Vol.:(0123456789) 1 3 Environmental Earth Sciences (2020) 79:415 https://doi.org/10.1007/s12665-020-09160-7 THEMATIC ISSUE Treated water quality based on conventional method in Langat River Basin, Malaysia Minhaz Farid Ahmed 1  · Mazlin Bin Mokhtar 1 Received: 21 September 2019 / Accepted: 29 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract The water of Langat River is not suitable for drinking without treatment because of chemical pollution from both the point and non-point pollution sources, although it is one of the primary sources of drinking water in Selangor state, Malaysia. There is no signifcant study in Malaysia that has investigated the efciency of treatment plants to remove metals from treated water. Therefore, Chelex 100 resin-ion exchanged method was applied to investigate the raw water samples and treated water samples of eight treatment plants. Samples were analyzed by Inductive Coupled Plasma-Mass Spectrometry for the dissolved concentrations of aluminium, arsenic, cadmium, chromium, and lead, which have complied with the drinking water quality standard of Ministry of Health Malaysia and World Health Organization. However, the average metal removal efciency is about 52.48 ± 8.89% from treated water by the treatment plants based on a single sampling and this could be considered a preliminary indication to upgrade the treatment technology in Malaysia, because the efciency in removing trace metals by the plants may vary in hourly samplings. Keywords Malaysia · Trace metals · Contamination · Ion exchange · Drinking water Introduction Arsenic (As), Chromium (Cr), Cadmium (Cd), and Lead (Pb) are globally considered as detrimental trace metals for the aquatic environment because of its toxicity, abundance, and persistence in the water (Islam et al. 2015; Shakeri et al. 2014; Mohiuddin et al. 2011). Similarly, the ingestion of As, Cr, and Pb through drinking water has been considered as a contaminant of emerging concern for human health (Sauvé and Desrosiers, 2014; Deshommes et al. 2012; Hu et al. 2010; He et al. 2019; He and Wu 2019; Li and Wu 2019). These trace metals are toxic, and can be persistently accumulated in human bodies. Therefore, the chemically contaminated drinking water with trace metals is a life risk issue of the present and future generations (Şener et al. 2014). This is particularly true in large river basins, as water pollution in large basins can yield serious negative health efects due to huge population hosted in the basins (Li et al. 2018, 2019). Langat River is one of the main sources of drinking water in the state of Selangor, Malaysia and it provides drinking water to more than half of the populations (i.e., > 1.59 mil- lion) in the state (Ahmed et al. 2016a, b, 2018a, 2019; Juahir et al. 2011). However, both the point source, e.g., mining, efuent, and sewage treatment plants, animal husbandries, waste dumping, etc. (Al-Mamun and Zainuddin, 2013; Al- Odaini et al. 2013; Juahir et al. 2010) and nonpoint source, e.g., natural weathering of rocks and minerals, atmospheric precipitation, foods, landslides, etc. (Rwoo et al. 2017; IPCC 2014; Ali et al. 2012) attributes seriously to the river pollution (Ahmed et al. 2018b). Hence, Department of Envi- ronment Malaysia ranked Langat River as Class III (DOE, 2013) that requires large scale treatment before drinking. There are in total 34 Water Treatment Plants (WTPs) in Sel- angor and Kuala Lumpur. Among the WTPs, 9 WTPs are based on the conventional alum coagulation and lime soften- ing method at Langat River Basin. However, all the WTPs in This article is a part of the Topical Collection in Environmental Earth Sciences on “Water in Large Basins” guest edited by Peiyue Li and Jianhua Wu. * Minhaz Farid Ahmed minhazhmd@yahoo.com * Mazlin Bin Mokhtar mbmlestari@hotmail.com; mazlin@ukm.edu.my 1 Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia (UKM), 43600 UKM Bangi, Selangor, Malaysia