Circular economy inspired utilization of tea waste in dye pollution mitigation

The use of industrial dyes in various sectors, especially, paper and textile, where synthetic chemical dyes are predominantly used, has often posed environment challenges. The given study evaluates the recycling potential of tea waste as a dye (methylene blue) adsorbent and a substrate for production of industrially important enzymes. Evaluative experiments on adsorption ability of tea waste showed more than 90% adsorption under optimized incubation conditions. A successive use of dye-adsorbed tea waste as solid substrate for the growth and production of industrially important enzyme, laccase, by Phanerochaete chrysosporium, one of the most industrially relevant white rot fungi, exhibited promising results. Significant laccase activity was observed for the dye adsorbed tea waste, under optimized conditions of solid state fermentation (SSF). Further, the resultant spent fungal-tea waste-biomass was subjected to a 2nd cycle of adsorption & enzyme production. More than 75% dye decolorization ability and more than 45% laccase activity was retained for spent fungal-tea-waste-biomass after 2nd cycle of adsorption-fermentation. Tea waste can be a good option of a low cost adsorbent for environmental pollutants like harmful synthetic dyes. Multiple cycles of adsorption-enzyme production using such low cost substrates offer an opportunity to add value to such natural waste and also additionally decrease the cost of production of industrially relevant enzyme, laccases, in the light of circular economy principles. Further investigations on substrate modification, cost estimates, combinatorial approaches, etc., to enhance bioremediation potential of tea waste and potential integration into existing treatment processes will help in better exploration of tea waste in bioremediation.