In-situ alkaline enhanced two-stage anaerobic digestion system for waste cooking oil and sewage sludge co-digestion.

Anaerobic digestion is a promising way for resource recovery from waste cooking oil (WCO) due to its high bio-methanation potential. In-situ mild alkaline (pH 8) enhanced two-stage continuous stirred tank reactors (ALK-2-CSTRs) were implemented to explore its efficiency in co-digesting WCO and sewage sludge with stepwise increase of WCO in the co-substrates. Results demonstrate that the ALK-2-CSTRs effectively promoted methane yield from the co-substrates via promoting hydrolysis, long chain fatty acids (LCFAs) degradation and protecting methanogens from exposure to high concentration of LCFAs directly.

The role of methanogens in acetic acid production under different salinity conditions.

In this study, a fed-batch acidogenic reactor was operated at a 3 d hydraulic retention time (HRT) and fed with alkaline pre-treated sludge to investigate salinity effects on methanogens' abundance, activities and their consumption of produced acetic acid (HAc) and total volatile fatty acids (VFAs). The salinity concentration was increased step-wise by adding sodium chloride. At 3‰ (parts per thousand) salinity, the average produced volatile fatty acids (VFAs) concentration was 2410.

Impact of undissociated volatile fatty acids on acidogenesis in a two-phase anaerobic system.

This study investigated the degradation and production of volatile fatty acids (VFAs) in the acidogenic phase reactor of a two-phase anaerobic system. 20 mmol/L bromoethanesulfonic acid (BESA) was used to inhibit acidogenic methanogens (which were present in the acidogenic phase reactor) from degrading VFAs. The impact of undissociated volatile fatty acids (unVFAs) on "net" VFAs production in the acidogenic phase reactor was then evaluated, with the exclusion of concurrent VFAs degradation.

Acetic acid effects on methanogens in the second stage of a two-stage anaerobic system.

This study reports on biomass tolerance towards high concentrations of acetic acid (HAc) within the system. Biomass from the second stage of a two-stage anaerobic sludge digestion system was used for this study. Microbial community analysis by 454 pyrosequencing highlighted hydrogenotrophic Methanomicrobiales was the predominant archaeal population in the second stage (>99% of the total archaeal community).

Determination of the archaeal and bacterial communities in two-phase and single-stage anaerobic systems by 454 pyrosequencing.

2-Phase anaerobic digestion (AD), where the acidogenic phase was operated at 2day hydraulic retention time (HRT) and the methanogenic phase at 10days HRT, had been evaluated to determine if it could provide higher organic reduction and methane production than the conventional single-stage AD (also operated at 12days HRT). 454 pyrosequencing was performed to determine and compare the microbial communities. The acidogenic reactor of the 2-phase system yielded a unique bacterial community of the lowest richness and diversity, while bacterial profiles of the methanogenic reactor closely followed the single-stage reactor.

The effect of pH on solubilization of organic matter and microbial community structures in sludge fermentation.

Sludge fermentation between pH 4 and 11 was investigated to generate volatile fatty acids (VFA). Despite the highest sludge solubilization of 25.9% at pH 11, VFA accumulation was optimized at pH 8 (12.

Dynamics of propionic acid degradation in a two-phase anaerobic system.

This paper reports on propionic acid (HPr) degradation in a laboratory scale two-phase anaerobic system, where HPr was accumulated in the acidogenic reactor and degraded in the methanogenic reactor. Batch tests using biomass from the two-phase anaerobic system showed HPr degradation was rarely detectable in the acidogenic reactor when HPr concentration ranged from 639 to 4531mgHPrL(-1) and at pH 4.50 to 6.

Comparison of single-stage and two-phase anaerobic sludge digestion systems - Performance and microbial community dynamics.

This study compared reactor performance and the respective microbial community dynamics in the conventional single-stage and 2-phase anaerobic digestion (AD) systems, treating municipal sludge to generate methane. The 2-phase system's COD and VS reduction, and methane production could be maintained throughout the three HRTs tested (p=0.05), which was associated with an increase in organic loading (30d=1.

In vivo self-assembly of fluorescent protein microparticles displaying specific binding domains.

In this study, fluorescent proteins (FPs) were engineered to self-assemble into protein particles inside recombinant Escherichia coli while mediating the display of various protein functionalities such as maltose binding protein or IgG binding domains of Protein A or G, respectively. Escherichia coli produced functional FP particles of up to 30% of cellular dry weight. The use of respective FP particles displaying certain binding domains in diagnostics and as bioseparation resins was demonstrated by direct comparison to commercial offerings.