Anaerobic fermentation is considered as a cost-effective way of biomass waste disposal. Chromium (Cr) is one of the heavy metals that often been blamed for unsatisfactory operation or failure of anaerobic fermentation. The impact of Cr (added as K₂Cr₂O₇) on mesophilic anaerobic fermentation of Phragmites australis straw and cow dung was demonstrated by investigating the biogas properties, process stability, substrate degradation and enzyme activities during the fermentation process. The results showed that 30, 100 and 500 mg/L Cr⁶⁺ addition increased the cumulative biogas yields by up to 19.00%, 14.85% and 7.68% respectively, and brought forward the daily biogas yield peak. Meanwhile, the methane (CH₄) content in the 30 (52.47%) and 100 (40.57%) mg/L Cr⁶⁺-added groups were generally higher than the control group (37.70%). Higher pH values (close to pH 7) and lower oxidation-reduction potential (ORP) values in the Cr⁶⁺-added groups after the 15th day indicated the better process stability compared to the control group. Taking the whole fermentation process into account, the promoting effect of Cr⁶⁺ addition on biogas yields was mainly attributable to better process stability, the enhanced degradation of lignin and hemicellulose, the transformation of intermediates into VFA, the higher coenzyme F₄₂₀ activities and the efficient generation of CH₄. These results demonstrate that an appropriate addition of Cr⁶⁺ could enhance the anaerobic fermentation which support the regulations utilizing of the Cr⁶⁺ contaminated biowaste.

厌氧发酵被认为是处理生物质废物的一种经济有效的方式。铬（Cr）是经常因操作不当或厌氧发酵失败而引起的重金属之一。通过研究发酵过程中的沼气特性，工艺稳定性，底物降解和酶活性，证明了Cr（以K ₂ Cr ₂ O _{7的形式添加}）对芦苇秸秆和牛粪的中温厌氧发酵的影响。结果表明，添加^30、100和500 mg / L Cr ⁶⁺可使累计沼气产量分别增加19.00％，14.85％和7.68％，并推动了每日沼气产量峰值。同时，甲烷（CH₄）的Cr ⁶⁺添加量为30（52.47％）和100（40.57％）mg / L组中的含量通常高于对照组（37.70％）。在第15天后，添加Cr ^6+的组中较高的pH值（接近pH 7）和较低的氧化还原电位（ORP）值表明，与对照组相比，工艺稳定性更好。考虑到整个发酵过程，添加Cr ⁶⁺对沼气产量的促进作用主要归因于更好的过程稳定性，增强的木质素和半纤维素降解，中间体向VFA的转化，较高的辅酶F ₄₂₀活性和有效生成CH ₄。这些结果表明，适当添加Cr ⁶⁺可以增强厌氧发酵，这支持了利用Cr ⁶⁺污染的生物废物的法规。