利用剩余污泥水解酸化液合成聚羟基脂肪酸酯的研究

以城市污水处理厂剩余污泥水解酸化产物为原料,研究了罗氏真养菌(Ralstonia eutropha)H16在水解酸化液中的生长规律和聚羟基脂肪酸酯(PHAs)积累特性,同时分析了H16对水解酸化液中各种有机酸组分的利用规律. 结果表明,以剩余污泥52℃中温水解酸化48h的水解酸化液为培养基,在HAc水解酸化液(C/N/P=100/10/1, TOC＝2881mg/L,乙酸占总有机酸含量36.1%)中,H16最先利用乙酸和正丁酸来进行自身的生长和PHAs的合成,合成的主要产物是聚羟基丁酸酯(PHB);随后开始利用丙酸和正戊酸,在此过程中聚羟基戊酸酯(PHV)的含量也逐步上升,菌体量同步增长, H16在40h左右处于平稳期,并且达到最大积累率为12.51%(占菌体干重);最后利用的是异丁酸和异戊酸,但是此时H16已经进入衰亡期,菌体量和PHAs合成率都在下降.当以HVa水解酸化液(C/N/P=100/10/1, TOC＝2358mg/L,异戊酸占总有机酸含量29.0%)为培养基时, H16在18h达到生长的峰值,24h达到PHAs合成率的最大值为32.14%(占菌体干重),PHV为PHAs的主要形式.

Polyhydroxyalkanoates production by Ralstonia eutropha H16 fed by waste sludge anaerobic fermentative liquid

Polyhydroxyalkanoates (PHAs) accumulation and carbon consumption by Ralstonia eutropha H16 were investigated in anaerobic fermentative liquid (AFL) of waste activated sludge (WAS). The WAS was fermented at 52℃ with a sludge retention time (SRT) of 48 hours in hydrolysis reactor to form AFL, in which the volatile fatty acids(VFAs) were feasible carbon source for PHAs synthesis. When acetic acid was the predominant component of VFAs in the AFL (C/N/P≈100/10/1,TOC＝2881mg/L, acetic acid/total VFAs=36.1%), R. eutropha H16 could utilize acetic acid and n-butyric prior to other VFAs for cell growth and PHAs synthesis, and the major monomer of PHAs was hydroxybutyrate (HB). Propionic and n-valeric acid were utilized at 20~40 hours after inoculation as hydroxyvalerate (HV) monomer content increasing. The maximum PHAs content detected in the cells was 12.51% (dry weight) after 40-hour reaction, and then iso-butyric and iso-valeric acid were utilized but both PHAs synthesis and cell growth decreased. When iso-valeric acid was the predominant VFA in the AFL (C/N/P≈100/10/1, TOC＝2358mg/L, iso-valeric acid/total VFAs=29.0%), the maximum PHAs content detected in the cells was up to 32.14% (dry weight) at 24-hour of growth and hydroxyvalerate (HV) was the major monomer of PHAs.