Impact of bottom ash addition on Pleurotus ostreatus cultivation on coffee ground substrate

The study aimed to explore the potential use of coal-fired power plant bottom ashes in Pleurotus ostreatus cultivation using spent coffee grounds. The study analyzed five compositions of growth substrate for mushrooms: pure coffee grounds (I) as a control sample; coffee grounds substrate with the addition of 1% (II); 5% (III); 10% (IV) bottom ash; and bottom ash alone (V). The study revealed that compared to the control sample (I), the addition of 1% bottom ash (II) did not affect the time of mycelium growth but slowed fruiting body growth by 4 days. With 5% addition (III), mycelium growth slowed by 6 days, and fruiting body growth by 7 days. At 10% (IV), growth was completely inhibited. Compared to sample (I), fruiting bodies grown on sample (II) had higher phosphorus, copper, and zinc accumulation, while chromium, nickel, and lead levels were lower in fruiting bodies grown on samples (II) and (III). Additionally, fruiting bodies grown on samples (II) and (III) contained less iron, silicon, selenium, aluminum, calcium, and magnesium. The results presented in the article regarding the levels of contamination in the cultivated mushrooms and in the substrate after cultivation, indicate the potential for their further management.