177 treated permeate achieves a quality suitable for partial reuse as process or industrial water, thereby reducing abstraction from surface water resources. As a result, the salinity of discharged water is significantly reduced (to below 10–15 g/dm³ in the reference configuration), and the overall environmental pressure at the catchment scale is substantially mitigated. A comparative summary is presented in Table 2. Table 2 – Comparison of environmental impacts (before and after) Parameter Reference state (before) Transformation variant (after) Mine water flow 10,000 m³/day 10,000 m³/day Mean salinity 30 – 60 g/dm³ <10 – 15 g/dm³ Salt load into the receiver 110 – 220 thousand tons/year 25-90 thousand tons/year Salt load reduction - 60 – 85% Process water utilization None Partial In the reference configuration, mine water drainage, treatment, and discharge are fully supplied by electricity from the national grid. The annual energy demand of the water management system is estimated at 20–25 GWh, corresponding to indirect CO₂ emissions of approximately 10,000–12,000 tonnes per year. In the transformation scenario, integration of a 5–10 MWp photovoltaic (PV) installation enables the generation of approximately 5–10 GWh of electricity annually. This corresponds to 25–40% coverage of the system’s energy demand and reduces indirect CO₂ emissions by an estimated 4,000–7,000 tonnes per year. In addition to emission reductions, partial energy self-sufficiency decreases operating expenditures associated with electricity purchases from the external grid. A further improvement is achieved through the implementation of a methane capture and utilization module. In the reference state, methane emissions are only partially controlled and are not fully utilized for energy purposes. The assumed capture potential of 0.5–2.0 million m³ CH₄ per year enables its use in combined heat and power (CHP) systems or as process fuel. Methane utilization leads to: ● direct reduction of methane emissions to the atmosphere, ● generation of additional electricity and/or heat, ● increased stability of water supply, especially during periods of limited renewable energy production. From a system-wide perspective, the methane module functions as a dispatchable energy source that complements variable renewable generation and further improves the overall
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