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RWL Water Italia S.r.l. - Technological solutions for the dairy production chain


RWL Water Italia S.r.l.

RWL Water Italia S.r.l. specialises in the design, production and installation of turnkey plants for the treatment of water and other products, offers innovative technological solutions for the entire dairy production chain and in particular supplies systems for:


Soft water for drinking comes from surface and/or deep basins.
The main problems with surface water are the presence of turbidity, micropollutants and high bacterial load.

The potabilization processes adopted in this case must provide water with physical-chemical-bacteriological characteristics in compliance with the current laws. The main processes are:

  • Filtering on sand
  • Filtering on activated carbon

Pollution of the aquifers is due to substances like ammonia, hydrogen sulphide and methane, iron, manganese, carbonic acid and humic substances.
For removal of these substances, RWL Water Italia S.r.l. has developed the technique of biological filtering.

Lastly, arsenic can be present in both deep and surface water; the permitted concentration of arsenic in drinking water, at European level, is 10 μg/l.

RWL Water Italia S.r.l. currently uses two different technologies:

  • patented process with anionic resins regenerated with brine;
  • process with hybrid resins.


The water taken from the aquifers and springs contains dissolved substances of various types, mostly calcium, magnesium, sodium and potassium salts, which determine the salinity of the water; these salts can cause serious problems such as corrosion and scaling, resulting in obstructions and losses of efficiency in steam boilers and heat exchangers.

To ensure the production of quality process water, the dissolved salts must therefore be totally or partially eliminated, via a demineralization process, which can be performed by means of:

  • ionic exchange resins;
  • osmotic membranes (reverse osmosis).


Flotation is a system of solid-liquid separation via the introduction of very fine air bubbles which cause the solids, oils and fats present in the water to rise to the surface. These bubbles adhere to the foreign substances, reducing their apparent density, and drag them to the surface.
The bubbles are produced by saturating with air under pressure a part of the fluid recirculated by the end of the system; this flow is re-introduced at atmospheric pressure at the beginning of the system where the bubbles form.
The initial phase of the process involves dosages of coagulant and flocculant to facilitate removal of the suspended solids and colloidal particles.


Aerobic processes use the ability of the natural microbial populations to break down the biodegradable substance present in the waste water in order to obtain material and energy for their growth and reproduction. This results in the formation of aggregates or flocs of organic substance and micro-organisms which can rapidly sediment.
One of the commonest and most reliable aerobic treatment processes is the activated sludge system, with removal of the carbon and nutrients (first and foremost: nitrogen and phosphorus), known also as nitrification-denitrification process.


Anaerobic digestion is a biological process via which, in the absence of oxygen, the organic substance is broken down by micro-organisms with the production of biogas (renewable energy) consisting mainly of methane (CH4) and carbon dioxide (CO2), convertible into electrical and thermal energy.
The material coming out of the digester is a liquid sludge, not yet fully stabilised (the organic material has not been completely broken down), which will be separated into its solid and liquid parts. The liquid fraction can undergo aerobic treatment, or be recirculated in the digestion process.
The solid fraction can be used as a fertiliser or disposed of by specialist firms.


In addition to proteins, whey contains lactose and mineral salts which can be recovered and converted into substances with a high added value.

The demineralization process aims to preserve the whey lactose and proteins by reducing the mineral load (up to -90%). It is based on ionic exchange resins, i.e. insoluble organic substances able to exchange their ions with other ions having the same load and contents in the solution in which they are immersed.

Demineralized whey, subsequently crystallised and dried, is widely used as a basic ingredient in baby food, replacing mother’s milk, and as a raw material for various food products; it is also used in the pharmaceutical industry..


Chromatographic separation is an innovative process able to minimise the salinity of the permeate, maximising the recovery and quality of the lactose.

The technology developed by RWL Water Italia S.r.l. is based on the ISMB (Improved Simulated Moving Bed) chromatographic system which, in addition to guaranteeing process continuity, considerably reduces water consumption, does not use chemical agents and reduces the saline content of the starting material by over 90%.


The disposal of scotta, buttermilk and other dairy by-products is an issue that has long been neglected and is actually becoming a problem for an increasing number of dairy firms, which use these by-products as pig feed or even try to dispose of them, with relative process costs, often in breach of environmental regulations.

With its thirty years of experience in biogas production technologies, RWL Water Italia S.r.l. has carried out a series of pilot tests, the results of which highlight that if these by-products undergo anaerobic treatment, they generate biogas with a very high yield index.

Visit the interactive Simulator to calculate Whey, Scotta and Buttermilk exploitation, implemented by RWL Water Italia S.r.l..


The scotta (or buttermilk or other by-product) will firstly undergo anaerobic fermentation. Once it has been digested, the exhausted scotta (called "digestate") will be separated into its solid and liquid components. The solid part of the digestate, which has a much lower volume than the starting liquid (and is therefore easier to manage) will be disposed of in agriculture or by specialist firms (composting). The liquid part will be sent to the existing treatment plant (which may have been upgraded to cope with the higher load) or disposed of directly via the sewerage system.

The anaerobic digestion process can be effectively applied also to whey, but given the existence of alternative technologies which allow transformation of its chemical components (into products with a high added value such as demineralized whey, powdered lactose..) thereby improving the firm’s productivity, it should be considered as an alternative solution, for example, to demineralization or chromatographic separation.