Converting wastewater sludge to lipid is considered as one of the best strategies of sludge management. The current problem of lipid production from wastewater sludge is the low yield (0.10–0.16 g lipid/g dry sludge) due to the low availability of easily uptaken materials (such as soluble monosaccharide and oligosaccharide) in sludge to oleaginous microorganism (Rhodotorula glutinis, Trichosporon oleaginosus, Lipomyces starkeyi). Pretreatments are efficient methods to improve sludge bioavailability. This study is aimed to achieve high lipid production from sludge and high sludge reduction. In this study, it was observed that the soluble chemical oxygen demand (SCOD) had significantly increased after different pretreatment. The SCOD in the supernatant was increased from 32.64 to 180.25 mg/L, 924.16 mg/L, 1029.89 mg/L and 3708.31 mg/L after acidic (pH 2 for 2 h), alkaline (pH 12 for 2 h), microwave irradiation (15 min with 5 min interval), and ultrasonication (30 min at 450 W and 20 kHz frequency with 5 s on and 2 s off mode) pretreatment, respectively. Pretreatments have also increased the release of total nitrogen (TN) and total phosphorus (TP) from solids. The sludge after different pretreatments were used as a medium for lipid production, and the highest lipid content (36.67% g/g) was obtained in the fermentation with ultrasonication pretreatment sludge, and the sludge reduction was 63.10%. For other pretreatments, the lipid content and sludge reduction were 18.42% and 32.63% in acid pretreatment case, 21.08% and 36.44% in alkaline pretreatment case, and 26.31% and 43.03% in microwave pretreatment case, respectively. It was found that ultrasonication pretreatment was the most efficient way to increase the sludge biodegradability (SCOD) and to release TN and TP from solid phase to liquid phase. Pretreated sludge for lipid production achieved significant improvement in lipid yield and sludge reduction. Lipids produced from pretreated sludge were transesterified to biodiesel and the analysis showed that biodiesel had a similar composition as commercial biodiesel. The study reveals that pretreatment on sludge is a promising method for enhancing biological sludge management efficiency.

中文翻译：

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在脂质生产中增强污水污泥减少和再利用的预处理

将废水污泥转化为脂质被认为是污泥管理的最佳策略之一。当前废水污泥生产脂质的问题是产量低（0.10–0.16 g脂质/ g干污泥），这是由于污泥中易摄取的材料（例如可溶性单糖和寡糖）对油性微生物（Rhodotorula glutinis， Trichosporon oleaginosus，Lipomyces starkeyi）。预处理是提高污泥生物利用度的有效方法。这项研究旨在实现污泥的高脂质生产和污泥的大量减少。在这项研究中，观察到不同的预处理后可溶性化学需氧量（SCOD）显着增加。上清液中的SCOD从32.64增加到180.25 mg / L，924.16 mg / L，1029.89 mg / L和3708。酸性（pH 2持续2 h），碱性（pH 12持续2 h），微波辐射（15分钟，间隔5分钟）和超声处理（450 W和20 kHz频率30分钟，持续5 s）后为31 mg / L和2 s off模式）预处理。预处理还增加了固体中总氮（TN）和总磷（TP）的释放。将经过不同预处理的污泥用作产脂质的介质，在超声预处理污泥的发酵中获得最高的脂质含量（36.67％g / g），污泥减少率为63.10％。对于其他预处理，在酸预处理情况下，脂质含量和污泥减少分别为18.42％和32.63％，在碱性预处理情况下分别为21.08％和36.44％，在微波预处理情况下分别为26.31％和43.03％。发现超声预处理是增加污泥生物降解能力（SCOD）和从固相到液相释放TN和TP的最有效方法。用于脂质生产的预处理污泥在脂质产量和污泥减少方面实现了显着改善。由预处理的污泥产生的脂质被酯交换为生物柴油，分析表明生物柴油的成分与市售生物柴油相似。研究表明，对污泥进行预处理是提高生物污泥管理效率的一种有前途的方法。由预处理的污泥产生的脂质被酯交换为生物柴油，分析表明生物柴油的成分与市售生物柴油相似。研究表明，对污泥进行预处理是提高生物污泥管理效率的一种有前途的方法。由预处理的污泥产生的脂质被酯交换为生物柴油，分析表明生物柴油的成分与市售生物柴油相似。研究表明，对污泥进行预处理是提高生物污泥管理效率的一种有前途的方法。