Essential and Toxic Elements in Drinking Water:

Overview

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Key numbers

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West Pomeranian University of Technology in Szczecin https://orcid.org/0000-0001-8465-7509
License:   This work is licensed under a Creative Commons Attribution 4.0 International License.
treatment process reduced the concentrations of these compounds in water by a range of 48.5 to 97%.
28.6 to 60.8%. Trace element concentrations in treated sewage were below MAC values in all the samples
tested, and were from 1.15% (Pb) to 6.23% (As) MAC for toxic elements. Concentrations of both essential
had a significant (p<0.05) effect on decreasing concentrations of trace elements.
Reductions in the most dangerous elements fluctuated from 48.5 (As) to 97% (Pb).
Wastewater treatment reduced the concentration of Pb and As by over 50%.
manganese, and copper, but it can also be a source of harmful elements (Vriens et al. 2017). Water
techniques are combined with the aim of increasing treatment efficiency (Crini and Lichtfouse 2019).
recovered from wastewater treatment sludge (Barakat 2011). This is why it is so important to have
globally (Bos et al. 2016). In European Union (EU) countries, the quality of water intended for human
consumption is regulated by Directive 98/83/WE (1998, 2015), and in Poland additionally by the
Regulation of the Minister of Health of 2017 (Council Directive 2015; Journal of Laws item. 2294 2017).
potentially toxic, and the high consumption of drinking water of 2.0 – 2.5 l/day (EFSA 2010).
focused on reducing organochlorine compounds (Cybulski et al. 2021).
2 Materials And Methods
2.1 Study material
has an area of 35 km2 and is the fifth largest in Poland and the second largest in the voivodeship. The
that are located in the deep-profundal zone. The intakes are fitted with 40 mm mesh gratings. The raw
(Fig. 1). The wastewater tested was from the Pomorzany Wastewater Treatment Plant, from which raw
outflow canal. The study began in March 2017, and ran until March 2019. The parameters analyzed are
presented in Table 1.
Sampling was performed four times monthly. Each time, three samples of 5 l of raw water,
elements (zinc, nickel, iron, manganese, copper, lead, and arsenic), and a total of 1,152 samples of all
Production Plant through a pipeline fitted with a rotary 2 mm mesh capable of retaining particles larger
coagulant (Kemipol, Poland; with the following properties – pH - 3.6±0.4; alkalinity - 85±5%, density -
1150 kg/m3,aluminium content - 6.0±0.5%; chlorides - 5.0±1.0%), flocculation using polyelectrolytes, and
2.1.2 Treating wastewaters
years. This plant treats wastewater from approximately 50% of the urban area. The treatment stages are
presented in Fig. 3. The wastewater treatment process utilizes two types of coagulators: PIX (Kemipol,
Poland; PIX 113 with the following properties—total iron (Fe) 11.8 ± 0.4%; density in kg/m3 (20°C) 1500 –
1570; pH of less than 1— and PAX 16 (Kemipol, Poland) with the following properties—Al2O3 content –
15.5± 0.4%; chlorides (Cl–) – 19.0 ±2.0%; alkalinity – 37.0± 5.0%; density in kg/m3 (20°C) 1330 ± 20; pH
pH < 2 with the aim of avoiding contamination and trace element precipitation. Additionally, immediately
before beginning the analysis, all the samples were filtered through 0.45 μm glass fiber filter paper
2.2.1 Digestion and ICP-AES analysis
to the procedure PN-EN ISO 15587-2: 2005 (Polish Norm 2005). For this, 200 ml of water was
concentrated in quartz beakers on a heating plate, 3 ml of concentrated HNO3 (Merck, Germany) was
added, and the solution was evaporated to dryness. For wastewater digestion, larger amounts of HNO3
(from 5 to 20 ml) were added until the light-color of sample. The resulting pellet was dissolved in 2 ml of
15% HNO3 (Merck) and transferred quantitatively with deionized water (Barnstead Easy pure UV) to a

Methods (brief)

performed with inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The water
The concentrations of trace elements (>LOD) in drinking water were below maximum acceptable
28.6 to 60.8%. Trace element concentrations in treated sewage were below MAC values in all the samples
The raw water was sampled from Lake Miedwie, which is a drinking water source and the largest
wastewater was sampled at the grating station, while treated wastewater samples were collected at the
Sampling was performed four times monthly. Each time, three samples of 5 l of raw water,
drinking water, raw wastewater, and treated wastewater were collected to be tested for levels of trace
elements (zinc, nickel, iron, manganese, copper, lead, and arsenic), and a total of 1,152 samples of all
samples were preserved with nitric acid (Merck, GmbH Germany).
Immediately after collection, water samples were acidified with concentrated HNO3 to a solution
before beginning the analysis, all the samples were filtered through 0.45 μm glass fiber filter paper
2.2.1 Digestion and ICP-AES analysis
Water samples for determinations of the general forms of the elements selected were digested according
added, and the solution was evaporated to dryness. For wastewater digestion, larger amounts of HNO3
(from 5 to 20 ml) were added until the light-color of sample. The resulting pellet was dissolved in 2 ml of
inductively coupled plasma atomic emission spectrophotometry (ICP-AES; Yobin Yvon JY-24) fitted with a
257.610 nm; Ni – 231.604 nm; Zn – 213.856 nm; As – 228.812 nm; Pb – 220.353. All samples were
Fe (97.2%), Mn (99.0%), Cu (96.4%), Pb (98.6%), and As (97.7%). The limit of detection (LOD) and limit of

Implications

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
3171d06	2026-08-02	major	1 section added
bc84bfc	2026-08-02	major	6 sections added; narrative text revised