Hygienic assessment of tap water quality by sanitary-chemical parameters and improvement of the scientific methodological approaches of their assessment in accordance with the requirements of the european legislation

Abstract

Aim. The aim of the study was to carry out a hygienic assessment of the quality of tap water produced from the Dnipro River water in relation to the content of sanitary-chemical indicators and to improve the scientific and methodological approaches to their evaluation, according to the relevant indicators, taking into account the requirements of European legislation.Materials and methods. The materials of the Communal Enterprise «Dniprovodokanal»,Communal Enterprise «Vodokanal» (Zaporizhzhya), Communal Enterprise «Berdyanskvodokanal», the Communal Enterprise «Oblvodokanal» regarding the technologies of water purification, the quality of the outgoing and plumbing drinking water for 2015-2017 were analyzed. The requirements of the normative documents - ДСанПіН 2.2.4-171-10 "Hygienic requirements for drinking water intended for human consumption" and Directive 98/83/EC of 3 November 1998 on the quality of water intended for human consumption. While conducting the research were used following methods: hygienic monitoring, expert evaluation and mathematical statistics.Results. It was found out that at the investigated water supply stations that clean the river Dnipro water, technologies of water treatment had a different type of facilities for coagulation and clarification, presence or absence of preamonization, flocculation, coagulation, type of chlorinated reagent (liquid chlorine or sodium hypochloritе), trademark of aluminum hydroxychloride. The exceedances of nine indicator sanitary-chemical parameters: turbidity, color, taste, permanganate demand, ammonium, hydrogen indicator, aluminum, iron, manganese — were found in potable tap water. It was discovered that the most problematic parameter is the permanganate demand (PD), the number of samples of potable water which didn't meet the standard for the content of this parameter in potable water of UC «Dniprovodokanal» and UC «Vodokanal» — 100 %, UC «Berdyanskvodokanal» —19,4 %. Maximum exceedance of standard for the PD (5mg/l) in comparison with other parameters was the highest (by two times). Other parameters were determined in different samples of potable water periodically in concentrations which didn't exceed the temporarily established hygienic standards, or episodically and slightly exceeded the standard. It was determined that treatment technologies for potable water, which were used on UC «Dniprovodokanal» (KPFS, DPFS), are more efficient for the increase of PD than technologies on UC «Vodokanal» (almost two times) and less efficient than technology, which allows for consistent potable water treatment on the stations of UC «Oblvodokanal» and UC «Berdyanskvodokanal» (by 1,2 and 1,3 times respectively). The quality of source water at the waterworks stations as to the content of water samples met the 2nd and 3d class of quality according to the DSTU 4808:2007. The results of researches on the quality of drinking water of 6 water supply stations also indicate the presence of 7 problem indicators (chloroform, dibromochloromethane, chlorine, nickel, selenium, phenols and petroleum products), the excess content of 4 of them testifies to anthropogenic pollution of water p. Dnepr. It was determined that according to the requirements of European legislation it is possible to decide to increase of standard of PD for water from Dnipro River, but only for determined and scientifically substantiated conditions in each particular case. For the crisis resolution in the sphere of potable water supply according to the requirements of European legislation DSanPin 2.2.4-171-10, the following should be added: the concept of “indicator” parameters, new parameter (electrical conductivity), and also indicative maximum permitted standards, which will meet the current regulations to 01.01.2020 in accordance with DSanPin 2.2.4-171-10. Today a new version of DSanPin 2.2.4-171-10 was developed, where the above-mentioned is described.Conclusions.1. It was proved, that for cleaning surface waters at water supplying stations there are used stale traditional technologies, so potable waters may continuously contain chloroform (in concentrations 1,8 MPC - 4,7 MPC), periodically dibromchlormethane ( to 3 MPC) and bound chlorine (to 1,1 MPC).2. It was determined, that nowadays potable water quality, which is produced from the water of Dnipro river, doesn’t meet the requirements according to 9 indicator parameters: turbidity, color, taste, and flavor, PD, ammonium, hydrogen ion exponent, iron, aluminum, manganese. When comparing with the other parameters, PD has the biggest maximum excess of the standard (5mg/l) (twice), the quantity of the non-standard samples for this parameter can be up to 100%.3. On the background of excess content of organic substances in the water of studied potable water intakes of r. Dnipro, there was found the anthropogenic pollution by such substances as: nickel, selenium, phenol and oil products. These substances are constantly or periodically revealed in water pipe drinking waters, including in concentrations, exceeding MPC.4. It was determined that according to the legislation requirements in acting DsanPiN 2.2.4-171-10 there is a need of making changes for the determination of indicator parameters. The principles and assessment criteria, which are needed to be taken into account by competent bodies if necessary to correct normative by indicator parameters, were determined