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In this study, the effectiveness of the Fenton process in removing natural organic matter (NOM) from groundwater was investigated. The subject of this study is groundwater characterised by increased content of NOM and iron (II) compounds. In laboratory-scale studies, the influence of the ratio of concentrations of Fe(II) ions, which are naturally occurring in groundwater, to hydrogen peroxide (H2O2) as well as oxidation time and pH on the removal efficiency of organic matter was determined. Indicators such as total organic carbon (TOC), dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), UV absorbance at 272 nm (UV272), and specific UV absorbance (SUVA254) were used to quantitatively and qualitatively assess the organic substances present in the raw water and after oxidation with Fenton's reagent. Analysis of the results obtained showed that the highest removal efficiency of organic substances in the deep oxidation process using the Fenton reaction was obtained for a concentration ratio of Fe(II) to H2O2 = 1:5. Acidification of the water samples to a pH of about 4 and extending the oxidation time to 30 min significantly increased the removal efficiency of organic substances including mainly dissolved organic substances containing aromatic rings. The organic substances containing aromatic rings, determined at a wavelength of 254 nm, were degraded to other organic intermediates. [ABSTRACT FROM AUTHOR]

The aim of the present study was to compare the effectiveness of coagulation process carried out using non-prehydrolysed coagulants (iron (III) sulphate (VI) and aluminium sulphate (VI)) and prehydrolysed polyaluminium chlorides differing in basicity in the removal of natural organic matter (NOM) from groundwater. Volume coagulation was carried out in groundwater samples after aeration at natural pH or at pH adjusted to 6.0–8.5. The Al species (Ala-monomeric, Alb-polymerized, Alc-colloidal) distribution in the aluminium coagulants were analyzed by the Ferron complexation timed spectrophotometry. The fraction distributions of NOM and residual aluminium after coagulation were analyzed as changes of coagulant dose and pH. The efficiency of polyaluminium chlorides in the removal of NOM was found to increase with the polymerization of the products of aluminium prehydrolysis. Prehydrolysed coagulants were of greater utility than non-prehydrolysed coagulants in removing not only non-dissolved, but also dissolved fractions of NOM, and they were efficient over a wider range of pH. When the proportion of dissolved organic carbon in the total organic carbon load increased, the efficiency of total organic carbon removal decreased regardless of the type of coagulant tested. The worst results in the removal of NOM were produced by the iron coagulant. [ABSTRACT FROM AUTHOR]

The subject of this research was groundwater from Quaternary formations with the increased concentration of organic substances. Successful treatment of such water generates technological problems and is practically impossible by means of traditional groundwater treatment processes. Laboratory tests showed that the prehydrolyzed aluminum coagulants (Flokor 1, Flokor 1ASW)had higher efficacy of organic (TOC, DOC) and inorganic (Fe, Mn) compound removal from groundwater than alum due to higher content of polymeric aluminum species. Water acidification up to pH=6 prior to coagulation, regardless of the coagulant type, led to an increased efficacy of organic substances and color impurities removal. Moreover, alkalization of water up to pH = 8.5 resulted in more efficient removal of iron, manganese and particles being a measure of water turbidity. It was demonstrated that with an increase in polymerization degree of aluminum coagulants both the remaining aluminum concentration in treated water as well as the coagulant sensitivity to changes in temperature and pH of the treated water decreased. [ABSTRACT FROM AUTHOR]

Laboratory research was carried out on groundwater containing iron-organic complexes. For this reason oxidation (O2 and KMnO4) and coagulation (alum and polyaluminium chloride Flokor 1.2A) processes were applied for water treatment. It was concluded that with increase in the coexistence ratio of organic substances and total iron in water (D = [TOC]/[Fe]), efficacy of Fe(II) to Fe(III) oxidation with dissolved oxygen decreased, while the oxidation time was increasing. This rule was not demonstrated for KMnO4 when used as an oxidizing agent. Laboratory tests revealed that the coagulation process markedly increased efficacy of groundwater contaminant removal; the efficacy depended on oxidizing agent and coagulant type and increased with their dose. Additionally, it was shown that for water samples after aeration, varying by the value of the coexistence ratio, an increase in the ratio was accompanied by decrease in the efficacy of contaminant removal in the coagulation process. [ABSTRACT FROM AUTHOR]