Characterization and valorization of incinerated distillery spent wash ash with sugarcane bagasse: An environmental perspective

Distilleries that use sugarcane molasses are among the most polluting industries in India. Many of these distilleries have recently adopted zero liquid discharge (ZLD) practices by incinerating distillery spent wash, which produces a large amount of incinerated ash as solid waste. This distillery's spent wash ash is often applied to agricultural practices as a source of potash without considering its other physicochemical properties. Therefore, the primary aim of this study is to characterize the incinerated spent wash ash to identify its organic and inorganic constituents for potential sustainable development applications while avoiding adverse effects on soil. The complete analysis of the ash revealed an alkaline pH of 9.50 ± 0.85, along with various salts and heavy metals, such as iron, nickel, and chromium (ranging from 2335.21 to 2363.00 mg/kg), as well as nitrogen (10400-11312 mg/kg) and potassium (11314.80-13550.00 mg/kg). Additionally, organic compounds like 2,4-dimethylbenzene and dichloroacetic acid, which are toxic and potentially carcinogenic, were detected. Seed germination tests using Vigna radiata showed that even at low concentrations (2%), the ash inhibited growth, with radicles being more negatively affected than plumules. These findings confirm that fresh incinerated ash is highly toxic and unsuitable for direct agricultural use. The study recommends proper optimization through composting or other degradation techniques to detoxify the ash before disposal, thereby contributing to sustainable waste management practices.