This paper presents the results of the technological and economic analysis of mine water treatment systems before their discharge into the environment. The following analysis enabled us to determine the profitability of the investment, taking into account the TSS (total suspended solids) concentration in mine water. The simulation results showed that it is economically profitable to apply a water treatment system if natural sedimentation carried out in underground mine water passages, or in sedimentation tanks located on the ground, is ineffective for TSS removal. Economic and financial parameters allow us to conclude that all analyzed variants of the application of a pre-treatment system are characterized by high economic effectiveness. This mainly results from the high profitability of an analyzed investment, comparatively low capital expenditure, and present low market percentage rates. The most profitable variant (TSS concentration is 1000 mg/dm³) brings significant economic indicators, i.e., high NPV–Net Present Value (100 319 270.28 PLN), a high NPVR–Net Present Value Ratio (8.96 PLN/PLN), and a short discount payback period (1 year 236.6 days). A high internal rate of return (157.8%) for this variant reduces the risk of losing profitability in a situation of growing capital costs in the monetary market.

Filtration efficiency in a conventional water treatment system was analyzed in the context of pre-hydrolyzed coagulant overdosing. Two commercial coagulants of different aluminum speciation were tested. A study was carried out at a water treatment plant supplied with raw water of variable quality. The lack of stability of water quality caused many problems with maintaining the optimal coagulant dose. The achieved results show that the type of coagulant had a very strong influence on the effectiveness of filtration resulting from the application of an improper coagulant dose. The overdosing of high basicity coagulant (PAC85) caused a significant increase of fine particles in the outflow from the sedimentation tanks, which could not be retained in the filter bed due to high surface charge and the small size of hydrolysis products. When using a coagulant of lower basicity (PAC70), it was much easier to control the dose of coagulant and to adjust it to the changing water quality.

In conventional treatment of variable quality mountain water, an inability to immediately adjust the coagulant dose to variations in water quality causes overdose or underdose of coagulant in relation to its optimal value. The results of the research showed that the reuse of post-coagulation sludge was an effective method to maintain high and stable coagulation effectiveness under both polyaluminium chloride (PACl) overdose and underdose conditions. Recycled sludge contains a large portion of insoluble aluminium hydroxides that could be utilized in underdose PACl conditions. Post-coagulation sludge recycled to a flocculation tank enabled the reduction of a dose of low basicity PACl by 15% compared to a dose required in conventional coagulation. In periods of coagulant overdosing, sludge addition prevented an increase in the number of fine particles in an outflow from sedimentation tanks that could not be retained in a filter bed.

Granular activated carbon (GAC) is used for removing an excessive amount of organic contaminants causing undesirable taste, odour or colour of water, and refractive micropollutants, such as heavy metals or toxic organic compounds. However, adsorption is one of the most expensive unit processes used in treatment and renewal of water. This is due to the high cost of granular active carbon and the necessity of its frequent exchange or regeneration. In the paper the authors present the results of the technological and economic analysis of preliminary water treatment systems before GAC filters. The analysis enabled to determine the profitability of these investments taking into account raw water quality and the life of carbon between regenerations. The simulation results showed that it is economically profitable to apply preliminary water treatment independently of analysed pretreatment systems.

The aim of the study was to assess contamination of bottom sediments with heavy metals (lead and zinc) and its influence on the dominant macrophytes in selected four Polish anthropogenic rivers. Due to metal concentration, the sediments were classified in terms of their purity by three criteria: geochemical criterion, LAWA classification and ecotoxicological criterion. The studies revealed that tested macrophytes (Common Reed and Yellow Iris) were characterized by low and very low accumulation coefficient translocation factors of heavy metals. Common Reed was the plant which, to the greatest extent, accumulated heavy metals and therefore it was proposed as an indicator of lead and zinc contamination of river sediments. Heavy metals were mainly accumulated in roots and were not transported to their shoots as evidenced by very low translocation factors. Yellow Iris accumulated heavy metals to a lesser extent than Common Reed, however, it showed higher translocation factors of these metals. Zinc was preferentially collected by both plants in comparison with lead, as confirmed by higher translocation factors for zinc. Streszczenie: Celem pracy była ocena stopnia zanieczyszczenia osadów dennych metalami ciężkimi (ołowiem i cynkiem) oraz ich wpływu na dominujące makrofity w wybranych czterech przekształconych antropogenicznie rzekach w Polsce. Ze względu na stężenie metali osady rzeczne zostały sklasyfikowane pod kątem ich czystości według trzech kryteriów: kryterium geochemicznego, klasyfikacji LAWA i kryterium ekotoksykologicznego. Badania wykazały, że badane makrofity (trzcina pospolita i kosaciec żółty) charakteryzowały się niskimi i bardzo niskimi współczynnikami akumulacji i translokacji metali ciężkich. Trzcina pospolita to roślina, która w największym stopniu akumulowała metale ciężkie i dlatego została zaproponowana, jako wskaźnik stopnia skażenia osadów rzecznych ołowiem i cynkiem. Metale ciężkie gromadziły się głównie w korzeniach i nie były transportowane do pędów, o czym świadczą bardzo niskie wartości współczynników translokacji. Kosaciec żółty akumulował metale ciężkie w mniejszym stopniu niż trzcina pospolita, jednakże w tym przypadku zaobserwowano wyższe współczynniki translokacji metali. Cynk był preferencyjnie pobierany przez obie rośliny w porównaniu do ołowiu, co potwierdzono wyższymi wartościami współczynników translokacji.