This research proposes and demonstrates, for the first time, the utilization of swine manure as a complex feedstock to produce high-value medium chain fatty acids (MCFA). The two-stage anaerobic digestion (AD) carboxylates platform was adopted for the conversion of swine manure to short chain fatty acids (SCFAs) and then SCFAs to MCFA (n-caproate, n-heptanoate, and n-caprylate) with ethanol supplementation. We defined the appropriate initial pH of 10.0 for SCFAs production with a carbon conversion rate of 71.2%, and acetate, propionate were the main products, which accounted for around 72.9% of the total SCFAs in the primary stage (I). Through the addition of ethanol, 61.3% of the converted carbon in the complex SCFAs solution was converted into MCFA (C6-C8) in the chain elongation stage (II), while only 6.7% was attributed to methane formation. The concentrations of n-caproate, n-heptanoate, and n-caprylate reached 8.6 g COD/L (3.9 g/L), 6.4 g COD/L (2.7 g/L), and 2.6 g COD/L (1.07 g/L), respectively. This study achieved a relatively higher concentration of n-heptanoate compared with past studies of MCFA from other feedstock. These findings demonstrated a new route for resource recovery and the operating parameters for producing MCFA from swine manure.

这项研究提出并首次证明了利用猪粪作为一种复杂的原料来生产高价值的中链脂肪酸（MCFA）。采用两阶段厌氧消化（AD）羧酸盐平台将猪粪转化为短链脂肪酸（SCFA），然后再将SCFA转化为MCFA（正己酸，正庚酸和正己酸）。辛酸）补充乙醇。我们定义了适合SCFA生产的初始pH值为10.0，碳转化率为71.2％，并且乙酸盐，丙酸酯是主要产品，在初级阶段（I）约占SCFA总量的72.9％。通过添加乙醇，复杂的SCFAs溶液中61.3％的转化碳在链延长阶段（II）中转化为MCFA（C6-C8），而只有6.7％归因于甲烷的形成。的浓度Ñ -caproate，Ñ -heptanoate和Ñ -caprylate达到8.6克COD / L（3.9克/升），6.4克COD / L（2.7克/升），和2.6g COD / L（1.07克/ L）。这项研究取得了相对较高的n浓度-庚酸酯与以往对其他原料的MCFA的研究相比。这些发现证明了一种新的资源回收途径以及从猪粪中生产MCFA的操作参数。