Department of Urban Water Management, Technical University of Berlin, Gustav-Meyer-Allee 25, 13355, Berlin, Germany; Berlin Centre of Competence for Water, Cicerostrasse 24, 10709, Berlin, Germany.
Department of Urban Water Management, Technical University of Berlin, Gustav-Meyer-Allee 25, 13355, Berlin, Germany.
Water Res. 2020 Sep 1;182:115910. doi: 10.1016/j.watres.2020.115910. Epub 2020 May 22.
Thermal alkaline pretreatment (TAP) of waste activate sludge (WAS) was carried out in pilot-scale over a year to investigate its seasonal effects on anaerobic digestion and its impact on dewaterability, sludge liquor quality and formation of soluble refractory COD (sCOD). Temperature of TAP was set at 65-70 °C and pH was increased by initial dosing of sodium hydroxide [NaOH] (50% w/w, 1-2.5 mL/L sludge) as alkali agent following 2-2.5 h reaction time. Pilot digesters were fed with primary sludge (PS) and hydrolyzed WAS (HWAS) and compared to a reference digester fed with PS and untreated WAS. Biogas yield increase due to TAP of WAS showed a sinusoidal trend throughout the year with maximum in summer (+42%), minimum in winter (+3%) and average of +20%, indicating a strong seasonal effect on TAP efficiency. Ammonium [NH-N], orthophosphate [PO-P] and sulphate [SO] in sludge liquor increased by 34.6%, 17.0% and 21.6% with TAP, respectively. Centrifugation tests showed no significant difference in dewaterability of both digestates with respect to total solids of sludge cake. Normalized capillary suction time of digestate increased due to TAP, indicating a lower capability for water release. Furthermore, detected sCOD after batch aerobic biodegradation tests showed an increase of 30.3% with TAP. Hence, implementation of TAP of WAS in full-scale will potentially lead to an increase of 0.8-1.1 mg/L of sCOD in effluent of six wastewater treatment plants (WWTP) in Berlin. In conclusion, TAP of WAS leads to increase in biogas production with a slighter negative impact on effluent COD quality than high-temperature thermal hydrolysis.
对废物活性污泥（WAS）进行了为期一年的中试规模的热碱性预处理（TAP），以研究其对厌氧消化的季节性影响及其对脱水性能、污泥液质量和可溶性难降解 COD（sCOD）形成的影响。TAP 的温度设定在 65-70°C，通过初始投加氢氧化钠[NaOH]（50%w/w，1-2.5mL/L 污泥）作为碱剂来提高 pH 值，并在 2-2.5h 的反应时间后进行。中试消化器中进料为初沉污泥（PS）和水解 WAS（HWAS），并与进料为 PS 和未经处理 WAS 的参考消化器进行了比较。由于 WAS 的 TAP，沼气产量增加呈现出全年正弦趋势，夏季最高（增加 42%），冬季最低（增加 3%），平均增加 20%，表明 TAP 效率具有很强的季节性影响。污泥液中的铵[NH-N]、正磷酸盐[PO-P]和硫酸盐[SO]分别增加了 34.6%、17.0%和 21.6%。离心试验表明，对于污泥饼的总固体，两种消化物的脱水性能没有显著差异。由于 TAP，消化物的归一化毛细抽吸时间增加，表明水释放能力降低。此外，在批量好氧生物降解试验中检测到 sCOD 增加了 30.3%。因此，在柏林的六个污水处理厂（WWTP）中，实施 WAS 的 TAP 可能会导致出水中的 sCOD 增加 0.8-1.1mg/L。总之，与高温热水解相比，WAS 的 TAP 导致沼气产量增加，对出水 COD 质量的负面影响较小。
