The period in which a source like water is getting more and more important, technologies and plants for water treatment are being installed in order to reduce pollution and contamination which plays a fundamental role. One of the main objectives of paper industry is the closure of water loops and consequently the reduction of fresh water consumption for environmental and economic reasons. In such situation equipments for water treatment holds a great importance allowing recycling of treated water in the process and in some conditions, to recover raw material.
O.M.C. Collareda Srl, a Company located in Schio, Vicenza – Italy, is a leading international company in the design, production and assembly of industrial and municipal water treatment plants. Their equipments and plants range allows facing a lot of different situations on field. Their functioning is based on the following different processes: dissolved air flotation, mechanical filtration of solids particles contained in raw water, liquid suspensions thickening, and biological treatments.
Dissolved Air Flotation (D.A.F.), represents a high performance chemical- physical separation process to be applied for water clarification, sludge thickening and raw material recovery; its done for the dissolution of the air into the water under pressure. Subsequently when the pressure is brought back to the atmospheric value by using a depressurization valve, a big amount of air gets released in the form of micro-bubbles, further mixing them with the solids suspended in the water. The air bubbles lift the suspended solids to the flotation surface, forming a floating sludge layer which is continually removed by a skimmer.
O.M.C. products – Deltafloat, a circular shaped floatation unit, and Tigerfloat, an innovative rectangular shaped unit, characterized by lamella system inside. The rectangular section is suitable for installation in reduced and narrow 
spaces. In addition, the inclined lamella system located inside the tank increases considerably the flotation surface, thus reducing the required area for its installation. The most important element to get a perfect flotation process is the Air Saturation Reactor – A.S.R., where, under pressure, the air is dissolved into the water. The unique and exclusive design of the A.S.R. dissolving system allows achieving an air saturation rate higher than 95% of the theoretical value related to Henry’s law.
Flotation units can be applied for paper machine’s back water clarification in order to recover fibres to be re-used immediately for the production process. They can be used for thickening of flotation cells foams or clarification of filtrate washers in deinking plants, as well as for effluent clarification, pre-treatment in biological plants and biological sludge thickening.
Separation and filtration represent mechanical processes and the main products manufactured by O.M.C. are the drum filter – Gammafilter, the continuous self cleaning sand filter – Omegafilter and the fractioning filter – Sigmafilter.
Gammafilter is a compact, sturdy and efficient machine with a very large filtering surface due to it’s V – shaped profile of the polyester shrinkable filtering cloths installed onto a circular drum. The main characteristic of Omegafilter has its own operating principle that permits a continuous feeding of water to be treated and, at the same time, washing of the sand bed without interruption of the process for sand back-washing. Sigmafilter represents a fractioning filter suitable to split solids of different sizes.
This range of equipments can be applied for spring or river water filtration before it is used for the production process. All of the above mentioned machines are typically installed after the fibres recovery system in order to remove the last suspended solids and to allow the water re-usage. They are also suitable for the filtration of paper mill
effluent or for biological plant discharge (tertiary filtration).
The Densidisc is a gravity filter which has discs equipped with metallic wires. It can be considered a filter, a thickener and a washer; its functioning is based on the mechanical separation of liquids from solids, while the last ones are thickened too. It can be applied before an existing and overloaded save-all unit in order to reduce the suspended solids. Another typical application concerns fibres thicken-ing in stock preparation plants, as well as floating sludge thickening.
Biological Treatment Plant
They represent the additional step of treatment for the water before its discharge (to the river or sewer) or its reusage in the production processes in order to reduce the fresh water consumption. The plants are designed in order to guarantee high efficiency removal of suspended solids, BOD and COD, reduced installation space and consequently reduced investment for the civil works.
OMC is adopting different technologies according to the specific projects:
• A.S.T. – Activated Sludge Treatment
• M.B.B.R. – Moving Bed Biofilm Reactor
• F.B.B.R. – Fixed Bed Biofilm Reactor
A careful design based on project by project basis and a continuous study of the new technologies and new products allows achieving high performance and results in terms of:
– High yield of depuration
– Low production of biological sludge
– Low energy consumption
– Low operating costs
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