TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Process: The degassed water from step (i) is subjected to an intermediate step (a) that is pre-filtration, in particular a sand filter, where the pre-filtered water is subjected to an intermediate step (b), which is a water softening, where at least a part of the CO2 formed in step (ii) is supplied to intermediate step (b). The water softening applied in intermediate step (b) comprises ion exchange process and pellet water softening. Pre-filtered water from intermediate step (a) is supplied in part directly to the ion exchange process and in part directly to the water softening in intermediate step (b). The CO2 formed in step (ii) is supplied to the ion exchange process. The ion exchange process used in intermediate step (b) is a mixed bed of weak acid ion exchanger in free acid form and a strong basic ion exchanger in the hydro carbonate form, where the water stream supplied to intermediate step (b) is disconcerted from one or more of the components selected from calcium (Ca), magnesium (Mg), sulfate (SO4), nitrate (NO3) and chlorine (Cl). A residual stream, obtained by the ion exchange process used in intermediate step (b), is supplied to the pellet water softening. Residual stream of calcium carbonate (CaCO3) is obtained from the pellet water softening applied in intermediate step (b), where CaCO3 residual stream is incinerated to calcium oxide (CaO) and subsequently brought into contact with water, in particular obtained by carrying out step (ii), where the obtained lime water is supplied to the pellet water softening. The water stream subjected to intermediate step (b), in particular derived from the ion exchange process and the pellet water softening, is further treated in an intermediate step (c), that is an after filtration step, in particular a sand filter, in particular that the stream subjected to intermediate step (c) further is treated in an intermediate step (d), that is an ion exchange process for the removal of color forming components, in particular that the brine stream obtained in intermediate step (d) is subjected to an intermediate step (k), that is nano filtration, where in intermediate step (k) a concentrate stream is obtained which is used for the regeneration of the ion exchange resin applied in intermediate step (d), preferably that the in intermediate step (k) obtained product stream, which product stream is rich in natural organic matter (NOM), is removed. The concentrate stream obtained in intermediate step (c) and/or the obtained concentrate stream from the intermediate step (a) are supplied to an intermediate step (f), that is an ultrafiltration step, where the product stream obtained in intermediate step (f) optionally is subjected to an intermediate step (g), that is a treatment with UV radiation, in particular that the concentrate stream obtained in intermediate step (f) is drained off. Before intermediate step (a) is carried out, the degassed water from step (i) is subjected to an intermediate step (h), that is an aeration step to remove residual gases such as methane (CH4) and CO2 from the already degassed water from step (i), which residual gases in particular are released to the atmosphere. At least a part of the CO2 formed in step (ii) is applied in one or more intermediate steps (a) to (h) for the correction of pH. At least a part of the gases obtained in step (i), in particular CH4, is compressed to liquid gas, which liquefied gas is used as a fuel component for motor vehicles. At least a part of the heat obtained in step (ii) is used for drying the residual streams containing solid substances, obtained in one or more intermediate steps (a) to (h). At least a part of the energy obtained in step (ii) is used as electrical energy in carrying out one or more of intermediate steps (a) to (h).