水热预处理对餐厨垃圾厌氧发酵产戊酸的影响

Effectiveness of hydrothermal pretreatment on valeric acid production during food waste fermentation

目前,厌氧发酵产戊酸受限于其产率低,且利用餐厨垃圾产戊酸的研究少有报道。水热预处理因其可以促进底物的溶出和水解,并且无需使用化学试剂及具有操作简单等优点而受到广泛的关注。本文研究了不同水热预处理温度下,分别接种酒曲和剩余污泥对餐厨垃圾厌氧发酵产戊酸的影响。结果表明:最佳水热预处理条件(180℃)下,戊酸产量分别可达16.19g COD/L(酒曲组)和18.55g COD/L(剩余污泥组),相比空白组提高了3.66倍和0.74倍,显著提高发酵产戊酸效率。通过代谢分析发现:水热预处理可提高丙酸的产量,为发酵产戊酸提供充足的底物;此外,水热预处理有效调控厌氧发酵底物醇酸比,削弱戊酸产庚酸的转换途径,实现了戊酸的积累。微生物群落分析发现:水热预处理可提高产戊酸功能菌巨球菌属(Megasphaera)和小类杆菌属(Dialister)的相对丰度,酒曲空白组无产戊酸功能菌的富集,水热预处理(180℃)后,Megasphaera和Dialister的相对丰度可达13.77%和2.26%;剩余污泥空白组Megasphaera的相对丰度为6.21%,水热预处理(180℃)后,Megasphaera的相对丰度增加至9.35%。

The production of valeric acid from anaerobic fermentation is currently limited by its low yield,and few studies have been reported on its production from food waste.Hydrothermal pretreatment has attracted widespread attention because it can promote the dissolution and hydrolysis of substrates,does not require the use of chemical reagents,and is simple to operate.In this paper,we investigated the effect of different hydrothermal pretreatment temperatures on the production of valeric acid during food waste fermentation inoculated with distiller yeast(DY)and waste activated sludge(WAS),respectively.The results showed that the yield of valeric acid could reach 16.19g COD/L(DY)and 18.55g COD/L(WAS)under the optimal hydrothermal pretreatment conditions(180°C),which were 3.66 times and 0.74 times higher than those of the blank group,significantly improving the valeric acid production.The metabolic analysis revealed that the hydrothermal pretreatment could increase the production of propionic acid and thus provide sufficient substrate for the production of valeric acid.In addition,the hydrothermal pretreatment effectively regulated the alcohol to acid ratio of the anaerobic fermentation substrate,and weakened the conversion pathway of valeric acid to heptanoic acid,thus leading to the higher accumulation of valeric acid.Microbial community analysis revealed that hydrothermal pretreatment increased the relative abundance of functional valeric acid-producing bacteria including Megasphaera and Dialister.It should be noted that there was no enrichment of functional valeric acid-producing bacteria in the DY-B group,while the relative abundance of Megasphaera and Dialister could reach 13.77%and 2.26%after hydrothermal pretreatment(180℃).Moreover,the relative abundance of Megasphaera in the WAS group was 6.21%and increased to 9.35%after hydrothermal pretreatment(180℃).