Kinetics study of fermentative hydrogen production from liquid swine manure supplemented with glucose under controlled pH

Kinetics of H₂ production from liquid swine manure supplemented with glucose by mixed anaerobic cultures was investigated using batch experiments under four different pH conditions (4.4, 5.0, 5.6, and uncontrolled). The temperature for the experiments was controlled at 37 ± 1°C and the length of experiments varied between 50 and 120 hours, depending upon the time needed for completion of each individual experiment. The modified Gompertz model was evaluated for its suitability for describing the H₂ production potential, H₂ production rate, and substrate consumption rate for all the experiments. The results showed that the Gompertz model could adequately fit the experimental results. The effect of pH was significant on all kinetic parameters for H₂ production including yield, production rate and lag time, and the substrate utilization rate. The optimal pH was found to be 5.0, at which a maximum H₂ production rate (0.64 L H₂/h) was obtained, and deviation from the optimal pH could result in substantial reductions in H₂ production rate (0.32 L H₂/h for pH 4.0 and 0.43 L H₂/h for pH 5.6). The results also showed that if pH was not controlled for the batch fermentation process, the substrate utilization efficiency could steeply decrease from 98.8% to 33.7%.     

Energy efficacy used to score organic refuse pretreatment processes for hydrogen anaerobic production

The production of hydrogen through Anaerobic Digestion (AD) has been investigated to verify the efficacy of several pretreatment processes. Three types of waste with different carbon structures have been tested to obtain an extensive representation of the behavior of the materials present in Organic Waste (OW). The following types of waste were selected: Sweet Product Residue (SPR), i.e., confectionary residue removed from the market after the expiration date, Organic Waste Market (OWM) refuse from a local fruit and vegetable market, and Coffee Seed Skin (CSS) waste from a coffee production plant. Several pretreatment processes have been applied, including physical, chemical, thermal, and ultrasonic processes and a combination of these processes. Two methods have been used for the SPR to remove the packaging, manual (SPR) and mechanical (SPRex). A pilot plant that is able to extrude the refuse to 200 atm was utilized. Two parameters have been used to score the different pretreatment processes: efficiency (ξ), which takes into account the amount of energy produced in the form of hydrogen compared with the available energy embedded in the refuse, and efficacy (η), which compares the efficiency obtained using the pretreated refuse with that obtained using the untreated refuse. The best result obtained for the SPR was the basic pretreatment, with η = 6.4, whereas the thermal basic pretreatment gave the highest value, η = 17.0 for SPRex. The best result for the OWM was obtained through a combination of basic/thermal pretreatments with η = 9.9; lastly, the CSS residue with ultrasonic pretreatment produced the highest quantity of hydrogen, η = 5.2.     

餐厨垃圾厌氧产氢综述

针对餐厨垃圾厌氧产氢过程,从工艺、单组分底物厌氧产氢和过程机理研究阐述了国内外进展,并对未来研究发展方向进行了展望.研究成果表明,餐厨垃圾厌氧发酵产氢过程可行,但影响因素多,系统不稳定,大部分研究停留在实验室小试阶段.尚需针对餐厨垃圾厌氧发酵产氢优势菌种选育、生态因子调控、代谢机理、反应器改进和系统控制模拟等方面开展研究,为该技术的大规模应用提供研究基础.     

Biohydrogen production by Clostridium butyricum and Rhodopseudomonas palustris in Co-cultures

This study evaluated biohydrogen production by co-culture of Clostridium butyricum and Rhodopseudomonas palustris. C. butyricum and R. palustris were grown separately and together as batch cultures. Hydrogen production, growth, NH₄-N, total volatile fatty acid production, and sucrose degradation were monitored. The hydrogen production of the co-culture produced 562 ml, R. palustris 426 ml, and C. butyricum 333 ml. The co-culture produced 2.16 mol H₂/mol sucrose, C. butyricum and R. palustris produced 1.77 and 1.64 mol H₂/mol sucrose, respectively. The co-culture was more efficient in the hydrogen production. Therefore, the co-culture is a good method for biohydrogen fermentation.