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Impact of Bottom Ash Addition on Pleurotus ostreatus Cultivation on Coffee Ground Substrate

Summary

This research explored using coal power plant waste (bottom ash) combined with spent coffee grounds to grow oyster mushrooms. The study found that small amounts of bottom ash (1-5%) could be safely used in mushroom cultivation while potentially improving certain nutrient levels in the mushrooms. This has several practical implications for everyday life: • Provides a new way to recycle both coffee waste and industrial ash waste • Could help create more sustainable and cost-effective mushroom cultivation methods • Offers potential solutions for improving poor quality soils using post-cultivation substrate • Demonstrates how waste materials can be transformed into valuable resources • Could lead to more environmentally friendly waste management practices in both industrial and agricultural sectors

Background

The Pleurotus species is the second most widely grown edible mushroom genus after Agaricus species. It can be grown on various waste materials including agro-industrial, food, and cellulose waste. Spent coffee grounds are already being used as suitable substrates for cultivating Pleurotus ostreatus in coffee-producing countries. Additionally, the disposal and accumulation of coal ashes in the environment is a concern, particularly from electricity generation. Bottom ash is a byproduct containing high concentrations of heavy metals and salts that requires safe disposal methods.

Objective

The study aimed to explore the potential use of coal-fired power plant bottom ashes in Pleurotus ostreatus cultivation using spent coffee grounds. The research sought to evaluate the accumulation of heavy elements in mushrooms grown on substrate with added bottom ash and assess the viability of using bottom ash as an additive in edible mushroom cultivation.

Results

Compared to the control sample, the addition of 1% bottom ash did not affect mycelium growth time but delayed fruiting body growth by 4 days. With 5% addition, mycelium growth slowed by 6 days and fruiting body growth by 7 days. At 10% concentration, growth was completely inhibited. Mushrooms grown on 1% bottom ash substrate showed higher accumulation of phosphorus, copper, and zinc, while maintaining lower levels of chromium, nickel, and lead compared to those grown on pure coffee grounds. Fruiting bodies grown on 1% and 5% bottom ash substrates contained less iron, silicon, selenium, aluminum, calcium, and magnesium.

Conclusion

The study demonstrates promising potential for managing both cultivated mushrooms and post-cultivation substrate. Mushrooms grown with 1-5% bottom ash showed improved nutrient profiles while maintaining lower heavy metal content. The post-cultivation substrate, particularly with low percentages of bottom ash, could potentially serve as soil amendments or fertilizers. The optimal bottom ash addition rate appears to be between 1-5%, though further safety testing is needed before broader implementation.
  • Published in:Scientific Reports,
  • Study Type:Experimental Research,
  • Source: 10.1038/s41598-024-83434-z
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