email: uimran.uspcasw@faculty.muet.edu.pk Received: 02 December 2019, Accepted: 19 September 2022, Published: 01 January 2023 K E Y W O R D S A B S T R A C T Azadirachta Indica Powdered Neem Seeds Turbidity Drinking Water Various natural products used for water treatment are becoming more popular due to their general safety, eco-friendly sludge production, ease of degradation, cost- effectiveness, and local availability. This research assessed the efficiency of powdered neem (Azadirachta indica) seeds in removing turbidity from the water. Batch experiments determined the optimum coagulant dose, pH level, mixing time, and mixing speed to reduce turbidity from kaolin-based synthetic turbid water. Powdered neem seeds with a pore size of about 0.45 mm were prepared and used in water treatment under optimum conditions. Results showed that a coagulant dose of 3 g of neem seeds/L, 13.2 pH level, 60 mins mixing time at 80 rpm mixing speed could reduce turbidity levels to 35 NTU from 250 NTU (86% removal). Findings suggest that powdered neem seeds can be a potential substitute for conventional chemical coagulants for drinking water treatment. 1. Introduction Many developing countries face a lack of access to clean drinking water at affordable prices. There is a need to develop low-cost and efficient water treatment alternatives that are feasible and sustainable [1]. Coagulation is a workable water treatment process for removing dissolved organic material and reducing colloidal particles [2,3]. When large amounts of dissolved organic material are present, water may exhibit discoloration and have an unpleasant odour and taste [4,5]. In addition, coagulation can reduce suspended particles and inorganic residues (e.g., iron hydroxides) [6]. The coagulation process can also eliminate some pathogens (i.e., viruses and bacteria) associated with the coagulated particles [7]. The World Health Organization (WHO) reported that up to 84% of viruses and 87% of bacteria could be reduced by sedimentation and coagulation, although results varied considerably [8]. Various synthetic organic polymers [9] and inorganic coagulants (e.g., aluminum sulfate [10,11], ferric chloride [10], calcium carbonate [10]) are often used as coagulants in drinking water treatment systems [12]. Conventionally, these chemicals can be effective in removing impurities from drinking water, but they present certain limitations. These chemicals are often high in price, and the discharge of the resultant sludge can impart environmental costs [13]. Furthermore, some