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Granulometric composition of suspensions contained in filter backwash water affects filter treatment technology selection. The paper describes results of granulometric composition studies on filter backwash water suspensions collected from 46 groundwater treatment plants. An original, modified Avrami equation was proposed to interpret the results of studies on granulometric composition determined by the use of laser diffractometer. The equation enabled identification of mechanism in which suspensions are formed in filter beds applied for groundwater iron and manganese removal process. The research showed that iron and manganese concentration growth in treated groundwater correlated with increase in the percentage of suspended particles with small equivalent diameter and in changeability range of particle equivalent diameters in backwash effluent. At low contents of iron and manganese compounds in treated water polydisperse suspensions were formed, characterized by narrower changeability range of particle equivalent diameters. [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]

A study algorithm of fi ltration materials susceptibility to autoactivation with manganese dioxide was presented, in the example of chalcedonite sand. This algorithm may serve as a basis for preliminary research plan development for groundwater treatment plant purposes. The proposed methodology was verified in studies on iron and manganese removal from groundwaters by fi ltration using chalcedonite as well as, for comparative purposes, quartz and anthracite-quartz sands. Technological characteristics of chalcedonite, quartz and anthracite-quartz deposits were received under the same research conditions and in line with the methodology developed. This allowed the manganese dioxide assisted autoactivation processes to be compared and a definite prevalence of chalcedonite over quartz and anthracite-quartz sands in the process of iron and manganese removal from water was demonstrated. [ABSTRACT FROM AUTHOR]