Kurita Water Industries Ltd., Kawada, Nogi, Tochigi, Japan.
Water Sci Technol. 2011;63(7):1467-75. doi: 10.2166/wst.2011.382.
A novel process scheme was developed to achieve economically feasible energy recovery from anaerobic digestion. The new process scheme employs a hybrid configuration of mesophilic and thermophilic anaerobic digestion with sludge ozonation: the ozonated sludge is first degraded in a thermophilic digester and then further degraded in a mesophilic digester. In small-scale pilot experiments of the new process scheme, degradation of VSS improved by 3.5% over the control (mesophilic-only configuration) with 20% less ozone consumption. Moreover, biogas conversion also improved by 7.1% over the control. Selective enrichment of inorganic compounds during centrifugation produced a dewatered sludge cake with very low water content (59.4%). This low water content in the sludge cake improved its auto-thermal combustion potential during incineration and added to the overall energy savings. We conducted a case study to evaluate power generation from biogas for a municipal wastewater treatment plant with an average dry weather flow of 43,000 m3/d. Electricity production cost was 5.2 ¢/kWh for the advanced process with power generation, which is lower than the current market price of 7.2 ¢/kWh. The new anaerobic digestion scheme with power generation may reduce greenhouse gas emissions by about 1,000 t-CO(2)/year compared with the conventional process without power generation.
开发了一种新颖的工艺方案，以实现从厌氧消化中获得经济可行的能量回收。新工艺方案采用中温和高温厌氧消化与污泥臭氧化的混合配置：臭氧化污泥首先在高温消化器中降解，然后在中温消化器中进一步降解。在新工艺方案的小型中试实验中，与仅采用中温配置的对照相比，VSS 降解提高了 3.5%，臭氧消耗减少了 20%。此外，沼气转化率也比对照提高了 7.1%。在离心过程中选择性富集无机化合物产生了水含量非常低（59.4%）的脱水污泥饼。污泥饼中的低水分含量提高了其在焚烧过程中的自热燃烧潜力，并有助于节省整体能源。我们进行了一项案例研究，以评估具有平均旱季流量为 43,000 m3/d 的城市污水处理厂的沼气发电。具有发电功能的先进工艺的电力生产成本为 5.2 美分/千瓦时，低于目前 7.2 美分/千瓦时的市场价格。与不发电的传统工艺相比，新型带有发电功能的厌氧消化方案每年可减少约 1,000 吨二氧化碳当量的温室气体排放。
