Organic neem compounds inhibit soft-rot fungal growth and improve the strength of anthracite bricks bound with collagen and lignin for use in iron foundry cupolas

Aims: To examine organic neem compounds for their effective growth inhibition of saprotrophic soft-rot fungi on anthracite bricks bound with collagen and lignin for use in iron foundry cupolas as an alternative fuel source. Methods and Results: Azadirachtin, crude neem oil (NO), and clarified neem oil extract (CNO) were combined with copper to inhibit the growth of the soft-rot fungus, Chaetomium globosum. A synergistic interaction was observed between CNO and a low dose of copper on nutrient media (two-factor anova with triplicate replication: P < 0·05). Interaction was confirmed on lab-scale collagen-lignin-anthracite briquettes by measuring their unconfined compressive (UC) strength. The effective collagen strength of the briquettes was enhanced by applying CNO to their surface prior to inoculation: the room temperature UC strength of the briquettes was 28 ± 4·6% greater when CNO (0·4 mg cm^-2) was surface-applied, and was 43 ± 3·0% greater when CNO plus copper (0·14 μg cm^-2) were surface-applied. Conclusion: Surface application of CNO and copper synergistically prevents fungal growth on bindered anthracite briquettes and increases their room temperature strength. Significance and Impact of the Study: This novel organic fungicidal treatment may increase the storage and performance of anthracite bricks in iron foundries, thereby saving 15-20% of the energy used in conventional coke production.