2025 Volume 23 Issue 3 Pages 179-193
Possible salt-accumulating plant species were investigated for their potential in phytoremediation of the salinised farmland in the Karakalpakstan region, Uzbekistan, together with its methane fermentation for the post-treatment of biomass. The examined plant species of Amaranthus retroflexus, Atriplex nitens, Bassia scoparia, and Karelina caspia yielded the highest biomass at the end of August, whilst high salt uptake was found during their young stage in spring. Based on the biomass weight per plant, the salt content, and the cultivation density, A. nitens was the most promising species, which might remove the salt from the soil with about 1.8 kg-NaCl equivalent/kg-dry soil in the peak period. The result suggested the consecutive cultivation of the plant species for 3–6 years would rehabilitate the farmland to allow growth of wheat, sunflower, and sorghum. The kinetic model modified from IWA-Anaerobic Digestion Model No.1 (ADM1) showed the above four plant species had a similar biodegradability to that of the ordinary energy crop (Erianthus arundinaceus). The model predicted 60–70% of the biomass chemical oxygen demand (COD) could be converted to methane at an solids retention time (SRT) of about 50–60 days in an anaerobic digester. When the SRT was extended to 200 days, the methane conversion efficiencies were expected to reach about 80%.
