Development of non-wood fibers has been one of strategies to ensure a sustainable fiber supply, including plantation management, reforestation and recycling. Some of alternative fibers are algae that can be used as raw material for papermaking. The Shiro Alga Carta papers made from algae in combination with Forest Stewardship Council certified fibers (FSC-fibers) were used for this research. Three offset inks were used in printing: vegetable-based inks with different amount of renewable raw materials and mineral oil-based ink. Three series of prints were made: non-varnished, varnished with water-based dispersion, and varnished with UV cured varnish. The possibility of reusing fibers was determined by methods of re-pulping (loop I, loop II, loop III). The vegetable based ink toward improved structure give bather results in terms of brightness, ink content and dirt count and area compared with the mineral oil-based ink. Something lower brightness gain and ΔERIC is obtained with water-based dispersion overprint samples. The lowest results are obtained for samples overprinted with UV cured varnish. The results of the research contribute to the explanation of paper/ink/varnish interaction on the reuse of the fibers, which takes into the area of the ecological sustainable development.

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The aim of this work was to determine the influence of the conventional offset printing technique and digital electrophotography printing with liquid toner (LEP) on some optical properties of recycled fibres. A series of LEP prints was made with the variation of the negative voltage of the developing drum (−200 V, −280 V, −350 V, and −430 V) after calibration of the machine and achieving standard densitometry values. Besides deinkability aspects, the quality of wastewater effluents after process of prints recycling was observed in order to make a conclusion regarding how different printing techniques, conditions in printing process, and different types of inks can affect the wastewater effluents. Results of image analysis showed that by increasing the negative voltage of developing drum in LEP printing technique, the formation of large ink particles on handsheet from recycled pulp increases. Depending on the size of the negative voltage of the developing drum, under the same experimental conditions, handsheets made from LEP recycled fibres have lower whiteness gain, brightness gain, and ΔERIC of handsheets compared to those made from the offset prints. In addition, a certain correlation was found between IEERIC (ink elimination), chemical oxygen demand (COD), and total organic carbon (TOC) of wastewater effluents after recycling of LEP prints and offset prints as well. Organic water pollution parameters (COD and TOC) showed higher values in wastewater after recycling of offset prints compared to recycling of LEP prints.

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