Ewelina Wojciechowska

Senior Engineer

(+47) 979 84 424
ewelina.wojciechowska@nibio.no

Place
Holt

Visiting address
Holtveien 66, 9269 Tromsø

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Abstract

Rapeseed oils are a valuable component of the diet. Mostly, there are refined oils deprived of valuable nutrients in the market, hence in recent times cold-pressed and unrefined oils have been available and popular among consumers. However, the low yield of this oil makes this product expensive. The aim of the study was to analyse the effectiveness of phosphorus reduction in crude oils, cold- and hot-pressed in the low-temperature bleaching process. Eight market-available bleaching earths was compared. The effectiveness of 90% was found with 2% (m/m) of Kerolite with hydrated magnesium silicate. An increase in the share of earths to 4% (m/m) resulted in the effectiveness of phosphorus reduction >90% in seven out of eight analysed cases. Bentonite activated with acid with the lowest MgO content was characterised by low efficiency <64%. The research shows that the effectiveness of phosphorus reduction was significantly affected by the composition of earths applied in the bleaching process at ambient temperature. The results of research confirm the high effectiveness of the process as it is not necessary to heat up the oil before the bleaching process. This method is recommended for existing and new industrial plant for two-stage rapeseed oil pressing.

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Abstract

When using food and green waste composts as peat-free plant growing media, there is a challenge that nutrient immobilisation and high pH and salts content limit plant growth. The present study explored the use of spent mushroom compost (SMC) of Agaricus subrufescens in a sustainable plant growing system where only vermicompost from digested food waste and composted green wastes were used, even for the seedling stage. However, negative effects of high compost inclusion were offset by adding SMC. Significantly higher plant yield was obtained in several of the SMC amended treatments in four out of five lettuce experiments and in one tomato experiment. In addition, an experiment with cucumbers showed that nutrients were not available to the plant when the mushroom mycelium was actively growing, but became available if the mushroom mycelium had been inactivated first by pasteurisation. A significant effect from SMC was not observed under full fertigation. This study demonstrated that the addition of pasteurised Agaricus mycelium colonised compost can successfully offset negative effects from high pH and EC as well as limited nutrient supply (and nitrogen immobilisation) in peat-free, compost-based growing media.