SOLVIA ReWater is a body of work on the treatment, polishing and reuse of water at a site. Part of the used water is returned to the process cycle as technical water after treatment, and the volume of the residual discharge falls where that is technically and economically justified.
SOLVIA ReWater brings the water and the effluent of a site into a single calculation: the raw water, its preparation, its use, the effluent that arises from it, treatment, polishing, reuse and the control of the residual discharge are taken as links of one chain rather than as two separate households. Water preparation, washing, the laundry, the membrane block and the treatment works of such a site are connected, and a decision on one link shifts the load on the next.
The water that comes back is technical water: it goes to equipment washing, to the make-up of separate systems and to preliminary and auxiliary operations, not into the potable circuit. What is selected is therefore not a single unit but a scheme — which stream is returned, to what quality it is brought, at which point of the process it enters, and what happens to the part that is not returned at all.
A recirculating water supply is not built on one filter or one general-purpose unit. Different sites produce different contaminants. At a car wash the water carries sand, clay, oil products, surfactants, fine suspended matter and road dirt. At a laundry it is lint, microfibres, detergents, organics, a raised temperature and a shifting pH on an unstable composition. At a food production site it is fats, proteins, an organic load and the residues of raw material and of cleaning agents.
Airport effluent stands apart: in winter it carries glycols and de-icing agents, salts and suspended matter, while a high COD and seasonal load peaks make it unlike domestic sewage. A different composition calls for a different sequence of stages, so the scheme is calculated from an actual analysis of the water and the effluent, and a universal scheme for every production site is not calculated at all.
Polishing answers for the quality of the water at the outlet, reuse answers for the stability of the cycle inside the site, and these are different tasks. As soon as part of the water is returned, salts and residual contaminants concentrate from pass to pass, and with them arises what a discharge scheme does not have: a salt balance, the risk of odour, sludge formation and membrane fouling.
Hence the second limit: not every treated water is returned to every point of the process. At a laundry a return to all the stages of washing is not considered — the water is better directed to technical operations, to preliminary stages and to auxiliary duties. The quality required at the point of return, the storage volume needed and the operating costs that are acceptable together decide what share of the water can be brought back.
Membrane stages — microfiltration, ultrafiltration, nanofiltration, reverse osmosis, membrane bioreactors and electrodialysis — give a more stable water quality, but alongside the treated water they produce a stream with a raised concentration of salts and contaminants. It does not dissolve into the scheme by itself and is taken as a separate process stream with a treatment of its own: anodic oxidation, cathodic treatment, sorption after the electrochemistry or electrodialysis, according to the composition of the water.
The return of water also raises the demands on membrane protection: as the salts concentrate the risk of mineral scaling grows, and the stability of a reverse osmosis unit depends not only on the quality of the membranes but on the antiscalant, on correct dosing and on control of the concentrate. Splitting the flow — one stream to membrane treatment, another to concentrate treatment, a third to polishing or to blending after a quality check — becomes part of the scheme: this is no longer one treatment plant but a system that manages several water streams.
Water that is returned calls for continuous control, because its quality bears on the process and not only on the outlet. Reuse schemes carry level, flow and pressure sensors, measurement of pH, redox potential, conductivity, dissolved oxygen and turbidity, control of dosing and of the membrane parameters, alarm signalling and remote monitoring with SCADA. The automation is there so that a deviation is seen in time and the human factor weighs less on the cycle.
For difficult sites the scheme is proved by a pilot on the real water rather than on a calculated model alone. A pilot shows the degree of treatment that can be reached and the stability of the quality, sludge formation, the behaviour of the membranes and of the concentrate, reagent consumption, energy use, the risk of odour and the demands on service. That order — a survey, a laboratory assessment, a pilot scheme and then scaling up — is what makes the return calculable for airports, production sites, laundries and car washes.
SOLVIA ReWater is SOLVIA's own line of work: a set of engineering solutions for biological treatment, membrane processes, electrochemical treatment, membrane protection, the retrofitting of existing vessels and automation, assembled to the task of a given site. The LAURUS vertical bioreactor platform, used in compact reuse schemes in the LAURUS MBR version, holds patent protection in Russia. The make-up of the schemes, the operating regimes and the calculated parameters are not disclosed in open materials and are selected for the individual project.
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