Delignification of straw with ozone to enhance biodegradability

Summary Wheat straw was treated with ozone to remove the lignin and increase its biodegradability. The attack of ozone on straw is not selective. Lignin and carbohydrates are oxidized concurrently though the rate of reaction with the latter is slower. A 50% reduction of the original lignin content is optimal for enzymatic hydrolysis. After treatment, 75% of the cellulose in straw is degraded within 24 h as compared to 20% in untreated straw. During ozonation lignin is converted to soluble products which to a great extent are biodegradable and thus yield a useful byproduct. At the moment, ozonation ranks among the more expensive methods of treatment. However, the economics may be improved by reducing the cost of ozone production; this is likely to take place in the near future due to technological improvements, and by reducing the ozone consumption by optimizing the process of ozonation.